Title of Invention

"A CARDIAC ASSIST DEVICE"

Abstract A cardiac assist device comprising: a cup configured to encompass, and to seal and conform to said heart from atrio-ventricular groove to apex throughout systolic and diastolic actuation by imposing negative pressure between said cup and said heart, said cup having a compliant exterior wall attached to a compliant interior liner forming a continuous annular cavity between said wall and said liner, wherein the liner comprises a tapered unbonded transition section reducing in thickness to a thin section forming the liner adjacent a liner portion attached to the wall; a drive system in closed fluid communication with said cavity to effect displacement of said cavity; a sensor measuring at least one parameter; and a control system in communication with said drive system and with said sensor. Fig. 10
Full Text The present invention relates to a cardiac assist device.
This invention relates in one embodiment to devices that assist a weak heart in providing the required pumping of blood, and more particularly to a mechanical cardiac assistance device which envelops the heart and applies periodic and focused hydraulic pressure waves to the heart in order to drive ventricular action (compression and expansion) in the proper sequence and intensity.
TECHNICAL FIELD
Mechanical devices that assist the human heart by providing proper systolic and diastolic actuation and circulatory function.
BACKGROUND ART
Traditional medical and surgical treatment of patients with failing pump function of the
heart is limited to blood-contacting devices which are technically difficult to install and result in
complications related to such blood contact as well as technical aspects of device installation.
Inadequate cardiac output remains a cause of millions of deaths annually in the United States.
Mechanical devices are proving to be a practical therapy for some forms of sub-acute and
chronic low cardiac output However, all currently available devices require too much time to
implant to be of value in acute resuscitation situations, resulting in loss of life before adequate
circulatory support can be provided. Furthermore, other non-blood contacting devices similar to
the current invention provide inadequate augmentation of cardiac function. Mechanical cardiac
assistance devices generally operate by providing blood pumping support to the circulation to
assist the failing heart.
A number of mechanical techniques for assisting heart function by compressing its outer
epicardial surface have been described and studied. These methods have focused on improving
cardiac performance by assisting the systolic (positive pumping) function of the heart. Such
techniques have been described as "direct cardiac compression" (DCC). DCC methods have
been investigated only in the laboratory setting, and there are no uses of such devices in human
subjects known to the applicants. Investigations regarding DCC have focused primarily on left
ventricular (LV) systolic and diastolic performance. Examples of DCC techniques include, but
are not limited to, cardiomyoplasty (the technique of wrapping skeletal muscle around the heart
and artificially stimulating it), the Cardio support system (Cardio Technologies, Inc., Pinebrook,

New Jersey) and the "Heart Booster" (Abiomed, Inc., Danvers, Massachusetts). Cumulative
results from laboratory investigations using these devices have all resulted in similar findings.
Specifically, DCC has been shown to enhance left ventricular (LV) pump function without any
apparent change in native LV oxygen consumption requirements; thereby, DCC has been shown
to improve LV pump function without increasing myocardial oxygen consumption and/or
requiring extra work from the heart.
DCC devices have been shown to only benefit hearts with substantial degrees of LV
failure. Specifically, DCC techniques only substantially improve the systolic function of hearts
in moderate to severe heart failure. In addition, the benefits of DCC techniques are greater
when applied to the relatively dilated or enlarged LV. Therefore the relative degree of
assistance provided by DCC improves as heart failure worsens and the heart enlarges or dilates
from such failure. DCC techniques clearly have a negative effect on diastolic function (both
RV and LV diastolic function). This is exhibited by reductions in diastolic volume that, in part,
explains DCC's inability to effectively augment the heart without at least moderate degrees of
failure. This also explains DCC's efficacy being limited to sufficient degrees of LV size and/or
dilatation, with significant dependence on preload, and/or ventricular filling pressures. Thus,
DCC requires an "adequate" degree of heart disease and/or heart failure to benefit the heart's
function. In addition, DCC devices have negative effects on the dynamics of diastolic
relaxation and, in effect, reduce the rate of diastolic pressure decay (negative dP/dt max),
increasing the time required for ventricular relaxation. This better explains why DCC
techniques require substantial degrees of LV and RV loading (i.e. increased left and right atrial
pressure or "preload") to be effective, as such increases serve to augment ventricular filling.
This latter point is particularly true with smaller heart size and/or less ventricular distension.
The critical drawbacks to DCC methods are multi-factorial and are, in part, summarized
in the following discussion. First, and foremost, these techniques do not provide any means to
augment diastolic function of the heart necessary to overcome their inherent drawback of
"effectively" increasing ventricular stiffness. This is illustrated by the leftward shifts in the enddiastolic
pressure-volume relationship (EDPVR) during DCC application. This effect on the
EDPVR is seen with DCC devices in either the assist or non-assist mode. Clearly, RV diastolic
function is impaired to a far greater degree by DCC due to the nature both the RV wall and
intra-cavity pressures. Furthermore, studies of DCC devices have all overlooked the relevant
and dependent impact these techniques have on right ventricular dynamics, septal motion and
overall cardiac function. Because the right ventricle is responsible for providing the "priming"
blood flow to the left ventricle, compromising right ventricular function has a necessary
secondary and negative impact on left ventricular pumping function when these load-dependent
devices are utilized. Furthermore, the ventricular septum lies between the right and left
ventricle and is directly affected by the relevant forces placed on both the RV and LV. Another
related and fundamental drawback to DCC devices is their inability to continuously monitor
ventricular wall motion and chamber dynamics that are intuitively critical to optimizing the
assist provided by such mechanical actions on the right and left ventricular chambers which
behave in an complex, inter-related fashion. Finally, studies regarding DCC methods have
failed to adequately examine the effects of these devices on myocardial integrity.
The Direct Mechanical Ventricular Assist device (hereinafter abbreviated as DMVA) is
an example of one type of mechanical cardiac assistance device. In general, a DMVA system
comprises two primary elements: (a) a Cup having dynamic characteristics and material
construction that keep the device's actuating liner membrane or diaphragm closely conformed
to the exterior surface (or epicardium) of the heart throughout systolic and diastolic actuation,
and (b) a Drive system and control system combination that cyclically applies hydraulic
pressure to a compression and expansion liner membrane or membranes located on the interior
surfaces of the Cup in a manner that augments the normal pressure and volume variations of the
heart during systolic and diastolic actuation. The cyclic action of the device cyclically pushes
and pulls on the left and right ventricles of the heart.
By providing this cyclic motion at the appropriate frequency and amplitude, the
weakened, failing, fibrillating, or asystolic heart is driven to pump blood in a manner which
approximates blood flow generated by a normally functioning heart. Pushing inwardly on the
exterior walls of the heart compresses the left and right ventricles into systolic configuration(s),
thereby improving pump function. As a result, blood is expelled from the ventricles into the
circulation. Immediately following each systolic actuation, the second phase of the cycle
applies negative pressure to the liner membrane to return the ventricular chambers to a diastolic
configuration by pulling on the outer walls of the heart. This is termed diastolic actuation and
allows the ventricular chambers to refill with blood for the next compression.
In the preferred embodiment of the present invention, the Cup is installed on the heart
typically by using apical vacuum assistance, i.e. vacuum applied to the apex of the Cup. Such a
preferred embodiment enables a non-traumatic and technically simple means of cardiac
attachment of the Cup device in the patient and facilitates diastolic actuation. To install the
Cup, the heart is exposed by a chest incision. The Cup is positioned over the apex of the heart
in a position such that the apex of the heart is partially inserted therein. A vacuum is applied to
the apex of the Cup, thereby pulling the heart and the Cup together, such that the apices of the '
Cup and the heart, and the inner wall of the Cup and the epicardial surface of the heart become
substantially attached. Connections are then completed for any additional sensing or
operational devices (typically integrated into a single interface cable) if the particular Cup
embodiment comprises such devices. This procedure can be accomplished in minutes, and it is
easy to teach to individuals with minimal surgical expertise.
Effective DMVA requires that the Cup and Drive system satisfy multiple and complex
performance requirements. Preferred embodiments of the Cup of the present invention satisfy
these critical performance requirements in a manner that is superior to prior art DMVA devices.
Heretofore, a number of patents and publications have disclosed Direct Mechanical
Ventricular Assist devices and other cardiac assistance devices, the relevant portions of which
may be briefly summarized as follows:
United States patent 2,826,193 to Vineberg discloses a Ventricular Assist device that is
held to the heart by a flexible draw-string. Vineberg uses a mechanical pump to supply systolic
pressure to the heart to assist the heart's pumping action.
United States patent 3,034,501 to Hewson discloses a similar Ventricular Assist device,
comprised of silastic, which permits varying pressures to be exerted on various portions of the
heart.
United States patent 3,053,249 to Smith discloses a Ventricular Assist device capable of
delivering systolic pressure to a heart. The Smith device utilizes adhesive straps to attach the
device to the heart.
United States patent 3,233,607 to Bolie illustrates a Direct Assist device that varies the
level of systolic pressure depending on the changes of blood flow occasioned by exercise. The
Bolie device claims to be fully implantable. United States patent 3,449,767 to Bolie discloses
system for controlling the pressure delivered to the balloons that control the DMVA unit.
United States patent 3,279,464 to Kline teaches a method of manufacture of a
Ventricular Assist device. Kline's device provides only systolic pressure to the heart.
United States patent 3,371,662 to Heid discloses a Ventricular Assist device in the form
of a cuff. The cuff may be implanted with defibrillating electrodes.
United States patent 3,376,863 to Kolobow illustrates a Ventricular Assist device that
delivers systolic pressure to the heart. The Kolobow device possesses an expandable collar
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about the periphery of the device's opening. The heart may be sealed within the device by
expanding the collar.
United States patent 3,455,298 of Anstadt discloses a Direct Mechanical Ventricular
Assist device capable of delivering both systolic and diastolic pressures. The diastolic action is
achieved by use of a vacuum. A second vacuum source functions to hold the device to the heart.
Anstadt further defines the geometry of the device in United States patent 5,199,804. The
geometry of the invention is described so as to accommodate hearts of various sizes as well as
prevent the heart from being expelled from the device during the systolic expansion of the
bladders.
United States patent 3,478,737 of Rassrnan discloses a Ventricular Assist device in the
form of a cuff.
United States patent 3,513,836 to Sausee discloses a Ventricular Assist device that
delivers systolic pressure to the heart by a multiplicity of bladders. Increasing the pressure in
selected bladders may preferentially pressure selected portions of the heart.
United States patent 3,587,567 to Schiff discloses a Direct Mechanical Ventricular
Assist device that is capable of delivering both systolic and diastolic pressures to a heart. The
device may further comprise electrodes that permit defibrillation of the heart. The device is
held to the heart by a mild vacuum pressure, which also supplies the diastolic action.
United States patent 3,613,672 to Schiff discloses a cup with a flexible outer shell that
allows for the insertion of the device through a relatively small surgical incision. The patent
also discloses the use of sensors, such as electrocardiogram equipment, in conjunction with the
cup. Additional reference may be had to United States patents 3,590,815 and 3,674,381 also to
Schiff.
United States patent 4,048,990 to Goetz discloses a Ventricular Assist device that
delivers both systolic and diastolic pressures to a heart. The outer shell of the Goetz device is
inflatable, so as to allow installation with minimal trauma to the patient.
United States patent 4,448,190 to Freeman discloses a Ventricular Assist device that
delivers systolic pressure to a heart by means of a strap physically attached to the heart. A
similar device is disclosed in United States patents 5,383,840 and 5,558,617 to Heilman. The
Heilman patent discloses the use of defibrillation devices and materials that promote tissue ingrowth
to assist in adhering the device to the heart.
United States patent 4,536,893 to Parravicini discloses a Ventricular Assist device in the
form of a cuff that applies pressure to selected portions of the heart. The patent also discloses
the use of sensors, such as an electrocardiograph, in conjunction with the cuff.
United States patent 4,621,617 to Sharma discloses a Ventricular Assist device wherein
the heart is disposed within two sheets of metal. An electromagnetic field draws the sheets
together, thus compressing the heart.
United States patent 4,684,143 to Snyders discloses a Ventricular Assist device with a
collapsible outer shell. Such a device may be installed with minimal trauma to the patient.
Additional reference may be had to United States patents 5,169,381 and 5,256,132 also to
Snyders.
United States patent 4,979,936 to Stephenson discloses a fully implantable Ventricular
Assist device. Stephenson's device comprises a first bladder fluidly connected to a second
bladder. The first bladder is disposed within a muscle, while the second bladder is disclosed
next to or around the heart. The muscle may then be electrically contracted, thus, forcing fluid
out of the first bladder and into the second bladder. The expansion of the second bladder thus
compresses the heart.
United States patent 5,273,518 to Lee discloses a fully implantable Ventricular Assist
device similar to the muscle powered devices mentioned above. United States patents
5,098,442 and 5,496,353 to Grandjean, 5,562,595 to Neisz, 5,658,237, 5,697,884, and
5,697,952 to Francischelli, 5,716,379 to Bourgeois and 5,429,584 to Chiu disclose a similar
device. United States patent 5,364,337 to Guiraudon discloses a means for controlling the
contraction of the muscle, which in turn, controls the compression of the heart.
United States patent 5,098,369 to Heilman discloses a Ventricular Assist device that is
comprised of materials that allow for tissue in-growth, thus adhering the device to the heart. The
use of defibrillating electrodes and electrocardiographs are also disclosed.
United States patent 5,131,905 to Grooters discloses a Ventricular Assist device that
applies systolic pressure to the heart. The Grooters device is held in position around the heart
by a plurality of straps.
United States patents 5,385,528, 5,533,958, 5,800,334, and 5,971,911 to Wilk disclose a
Direct Mechanical Ventricular Assist device suitable for emergency use. The inflatable device
may be quickly installed in an emergency situation through a small incision. United States
patent 6,059,750 to Fogarty discloses a similar device.
United States patent 5,713,954 to Rosenberg discloses a Ventricular Assist device in the
form of a cuff that provides systolic pressure to a heart. The disclosed cuff is suitable for
applying pressure to specified portions of the heart, may be equipped with EKG sensors, and is
fully impl an table.
United States patents 5,738,627 and 5,749,839 to Kovacs disclose a Direct Mechanical
Ventricular Assist device that provides both systolic and diastolic pressure to a heart. The
disclosed cup adheres to the heart by way of a vacuum, which also provides diastolic pressure to
the heart. The opening of the device is equipped with an inflatable collar. When inflated, the
collar provides a seal to assist in establishing the vacuum.
United States patent 6,076,013 to Brennan discloses a cup that senses electrical activity
within the heart and provides electrical stimulation to assist the heart in its contractions.
United States patent 6,110,098 to Renirie discloses a method for treatment of fibrillation
or arrhythmias through the use of subsonic waves.
United States patent 6,206,820 to Kazi discloses a Ventricular Assist device that
compresses only the left ventricle and allows the other cardiac regions to expand in response to
the contraction.
United States patent 6,238,334 to Easterbrook discloses a Ventricular Assist device that
provides both systolic and diastolic pressure to a heart. Easterbrook discloses the use of a cup
to apply a substantially uniform pressure to the heart's surface, which is necessary to avoid
bruising of the muscle issue. Through the reduction of transmural pressure, a substantially
lower driving pressure may be utilized. This assists to avoid traumatizing heart tissue.
United States patent 6,251,061 to Hastings discloses a Ventricular Assist device that
provides systolic pressure to a heart through the use of ferrofluids and magnetic fields.
United States patent 6,432,039 to Wardle discloses a Ventricular Assist device that
comprises a multiplicity of independently inflatable chambers that delivery systolic pressure to
selected portions of a heart. Wardle also discloses the use of redundant "recoil" inflatable
balloons.
United States patent 6,464,655 to Shashinpoor discloses a fully implantable robotic hand
for selectively compressing the ventricles of a heart. The robotic hand is programmable via a
microprocessor.
United States patents 6,328,689 to Gonzalez and 6,485,407 to Alfemess disclose a
flexible jacket adapted to be disposed about a lung. By applying expansive and compressive
forces, the lung may be assisted.
Optimal DMVA performance requires that the Cup be properly fit on the heart, be
adequately sealed against the ventricular epicardium, and that the volume vs. time displacement
profile of the Cup liner(s) produces the desired ventricular dynamics to achieve optimal,
dynamic systolic and diastolic conformational changes of the ventricular myocardium. The
optimum pressure-flow drive mechanics will vary from patient to patient, depending upon such
factors as the actual fit of the Cup to the heart, the specific nature of the patient's disease, and
the patient's normal cardiac rhythm. These factors make it difficult to pre-operatively define
the optimum liner time-displacement profiles or hydraulic drive unit control parameters capable
of satisfying every patient's unique DMVA requirements.
It is well known that diseased heart tissue can be very fragile, i.e. such tissue is of lower
resistance to shear forces and/or less tensile strength than healthy heart tissue. Thus physicians
lacking due caution can easily perforate or injure diseased hearts with their fingers while
applying gentle pressure during open heart massage by the high pressure at a finger tip adjacent
to a low pressure or pressure void between fingers. This previous example describes an acute or
rapidly induced emergency situation. However, the persistent application of forces to the heart
can also cause potentially catastrophic damage to the heart by fatiguing and severely bruising
the heart muscle and/or abrading the heart surface, which can ultimately prevent the heart from
functioning.
Direct mechanical ventricular actuation (DMVA) is a means of providing ventricular
actuation to achieve biventricular compression (termed "systolic actuation") and active
biventricular dilatation (termed "diastolic actuation"). In one embodiment, DMVA utilizes
continuous suction to maintain a seal between the actuating diaphragm and the surface of the
heart, which enables the device not only to compress the heart, but also effectively provide
diastolic actuation by virtue of the diaphragm maintaining attachment to the epicardial surface
during the phase of ventricular actuation. Therefore, DMVA overcomes major drawbacks of
DCC devices by augmenting diastolic function. This is essential, given that any such DCC
device that encompass the ventricles and applies external forces will have inherently negative
impacts on diastolic function. The present invention overcomes this, by enhancing diastolic
function as demonstrated by an increased rate of diastolic pressure decay and an associated
reduced time constant for active ventricular chamber dilatation ("diastolic actuation").
The general principles of effective ventricular compression and ventricular dilatation can
only be delivered in an optimal fashion if the effects on both right and left ventricular function
are taken into account and such forces are applied in the appropriate temporal and spatial
distribution, which is dictated by the material characteristics and delivery of the appropriate
drive mechanics using appropriately fashioned pressure and/or flow dynamic profiles. These
drive dynamics and material characteristics of the diaphragm and housing of the device are also
critical in achieving the best functional result, with the least cardiac trauma.
The appropriate dynamic fit of the DMVA device and its interaction with the heart
throughout the actuating cycle is critical, and mandates that RV/LV dynamics are monitored. In
particular, fit of the device in the diastolic mode must allow for adequate expansion of both the
LV and RV chambers, with particular attention to the RV due to its lower-pressure, compliant
properties. Inadequate size and/or diastolic assist will predominantly compromise RV filling,
resulting in diminished RV output, and in turn, reductions in overall cardiac output. In contrast,
systolic actuation places emphasis on adequate degrees of LV compression. Adequate LV
chamber compression requires attention to regulation of variables including maximum systolic
drive volume delivery, maximum systolic pressure, and systolic duration.
More simply stated, adequate LV compression is that degree of compression that results
in LV stroke volumes approximately equal to optimal RV stroke volumes. The interrelationship
of these chambers dictates that both RV and LV chambers need to be monitored.
Appropriate RV and LV actuation by the DMVA system requires active, real-time measurement
of both operational parameters and hemodynamic responses, which are utilized in the DMVA
adaptive control algorithms to achieve optimal pump function and other more sophisticated
operations such as device weaning and analysis of myocardial recovery.
Functional interactions between the right ventricle and left ventricle under mechanical
systolic and diastolic actuation are relatively complex and difficult to describe and/or
characterize. These are dynamic interactions that are not necessarily predictable based on premeasured
variables, but rather depend on a broad number of physiologic variables. These
interactions are not independent; thus the behavior of one chamber has an impact on the other.
Continuous monitoring of these two chambers allows the drive control to utilize an adaptive
algorithm to constantly alter DMVA control parameters to achieve optimal cardiac actuation
and hemodynamic output. Examples of this include, but are not limited to adjustment of
pressure/volume relationships to maintain balanced RV/LV output, control of pressure rise
times to avoid hemiation of the right ventricle, and reduction of negative drive pressure during
diastole based on loss of contact between the DMVA liner and the heart wall.
The variability of a broad range of physiologic states across the patient population will
dictate that these and other parameters will require responses that may be somewhat unique to
each patient. Thus parametric control that benefits from broad demographic information, from
physician input, and from real-time patient response data will result in the best outcome for the
individual patient.
Therefore a heart-assist device is needed that does not cause damage to the heart as a
result of its mechanical action on the heart. There also exists a need for a sensing and control
means to ensure that such a device (1) is properly positioned and/or installed on the heart, (2)
adequately seals against the heart, (3) achieves the desired systolic and diastolic action at
installation and over the implanted life of such device, (4) operates within desired parameters
to achieve optimal cardiovascular support, and (5) detects changes, such as impending device
failure, in time to take corrective action.
There is also a need for a process to accomplish the above tasks very quickly, in order to
avoid brain death and other organ damage. The inherent ability of the DMVA Cup of the
present invention to be installed in a very short period of time with no surgical connection to the
cardiovascular system of the patient needed enables the Cup of the present invention to save
patients who require acute resuscitation, as well as to minimize the number of failed
resuscitations due to improper installation or drive mechanics.
There is also a need for a device that does not contact the blood so that anticoagulation
countermeasures are not needed, and so that the potential for infection within the blood is
reduced.
It is therefore an object of this invention to provide a Direct Mechanical Ventricular
Assist device that does not do damage to the heart as a result of its mechanical action on the
heart.
It is a further object of this invention to provide a Direct Mechanical Ventricular Assist
device that is technically straightforward to properly install on the heart.
It is an additional object of this invention to provide a Direct Mechanical Ventricular
Assist device that may be installed on the heart and rendered functional by a procedure that is
accomplished in a few minutes.
It is another object of this invention to provide a Direct Mechanical Ventricular Assist
device that adequately seals against the heart, thereby enabling more precise operation of the
device.
It is an additional object of this invention to provide a Direct Mechanical Ventricular
Assist device that drives the systolic and diastolic action of the heart within precisely defined
and controlled parameters.
It is a further object of this invention to provide a Direct Mechanical Ventricular Assist
device that provides a healing environment within the body of the patient, including the heart
itself.
It is another object of this invention to provide a Direct Mechanical Ventricular Assist
device that provides measurements of the systolic and diastolic action of the heart to which it is
fitted.
It is a further object of this invention to provide a Direct Mechanical Ventricular Assist
device that provides an image of the functioning heart to which it is fitted.
It is a further object of this invention to provide a Direct Mechanical Ventricular Assist
device that contains sensors and provides sensory feedback relative to the functioning heart to
which it is fitted.
It is another object of this invention to provide a Direct Mechanical Ventricular Assist
device that can provide electrical signals to the heart to pace the systolic and diastolic functions
thereof.
It is an object of this invention to provide a Direct Mechanical Ventricular Assist device
that has no direct contact with circulating blood, thereby reducing the risk for thrombogenic and
bleeding complications, decreasing the potential for infection of the blood, and eliminating the
need for anticoagulation that has many serious complications, especially in patients with serious
cardiovascular disease and recent surgery.
It is another object of this invention to provide electrophysiological support, such as
pacing and synchronized defibrillation, that can be integrated with mechanical systolic and
diastolic actuation.
It is another object of the present invention to provide a DM VA device that can augment
cardiac function without any surgical insult to the heart and/or great vessels.
It is another object of the present invention to provide a DMVA device that can put the
heart to rest so that it can heal itself from an acute insult while having an improved flow of
oxygenated blood.
It is a further object of the present invention to provide a DMVA device having a
detachable liner, which can thus enable the DMVA device to be removed from the patient with
no trauma to the heart of the patient.
It is a further object of the present invention to provide a DMVA device having a
therapeutic liner or seal, thereby enabling the direct administration of therapeutic agents to the
heart of the patient.
It is a further, object of the present invention to provide a DMVA device that allows
dynamic monitoring of the operation thereof, and the resultant right ventricle and left ventricle
actuation, to permit optimization of pump function of the heart.
It is a further object of the present invention to provide a DMVA device comprising a
volumetrically regulated fluid drive utilizing drive flow/volume sensors integrated with sensing
and analysis of DMVA device/biventricular interactions, thereby enabling optimization of
resulting biventricular actuation.
It is a further object of the present invention to provide a DMVA device comprising a
pressure regulated drive that regulates DMVA drive mechanics independent of volume,
utilizing analysis of drive pressure dynamics integrated with analysis of volume changes with
the cup and within the right and left ventricles.
DISCLOSURE OF THE INVENTION
In accordance with the present invention, there is provided a process for assisting the
function of a heart disposed within a body and comprising an outer wall, said process
comprising the steps of measuring at least one parameter that is indicative of said function of
said heart, applying a compressive force to a portion of said outer wall of said heart, and
applying an expansive force to said portion of said outer wall of said heart.
In accordance with the present invention, there is further provided an apparatus for
assisting the function of a heart disposed within a body and comprising an outer wall, said
apparatus comprising a cup-shaped shell having an exterior wall, an interior wall, an apex, and
an upper edge; a liner having an outer surface and an inner surface, an upper edge joined to said
interior wall of said cup-shaped shell, and a lower edge joined of said interior wall of said cupshaped
shell, thereby forming a cavity between said outer surface thereof and said interior wall
of said shell; and a drive fluid cyclically interposed within said cavity, said drive fluid applying
a uniform force on a portion of said outer wall of said heart.
In accordance with the present invention, there is further provided an apparatus for
assisting the function of a heart disposed within a body, and comprising an outer wall, said
apparatus comprising a cup-shaped shell having an exterior surface and an interior surface; a
liner having an outer surface, an upper edge joined to said interior surface of said cup-shaped
shell, and a lower edge joined of said interior surface of said cup-shaped shell, thereby forming
a cavity between said outer surface thereof and said interior surface of said shell; a drive fluid
cyclically interposed within said cavity; and at least one sensor measuring at least one
parameter.
In accordance with the present invention, there is further provided a process for assisting
the function of a heart disposed within a living body of a patient, and comprising an outer wall,
said process utilizing a controller and comprising the steps of importing at least one value of at
least one parameter relating to said function of said heart into said controller; using an algorithm
to formulate at least one command instruction, based upon said at least one value of said one
parameter; and exporting said at least one command instruction from said controller.
In accordance with the present invention, there is further provided a therapeutic
apparatus for delivering at least one therapeutic agent directly and preferentially to a desired
tissue to be treated, comprising at least one membrane comprised of means to deliver said agent
to said desired tissue, said membrane being in contact with at least a part of said desired tissue
to be treated; and at least one shell surrounding said membrane, said shell isolating said
membrane from tissues other than said desired tissue to be treated.
In accordance with the present invention, there is further provided an apparatus for
assisting the pumping of circulating blood by a heart disposed within a body, and comprising an
outer wall, said apparatus comprising means for applying a uniform force to a portion of said
outer wall of said heart by a membrane; means to drive said membrane by cyclic application of
a drive fluid thereto; and means for cyclic pumping of said drive fluid implanted within said
body, wherein said circulating blood is isolated from contact with said apparatus.
In accordance with the present invention, there is further provided an apparatus for
assisting the function of a heart disposed within a body, and comprising an outer wall, said
apparatus comprising a cup-shaped shell having an exterior wall, an interior wall, and an upper
edge; a liner having an outer surface, an upper edge joined to said interior wall of said cupshaped
shell, and a lower edge joined of said interior wall of said cup-shaped shell, thereby
forming a cavity between said outer surface thereof and said interior wall of said shell; a drive
fluid cyclically interposed within said cavity; and a seal comprising a base joined to said upper
edge of said cup-shaped shell, a tip, and means for deploying said tip of said seal contiguously
with said outer wall of said heart.
In accordance with the present invention, there is further provided an apparatus for
assisting the function of a heart disposed within a body, and comprising an outer wall, said
apparatus comprising a cup-shaped shell having an exterior wall, an interior wall, and an upper
edge; and a liner having an outer surface and an inner surface, an upper edge joined to said

interior wall of said cup-shaped shell, and a lower edge joined of said interior wall of said cupshaped
shell, thereby forming a cavity between said outer surface thereof and said interior wall
of said shell, wherein said liner is detachable from said cup-shaped shell.
In accordance with the present invention, there is further provided an apparatus for
assisting the function of a heart disposed within a body, and comprising an outer wall, said
apparatus comprising a cup-shaped shell having an exterior wall, an interior wall, and an upper
edge; and a liner having an outer surface and an inner surface, an upper edge joined to said
interior wall of said cup-shaped shell, and a lower edge joined of said interior wall of said cupshaped
shell, thereby forming a cavity between said outer surface thereof and said interior wall
of said shell, wherein said liner comprises a first therapeutic agent.
The DMVA device of the present invention described above is advantageous because
compared to other prior art devices, it precisely drives the mechanical actuation of the
ventricular chambers of the heart without damaging the tissue thereof, or the circulating blood;
it may be installed by a simple procedure that can be quickly performed; it provides functional
performance and image data of the heart; and it can provide electrophysiological monitoring and
control of the heart, including pacing and cardioversion-defibrillation electrical signals to help
regulate and/or synchronize device operation with the native electrical rhythm and/or
contractions thereof. As a result of the invention, a greater variety of patients with cardiac
disease can be provided with critical life-supporting care, under a greater variety of
circumstances, including but not limited to, resuscitation, bridging to other therapies, and
extended or even permanent support. Finally the device can support the heart through a period
of acute injury and allow healing that results, in some conditions, to full recovery of
unsupported heart function, which has not been achieved by any other device.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described by reference to the following drawings, in which like
numerals refer to like elements, and in which:
Figures 1A - 1H are graphical representations of time dependent pressure and volume
relationships of blood displaced by the left and right ventricles of a healthy human heart, of an
unhealthy human heart, and of a DMVA-assisted heart during systole and diastole;
Figures II- U are graphical representations of time dependent blood pressure within the
left and right ventricles of a healthy human heart, and of a DMVA-assisted heart, respectively,
during systole and diastole;
Figures IK- 1L are graphical representations of time dependent blood flow rates ejected
from the left and right ventricles of a healthy human heart, and of a DMVA-assisted heart
during systole;
Figure 1M is a graphical representation of time dependent blood flow rates into and out
of the ventricles of the heart taken over a sequence of two DMVA assisted complete cardiac
cycles;
Figures 2A - 21 are cross-sectional schematic views depicting a sequence of actions of
DMVA device of the present invention a heart, which assist the systolic and diastolic functions
thereof depicted graphically in Figures 1A- 1M;
Figures 2J - 2O are cross-sectional schematic views depicting undesired operations
and/or effects of a DMVA device, which is lacking the proper control and/or structural features
provided in accordance with the present invention;
Figures 2P - 2R are cross-sectional schematic views depicting operations and/or effects
of a DMVA device on a heart afflicted with pulmonary hypertension and right ventricular
hypertrophy;
Figures 2S - 2U are cross-sectional schematic views depicting operations and/or effects
of a DMVA device on a heart afflicted with dilated cardiomyopathy;
Figure 3A and 3B are cross-sectional schematic views depicting the action of a liner of a
prior art DMVA device upon the wall of the heart;
Figures 4A, 4B, and 4C are cross-sectional schematic views depicting the action of the
liner of one preferred DMVA Cup of the present invention upon the wall of the heart;
Figure 5A is a flow chart of a general method for using sensor data to guide DMVA
installation and assess cardiac performance under the influence of DMVA;
Figure 5B is a flow chart of a more specific algorithm for automatically adjusting the
function of an embodiment of the DMVA Cup;
Figures 6A, 6B, and 6C are schematic representations of a sensor installed in a DMVA
Cup engaged in systolic actuation;
Figure 7 is a schematic representation of a sensor installed in a DMVA Cup engaged in
diastolic actuation;
Figure 8 is a schematic representation of a DMVA Cup with an MRI coil embedded
therein;
Figure 9A and 9B are schematic representations of an external X-ray imaging procedure
used to collect data on a patient and data on a DMVA Cup fitted therein;
Figures 10A is a schematic representation of electrophysiological sensors and/or
electrodes integrated into a DMVA device, shown during systolic compression of a heart;
Figure I OB is a schematic representation of the electrophysiological sensors and the
liner of the DMVA device of Figure 10A;
Figure 11 is a schematic representation of working fluid pressure and/or flow rate
sensors integrated into the Cup and Drive Assembly;
Figure 12 is a schematic representation of an alternate embodiment of working fluid
pressure sensors integrated into the Cup and Drive Assembly;
Figure 13 is a schematic representation of several embodiments of position sensing
means for detection of the position of the liner of the DMVA apparatus during operation;
Figure 14 is a schematic representation of a DMVA Cup with imaging contrast agents
applied to critical Cup components;
Figure 15 is a schematic diagram of an overall control system with performance
feedback, for operation and control of the DMVA apparatus;
Figure 16A is a schematic representation of a further embodiment of the DMVA
apparatus of the present invention, comprising an integrated seal and liner with a rolling
diaphragm;
Figure 16B is a detailed view of one embodiment of a bond between a rolling diaphragm
and a cup shell of the DMVA apparatus of Figure 16A;
Figure 17A - 17H are detailed views of alternate embodiments of flat and rolling
diaphragm liners of the DMVA apparatus, particularly showing the bonds between such flat and
rolling diaphragm liners and the cup shell;
Figure 18A - 18C are detailed views of alternate embodiments of several DMVA cup
seals, in which the free shape, initial installed shape, partially recovered shape, and final
position are shown;
Figure I9A is a cross-sectional view of an active seal by which the DMVA apparatus
more firmly engages the heart;
Figure 19B and 19C are detailed cross-sectional views of the active seal of Figure 19A,
shown in the passive and active states, respectively;
Figure 20 is a cross-sectional view of an active seal similar to the seal of Figure 19A -
19C, further comprising an active release mechanism that is activated when the DMVA
apparatus is installed on the heart;
Figure 21A is a cross-sectional view of a passive seal comprising a release mechanism
that is deployed when the DMVA apparatus is installed on the heart, shown prior to engagement
and sealing thereto;
Figure 21B is a cross-sectional view of the passive seal of Figure 21 A, shown in the free
and the engaged/sealed state;
Figure 22A is a cross-sectional view of one embodiment of a liner and seal of the
DMVA apparatus, comprising locally specialized materials and/or surface textures;
Figure 22B is a detailed cross-sectional view of one liner of the DMVA apparatus of
Figure 22A;
Figure 23A is a cross-sectional view of another embodiment of the DMVA apparatus,
further comprising means for disengagement of the seal thereof that is attached to the heart;
Figures 23B and 23C are detailed cross-sectional views of embodiments of detachable
seals of the DMVA apparatus of Figure 23A;
Figure 24 is a cross-sectional side view of one embodiment of a DMVA cup formed
with a hollow wall structure comprised of alternating structural ribs and cavities disposed in
horizontal planes;
Figure 25A is a cross-sectional top view of another embodiment of a DMVA apparatus
formed with a hollow wall structure comprised of alternating structural ribs and cavities
disposed in longitudinal planes;
Figure 25B is a detailed cross-sectional top view of a structural joint between a rib and
an outer shell of the DMVA apparatus of Figure 25A;
Figure 26 is a schematic diagram of an overall control system with performance
feedback, for operation and control of the DMVA apparatus;
Figure 27 is a schematic diagram of a DMVA control system, including the relationships
between algorithms, input data, and output data for operation and control of a DMVA apparatus
in the practice or cardiac regeneration.
Figure 28 is a cross-sectional view of another embodiment of a DMVA apparatus,
further comprising an implantable reciprocating pump used to drive systolic and diastolic
actuation of the DMVA Cup and heart therein; and
Figure 29 is a cross-sectional view of another embodiment of a DMVA apparatus,
further comprising an implantable phase change pump used to drive systolic and diastolic
actuation of the DMVA Cup and heart therein.
The present invention will be described in connection with a preferred embodiment,
however, it will be understood that there is no intent to limit the invention to the embodiment
described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents
as may be included within the spirit and scope of the invention as defined by the appended
claims.
BEST MODE FOR CARRYING OUT THE INVENTION
For a general understanding of the present invention, reference is made to the drawings.
In the drawings, like reference numerals have been used throughout to designate identical
elements.
In describing the present invention, a variety of terms are used in the description.
Standard terminology is widely used in cardiac art. For example, one may refer to Bronzino,
J.D., The Biomedical Engineering Handbook, Second Edition, Volume I, CRC Press, 2000, pp.
3-14 and 418 - 458; or Essential Cardiology, Clive Rosendorf M.D., ed., W.B. Saunders Co.,
2001, pp. 23 - 699, the disclosures of which are incorporated herein by reference.
As used herein, the term Cup is meant to indicate the Direct Mechanical Ventricular
Assist device of the present invention, such device comprising a cup-shaped outer shell. The
terms Cup, DMVA Cup, DMVA device, and DMVA apparatus are used interchangeably in this
specification and are intended to denote the overall Direct Mechanical Ventricular Assist device
of the present invention in its various embodiments, unless specifically noted otherwise.
As used herein, the abbreviation LV is meant to denote the term "left ventricle", or "left
ventricular" and the term RV is meant to denote the term "right ventricle, or "right ventricular",
as appropriate for the particular context.
"Right" and "left" as used with respect to the ventricles of the heart are taken with
respect to the right and left of the patient's body, and according to standard medical practice,
wherein the left ventricle discharges blood through the aortic valve into the aorta, and the right
ventricle discharges blood through the pulmonic valve into the pulmonary artery. However, the
Figures of the instant application, which depict the present invention and the heart contained
therein are taken as viewed facing the patient's body. Accordingly, in such Figures, the left
ventricle depicted in any such Figure is to the right, and vice-versa just as is done in convention
when viewing radiographs and figures of related organs in the medical field. For the sake of
clarity in such Figures, the left and right ventricles are labeled "LV" and "RV", respectively.
As used herein, the terms "normal heart", and "healthy heart" are used interchangeably,
and are meant to depict a nominal, unafflicted human heart, not in need of DMVA assistance or
other medical care.
As used herein, the term cardiac function is meant to indicate a function of the heart,
such as the pumping of blood in systemic and pulmonary circulation; as well as other functions
such as healing and regeneration of the heart following a traumatic event such as e.g.,
myocardial infarction. Parameters indicative of such functions are physical parameters,
including but not limited to blood pressure, blood flow rate, blood volume, and the like; and
chemical and biological parameters such as concentrations of oxygen, carbon dioxide, lactate,
etc.
As used herein, the term cardiac state is meant to include parameters relating to the
functioning of the heart, as well as any other parameters including but not limited to
dimensions, shape, appearance, position, etc.
Critically important to the effective operation of DMVA is the continuous monitoring of
changes in both right and left ventricular geometry (e.g. RV and LV end systolic and end
diastolic volumes and-dimensional characteristics); 2) Ventricular dynamics (e.g. dynamic
changes in chamber size, flow velocities, calculated pressure gradients and wall motion
alterations throughout the DMVA cycle); 3) ventricular interactions (the dependent effects that
items 1 and 2 have on one another; 4) device/cardiac interactions (e.g. the relationship between
the device's actuating diaphragm and the epicardial surface throughout the actuating cycle, and
e.g. the effects on conformational changes in ventricular wall contour, RV herniation).
Therefore, in one embodiment of the present invention depicted in Figures 6A - 7 and
described subsequently in this specification, at least one ultrasonic probe is integrated within the
DMVA heart cup and utilized to continuously monitor the right and left ventricular chambers
and the related device-epicardial interactions that dictate these conformational changes,
dynamics, volumetric changes, flow velocities of the RV and LV throughout DMVA actuating
cycle. Such visual and sensory analysis of right and left ventricular compression allows control
parameters to be adjusted using control algorithms in a continuous manner to achieve optimal
profile to achieve maximal right and left ventricular support. This monitoring is critical for a
number of reasons relating to the unique challenges of supporting the heart using DMVA.
There are a number of control algorithms that the DMVA drive control will implement
in achieving optimal cardiac actuation. For example, the ongoing changes in pulmonary and
systemic vascular resistance and flow velocities occur during DMVA support are, in part,
dictated by the right and left ventricles' response to external actuating forces. The force delivery
from the drive can be adjusted in response to these measured variables to both achieve more
favorable hemodynamics, and ensure force delivery is adequate to overcome the inherent
resistance characteristics of the pulmonary and systemic vascular beds and valvular structures.
The systolic and diastolic actuating forces need to be adjusted in order to achieve an optimal
biventricular effect. These forces are adjusted (change in pressure/time and/or change in
volume/time) to effect incremental parts of both the systolic and diastolic actuating phases.
Some generic examples of such drive dynamic optimization. are explained in the following
paragraphs.
The early part of systolic actuation primarily focuses on right ventricular dynamics.
Visualization of the right ventricular chamber implies that early systolic compressive forces are
relatively gentle and allow maximal compression of the right ventricle. Compression of the
right ventricle must focus on avoiding and/or reducing the degree of right ventricular hemiation
that is the result of abrupt early systolic compression. Such RV herniation seen at the base
(upper edge) of the device essentially allows blood to accumulate in that portion of the right
ventricular free wall that is bulging outside of the device. Such herniation of blood is associated
with equal reductions in pulmonary blood flow and overall reduced cardiac output as these
reductions in flow are mirrored by reduced left ventricular filling.
The later half of the systolic actuation cycle focuses on maximal left ventricular
compression, while avoiding excessive left ventricular compression. Some key characteristics
of left ventricular compression include achieving that degree of left ventricular compression,
which results in the greatest ventricular ejection without allowing endocardia! (inner) surfaces
of the heart to touch one another. If the LV is not adequately compressed, blood will
accumulate within the lungs and lead to pulmonary edema.
Both the absolute degree of systolic compressive force and the timing of systolic
compression are altered in an effort to maximize left ventricular emptying characteristics. By
following these principles, left ventricular forward flow is maximized (as evidenced by the
greatest reduction in left ventricular volume during compression) while trauma associated with
contact of the inner ventricular chambers is avoided. In other words, with optimal LV
compression (systolic actuation) there is always a fluid medium between the inner surfaces of
the heart. Excessive forces can lead to excessive displacement of left ventricular blood
allowing the inner surfaces to touch one another and traumatize one another. Likewise,
Excessive forces during early compression result in herniation and friction between the right
ventricular free wall and septum within the right ventricular chamber.
Similarly, right and left ventricular dynamics are monitored to insure optimal diastolic
actuation. A fundamental principle of optimal DMVA assistance is accomplishing right and left
ventricular diastolic actuation, while achieving maximal diastolic volumes. This is achieved by
increasing the negative dP/dt (change in pressure/change in time) and/or dV/dt (change in
volume/change in time) to achieve an optimal diastolic actuation that augments the rate of
diastolic filling and overcomes the inherent otherwise negative (constrictive) effects of DCC, or
any compression methods. Such diastolic actuation is adjusted to that point where maximal -
dP/dt is achieved without allowing separation between the actuating diaphragm and epicardial
surface of the heart.
Any separation of the actuating diaphragm from the epicardial surface of the heart
indicates that the negative applied forces during that phase of the actuating cycle are too abrupt
and need to be delivered in a more gradual fashion. Separation of the liner from the heart
during diastolic actuation essentially removes the actuating force from the epicardium resulting
in the heart growing passively and/or going in a non-assisted manner. The details of
embodiments of the DMVA apparatus of the present invention comprising means for sensing of
left and right ventricular chambers and the related changes/drive control algorithms in drive
mechanics will be detailed to a greater extent subsequently in this specification.
The preferred material characteristics will also be further defined subsequently in this
specification. However, general characteristics are provided in the following paragraphs. The
optimal characteristics for the liner may best be generally described as that which has near
"isotropic" behavior. In other words, the liner material acts on the ventricular muscle in a
manner that allows the ventricular muscle to change its conformational shape in a manner that
best follows the heart's natural tendencies. In this manner, the material does not "deform" the
heart outside of a range dictated by the muscle's natural tendency to change conformation when
such external forces are applied.
However, this is not to say that the heart is compressed in a manner that replicates the
normal beating state. On the contrary, the systolic and diastolic conformational changes that
result from DMVA actuation clearly differ to some degree from what one expects during
contraction and dilatation of an otherwise normal functioning heart. However, it is important
that the liner and Cup shell materials allow the myocardium to undergo such mechanically
induced conformational changes in a manner that permits the muscle to deform based on its
physical characteristics and tendencies. Less ideal materials lead to more potential trauma and
have their own tendency to fold and deform in a manner that alters the heart's "natural"
tendency and these types of material characteristics lead to myocardial injury.
The compliant nature of the device housing permits it to constantly change shape in
response both to the actuating forces applied to the heart and changes in the heart's size and/or
shape. This characteristic contributes to decreased ventricular trauma, ease of application as the
housing can be deformed to fit through small incisions, and important dynamic conformational
changes that constantly respond to the heart's changing shape. The housing of the device is
constructed of a flexible material that has appropriate compliance and elastic properties that
allow it to absorb the systolic and diastolic actuating forces in a manner that somewhat buffers
the effect of the liner on the heart. (For example, abrupt reductions in drive fluid pressure are
dampened such that cavitation and disengagement with the heart are avoided, and during
systole, abrupt increases in drive fluid pressure are dampened such that bruising of the heart are
avoided.) The unique qualities of this housing lessen the risk for inadvertent excessive forces to
be applied to the heart at any time of the cycle. The shell conforms to the dynamic changes in
the right and left ventricles throughout compression and relaxation cycles as well as overall,
ongoing changes related to variances in heart size over time which occur as a consequence of
continued mechanical actuation and related "remodeling" effects on the heart.
Sensor and Control Related Aspects of the Invention
The present invention also comprises a method for utilizing sensors and sensor data to
(1) help install DMVA devices and to (2) assess cardiac performance under the influence of
DMVA. The sensor data so obtained helps real-time verification that the device has been
properly installed, and is operating properly and achieving desired cardiac performance. The
sensory data also allows the operating parameters of the Cup to be adjusted in real time to
respond to changing physiology of the patient's cardiovascular system. There are at least ten
sensor and control related aspects to the present invention, all of which are described herein:
1. A method for using sensor data in conjunction with cardiac assist devices (not limited
only to DMVA or DMVA Cups) to perform such functions as guiding device
installation, and optimization of device performance and guiding the placement and
operation of other cardiac devices and systems.
2. Specific cardiac performance measures appropriate for sensing (sensor data).
3. Specific device feedback control parameters.
4. Specific feedback control methods and algorithms.
5. Specific sensor types and sensor locations.
6. The use of contrast agents to enhance sensor sensitivity and specificity.
7. Sensor interfaces.
8. User interfaces.
9. Sensor data recording and analysis capabilities.
10. Specific device performance measures appropriate for sensing (sensor data).
These aspects of the present invention will be described briefly here in the specification,
and in more detail subsequently, with reference to the drawings.
Invention aspect 1: A method for using sensor data in conjunction with cardiac assist
devices is briefly described as follows, and subsequently described in detail with reference to
Figure 5A. This aspect is directed to a general method for using sensor data to guide
installation of DMVA devices, and to assess cardiac performance under the influence of
DMVA. The method includes the following steps, which are offered here as illustrative and not
limiting:
Step 1: Establish patient baseline performance.
Step 2: Establish required performance improvement objectives.
Step 3: Pre-check DMVA device to verify critical aspects of performance (Optional)
Step 4: Surgically install DMVA device in the patient.
Step 5: Actuate DMVA device using predetermined settings from steps 1 and 2.
Step 6: Operate the DMVA device and collect sensor data. See also Invention Aspects
#5 (Specific sensor types and sensor locations)
Step 7: Analyze sensor data. See also Invention Aspects #2 (Sensor Data), #9 (Sensor
data recording and analysis capabilities), and #10 (Specific device performance
measures appropriate for sensing) for specific data and data analysis methods.
Step 8: Adjust DMVA control parameters.
Step 9: Repeat steps 6-7 until desired cardiac performance is achieved.
Step 10: Program data recorder-transmitter (Optional)
Step 11: Prepare patient for recovery.
Step 12: Monitor patient's cardiac performance
Invention Aspect 2: Sensor data. The sensor data collected in Step 6 of the preceding
method of Invention Aspect 1 preferably includes without limitation the types of data listed
below. The specific sensor types and sensor locations (also see Invention Aspect 5) will
subsequently be described in more detail in conjunction with Figures 6A - 14.
1. Anatomical data, such as e.g., motion of the heart wall sensed by implanted
accelerometers; fit of the Cup to the heart sensed by an implanted ultrasound
transducer/sensor device; and/or cardiac ventricular blood volume displacement inferred
by a sensor that measures the DMVA device working fluid volume. Additionally, the
DMVA device includes sensor data such as e.g., data from an ultrasonic
transducer/sensor that can be analyzed and compiled to produce images of the heart and
Cup. Such image data is particularly useful, as it provides the physician with the
information required to verify proper fit of the Cup to the heart, and to verify that proper
systolic and diastolic actuation are being achieved, including but not limited to dynamic
changes in ventricular wall and septal geometry, RV/LV relationships, and epicardialliner
relationships.
2. Hemodynamic data, such as the following: a) blood flow rate, inferred by calculation
from the DMVA device working fluid flow rates; b) right ventricle - left ventricle
interactions; c) aortic blood pressure, such as by normalization of e.g., traditionally
obtained blood pressure data and/or calculations based on data from pressure sensors
located in the DMVA device working fluid at a point near the contact with the
myocardium, and/or pressure/volume data from the working fluid, and/or acoustic data
from the flow at the aortic valve over time; d) pulmonic blood pressure, such as by
normalization of e.g., traditionally obtained blood pressure data and/or calculations
based on data from pressure sensors located in the DMVA device working fluid at a
point near the contact with the myocardium, and/or pressure/volume data from the
working fluid, and/or acoustic data from the flow at the pulrnonic valve over time; e)
RV and LV stroke volumes; f) flow velocities across all four cardiac valves, based upon
measured or calculated pressure gradients.
3. Functional data, such as cardiac ejection fraction, obtained from calculations based upon
the above anatomical and/or hemodynamic data and/or calculations based on direct
ultrasound images from the Cup's entrained ultrasound transducer/sensor device; and
RV-LV fit and relationships.
4. Electrophysiological data, such as electrical voltages and changes in voltages over time
obtained by electrical sensors located on the interior surfaces of the Cup and in contact
with the myocardium; voltage differences, obtained by comparisons between such
sensors located at different points on the myocardium; voltage differences over time,
obtained from such multiple sensors; electrical currents and current changes over time
obtained from such electrical sensors. It is to be understood that in some embodiments,
the DMVA Cup will electrically isolate the heart to some extent, making standard
electrocardiographic monitoring more difficult. However, this isolation also enables
electrophysiological monitoring and stimulation devices located within the Cup to
operate more effectively; since they are less susceptible to electrical noise, particularly
from external sources. Thus, the DMVA Cup is able to focus the delivery of electrical
stimulation energies to tissues enclosed therein. To use such a property advantageously,
the DMVA Cup further comprises integrated electrical measurement capabilities (such
as e.g., electrocardiograms) and integrated electrical stimulation capabilities (such as
e.g., pacing and cardioversion-defibrillation), wherein such measurement capabilities
and such stimulation capabilities are further integrated into a feedback control loop by
which the natural contractions of the heart within the Cup are fully controlled, as well as
being assisted. In one further embodiment, the practice of apica! pacing is used, wherein
electrical stimulation signals are applied to the heart at the apex of the DMVA Cup. In
such an embodiment, the apical pacemaker is grounded to the patient so that a current
applied thereto does not produce a potential difference, thereby enhancing safety for the
patient.
5. Biochemical/biologic data; such as the following examples: a) blood oxygenation from
an optical oxygen sensor in contact with the myocardium; b) blood glucose from optical
glucose sensors in contact with the myocardium; c) osmolality from an optical
osmolality sensor; d) lactate or lactic acid or other fatigue marker from a fluorescence
probe sensor or near infrared sensor; e) drug uptake, from optical drug sensors in
contact with tissue; and f) molecular markers of cell signaling, cellular stress and
ventricular remodeling, including but not limited to cytokines, parahormones, nitric
oxide, free-oxygen radicals, heat-shock proteins, metalloproteinases and related cellular
substrates.
6. Acoustical data, such as the naturally occurring sounds of the heart and lungs. More
specifically such data may include the following: a) data from microphones in contact
with the heart that detect naturally occurring sounds, such as those sounds generated by
muscle contraction, operation of the valves of the heart, heart murmur/arrhythmia,
laminar or turbulent blood flow within the ventricles or through the heart valves; and the
Si, S2> Sj, and S4 sounds; b) data from microphones in contact with the lung(s) that
detect breath sounds collected for purposes such as monitoring of respiratory rate; c)
data from microphones in contact with the working fluid powering the Cup that detect
sound generated by leaks and partial blockages or kinking; d) data from microphones
that detect the response of tissue to sonic energy introduced into such tissue, such as
ultrasonic energy or Doppler frequency sonic energy detected at microphones in all of
such locations; e) data from microphones that detect sound indicators of device -
cardiac interactions including frictional/abrasive actions, liner separation from the
surface of the heart, and liner-housing contact/separation.
7. Tissue characteristics data, such as the following: a) stiffness, derived from data from
strain gauges in contact with various points on the myocardial surface; b) the extent of
vascularization, derived from data from optical sensors of capillary blood flow in
contact with the myocardium; and c) drug or other therapeutic agent uptake, derived
from data from sensors in the device.
8. Temperature data, such as such as the following: a) temperature of the myocardium,
derived from data from temperature sensors located in contact with the myocardium; b)
temperature of the drive fluid, derived from data from temperature sensors located in
contact with the drive fluid; c) temperature from the lungs derived from data from
temperature sensors located in the portion of the Cup that is in contact with the lung; and
e) core body temperature measurement derived from data from temperature sensors
located on the exterior of the shell wall of the DMVA Cup, or on the fluid drive or
vacuum tubing thereof. Such core body temperature data are particularly useful in the
early detection of infection, and in instances where the DMVA drive fluid is cooled in
order to provide cooling of the myocardium, the brain, and/or the core body temperature.
9. Optical data, such as from optical sensors that detect a) motion, spectral absorption
variation, and/ or refractive index variation produced by the simultaneous introduction
of other forms of energy, such as mechanical energy, e.g., vibration and/ or ultrasound;
b) the response of tissue to optical interrogation with different wavelengths and/ or
combinations of wavelengths of light.
10. Mechanical data, such as the mechanical strain of critical Cup features, e.g., liner and/or
Cup shell flexures.
Invention Aspect 3: DMVA feedback control parameters. The above sensor data can be
used to control DMVA operation and cardiac performance. In the present invention these
parameters preferably include without limitation the following device control parameters, which
will subsequently be described in more detail with reference to Figures 15, 26, and 27:
1. The total volume of fluid delivered to or removed from the Cup liners.
2. Differential volumes of fluid delivered to or removed from the Cup liners (e.g. RV
versus LV).
3. The rate of fluid flow to or from the Cup liners.
4. The pressure with which the fluid is delivered to or removed from the Cup liners.
5. The timing of fluid delivery to or removal from the Cup, relative to such factors as
cardiac electrophysiological rhythm, respiratory cycle, and synchronization between RV
and LV function; and the relationship between such timing and rates of change of fluid
pressure and fluid volume to/from the Cup.
6. The frequency of fluid delivery to or removal from the Cup, relative to such factors as
metabolic demand, respiratory rate, blood oxygenation, and heart rate.
7. The temperature of the fluid delivery to or removal from the Cup, relative to such factors
as myocardial temperature, body temperature, lung temperature, and/or clinical data
from the patient.
8. The electrical pacing of the heart, such as by the physical action of the device on the
heart and/or a pacemaker incorporated into the Cup located at the apex of the heart, or
elsewhere; all of which can be alternated to best suit the condition of the heart.
9. The actuation of other cardiac assist devices, such an intra-aortic balloon assist device.
10. The actuation of respiratory assist devices, such as a respirator.
11. The actuation of alarm circuits, such as to alert the clinical and/or technical staffs of
device malfunction or unacceptable patient responses.
12. The conformational changes of the RV free wall, LV free wall and septum during
systolic and diastolic actuation.
13. The liner-cardiac interactions including linear slippage and separation.
14. The geometric-volumetric and relevant spatial changes in the RV and LV and their
dependent actions on one-another.
15. Volume/geometric changes between the liner and shell.
Invention Aspect 4: DMVA feedback control methods and algorithms. The above
sensor data of invention aspect 2 can be analyzed to control DMVA operation and cardiac
performance in multiple ways including without limitation the following device control
methods and algorithms, some of which will subsequently be described in more detail with
reference to Figures 15,26, and 27.
1. Procedures to verify proper DMVA device installation. This method and algorithm
includes without limitation the ability to a) verify that the Cup is properly seated on and
oriented against the heart; b) verify adequate sealing of the Cup against the heart; c)
verify the absence of excessive volumes of fluid between the Cup liner and
myocardium; d) verify proper systolic and diastolic motion of the heart, including right
and left ventricles and RV-LV interactions; e) verify absence of leaks in the device; f)
verify absence of leaks in the lungs; g) verify normal outflow characteristics of the
heart; and/or h) maintain constant thorax volume to help reduce psychological issues.
2. Method and algorithm to achieve effective RV and LV actuation, including RV and LV
geometric/volume changes. This method and algorithm includes without limitation the
ability to finely control ventricular pressure-volume relationships and conformational
changes of the LV and RV free wall, septum and ventricular cavities over the full range
of cardiac output. Detailed descriptions of embodiments of this method and algorithm
are provided subsequently in this specification, with reference in particular to Figures
1A-1M, 2A-2I,and5B.
3. Method and algorithm to minimize trauma to myocardial tissues. This method and
algorithm includes without limitation the abilities to a) achieve uniform or near uniform
contact force and/or pressure across the liner-myocardium interface to minimize or
eliminate deep bruising, such as that resulting from shear between tissue planes that is
generated by variations in surface pressures on said tissue planes; b) minimize shear
stress at the liner-myocardium interface and at the seal-myocardium interface to avoid
abrasion of myocardial tissues; and c) minimize the LV endocardial-endocardial
contact/trauma as well as reduce the RV-septal herniations and associated abrasions of
these two endocardial surfaces.
4. Method and algorithm to achieve effective compression of the heart during systole, and
effective expansion of the heart during diastole. This method and algorithm includes
without limitation the ability to a) achieve optimal RV-LV filling, emptying,
conformational/geometric changes and related interactions; and b) control the optimum
range of Cup liner position-time profiles during systole and diastole, including the use of
Cup walls with controlled flexibility to provide "elastic recoil" helpful to achieve
effective diastolic action. Detailed descriptions of embodiments of this method and
algorithm are provided subsequently in this specification, with reference in particular to
Figures 1A - 1M, and 2A - 21.
5. Methods and algorithms to help promote natural healing of the heart, including the
following, for which detailed descriptions are provided subsequently in this
specification, with reference in particular to Figures 1A - 1M, 2A - 2F, 26, and 27:
a) Method of complimentary support. This method controls the amount of work
performed on the heart by the DMVA device based upon the amount of work
that the heart is capable of performing on its own. Adjusting compression to
allow cardiac conditioning using compressions for alternate cardiac cycles and
using the un-compressed cycle to analyze the heart's native function and then
adjusting the systolic and diastolic actions in accordance with this learned
information. Such conditioning may occur for time intervals that are dictated by
the heart's subsequent behavior. Evidence of reduced function may indicate the
need for more support while evidence of increased native heart function may
indicate recovery that would permit further reductions in support, and/or longer
conditioning intervals.
The work performed by the DMVA device to achieve required cardiac output
will be related to the pumping ability of the native heart without DMVA
assistance. A severely damaged or totally arrested heart requires more work
from the DMVA device than a heart that was capable of pumping at normal
capacity. The native heart's function will be measured during noncompression/
non-actuating cycles of DMVA support during either intervals of
non-actuation or during 1:2 actuation. DMVA assist can then be provided in a
graduated manner depending on the underlying heart's function. Drive variables
such as timing of actuation and the relative forces applied throughout the DMVA
cycle can be appropriately adjusted to address both overall changes in function as
well as differences in RV vs. LV dysfunction and more specific aspects of
diastolic vs. systolic dysfunction within the cardiac cycle.
In this manner, DMVA forces can be directed to specifically address the
components of RV vs. LV and systolic vs. diastolic dysfunction. Furthermore,
the device can be adjusted over time in accordance to the recovery of myocardial
function, which may differ between the RV and LV and/or between systole vs.
diastole. Appropriate adjustments within the DMVA actuation drive parameters
will respond and optimize the pertinent needs of the heart to improve
conditioning and reduce excessive actuation whenever possible. Trial
conditioning algorithms will be designed in this manner.
In one embodiment of the present invention, fluid flow volume sensors, and/or
fluid flow rate sensors, and/or fluid pressure sensors within the liner and/or drive
assembly supply this information to the control unit, which delivers only enough
fluid to the liners to make up the hemodynamic performance that the heart is
incapable of supplying by itself. In this way, the DMVA device provides
variable heart assistance capable of augmenting heart function as much or as
little as is required to achieve normal cardiac output, thereby enabling the heart
to continue to perform in an effective manner, making it possible for natural
healing mechanisms to continue to operate effectively, and to prevent
deconditioning of the myocardium. Brief periods of inactivation of the Cup, or
even counter-pulsatile flow to recondition and/or challenge the heart, are
possible. Again, use of unassisted intervals or l-to-2 (alternate cycles), l-to-3,1-
to-4 etc., augmented assist cycles will allow periodic assessment of cardiac
function which will dictate tailoring of drive parameters to allow conditioning,
and determination of when DMVA assist can be reduced or possibly removed.
It is to be understood that working fluid pressure and volumetric flow rate can be
measured in many ways. In yet another embodiment of the present invention,
this can include without limitation the measurement of the actual physical
displacement of the liners, physical displacement or movement of drive system
pumps, the energy required to move drive system pumps, etc.
b) Method of synchronous support. This method synchronizes the actuation of the
DMVA device to the heart's natural rhythm, thereby providing a hemodynamic
output in phase with the heart's natural rhythm. Adjustments in compression can
be altered in relation to the electophysiology of the heart to accomplish varied
degrees of cardiac assist. Earlier application offerees will be used when the goal
is to maximally reduce cardiac work and compress the heart prior to its native
contraction. Alternatively, delaying actuating forces in an incremental fashion
will allow the heart to take on a greater degrees of work. These principles will
be applied to both optimization of general DMVA actuation and to the
previously stated aims of conditioning the heart.
c) Method of asynchronous support. This method actuates the DMVA device at a
frequency that is out of phase with heart rhythm. This method is preferable if the
patient's own natural cardiac rhythm is defective, and is used to help the heart
return to a desired cardiac rhythm. In this embodiment, the device can function
as a mechanical pacemaker and "overdrive" the pacing mechanisms of the heart
to achieve a more favorable electrophysiological result, which will serve to
improve overall pump function and aid in recovery aspects of DMVA therapy.
Accordingly, either the use of an integrated electrical pacemaker, or the
principles of the mechanical stimulus of DMVA compression creating an
electrical stimulus, or both, can both play a role depending on which proves to be
more ideal and/or advantageous for the particular set of goals to be achieved by
the DMVA Cup (e.g., improving general pump function, conditioning etc.)
d) Method of training. In a further embodiment of the present invention, Cup liner
inflation/deflation is controlled to provide periodic training episodes. During
this method, lactate, lactic acid, or molecular markers such as cytokines,
parahormones, heat shock proteins, ANP, metalloproteinases, and other fatigue
markers, or markers of muscle strain demonstrated electrophysiologically, are
monitored to allow the heart to be safely challenged without inducing excessive
fatigue in the heart. Alternatively or additionally, the electrogardiographic
output of the patient is monitored, wherein certain EKG characteristics may be
detected, such characteristics being indicative of anoxia of tissue.
e) Method of support coupled with artificial pacing of the heart. This method
synchronizes the actuation of the DMVA device to the cardiac rhythm by
synchronization with artificial pacing, such as with electrical pacing electrodes
incorporated into the Cup, thereby providing a hemodynamic output that is in
phase with the paced heart rhythm.
f) Method of optimal DMVA. This method utilizes electrical stimulation to cause
the heart to contract by an optimal DMVA flow rate.
6. The use of diagnostic methods to help guide DMVA support. Reference may be had
within this specification to Invention Aspects 9 (Recording and Analysis of Sensor
Data), specifically Section 7 (Biochemical data), Section 8 (Temperature data), and
Section 9 (Optical data) for a more detailed description of these methods and algorithms.
7. Methods to verify proper device operation and reliability. Reference may be had within
this specification to Invention Aspect 10, Specific device performance measures
appropriate for sensing, for a more detailed description of methods and algorithms.
8. Methods to use the DMVA device to measure function of the heart. In one embodiment,
this method uses the device to measure change in pressure within the DMVA fluid drive
tubing and/or liner cavity created by heart contraction to determine need for ongoing
DMVA mechanical support or other therapy(s).
Invention Aspect 5: Specific sensor types and sensor locations. Specific sensor types to
obtain DMVA operational data and patient data include the following, which are subsequently
described in more detail in this specification with reference to Figures 6A - 13:
1. Ultrasound sensors
2. Magnetic resonance imaging (MRI) coils
3. Strain gauges
4. Thermometers
5. Accelerometers
6. Pressure transducers
7. Microphone / Sound generator arrays
8. Optical sensor / illuminator arrays: Camera / IR Detectors / Chemical sensors
9. Electrical signal detection
10. Electrical energy delivery electrodes
Specific sensor locations to obtain DMVA operational data and patient data include the
following:
1. In contact with the lung
2. In contact with the heart
3. In contact with the drive line chest entry site
4. In the Cup drive fluid
5. In the wall of the Cup
6. In the membrane of the liner
7. Attached to an externally controlled 3-D motion device free to move within the
mediastinum.
Invention Aspect 6: Contrast agents to enhance sensor sensitivity and specificity. The
minimal dimensions of components of the DMVA device, such as the Cup liner, make such
components difficult to image with ultrasound, MRI, and X-ray imaging procedures. In further
embodiments of the present invention, imaging contrast agents are incorporated into critical
components of the Cup to enhance the images obtained thereof. Such imaging contrast agents
may include ultrasonic contrast agents, magnetic resonance imaging contrast agents, and
radiopaque contrast agents, and are subsequently described in more detail in this specification
with reference to Figure 14.
Invention Aspect 7: Sensor interfaces. The sensors integrated into the DMVA device
can be linked to external data recording, data analysis, and data reporting systems in several
ways, including without limitation the following means:
1. Intra-operatively (i.e. directly through surgical incisions).
2. Percutaneously (i.e. directly through minimally invasive surgical incisions such as a
puncture, or directly through the skin).
3. Telemetrically (i.e. transmission to remotely located receivers located away from the
patient). In this embodiment, the DMVA system contains telemetry means for
transmitting physiological data to internal or external event recorders, or external
receiving means. The telemetry means can include transmission of measurements
directly from the sensors, or transmission to the control unit, which in turn transmits the
desired information. In such an embodiment, the internal event recorder and/or
transmission means may receive their power from the external device collecting the
data, via such means as radio frequency, or optical transmission through tissue.
Invention Aspect 8: User interfaces. The user interfaces used with the present
invention include without limitation the following means to provide information to the health
care professional:
1. Visual displays for anatomical data, as well as the display of hemodynamic data,
functional data, electrophysiological data, biochemical data, acoustical data, and tissue
characteristics, using known methods for visually encoding these parameters.
2. Graphical displays of multivariate data such as ECG traces, electrophysiological maps,
and acoustical signatures, blood pressure-time profiles, etc.
3. Quantitative feedback of scalar measures of parameters such as hemodynamic data,
functional data, electrophysiological data, biochemical data, acoustical data, and tissue
characteristics.
4. As above, but for, tracking and rewarding training progress.
Invention Aspect #9: Sensor data recording and analysis capabilities. Specific data
recording and analysis capabilities of the present invention are dependent upon the type of data
being recorded and analyzed and include the following, to be described subsequently in detail in
this specification with reference in particular to Figures 6A - 15:
1. Image data pertaining to the operation of the DMVA device, and to the assisted heart
contained therein. Image data includes data collected from ultrasound probes, MRI
receive or transmit coils, X-ray images, computed tomography images, or images from
other imaging methods. Image data can be recorded and analyzed to make anatomical
assessments of the heart and DMVA device. More specifically; image data can be
examined to assess the following: a) The fit of the DMVA device (e.g. Cup) to the
heart; b) The motion of the heart walls and chambers under DMVA support; c) Cardiac
right and left ventricular and atrial inputs (e.g. filling effectiveness); d) Cardiac
ventricular and atrial outputs (e.g. cardiac ejection fraction); e) Blood flow rate and
blood flow velocity (e.g. analysis of Doppler ultrasound images), all of which can be
used to predict and optimize the effectiveness of DMVA device operation; f) specific
RV/LV interactions, geometric changes, and/or rate of volume changes; g) functional
assessment of the native heart's performance and the relative effect of the device on
such pump performance; and proper operation and overall reliability of the DMVA
device.
2. Accelerometer data to assess the mechanical motion of critical heart and DMVA device
parameters. Analysis of accelerometers implanted into the DMVA device (e.g. liner
walls) can be analyzed to assess the mechanical motion of critical heart and DMVA
device parameters, including the motion of the heart walls and chambers under DMVA
support, and the motion of the DMVA liners under the control of the Drive Unit, which
can be used to predict and optimize the effectiveness of DMVA device operation, and to
verify proper operation of the DMVA device and therefore the reliability of the device.
3. Data relating to the pressure and flow of DMVA drive fluid, which is correlated with the
performance of the assisted heart contained within the DMVA device. The motion of
the DMVA device working fluid translates directly to the displacement of the heart
walls and chambers. Therefore DMVA device working fluid data can be analyzed to
assess the mechanical motion of the heart walls under DMVA support, which in turn can
be analyzed to estimate cardiac right and left ventricular and atrial inputs (e.g. filling
effectiveness), estimate cardiac right and left ventricular and atrial outputs (e.g. cardiac
ejection fraction), and estimate blood flow rates and velocities. The motion of DMVA
working fluid data can also be used to estimate right and left ventricle blood pressure
through calibration of working fluid flow rate to traditionally obtained blood pressure.
The pressure of the DMVA device working fluid translates directly to the pressure
placed on the heart walls and chambers. DMVA device working fluid pressure can be
recorded from pressure sensors located in the DMVA device working fluid at a point
near the contact with the myocardium, or from pressure-volume data recorded from
within the working fluid pumping system. These data can be analyzed to estimate
pulmonary and systemic blood pressure blood pressure directly, or indirectly through
calibration of fluid pressure to traditionally obtained blood pressure.
4. Blood pressure data that is sensed and recorded directly through the use of traditional
blood pressure measurement sensors incorporated into the DMVA device, such as invivo
pressure sensors or external "cuff-based" sensors. These data can be recorded and
analyzed to provide pulmonary and systemic blood pressure feedback to the DMVA
device.
5. Acoustical data that is collected and analyzed by microphones located externally or on
or within the DMVA device including sounds produced, by the DMVA device and
sounds produced by patient respiration, circulation, and tissue responses, such as the
following: a) sounds such as that generated by blood flow through the aortic valve or
pulmonic valve, which have been shown to correlate with the rate of blood flow through
such valves, and which can be analyzed to estimate the rate of blood flow through such
valves achieved by the DMVA device; b) sounds and/or vibrations such as that
generated by muscle contraction (such as e.g., contraction of the heart or diaphragm
muscle), which can be analyzed with signal processing methods such as fast Fourier
transforms or other suitable techniques to estimate the condition of the muscle and/or
the presence of disease or fatigue; c) sounds such as breath sounds, which can be
analyzed to determine and monitor respiratory rate; d) sounds generated by the DMVA
system, including sounds generated by working fluid leaks, partial blockages or kinking,
which can be analyzed to verify proper operation of the device and to predict and
prevent future device failures; and e) sounds generated by tissues in response to sound
energy introduced into the tissues, such as ultrasound energy or Doppler frequency
sound energy, which can be analyzed to determine distance, shape, velocity, flow,
particle size distribution, and the like. In particular, the well-known first, second, third,
and fourth heart sounds SI, S2, S3, and S4 may be collected by such microphones or
other acoustic detection means and analyzed with appropriate signal processing methods
and algorithms. The use of such heart sounds in diagnosis of cardiovascular conditions
is described in Chapter 7 of the text Essential Cardiology. Principles and Practice. C.
Rosendorf, 2001, the disclosure of which is incorporated herein by reference. In one
embodiment, the geometry of the DMVA Cup of the present invention provides
enhanced ability to measure cardiac sounds by virtue of the isolating effect of the shell
and liner; the density differences between the heart and Cup shell, and Cup shell and
drive fluid; and the approximately parabolic shape of the Cup shell which focuses such
sounds within the shell.
6. Electrophysiological data that can be recorded by sensors located on or within the
DMVA device and in contact with the heart, including the following: a) cardiac rhythm,
rhythm disturbances/dysrhythmias; b) cardiac voltages; c) changes in voltages over
time; d) spatial voltage differences, such as differences obtained by comparisons
between said sensors located at different points on the myocardium; e) temporal voltage
differences, such as differences obtained from single or multiple sensors over time; f)
current within tissues; g) changes in current over time, such as obtained from single or
multiple sensors over time; h) spatial current differences, such as differences obtained
by comparisons between said sensors located at different points on the myocardium; i)
temporal current differences, such as differences obtained from single or multiple
sensors over time; and j) RV/LV electro-mechanical relations. Alternatively, sensors
may be located external to the DMVA device, such as surface-mounted EKG sensors
that are in communication with the DMVA system. The data from these sensors can be
analyzed to assess the electrophysiological performance of the heart and synchronize (or
de-synchronize) the operation of the DMVA device with the electrical rhythm of the
heart.
7. Biochemical/metabolic data acquired, recorded and analyzed from sensors located on or
within the DMVA device and in contact with the myocardium, blood, or other tissues,
include the following: a) measurement of blood oxygenation, such as from an optical
oxygen sensor in contact with the myocardium or blood, which is analyzed to determine
the effectiveness of DMVA pulmonary support; b) measurement of blood glucose, such
as from optical glucose sensors in contact with the myocardium or blood, which is
analyzed to determine the effectiveness with which glucose is delivered to the
myocardium ; c) measurement of tissue osmolality, such as from optical osmolality
sensor, which is analyzed to determine the pH of the myocardium; d) measurement of
tissue lactate or lactic acid, molecular markers of the myocardium including but not
limited to nitric oxide, oxygen free radicals, heat shock proteins, AMP, parahormones,
metalloproteinases or other fatigue markers, which are analyzed to determine the fatigue
characteristics of the myocardium; and e) measurement of drug or other therapeutic
agent uptake, such as from optical drug sensors in contact with tissue, which is analyzed
to determine the concentrations of drugs or other therapeutic agents in the myocardium..
8. Temperature data that can be recorded and analyzed from sensors located on or within
the DMVA device pertaining to the DMVA device, the myocardium, the blood, and/or
the lungs, including the following, a) temperature of the myocardium obtained from
temperature sensors located in contact with the myocardium, which for example can be
analyzed to determine the presence of infection in myocardial tissues; b) temperature of
the drive fluid obtained from temperature sensors located in contact with the drive fluid,
which for example can be used to regulate and monitor the temperature of the
myocardium; and c) temperature of the lungs, such as from temperature sensors located
in the portion of the Cup that is in contact with a lung, which can be used for example to
monitor the temperature at which respiration takes place.
9. Optical data that can be recorded and analyzed from sensors located on or within the
DMVA device pertaining to the DMVA device, the myocardial tissue, and/or the blood,
including the following: a) spectral absorption variation, motion, and/ or refractive
index variation, which can be analyzed for example to determine the extent of
vascularization of myocardial tissues, drug uptake, etc; b) response of tissue to optical
interrogation with different wavelengths and/ or combinations of wavelengths of light,
which can be analyzed for example to determine drug uptake; and c) opto-mechanical
data, such as variations in motion, spectral absorption, and JOT refractive index produced
by the simultaneous introduction of other forms of energy, such as mechanical energy,
such as vibration and/ or ultrasound, which can be analyzed for example to determine
tissue conditions such as e.g., muscular degeneration, including compositional changes
indicated by the presence of fat and/or fibrous tissue, and by the loss of contractility,
elasticity, density, range of motion, and bulk thickness.
10, Strain data obtained from strain gauges in contact with various points on the myocardial
surface that can be analyzed to determine tissue physical characteristics, such as e.g.,
tissue "stiffness".
Invention Aspect 10: Specific device performance measures appropriate for sensing.
Critical DMVA system performance parameters which are indicative of the quality of system
performance and suitable for measurement include the following, to be described subsequently
in detail in this specification with reference in particular to Figures 6A - 15:
1. Differences and/or similarities in RV and LV volumes.
2. Systolic and diastolic volumes.
3. The dynamics of RV and LV compression and decompression.
4. The total volume of fluid delivered to or removed from the Cup liners.
5. Rate and dynamics of ventricular emptying and filling during systolic and diastolic
actuation, respectively, for both the RV and LV; the rate and flow characteristics across
the native cardiac valves; and the conformational changes in the septum and LV and RV
free walls during both systolic and diastolic actuation and the relationship of LV
changes on RV changes as vice-versa. Measurement of the'volume of working fluid
delivered to or removed from the Cup equates directly to displacement of the Cup liners,
and therefore can be used to verify proper systolic and diastolic actuation of the heart.
Differences between the volume of working fluid delivered to or removed from the Cup
liners can also be measured. Differences in fluid delivered to and from the Cup liner
would suggest a leak in the fluid delivery system and reason for immediate corrective
action.
6. The rate of fluid flow to or from the Cup liners. When an incompressible drive fluid is
used in the DMVA device, the rate of fluid flow into or out of the Cup liner equates
directly to the rate of displacement of the Cup liners, which in turn equates directly to
the rate of cardiac output and the volume of such output. Therefore, in such an
embodiment, measurement of working fluid flow rate can be used to verify desired
cardiac volumetric output and pressure thereof.
7. The pressure with which the fluid is delivered to or removed from the Cup liners. The
pressure at which working fluid is delivered to or removed from the Cup liner correlates
with the rate of displacement of the Cup liners which in turn correlates directly with
systolic or diastolic blood pressure. Therefore, measurement of working fluid pressure
can be used to verify and/or infer cardiac blood pressure. Also; a reduction in working
fluid pressure at a given working fluid flow rate could suggest a leak in the fluid
delivery system and reason for immediate corrective action. Also; an increase in
working fluid pressure at a given working fluid flow rate could suggest a potential
obstruction in the fluid delivery system and reason for immediate corrective action, or
could alternatively indicate an increased resistance to pulmonary or aortic blood flow in
the patient, which would also indicate immediate medical action.
8. The energy consumption of the DMVA drive system. Increases in drive system energy
consumption to maintain a constant volume and/or rate of working fluid output could
suggest impending failure of drive unit and/or Cup components and reason for
immediate corrective action. A preferred way of analyzing energy consumption is to
compare the ratio of the product of the drive unit output pressure and volume rate of
working fluid flow to the drive unit input energy, which in one embodiment can be in
the form of the product of drive unit input voltage and current. A decrease in this value
suggests a decrease in system operating efficiency and reason for immediate corrective
action. Alternately an increase in the above ratio indicates an improvement in cardiac
performance, since less energy is required to establish a given level of cardiac output.
9. Working DMVA fluid pressure-volume relationship as a function of time. Since liner
displacement equates directly to cardiac performance, and changes in the actuating
volumes directly relate to displacement of the RV and LV and therefore cardiac output,
measurement of working fluid pressure-volume-time relationships enables prediction of
pump function, and working fluid - RV/LV interactions.
10. Acoustic data generated by the DMVA system. Acoustical data collected from
microphones located on or within the DMVA device can be used to identify early-on
impending failures of Cup and/or drive unit sub-systems and components.
11. The timing of working fluid flow. Measuring the timing of fluid delivery to or removal
from the Cup, relative to cardiac electrophysiological rhythm, enables verification that
the DMVA support is in proper synchronization with heart electrical or mechanical
activity or other patient support devices such as a respirator.
12. The frequency of working fluid flow relative to cardiac rhythm. Measuring the
frequency of fluid delivery to or removal from the Cup, relative to such factors as
respiratory rate, or blood oxygenation, enables verification that the DMVA support is
keeping up with metabolic demand.
13. The temperature of the fluid delivered to and removed from the Cup. Measuring
working fluid temperature ensures that the Cup is maintaining proper myocardial
temperature. It is to be understood that such temperature may be more than or less than
normal temperatures, and that the temperature of the drive fluid may be controlled in
such a manner as to control the temperature of the patient. '
14. The mechanical strain of critical Cup features. Measurement of the strain of critical
features of the Cup, such as liner flexure points, can be used to predict future device
failures well in advance of their occurrence, and therefore enable action to be taken to
avoid the effects of such failures. Alternatively, redundant liners may be used to prevent
the effect of a single membrane liner failure.
15. Leakage of body fluids into the Cup. Measurement of the flow of body fluid into the
Cup, such as between the Cup liner and myocardial tissues, provides an indication of the
failure of the Cup seal, which can adversely affect the systolic and diastolic actuation
provided by the Cup. A preferred means to measure this flow is to measure the flow of
fluid through the drain (vacuum port) in the Cup. Analysis of any fluid collected
enables determination of the source thereof, and whether related medical action is
needed.
In summary, therefore, the DMVA device of the present invention in its numerous
smbodiments is a device that provides mechanical assistance to the ventricles of the heart,
comprising electronic digital and/or analog and/or image sensing means to sense operational
parameters thereof or of the myocardium; data acquisition means to acquire data on such
parameters; computing means to analyze such parametric data, and to derive and/or select
algorithms to control to drive fluid volume and/or pressure of the drive fluid thereof, thereby
controlling the driving of the ventricles of the heart. With regard to physical structure, the
DMVA device of the present invention in its numerous embodiments comprises an integrated
drive system that controls the pressure and/or flow rate of drive fluid delivered thereto and
withdrawn therefrom, and a shell and liner which contact and displace the ventricles of the heart
in an atraumatic manner, i.e. a manner that does not cause trauma to the tissue of the heart.
The DMVA device of the present invention will now be described in detail, with
reference to Figures 1A - 29. This description will begin with a description of the systolic and
diastolic cycles of a healthy human heart, the systolic and diastolic cycles of an unhealthy
human heart (of which there are many variants), and in general, how the DMVA device of the
present invention provides assistance to an unhealthy human heart, such that on a short time
scale, such heart is assisted in providing life sustaining circulatory function. In a subsequent
description in this specification, the manner in which the DMVA device of the present
invention provides assistance to an unhealthy human heart on a long time scale according to
various algorithms is provided. In some embodiments, such assistance entails the delivery of
therapeutic drugs or other therapeutic agents, and/or cardiac regeneration agents, such that the
heart is assisted in an overall healing process and is restored to a state in which DMVA is no
longer required. Such therapeutic agents include but are not limited to anti-inflammatory
agents, gene therapy agents, gene transfer agents, stem cells, chemo-attractants, cell
regeneration agents, ventricular remodeling agents, anti-infection agents, tumor suppressants,
tissue and/or cell engineering agents, imaging contrast agents, tissue staining agents, nutrients,
and mixtures thereof.
It is to be understood that the Figures 1A - 1M, which depict time-dependent volumes,
pressures, and flow rates of blood displaced by the ventricles of DMVA-assisted and nonassisted
hearts are illustrative in nature, and are not meant to indicate precise quantitative values
thereof, nor the sole beneficial functions thereof. It is to be further understood that
representations of such parameters with respect to an "unhealthy heart" are also illustrative in
nature, and may vary widely, depending upon the particular cardiac disorder that is affecting
such unhealthy heart, which can vary from incremental degrees of worsening dysfunction to
cardiac standstill ("cardiac arrest"). . Accordingly, the particular representations of DMVA
assistance to such examplary unhealthy hearts are to be taken as one embodiment of assistance
thereto, and that many other time dependent pressure, volume, and/or flow rate curves and
resulting mechanical assistance can be provided by the DMVA device to such unhealthy or even
non-beating hearts, which may be equally or more beneficial. A key attribute of the DMVA
device of the present invention is the capability thereof to sense the performance of the heart
and the performance of the device itself, and with embedded algorithms in the control system
thereof, to select and execute a beneficial sequence of assistive actions to the heart to which it is
fitted.
In the following description of Figures 1A - 1M, references to ventricular volume are
taken with respect to the blood volume contained within the ventricles, rather than blood
volume displaced from the ventricles. Thus it will be apparent that blood volume in the
ventricles is shown to decrease to a minimum at the completion of systole, and to increase to a
maximum at the completion of diastole. Blood pressure is to be considered from a frame of
reference within the ventricles unless noted otherwise. Also with regard to Figures 1A - 1M
and in various subsequent Figures, the use of the upper case letter "S" is meant to indicate
systole, and the use of the upper case "D" is meant to indicate diastole.
Figures 1A - 1H are graphical representations of time dependent pressure and volume
relationships of blood displaced by the left and right ventricles of a healthy human heart, of an
unhealthy human heart, and of a DMVA-assisted heart during systole and diastole. Figure 1A
in particular is a representation of the time dependence of the volume of the left ventricle during
one complete cardiac cycle including systole (S) and diastole (D), for a normal healthy heart and
for one embodiment of a DMVA-assisted heart. Referring to Figure 1 A, there is depicted the
time dependent left ventricular volume curve 2020 (solid line) for a healthy heart, and the time
dependent left ventricular volume curve 1020 (dashed line) for one embodiment of a DMVAassisted
heart, illustrated in general in Figures 2A - 21 and subsequently described in this
specification.
Several preferred features of the DMVA apparatus and method of the present invention
are illustrated in curve 1020 of Figure 1A. In the preferred embodiment, the DMVA Cup is
fitted to the heart such that the end diastolic volume 1022 of the DMVA assisted heart is
slightly less (by volume difference 1023) than the end diastolic volume 2022 of a normal heart.
In this manner, an enlarged heart to which the DMVA device is fitted is favorably constrained
or "girdled" from its otherwise dilated geometry and appropriately supported. Although, the
normal heart is somewhat constrained by such fitting of the device, additional systolic and
diastolic actuation compensate for such decreases in end-diastolic volume during the course of
DMVA assistance resulting in stroke volume similar to the normal state. The overall coupling
and response of the heart to DMVA assistance is enhanced.
Another preferred feature of the DMVA apparatus and method is the ability thereof to
compress the left ventricle to a lesser end systolic volume 1024 than the normal heart LV endsystolic
volume 2024. Thus, although in one embodiment, the cardiac cycle in DMVA
assistance begins at a lower LV end diastolic volume 1022, it achieves a correspondingly lower
LV end systolic volume 1024, so that the total blood volume displaced from the left and right
ventricles (stroke volume) is comparable to that of a normal heart. In spite of this further
compression of the heart by one embodiment of the DMVA device, such device achieves the
compression in a manner that does not significantly bruise of abrade the heart, as will be
described subsequently in this specification.
In the embodiment depicted in Figure 1A, the DMVA device achieves end-systolic
volume 1024 at a time 1026 of the actuating cycle slightly later than the time 2026 of a normal.
heart's cardiac cycle. And, the DMVA device ensures adequate LV compression by such
relative increases in this portion of the actuating cycle. Thus, in order to achieve adequate
diastolic filling, and achieve such filling within the remaining time of the actuating cycle, the
DMVA device is operated such that it provides active assistance to the heart in diastole. Such
active assistance is indicated by the steeper slope 1028 (change in volume/change in time or
dV/dt) of the DMVA-assisted LV volume curve 1020, compared to the slope 2028 of the
normal heart LV volume curve 2020. Such assistance is notably important to overcome such
forces that otherwise impair diastolic filling and constrain end-diastolic geometry as seen with
related devices. The sensors, control algorithms, and numerous structural features such as the
Cup shell, liner, and seal of the DMVA device that are described subsequently in this
specification enable this active assistance capability.
Such sensors, algorithms, and features enable the DMVA device and method to be
adapted as required to provide assistance to an unhealthy heart in a manner that is optimal for
the particular disorder afflicting such heart. Figure IB is a representation of the time
dependence of the volume of the left ventricle during one complete cardiac cycle including
systole (S) and diastole (D), for a normal healthy heart, for another embodiment of a DMVAassisted
heart, wherein such heart is unhealthy and in a distended condition such as the heart
depicted in Figures 2P - 2R and described subsequently in this specification. Referring to
Figure IB, curve 3030 (dotted line) represents the left ventricular volume of the unhealthy heart
during a cardiac cycle, as compared to the LV curve 2020 (solid line) for a normal heart. It will
be apparent that there is a substantial difference 3031 between the end diastolic volume 2022 of
a healthy heart, and the end diastolic volume 3032 of the unhealthy, dilated heart in Figure IB.
It will be further apparent that the volumetric output of such an unhealthy heart is much less
than a normal heart, as indicated by the difference 3033 between the end systolic volumes
thereof.
Curve 1030 (dashed line) depicts the LV volume of the assisted unhealthy heart, which
is provided assistance by the DMVA device. The DMVA device is fitted and programmed to
operate at a lesser end diastolic volume 1032 than the end diastolic volume 3032 of the
unhealthy heart, which benefits the unhealthy heart by reducing myocardial stretch and/or wall
tension. The embodiment depicted in Figure IB, illustrates that DMVA support of the
unhealthy, dilated heart operates at a higher end diastolic volume than the end diastolic volume
2022 of an otherwise normal beating heart without DMVA assist. Ventricular remodeling
during assistance may allow the DMVA assisted heart to achieve lower end-diastolic volumes
that may benefit the heart by improving its chance for recovery. However, in any event, the
DMVA assisted heart can achieve end systolic volume(s) 1034 that are significantly less than
the end systolic volume(s) 3034 of the unhealthy unassisted heart in order to effectively
improve stroke volume and improve total cardiac output. Thus a substantial difference in
output between the unhealthy heart and the assisted heart is achieved, as indicated by the
relative area 1035 between curves 1030 and 3030. It will be apparent that the net stroke volume
output of the assisted heart is approximately the same as that of a healthy heart and can be
varied by adjustments in drive dynamics as deemed appropriate to both minimize myocardial
stress and achieve optimal ventricular dynamics. Adjustments in cycle rate can be further
adjusted to effect overall cardiac output as dictated by physiologic needs of the body. This
output is achieved while "tailoring" the fit and operation of the DMVA device to the particular
unhealthy heart in a manner that does not damage such heart while providing assistance thereto.
In the embodiment depicted in Figure IB, the unhealthy heart is provided with active assistance
during systole and diastole, as indicated by the relatively steep slopes 1037 and 1038,
respectively, of curve 1030 as compared to the relatively gradual slopes 3037 and 3038,
respectively of curve 3030 for the unassisted unhealthy heart.
Figure 1C is a representation of the time dependence of the volumetric changes of the
right ventricle during one complete cardiac cycle for a normal healthy heart and for one
embodiment of a DMVA-assisted heart. Referring to Figure 1C, there is depicted the time
dependent right ventricular volume curve 2040 (solid line) for a healthy heart, and the time
dependent right ventricular volume curve 1040 (dashed line) for one embodiment of a DMVAassisted
heart, illustrated in general in Figures 2A - 21 and subsequently described in this
specification.
In the DMVA embodiment depicted in Figure 1C, some similar preferred features are
illustrated in curve 1040, as were depicted in curve 1020 of Figure 1A. In the preferred
embodiment, the volume of the DMVA Cup and the displacement of the liner therein are fit
such that the RV end diastolic volume 1042 of the DMVA assisted heart is slightly less (by
volume difference 1043) than the RV end diastolic volume 2042 of a normal heart, as for the
LV end diastolic volumes 1022 and 2022 of Figure 1 A. Additionally, the DMVA apparatus has
the ability thereof to compress the right ventricle to a lesser end systolic volume 1044 than the
normal heart RV end systolic volume 2044. Thus as in Figure 1A, although the cardiac cycle in
DMVA assistance begins at a lower RV end diastolic volume 1042, it achieves a
correspondingly lower RV end systolic volume 1044, so that the total blood volume displaced
from the right ventricle is comparable to that of a normal heart.
In the embodiment depicted in Figures 1A and 1C, the timing of DMVA assisted
systolic action of the right ventricle differs from that of the left ventricle. Such a DMVA
embodiment is driven by a single fluid source and comprises a single cavity within the Cup.
Hence the liner therein is subjected to a single fluid pressure source uniformly distributed over
the surface thereof, and hence simultaneously over the surface of the RV and LV walls. In
general (although exact circumstances will vary depending upon the particular disorder of the
unhealthy heart), because of the relative timing of the tricuspid and mitral valve closings and
pulmonary and aortic valve openings, and because the nominal pulmonary blood pressure is
substantially lower compared to the nominal aortic blood pressure, and the RV free-wall is
generally less resistant than the LV free wall to such forces, the right ventricle will yield and
compress before the left ventricle and to a greater extent, as depicted in Figure 2C.
Thus, as indicated by the sequence of Figures 2A - 2G, the systolic actuation and
corresponding displacement of blood from the right ventricle begins substantially in advance of
and is completed before the corresponding displacement of blood from the left ventricle. In the
embodiment depicted in Figures 1C and 1A, systolic actuation of the right ventricle is relatively
complete at a time 1046 that is substantially earlier and/or more rapid than the normal RV
ejection time that comparatively ends at time 2046. The overall time for RV ejection is thereby
relatively abbreviated. During the time interval 1049 required to complete DMVA assisted
systole for the left ventricle and to begin diastole, the right ventricular free wall is squeezed,
fixed and maintained in a position with the septum at a relatively constant end systolic volume
1044.
Subsequently, active diastolic assistance is provided to the right ventricle, as for the left
ventricle assistance described and shown in Figure 1A. It will be apparent that the slope 1048
(change in volume/change in time or dV/dt) of curve 1040 for the DMVA assisted heart is
generally steeper than the corresponding slope 2048 of curve 2040 for the normal heart for right
ventricular diastolic actuation, as was previously noted for the left ventricular diastolic
actuation.
Figure ID is a representation of the time dependence of the volume of the right ventricle
during one complete cardiac cycle for a normal healthy heart (curve 2040, solid line), and for an
embodiment of a DMVA-assisted heart, wherein such heart is unhealthy (curve 1040, dashed
line). Referring to Figure ID, curve 3040 (dotted line) represents the right ventricular volume
of the unhealthy heart during a cardiac cycle, as compared to the RV curve 2040 for a normal
heart. It will be apparent that the volumetric output of such an unhealthy heart is much less than
a normal heart, as indicated by the difference 3043 between the end systolic volumes thereof.
Curve 1040 depicts the RV volume of the assisted unhealthy heart, which is provided
assistance by the DMVA device. In the embodiment depicted in Figure ID, the DMVA device
is fitted and programmed to operate at a slightly lesser end diastolic volume 1042 than the end
diastolic volume 3042 of the unhealthy heart. As with the LV, such reductions in end-diastolic
volumes benefit the heart by reducing diastolic stretch of the heart muscle and improve the
opportunity for healing. However, the DMVA assisted heart can achieve end systolic volumes
1044 that are significantly less than the end systolic volume 3044 of the unhealthy unassisted
heart in order to obtain an adequate stroke volume. Thus a substantial difference in output
between the unhealthy heart and the assisted heart is achieved, as indicated by the difference
1045 between end systolic volumes 1044 and 3044. In the embodiment depicted in Figure ID,
the end systolic volume 1044 of the DMVA assisted heart is less than the end systolic volume
2044 of a normal heart; however in other embodiments, the DMVA device is programmed to
substantially match the end diastolic volume 2042 (see Figure 1C) and the end systolic volume
2044 of a healthy heart, such that the net RV blood volume output of the assisted heart is
approximately the same as that of a healthy heart. This output is achieved while "tailoring" the
fit and operation of the DMVA device to the particular unhealthy heart in a manner that does
not damage such heart while providing assistance thereto. In the embodiment depicted in
Figure ID, the unhealthy heart is provided with active assistance during systole and diastole, as
indicated by the relatively steep slopes 1047 and 1048 as compared to the relatively weak slopes
3047 and 3048 of curve 3040 for the unassisted unhealthy heart.
Figure IE is a representation of the time dependence of the blood pressure within the left
ventricle during one complete cardiac cycle for a normal healthy heart and for one embodiment
of a DMVA-assisted heart. The curve representing the DMVA assisted heart is "shifted"
slightly to the right for the purpose of illustrating general differences in these two cycles.
However, DMVA assistance of the heart would optimalJy begin before natural contraction of
the heart to reduce the work of the heart. With this understanding, Figure IE depicts the time
dependent left ventricular pressure curve 2050 for a healthy heart (solid line), and the time
dependent left ventricular pressure curve 1050 (dashed line) for one embodiment of a DMVAassisted
heart, illustrated in general in Figures 2A - 21 and subsequently described in this
specification. In the preferred embodiment, the DMVA Cup is fitted to the heart, with the
displacement of the liner therein such that the very early diastolic pressure 1052 of the DMVA
assisted heart may be slightly less than the very early diastolic pressure 2052 of a normal heart.
(However this is not shown in pressure difference 1053.) The end-diastolic pressures are
however increased (as illustrated in pressure difference 1053) which reflects the fit of the
DMVA device and its physical effect on ventricular pressures in the normal heart. In this
manner however, an enlarged heart to which the DMVA device is fitted is constrained and
supported; and an un-enlarged heart is prevented from undesired enlargement as was described
for Figure 1 A.
Another preferred feature of the DMVA apparatus and method is the ability thereof to
pressurize the left ventricle to a greater peak systolic pressure 1054 than the normal heart LV
maximum systolic pressure 2054. Yet another preferred feature is the ability to attain greater
relative increases and decreases in pressure (dP/dt) as indicated by slopes 1056 and 1058
respectively, when compared to those of a healthy heart. Such capabilities enable the DMVA
device to be more effectively matched to the requirements of the particular unhealthy heart
needing assistance but are also adjusted to the lowest incremental rise required in order to
reduce the likelihood of cardiac injury. The DMVA apparatus of the present invention is thus
atraumatic with respect to the heart.
Figure IF is a representation of the time dependence of the pressure of the left ventricle
during one complete cardiac cycle for a normal healthy heart, and for an embodiment of a
DMVA-assisted heart, wherein such heart is unhealthy. Referring to Figure IF, curve 3050
(dotted line) represents the left ventricular pressure of the unhealthy heart during a cardiac
cycle, as compared to the LV curve 2050 (solid line) for a normal heart. It will be apparent that
the LV pressure of such an unhealthy heart is much less than a normal heart, as indicated by the
difference 3053 between the peak systolic pressures thereof. Curve 1050 (dashed line) depicts
the LV pressure of the assisted unhealthy heart, which is provided assistance by the DMVA
device.
In the embodiment depicted in Figure IF, the DMVA device is fitted and programmed
to operate at a lower diastolic pressures 1052 than the diastolic pressure 3052 of the unhealthy
heart. Although not shown in Figure IF, the DMVA device has the further ability to reduce
early diastolic pressures even below that of the normal healthy heart by virtue of diastolic
actuation. Additionally, the DMVA assisted heart achieves a peak systolic pressure 1054 that is
significantly greater than the peak systolic pressure 3054 of the unhealthy unassisted heart.
Furthermore, a substantial difference in pressure between the unhealthy heart and the assisted
heart is maintained for a greater portion of the cardiac cycle, as indicated by the region 1055
between pressure curves 1050 and 3050. This is followed by a more rapid decrease in pressure
(dP/dt) as indicated by slope 1058 of curve 1050. Thus, in the embodiment depicted in Figure
IF, the unhealthy heart is provided with active assistance during systole and diastole, as
indicated by the relatively steep slopes 1056 and 1058 as compared to the relatively weak slopes
3056 and 3058 of curve 3050 for the unassisted unhealthy heart. As indicated previously, such
values of dP/dt for the DMVA assisted heart, while significantly greater (i.e. steeper in slope)
than those of an unassisted unhealthy heart, they are adjusted to be somewhat more approximate
to the overall characteristics of those for a healthy heart.
Figure 1G is a representation of the time dependence of the blood pressure within the
right ventricle during one complete cardiac cycle for a normal healthy heart and for one
embodiment of a DMVA-assisted heart. Referring to Figure 1G, there is depicted the time
dependent right ventricular pressure curve 2060 (solid line) for a healthy heart, and the time
dependent right ventricular pressure curve 1060 (dashed line) for one embodiment of a DMVAassisted
heart, illustrated in general in Figures 2A - 21 and subsequently described in this
specification. In the preferred embodiment, the DMVA Cup is fitted to the heart, and the
displacement of the liner therein is controlled such that the RV diastolic pressure 1062 of the
DMVA assisted heart is slightly greater (by pressure difference 1063) than the RV diastolic
pressure 2062 of a normal heart. Again, as with the LV and not shown in this figure is the
ability of DMVA to achieve early diastolic pressures that are actually lower that the normal
beating heart which reflects the devices pronounced capability to augment diastolic filling.
Another feature of the DMVA apparatus and method is the production of pressure in the
right ventricle to a greater peak systolic pressure 1064 than the normal heart RV maximum
systolic pressure 2064. It can be seen that the pressure difference 1065 between these peak
systolic pressures is greater than the corresponding difference 1057 between the peak systolic
pressure 1054 of the assisted heart and the peak systolic pressure 2054 of the normal heart (see
Figure IE). This greater difference is due to the additional pressure needed to displace blood
from the left ventricle. Such an increased pressure, which is provided by the DMVA fluid drive
system, occurs during the time that the RV is nearly fully compressed by the action of the
DMVA device. Thus the higher peak systolic pressures 1064 of the DMVA assisted heart are
reflected into the pulmonary circulation and do not produce an increase in pulmonary blood
pressure within the patient.
Figure 1H is a representation of the time dependence of the pressure of the right
ventricle during one complete cardiac cycle for a normal healthy heart, and for an embodiment
of a DMVA-assisted heart, wherein such heart is unhealthy. Referring to Figure 1H, curve 3060
(dotted line) represents the right ventricular pressure of the unhealthy heart during a cardiac
cycle, as compared to the RV curve 2060 (solid line) for a normal heart. It will be apparent that
the RV systolic pressure of such an unhealthy heart is much less than a normal heart, as
indicated by the difference 3063 between the peak systolic pressures thereof. Curve 1060
(dashed line) depicts the RV pressure of the assisted unhealthy heart, which is provided
assistance by the DMVA device and it should be noted again that the early diastolic pressures
can be less than that of the normal beating heart (not shown) by virtue of the ability of DMVA
to actuate the heart into a diastolic configuration and thereby assist in early diastolic filling.
In the embodiment depicted in Figure 1H, the DMVA device is fitted and programmed
to operate at a lower early diastolic pressure 1062 than the early diastolic pressure 3062 of the
unhealthy heart. However, the DMVA assisted heart achieves a peak RV systolic pressure 1064
that is significantly greater than the peak RV systolic pressure 3064 of the unhealthy unassisted
heart. Additionally, a substantial difference in pressure between the unhealthy heart and the
assisted heart is maintained for a greater portion of the cardiac cycle, as indicated by the region
1065 between systolic pressure curves 1060 and 3060. This is followed by a more rapid
decrease in pressure (dP/dt) as indicated by slope 1068 of curve 1060. Thus, in the embodiment
depicted in Figure 1H, the unhealthy heart is provided with active assistance during systole and
diastole, as indicated by the relatively steep slopes 1066 and 1068 as compared to the relatively
weak slopes 3066 and 3068 of curve 3060 for the unassisted unhealthy heart. As indicated
previously, such values of dP/dt for the DMVA assisted heart, while significantly greater (i.e.
steeper in slope) than those of an unassisted unhealthy heart, are more closely representative of
those for a healthy heart.
Figures II - 1J are graphical representations of time dependent blood pressure within the
left and right ventricles of a healthy human heart, and of a DMVA-assisted heart during systolic
and diastolic actuation. Referring to Figure II, which depicts the left ventricle pressure 2050
(solid line) and the right ventricle pressure 2060 (dash/double-dot line) for a healthy heart on
the same time axis, it can be seen that the peak systolic pressure 2054 of the left ventricle is
considerably higher than the peak systolic pressure 2064 of the right ventricle. It can also be
seen that there is typically a small time difference 2055 between the occurrence of the peak
systolic pressure 2054 of the left ventricle and the peak systolic pressure 2064 of the right
ventricle.
Figure 1J depicts the left ventricle pressure 1050 (dashed line) and the right ventricle
pressure 1060 (dash/dot line) of a heart assisted by one embodiment of the DMVA apparatus.
Referring to Figure 1J, it can be seen that pressure increases occur approximately
simultaneously, since the DMVA drive fluid is applying the same uniform pressure through the
action of the liner therein to both ventricles. Accordingly, the peak systolic pressures 1054 of
the left ventricle and 1064 of the right ventricle occur at approximately the same time.
Therefore, the overall pressure rise of the RV is shifted to the left compared to the normal
beating heart. It will also be apparent the peak systolic pressure 1054 of the left ventricle is
considerably higher than the peak systolic pressure 1064 of the right ventricle, as a consequence
of the higher pressure needed for systemic circulation as compared to pulmonary circulation. It
can also be seen that the minimum right ventricle diastolic pressure 1061 is substantially lower
than the corresponding minimum left ventricle diastolic pressure 1051. In some circumstances
wherein particularly vigorous diastolic assistance is required, minimum right ventricle diastolic
pressure 1061 may even become slightly sub-atmospheric.
With regard to Figures II and 1J, it is to be understood that there is no intent that such
Figures are depicted on the same time scale, and that the cardiac cycle of a DMVA assisted
' heart occurs on approximately the same time scale as for the cardiac cycle of a normal heart.
Figures IK- IL are graphical representations of time dependent blood flow rates ejected
from the left and right ventricles of a healthy human heart, and of a DMVA-assisted heart
during systole. Referring to Figure IK, which depicts the blood flow rate 2070 (solid line)
ejected from the left ventricle and the blood flow rate 2080 (dash/double-dot line) ejected from
the right ventricle for a healthy heart on the same time axis, it can be seen that the ejections are
nearly concurrent, with the peak flow 2072 from the left ventricle preceding the peak flow 2082
from the right ventricle by a small interval 2083. It can also be seen that the flow for the right
ventricle occurs over a somewhat longer time interval, and that the area 2075 representing the
total volume displaced from the left ventricle is approximately equal to the area 2085
representing the total volume displaced from the right ventricle, since the volume of systemic
circulation is approximately equal to the volume of pulmonary circulation, with some variation
due to the physiologic shunting of blood. It is also noted that these relationships will vary in
accordance with different cardiovascular disease states.
Figure 1L depicts the blood flow rate 1070 ejected from the left ventricle and the blood
flow rate 1080 ejected from the right ventricle of a heart assisted by one embodiment of the
DMVA apparatus. Referring to Figure 1L, it can be seen that the ejections are not concurrent,
but that the ejections overlap to some degree. The peak flow 1082 from the right ventricle
precedes the peak flow 1072 from the left ventricle by interval 1083. It can also be seen that,
unlike the function of a normal heart, the majority of flow from the left ventricle occurs over a
somewhat shorter time interval, but like that of the normal heart, the area 1085 representing the
total volume displaced from the right ventricle is approximately equal to the area 1075
representing the total volume displaced from the left ventricle. Thus the volume of systemic
circulation is approximately equal to the volume of pulmonary circulation in a DMVA assisted
heart with appropriate small variations according to physiologic shunts. Again, it should also
be understood that these relationships will vary in accordance with different cardiovasucalar
disease states
With regard to the timing of blood flows of the DMVA assisted heart, it can be seen by
reference to Figures 2A - 21 (to be subsequently explained in detail in this specification) that the
DMVA apparatus compresses and empties the right ventricle prior to the time at which such
apparatus compresses and empties the left ventricle and in a relatively abbreviated time span
within any given comparative cycle rate when contrasted to the normal beating heart. As
previously explained, the precedence of the right ventricle is due to the timing of the pulmonary
and aortic valve openings, and because the nominal pulmonary blood pressure is lower
compared to the nominal aortic blood pressure and also due to the generally less resistant, thin
RV wall when compared to the thicker LV free wall and septum.
Figure 1M is a graphical representation of time dependent blood flow rates into and out
of the ventricles of the heart assisted by a DMVA device taken over a sequence of two complete
cardiac cycles. Referring to Figure 1M, there is depicted an overall left ventricle flow plot 1098
(dashed line) and an overall right ventricle flow plot 1099 (solid line) for two cycles. Left
ventricle flow plot 1098 comprises curves 1070 (dashed line, one per cycle) during systole, and
right ventricle flow plot 1099 comprises curves 1080 (solid line, one per cycle) during systole,
each with flow out of the ventricle being taken as a positive value. Left ventricle flow plot 1098
further comprises curves 1079 (dashed line, one per cycle) during diastole, and right ventricle
flow plot 1099 comprises curves 1089 (solid line, one per cycle) during diastole, each with flow
out of the ventricle being taken as a negative value.
It is to be understood that plots 1098 and 1099 of Figure 1M are for general illustrative
purposes only, and that interpretation of details thereof are not intended to be taken as limiting.
For example, the sharp reversals of flow depicted at the apices of curves 1070, 1080, 1079, and
1089 occur in practice as smooth, curved transitions when the time line is expanded or the
recordings are made with a greater speed. In addition, there may be a pause of relatively greater
duration than indicated between the completion of ventricular filling, and the next cycle of
ventricular emptying which are dictated by adjustments in the drive dynamics used to operate
the DMVA device. In general, the time scale of a DMVA assisted cardiac cycle is between
about 0.5 and 1.0 seconds (120 - 60 beats per minute). And, such variations in cycle rates will
result in relative changes in the pressure and flow characteristics. However, it is to be
understood that all of these variables, as well as many others are fully controllable in
accordance with the present invention.
Referring again to Figure IM, it can be seen that the ejections of blood from the right
and left ventricles are not concurrent, but that such ejections do overlap to some degree, as
depicted in Figure 1L. Although, during the embodiment of DMVA-assistance depicted in
Figure IM, the filling of the left and right ventricles are substantially concurrent, as a
consequence of the attachment of the liner of the DMVA device to the ventricular epicardium,
and the nearly simultaneous openings of the tricuspid and mitral valves, the DMVA device can
be adjusted to create more rapid filling in the early part of diastolic actuation such that the
filling of the right and left ventricles would be even more facilitated in the early part of diastolic
actuation. In certain circumstances, this may be advantageous, as it enables the controller to
utilize more time in systolic compression if these were for example required to more
appropriately compress the ventricles in the later half of the cycle. The converse is also true:
that is the controller could effectively empty the ventricles more rapidly, and based on the
evaluation of the pressure and flow curves, thereby dedicate more time to diastolic actuation to
ensure adequate filling. All of these adjustments require the evaluation of the resultant RV and
LV volumes to ensure appropriate filling and emptying of the ventricles in each half of the
cycle.
In one embodiment to be described subsequently in this specification, the ventricular
emptying and ventricular filling blood flows are inferred from a sensor in the DMVA device,
which measures the flow of drive fluid delivered to and from such device. In another
embodiment, such flows are detected by sensors in the pulmonary artery (RV) and descending
aorta (LV). (In the latter case, correction factors must be applied to account for blood flow out
of the brachiocephalic, left common carotid, and left subclavian arteries;
Figures 2A - 21 are cross-sectional schematic views depicting a sequence of actions of
DMVA device of the present invention on a heart, which assists the systolic and diastolic
functions thereof depicted graphically in Figures 1A - 1M. For the sake of simplicity of
illustration, only the ventricular portion of the heart that is contained in the DMVA Cup is
shown in Figures 2A - 21; the atria and valves are not shown, with it being understood that such
portions of the heart remain functional as commonly understood. Also for the sake of simplicity
of illustration, the liner of the DMVA Cup, which displaces the ventricles to perform systolic
and diastolic actuation, is shown as a simple membrane joined to the Cup shell wall. It is to be
understood that numerous other liner embodiments of the present invention, as described and
shown in this specification, are to be considered within the scope of the description of Figures
2A-2I.
Figure 2A is a cross-sectional elevation view of a heart in an uncompressed state
contained within the DMVA Cup prior to the beginning of systolic compression, and Figure
is a top cross sectional view taken along line 2B-2B of Figure 2A. The relative timing of the
situation of Figure 2A in the cardiac cycle is shown by arrow 2A of Figure 1L. Referring to
Figures 2A and 2B, heart 30 comprising left ventricle 32 and right ventricle 34 is contained and
secured within DMVA cup 100 by the action of vacuum drawn from tube 111 and by seal 113.
DMVA Cup 100 further comprises a housing 110 with dynamic properties formed by wall 112,
and elastic liner 114 attached to wall 112. In operation, a drive fluid is used to displace liner
114, with liner 114 preferably being of unitary construction, comprising a left portion 116 and a
right portion 118. Such drive fluid displaces a continuous annular cavity between liner 114 and
the inner surface of shell wall 112. Such annular cavity comprises a left cavity portion 117 (see
Figure 2C) and a right cavity portion 119 (see Figure 2C). Thus the ventricular chambers of the
heart are circumferentially compressed with the left ventricular free wall 33 of heart 30 being
displaced by the left liner portion 116, and the right ventricular free wall 33 of heart 30 being
displaced by right liner portion 118.
Figure 2C is a cross-sectional elevation view of a heart contained within the DMVA
Cup early in the process of systolic compression, approximately at the time indicated by arrow
2C of Figure IL. Referring to Figure 2C, DMVA drive fluid is delivered into a supply port (not
shown) in shell wall 112 and displaces liner 114, accumulating in cavity portion 119. The early
displacement of liner 114 predominantly compresses right ventricular wall 35 of the heart 30,
causing blood to flow from right ventricle 34 as indicated in Figure IL and described
previously. It can be seen in Figure 2C that although left ventricle wall 33 has been displaced
slightly by liner portion 116, intraventricular septum 31 has also been displaced toward right
ventricle 34. Accordingly, left ventricle 32 has not exhibited any volume reduction by DMVA
drive fluid, and blood flow from left ventricle 32 has therefore not begun, also indicated at time
2C of Figure IL.
Figure 2D is a cross-sectional elevation view of a heart contained within the DMVA
Cup at roughly the mid-point of systolic compression, and Figure 2E is a top cross sectional
view taken along line 2E-2E of Figure 2D, approximately at the time indicated by arrow 2D of
Figure 1L. Referring to Figures 2D and 2E, DMVA drive fluid continues to flow into a supply
port (not shown) in shell wall 112 into cavity portions 117 and 119, further displacing right
ventricular wall 33 and left ventricular wall 35 of heart 30. It can be seen that left liner portion
116 provides compression forces on the left ventricular wall 33 of heart that lead to the
reduction of the volume of left ventricle 32. Accordingly, blood flows concurrently from right
ventricle 34 and left ventricle 32 as indicated in Figure IL and described previously.
It can also be seen that in the preferred embodiment, the DMVA apparatus of the present
invention applies a force uniformly to the heart around the circumference thereof, such that the
heart is compressed in a manner that renders the heart with a substantially circular cross section
and with a minimum diameter at the plane defined by line 2E-2E of Figure 2D, and at the plane
defined by line 2H-2H in Figure 2G. As used in this specification, the term cardiac core
diameter is meant to indicate this diametrical minimum of the heart that occurs during DMVA
assistance by the apparatus of the present invention. The compression of the heart in such a
substantially circular cross section is considered an attribute and is made possible by the unique
structure of the embodiments of the Cup shells and liners of the present invention.
Figure 2F is a cross-sectional elevation view of a heart contained within the DMVA Cup
at yet a later time during systolic compression, approximately indicated by arrow 2F of Figure
IL. Referring to Figures 2F, DMVA drive fluid continues to flow into a supply port (not
shown) in shell wall 112, and has displaced right ventricle 34 to a point where the displacement
of the volume of right ventricle 34 is nearly complete. It can be seen that right ventricle wall
has been displaced nearly to a point of contact with and is beginning to "mold" to the right side
of the septum 31, which has been further displaced toward left ventricle 32, and that the rate of
blood flow from right ventricle 34 is decreasing rapidly, as indicated at arrow 2F of Figure 1L.
At this time, blood flow from left ventricle 32 is at a relatively high level, and a substantial
volume of left ventricle 32 remains to be displaced.
Figure 2G is a cross-sectional elevation view of a heart contained within the DMVA
Cup at a time late in systolic compression, and Figure 2H is a top cross sectional view taken
along line 2H-2H of Figure 2G, approximately at the time indicated by arrow 2G of Figure 1L.
Referring to Figures 2G and 2H, compression of right ventricle 34 is complete, wherein right
ventricle wall 35 is in contact and "molded" to the intraventricular septum 31, and wherein
blood flow from right ventricle 35 is substantially complete (see Figure 1L). Blood flow from
left ventricle 32 continues at a decreasing flow rate as left ventricle wall 33 and intraventricular
septum 31 are compressed in a circumferential fashion.
Figure 21 is a cross-sectional elevation view of a heart contained within the DMVA Cup
at the completion of systolic compression, approximately at the time indicated by arrow 21 of
Figure 1L. Referring to Figure 21, right ventricle wall 35 has remained squeezed against
intraventricular septum 31, left ventricle wall 33 has been nearly displaced to a point of contact
with intraventricular septum 31, and blood flow from left ventricle 32 has ceased (see Figure
1L). In the preferred embodiment, left ventricle 32 is generally not displaced to a point of
contact with intraventricular septum 31, as such contact of the heart tissues, if avoidable, is
generally undesirable. Because of the high degree of control of the DMVA Cup of the present
invention described in this specification, such precise limiting of the displacement of the
ventricles 32 and 34 is rendered possible.
Figures 2J - 2O are cross-sectional schematic views depicting undesired operations
and/or effects of a DMVA device, which is lacking proper control and/or structural features in
accordance with the present invention. Such conditions are avoided by use of the sensors,
controls, and algorithms of the present invention.
Referring to Figure 2J, there is depicted a heart 30 in a state of excessive compression
by DMVA device 100. It can be seen that excessive forces are placed on the entire ventricular
mass with the left ventricle 32 excessively compressed to a point where there is a large region
36 of contact between left ventricle wall 33 and intraventricular septum 31. In some instances,
;ntrapment of blood may occur in a pocket 37 formed at the base of left ventricle 32.
In instances where such excessive compression is sustained over a number of cycles, and
particularly if the DMVA Cup 100 is undersized for the particular heart 30, misalignment of the
heart within the Cup may occur as depicted in Figure 2K, wherein the heart is shown at the
conclusion of diastolic actuation. Referring to Figure 2K, it can be seen that the right ventricle
34 has been substantially displaced from with the Cup 100, and that apex 38 of heart 30 has
been displaced upwardly away from vacuum tube 111. Such a misalignment distorts
predominantly the right ventricle 34, and prevents proper operation of the DMVA Cup 100. RV
filling in particular is compromised. Such a circumstance is prevented by the use of a Cup of
sufficient size, diastolic actuation suction by the Cup 100, and by the use of sufficient vacuum
applied at vacuum port 111.
Figure 2L depicts a situation wherein a type of "cavitation" has occurred during diastolic
actuation, such that the left ventricle wall 33 and right ventricle wall 35 have become detached
and are no longer contiguous with left liner portion 116 and right liner portion 118, respectively.
As used herein the term "cavitation" does not refer to the generation of vacuum or a vapor
phase as a result of sudden relative motion in a volatile liquid medium, but refers to the
unwanted incursion of a fluid, either liquid or gas, into the interface between the Cup liner and
the myocardial surface. Bodily fluid or cavitated air has become entrained in such cavities 51
and 53. Such a condition is caused by one or more of the following: excessive diastolic
actuation, i.e. too much vacuum, or too rapid/too early an application of vacuum by the DMVA
drive fluid on the heart 30; a poor fit of seal 113 to heart 30; sealing/blocking of port 111 by
apex 38 of heart 30; or inadequate vacuum applied to vacuum port 111. In such a situation, RV
and LV filling are both compromised, as the DMVA device separates from the heart 30 during
diastolic actuation and the heart 30 fills passively and is not afforded diastolic assist. During
systole, the heart is expelled from the confines of the housing 110 rather than the blood being
expelled from within the ventricles 32 and 34. These are examples of decreased pumping of
blood into and out of ventricles 32 and 34 by inappropriate DMVA drive control. In instances
where such excessive compression is sustained over a number of cycles, substantially complete
detachment of the heart 30 from wall 112 of the Cup shell 110 may occur, as depicted in Figure
2M. It can be seen that apex 38 of heart 30 has become detached from vacuum port 111 of Cup
100. It is to be understood that the detachment shown in Figures 2L and 2M is depicted as an
extreme example, but that any accumulation of fluid or gas between the liner 114 and the
surface of the heart 30 is to be considered an unacceptable condition.
Figure 2N depicts a situation wherein herniation has occurred during systolic actuation,
such that the heart 30 is extruded from the DMVA Cup 100. Such herniation is a consequence
of excessive DMVA fluid pressure during early systolic actuation and predominantly affects the
RV infundibulum, i.e. the upper portion of the ventricle walls proximate to the atrio-ventricular
(AV) groove and/or basal portion of the RV free wall. Referring to Figure 2N, it can be seen
that heart 30 has been forced into misalignment within Cup 100, and that an upper portion 43 of
right ventricle wall (infundibulm or basal portion of the RV) 35 has been displaced upwardly
beyond seal 113. In instances where such excessive early systolic fluid pressure is sustained
over a number of cycles, displacement of both ventricles 32 and 34 of the heart 30 from the Cup
100 may occur, as depicted in Figure 20. It can be seen that apex 38 of heart 30 has become
detached with cavitation of air or fluid accumulation within the apical portion of the cup as the
heart is displaced 111 from the Cup 100, and that upper portion 43 of right ventricle wall 35 and
upper portion 41 of left ventricle wall 33 have been displaced beyond seal 113 of Cup 100.
Figures 2P - 2R are cross-sectional schematic views depicting operations and/or effects
of a DMVA device on a heart afflicted with pulmonary hypertension and/or right ventricular
hypertrophy. Referring to Figure 2P, DMVA Cup 100 is depicted therein at the end of diastolic
actuation. It can be seen that heart 60 afflicted with pulmonary hypertension (PHT) and/or RV
hypertrophy is characterized in particular by a thickening of right ventricle wall 65. The
operation of DMVA Cup 100 can be programmed and/or controlled such that the assistance
rendered to heart 60 is specifically matched to the needs thereof due to the PHT condition.
Figure 2Q depicts systolic compression of heart 60, at a point approximately midway
through such compression. It can be seen that the compression of right ventricle 64 and left
ventricle 62 occur nearly simultaneously, due to the comparable thickness of right ventricle wall
65, and to the higher pulmonary blood pressure of the PHT condition. Referring again to Figure
1L, which depicts time dependent blood flow rates ejected from the left and right ventricles of a
DMVA-assisted non-PHT heart, it can bee seen that there is a substantial time interval 1083
between the peak systolic blood flow 1082 of the right ventricle and the peak systolic blood
flow 1072 from the left ventricle. When DMVA assistance is provided to a heart afflicted with
PHT, time interval 1083 is much smaller, in some cases even approaching a zero time interval,
such that RV and LV blood flows are substantially simultaneous.
Figure 2R depicts systolic compression of heart 60, at the completion thereof. At end
systole, the RV pressure is only slightly less than the LV pressure, in contrast to the difference
1067 shown in Figure 1J for a DMVA-assisted non-PHT heart. In some instances, a higher
DMVA drive fluid pressure and/or systolic duration is required in order to complete systolic
actuation for a PHT-afflicted heart. Alteration of such drive dynamics is provided due to the
control capabilities of the present invention.
Figures 2S - 2U are cross-sectional schematic views depicting operations and/or effects
of a DMVA device on a heart afflicted with dilated cardiomyopathy. Referring to Figure 2S,
DMVA Cup 100 is depicted therein at the end of diastolic actuation. It can be seen that heart 70
afflicted with dilated cardiomyopathy (DCM) is characterized in particular by an overall dilation
or enlargement of heart 70, accompanied by a thinning of left ventricle wall 73, right ventricle
wall 75, and intraventricular septum 71, such that the volumes of left ventricle 72 and right
ventricle 74 are increased. The operation of DMVA Cup 100 can be programmed and/or
controlled such that the assistance rendered to heart 70 is specifically matched to the needs
thereof due to the DCM condition.
Figure 2T depicts systolic compression of heart 70, at a point approximately midway
through such compression. It can be seen that the compression of right ventricle 74 and left
ventricle 72 occur in a manner similar to that of non-DCM heart 30 of Figure 2D. Figure 2U
depicts systolic compression of heart 70, at the completion thereof. At end systole, the ventricle
volumes (particularly the LV volume) are greater than the corresponding end systole volumes of
right ventricle 34 and left ventricle 32 of DMVA-assisted non-DCM heart 30 of Figure 21.
Such larger end systolic volumes may be acceptable and more appropriate, since DMVA Cup
100 of Figure 2U has displaced the blood volumes from left ventricle 72 and right ventricle 74
that are comparable to such volumes displaced by a healthy heart, which is a desired result.
Delivery of such desired blood volumes is provided due to the control capabilities of the present
invention. Alternatively, such large ventricles may require more complete compression to
ensure no mismatch between RV and LV outputs. In such circumstances, the cycle rate can be
significantly reduced with attendant reductions in systolic dP/dt and reductions overall
compression rate which will result in less risk for trauma. Such adjustments are more favorable
for long-term support which would more likely be required for potentially bridging such
patients to cardiac transplant or other support devices.
In the present invention, the basic design of the Cup completely encompasses the heart
from the atrio-ventricular groove (A-V groove) to the apex of the heart. Such a construction
affords several advantages. A first advantage, enabled by liners of the present invention
working with the Cup shell of the present invention, is the ability of the internal liner to
compress or dilate the heart with a motion and force that is perpendicular to the heart tissue as
previously described. A second advantage of the Cup's dynamic geometry of the present
invention is the ability of the device to act and conform to both right and left ventricles in both
systolic and diastolic assist, thereby supporting both pulmonary and systemic circulation. A
third advantage is the ability of the device to better maintain both right ventricle and left
ventricle function.
The Cup's dynamic geometry, and the fluid drive control means of the DMVA device of
the present invention further provide for a full range of compression of the heart during systole,
and a full range of expansion of the heart during diastole. This capability enables the DMVA
device to provide a full range of Systolic Pressure-Volume Relationships and Diastolic
Pressure-Volume Relationships that can be incorporated into drive control algorithms and result
in optimal RV and LV pump performance. The present invention also provides total circulatory
support without direct blood contact, thereby decreasing the risk of thromboembolic
complications including clotting, strokes, and other associated severe morbidity, and in some
cases death, as well as significant blood cell lysis, which can adversely affect blood chemistry
and patient health. This feature also eliminates the need for anti-coagulation drugs which
reduces the risk for bleeding.
The present invention is a device that can be placed more rapidly than other existing
devices from the start of the procedure, and therefore enables the unique ability to acutely
provide life-sustaining resuscitative support, as well as continued short to long term support, as
deemed necessary. AH other cardiac assist device products (approved or in clinical trials)
known to the applicants require surgical implantation with operative times that far exceed the
ability of the body to survive without circulation. Physicians will welcome a device that can be
placed when routine resuscitation measures are not effective. The number of failed
resuscitations in the U.S. annually is estimated to be on the order of hundreds of thousands.
The device of the instant invention can support the circulation indefinitely as a means of bridgeto-
recovery, bridging to other blood pumps, bridging to transplant, or long-term total circulatory
support.
The present invention utilizes a seal design that facilitates the scalability and long-term
reliability of the seal. Specific critical seal design features include the seal length, thickness,
shape, and durometer; and the location of the seal against the heart at the atrio-ventricular (AV)
groove thereof. Additionally, one embodiment of the present invention utilizes a seal material
that promotes the controlled infiltration of fibrin, which further improves the scalability and
long-term reliability of the seal. Embodiments of the present invention also utilize a liner
material that promotes the controlled infiltration of fibrin, which further improves diastolic
action and helps to minimize motion of the liner against the heart, which further minimizes
60
abrasion between the liner and heart tissues. In all instances, the degree of infiltration of fibrin is
limited, so the DMVA Cup can be easily removed, once the patient has recovered or can safely
be bridged to another therapy.
In a further embodiment, the present invention also utilizes a liner that is biodegradable
and/or one that becomes permanently attached to the heart's surface (with or without
biodegradable properties) such that the device can be removed by detaching the housing from
the liner and the liner left in place. Such a liner can then instill favorable mechanical properties
to the heart and/or provide drugs or other therapies (e.g., gene therapy etc. as described in
greater detail elsewhere in this specification). Such therapeutic agents include but are not
limited to anti-inflammatory agents, gene therapy agents, gene transfer agents, stem cells,
chemo-attractants, cell regeneration agents, ventricular remodeling agents, anti-infection agents,
tumor suppressants, tissue and/or cell engineering agents, imaging contrast agents, tissue
staining agents, nutrients, and mixtures thereof. Such agents may be diffused or embedded
throughout all or part of the liner, or alternatively, such agents may be contained within a gap
formed within a liner comprising a first membrane in contact with the DMVA drive fluid, and a
second membrane in contact with the heart, wherein the second membrane is permeable to the
agent or agents.
Thereby, the Cup serves a dual purpose of support of the heart for a period of time, and
incorporating a therapeutic liner that is responsible for continued treatment of the underlying
disorder. The liner can simply provide additional structural integrity through its mechanical
properties, serve as a delivery agent, or a combination of both. Furthermore, the liner may
simply be inert in its action once the Cup is removed, but provides a simple, safe means of
device detachment without otherwise risking bleeding or trauma to the heart that might result if
it is removed. In yet another embodiment, and in the case wherein the seal has been caused to
be ingrown with myocardial tissue but the remainder of the liner is not ingrown with such
tissue, removal of the liner is effected by separation from the seal. Thus only the seal will be
left attached to the heart after Cup removal.
Many existing cardiac assist devices, such as Left Ventricular Assist Devices (LVADs)
require surgically perforating the cardiac chambers and/or major vessels. The present invention
eliminates the need to perforate the heart or major vascular structures, and provides the ability
to easily remove the device, leaving no damage to the heart and circulatory system once the
heart heals and cardiac function is restored, or when the patient can safely be bridged to another
therapy.
Existing cardiac assist devices, such as Left Ventricular Assist Devices (LVADs), which
include axial flow pumps, produce blood flow that is non-physiologic and not representative of
physiological pulsatile blood flow. The present invention avoids this condition and creates a
near-normal physiological pulsatile blood flow with blood passing through the natural chambers
and valves of the native heart, which is more beneficial for vital end-organ function and/or
resuscitation, particularly as it relates to restoring blood flow following a period of cardiac
arrest or low blood flow.
Furthermore, the present invention provides a controllable environment surrounding the
heart, which can be used to apply pharmaceutical and tissue regeneration agents, even at
localized concentrations that would not be tolerated systemically. This can be accomplished
with or without use of a cup liner that is left on the heart following device removal, depending
on the needs of the patient.
Furthermore, the present invention is able to augment heart function as is required to
create and maintain required hemodynamic stability in a manner that is synchronized with the
heart's native rhythm and in a manner that can alter the native rhythm toward a more favorable
state. The purely complimentary nature of this support relieves the stress on the heart and
promotes its healing.
As previously described, it is known that application of forces to the heart can cause
potentially serious, irreversible damage to the heart by fatiguing and severely bruising the heart
muscle, which can ultimately prevent it from functioning. The present invention avoids this
very serious and potentially life-threatening condition by controlling the direction of forces
applied to the heart and by controlling the magnitude of the difference between adjacent forces
applied to the heart.
Figure 3A and 3B are cross-sectional schematic views depicting the action of a liner of a
prior art DMVA device upon the wall of the heart. Referring to Figures 3A and 3B, in prior art
DMVA devices such as that disclosed in United States patent 5,119,804 of Anstadt, there is
provided a DMVA device 2 comprising a rigid or semi-rigid shell wall 4 (in contrast to the
present invention's dynamic housing characteristics), and an elastic liner 10 joined to wall 4 at
upper region 12 and lower region 14, thereby forming a cavity 6 between such liner 10 and wall
4. The Cup and liner surround the heart, the ventricle wall 40 of which is contiguous with liner
10.
In operation of prior art device 2, a fluid is pumped into cavity 6, thereby displacing
liner 10 inwardly from shell wall 4. This displacement forces ventricle wall 40 inwardly a
corresponding displacement, thereby resulting in systolic action of the heart. However, it is
noted that operation of the prior art device produces several effects that are undesirable. In
Figure 3A depicting the diastole state of the device and heart, at the interstice 8 of liner 10 and
ventricle wall 40, point 16 in the liner 10 and point 46 in the ventricle wall 40 are substantially
contiguous with each other; and point 18 in the liner 10 and point 48 in the ventricle wall 40 are
substantially contiguous with each other. Subsequently it is apparent that in Figure 3B
depicting the systole state of the device and heart, at the interstice 8 of liner 10 and ventricle
wall 40, point 16 in the liner 10 and point 46 in the ventricle wall 40 have been displaced from
other as indicated by arrows 17 and 47; and point 18 in the liner 10 and point 48 in the ventricle
wall 40 have also been displaced from each other as indicated by arrows 19 and 49.
This displacement is a consequence of several factors relating to the manner in which
the liner 10 is joined to the shell wall 4 and to the properties of the liner material, which can
produce localized non-uniformities in the stretching of the liner. The resulting displacement of
point 16 and point 46 away from each other, and point 18 and point 48 away from each other
produces localized shear stresses in these regions, which is very undesirable as previously
indicated. In addition, such displacement also results in slippage of the liner along the surface
of the ventricle wall, which over time can result in the undesirable abrading of the surface of the
ventricle wall.
It is also known that there are shear stresses created along the circumferential direction
of the ventricle wall, i.e. in the horizontal direction in the ventricle wall. Without wishing to be
bound to any particular theory, applicants believe that these stresses are due to the tendency of
the liners of prior art devices to self-subdivide during systolic action into nodes, wherein
uniform portions of the liner are displaced inwardly, divided by narrow bands of the liner that
are displaced outwardly. In one embodiment described in United States patent 5,119,804 of
Anstadt, four such nodes are observed to be present when the device is operated without being '
fitted to a heart.
It is also apparent that regions 42 and 44 of ventricle wall 40, which are contiguous with
upper region 12 and lower region 14 where elastic liner 10 is joined to wall 4, are subjected to
intermittent high bending and shear stresses as a result of the repeating transitions between
systolic and diastolic action of the device 2. Such intermittent bending and shear stresses can
fatigue the heart tissue in these regions 42 and 44, and are thus clearly undesirable.
Figures 4A, 4B and 4C are cross-sectional schematic views depicting the action of the
liner of the DMVA Cup of the present invention upon the wall of the heart. Figure 4A depicts
63
the diastole state of the device and the heart, Figure 4B depicts the device assisting the systolic
action of the heart at an intermediate stage of systolic action, and Figure 4C depicts the
completion of systolic action of the device and the heart. For the sake of simplicity of
illustration, the heart 30 of Figures 4A - 4C is shown with substantially thinner ventricle and
septum walls than would typically be present in a DMVA assisted heart. Accordingly, there is
no intent to limit the use of the DMVA device to a heart of such proportions.
Referring to Figure 4A, DMVA device 100 comprises a cup-shaped shell 110 having a
rigid or semi-rigid wall 112, and a liner 510 joined at upper region 512 and lower region 514 to
shell wall 112. Liner 510 joined to shell wall 112 thus forms a cavity 310 (or potential space)
therebetween, into which a fluid is intermittently delivered and withdrawn. Such intermittent
delivery and withdrawal of fluid to/from cavity 310 effects the cycling of the DMVA device and
the heart back and forth between the diastolic and systolic states.
In the preferred embodiment, liner 510 is provided with an upper rolling diaphragm
section 520 and a lower rolling diaphragm section 570, the effect of which is to apply uniform
pressure (positive or negative) to the surface of the heart that substantially eliminates stresses in
cardiac tissue that otherwise result from the action of prior art devices previously described. In
operation, liner 510 is completely unloaded and the action of the working fluid on the heart is
purely hydrostatic and normal to the wall 40 thereof. In other words, this embodiment of the
present invention prevents the formation of substantial forces within the heart muscle by
applying forces to the heart that are perpendicular to and uniform over the surface of the heart.
This embodiment also ensures that the magnitude of the difference between adjacent forces is
very small, as the fluid pressure within cavity 310 is isotropic. The use of such rolling
diaphragm, as well as preferred liner materials to be subsequently described in this
specification, eliminate the formation of shear forces within the heart muscle which leads to
bruising damage to the heart tissue which in turn leads to muscle fatigue and potential failure of
the heart. Thus the DMVA apparatus of the present invention is atraumatic, i.e. the apparatus
does not inflict any injury upon the heart.
Rolling diaphragm sections 520 and 570 at the top and bottom of liner 510 are intended
to reduce shear stresses in cardiac tissue that otherwise would result from the action of the
DMVA Cup 100. Regardless of how elastic the material chosen for the liner 510 is there will
be some stress induced in cardiac tissue if the prior art liner configuration is used. As described
previously, this is because there will be some central axis where there is no vertical motion
(slip) or shear stress relative to the adjacent heart wall, but above and below this axis the liner
will expand during systole and contract during diastole while the heart wall will not change in
exactly the same manner. Thus, the only way known to the applicants to reduce this lateral
shear stress is to create a situation where the liner is completely unloaded and the force of the
working fluid on the heart is purely hydrostatic, or normal to the surface. This is a critical
capability of one DMVA device of the present invention.
The rolling diaphragm geometry follows the approach used in traditional rolling
diaphragm pumps and fluid-to-fluid isolators. The design also greatly reduces stress
concentrations at the extreme upper and lower points where the liner 510 attaches to shell 110,
thus increasing the reliability of liner 110, further enabling the use of materials that may
previously not have been considered because of their susceptibility to fatigue failure in a prior
art liner configuration.
Referring again to Figure 4A, the rolling diaphragm liner 510 comprised of upper rolling
diaphragm section 520 and lower rolling diaphragm section 570 also eliminates the single
flexure regions of the diaphragms used in earlier Cup designs. As was previously described and
shown in Figures 3A and 3B, such regions 12 and 14 of prior art device 2 where elastic liner 10
is joined to wall 4, are subjected to intermittent high bending and shear stresses as a result of the
repeating transitions between systolic and diastolic action of such device 2.
In one embodiment, rolling diaphragm liner is directly bonded to DMVA Cup shell wall
112 at upper section 520 and lower section 570 thereof. Figure 16B depicts one embodiment of
such a bond between liner 540 and Cup shell wall 112 at lower joint region 514 therebetween.
Details of this structure are provided subsequently in this specification, also in conjunction with
Figure 16A. Referring again to Figure 4A, it will be apparent that a similar structure can be
provided for upper joint region 512 as is described subsequently in this specification and shown
in detail in Figure 16B.
As a result of such liner structures for upper joint region 512 and lower joint region 514,
the maximum deflection of rolling diaphragm liner 510 at the upper joint region 512 and lower
joint region 514 is reduced. Stated another way, the bending of the diaphragm at joint regions
512 and 514 is distributed over a larger length of the rolling diaphragm liner 510. The effect of
this design is to reduce the bending strain at any one point in the diaphragm 510 as it is
actuated. Reducing the bending strain substantially increases the life of diaphragm 510 and
therefore significantly improves its reliability.
Referring to Figure 4B, it can be seen that the displacement of the liner 510 by the filling
of cavity 310 with fluid effects the systolic action of the heart without inducing substantial
stresses in the ventricular wall 40 thereof. At the interstice 8 of liner 510 and ventricle wall 40,
point 316 in liner 510 and point 46 in ventricle wall 40 have remained substantially contiguous
with each other, and point 318 in liner 310 and point 48 in ventricle wall 40 have remained
substantially contiguous with each other. In addition it can be seen that the radius of curvature
in upper region 42 and lower region 44 of ventricle wall 40 is substantially greater than such
radius of curvature resulting from the use of the prior art device as depicted in Figure 3B. Thus
the bending stresses produced in regions 42 and 44 of ventricular wall 40 are substantially less
as a result of the use of rolling diaphragm liner 510 of the present invention. It can be further
seen that diaphragm liner 510 is engaged with ventricle wall 40 in a progressing rolling action
as indicated by upper arrows 516 and lower arrows 518.
Figure 4C is a cross-sectional view depicting the DMVA apparatus assisting a heart, at
the completion of systolic action of the device and the heart. Referring to Figure 4C, the
displacement of liner 510 of apparatus 102 is at its maximum value, having squeezed
ventricular walls 8 to an optimal conformational change wherein heart 30 has an approximately
"hour-glass" or "apple-core" shape, with a minimum diameter, (i.e. the "cardiac core diameter")
at the plane defined by opposing arrows 515. At the completion of systole, apparatus 100 has
caused, or assisted in the displacement of, a cardiac ejection fraction of approximately 0.55
from left ventricle 32 and right ventricle 34.
Even at the maximum displacement of liner 510, it can be seen that at the interstice 8 of
liner 510 and ventricle wall 40, point 316 in liner 510 and point 46 in ventricle wall 40 have
remained substantially contiguous with each other, and point 318 in liner 310 and point 48 in
ventricle wall 40 have remained substantially contiguous with each other; and that the radius of
curvature in upper region 42 and lower region 44 of ventricle wall 40 is substantially greater
than such radius of curvature resulting from the use of the prior art device as depicted in Figure
3B. Thus the bending stresses produced in regions 42 and 44 of ventricular wall 40 are
maintained at a low value.
Referring again to Figures 4B and 4C, it can also be seen that liner 501 has rolled
progressively as indicated by arrows 516 and 518, to a maximum extent along upper ventricle
regions 42 and lower ventricle regions 44 shown in Figure 4C. The force applied by liner 510
upon ventricle walls 40 at all points along interstice 8, resulting from the isotropy of the fluid
pressure within cavity 310, is substantially perpendicular to ventricle walls 40, as indicated by
arrows 515. Thus the presence of any shear force in the ventricle walls 40 is minimized.
In the preferred embodiment of apparatus 102, liner 510 is deployed against ventricle
walls 40 by a progressive rolling action as indicated by arrows 516 and 518. In contrast, prior
art DMVA devices deploy the liner against the ventricle walls exclusively by an elastic and
non-isotropic stretching of such liner, resulting in shear forces and/or abrasive slippage of such
liner along the ventricle walls, as previously described. Thus the rolling diaphragm liner 501 of
one embodiment of apparatus 102 has significant advantages over prior art DMVA devices.
Referring again to Figure 4A, DMVA apparatus 102 is provided with a first DMVA
drive fluid port 324 and a second DMVA drive fluid port 326. In one embodiment, the portion
of cavity 310 that is in communication with drive fluid port 324 is made separate from the
portion of cavity 310 that is in communication with drive fluid port 326. In addition, each of
ports 324 and 326 are provided with separate DMVA fluid supply/withdrawal means. In this
manner, the fluid cavity in communication with drive fluid port 324 can be filled and emptied
independently of the fluid cavity in communication with drive fluid port 326, so that right
ventricle 34 (see Figure 2A) can be actuated independently of left ventricle 34 (see Figure 2A).
A more detailed description of Invention Aspect 1, which is a method for using sensor
data in conjunction with cardiac assist devices, is now presented. Figure 5A is a flow chart
depicting such a method for using sensor data to guide DMVA installation and to assess cardiac
performance under the influence of DMVA. Referring to Figure 5A, method 900 includes the
following steps 902 - 924, which are offered here as illustrative and not limiting:
In step 902, the patient's pre-DMVA cardiovascular state of health is established, which
provides a baseline from which to assess improvement in patient health as a result of DMVA.
Subsequently, in step 904 required performance improvement objectives are established. In
step 904, the patient's existing pre-DMVA cardiovascular state of health is compared to normal
cardiac performance for the patient's population group and clinical condition. The difference
between the patient's baseline performance and normal population group and clinical condition
is used to help establish DMVA performance improvement objectives.
Step 906 is an optional pre-check of the DMVA device to verify critical aspects of
performance. In step 908, the DMVA device is surgically installed in the patient. The DMVA
device is subsequently actuated using predetermined settings in step 910, based upon data from
steps 902 and 904.
In step 912, the DMVA device is operated, and sensor data is collected to verify such
factors as follows: proper positioning of the DMVA device on the heart; proper sealing of the
DMVA device against the heart; the absence of excessive fluid between the heart and the inner
wall of the DMVA device, and that the DMVA control parameters are achieving the desired
systolic and diastolic action. Sensors and data acquisition means for performing such data
collection are described later in this specification.
In step 914, acquired data on the performance of the DMVA Cup device, and on the
condition of the patient are analyzed by computer/process controller means. Included in step
914 is the integration of other cardiovascular data (e.g. blood pressure), other cardiovascular
devices (e.g. pacemakers, balloon pump, etc.) and/or the effects of initiation of other features
incorporated into the Cup such as e.g., pacing electrodes.
Initial DMVA control parameters, such as the volume and timing of fluid delivery to the
DMVA Cup, may not achieve optimum hemodynamic performance. Thus in step 916, the
DMVA control parameters are adjusted to achieve desired hemodynamic performance (e.g.,
achievement and verification of balanced RV and LV outputs, optimization of such outputs to
ensure adequate overall cardiac output, and optimization to avoid cardiac injury, thereby
ensuring atraumatic operation of the DMVA apparatus). Such adjustment may be an iterative
process as indicated by step 918, wherein steps 912, 914, and 916 are repeated. In such an
iteration, additional sensor data is collected ( a second step 912) and analyzed (a second step
914) after the initial adjustment of DMVA control parameters to determine if additional
adjustment (a second step 916) is required. This sub-process (step 918) is repeated until desired
hemodynamic performance is achieved.
In one embodiment of method 900 of Figure 5A, wherein a data recording and
transmitting system is utilized, the physician activates such unit in step 920, including setting
acceptable levels of hemodynamic performance and programming these limits into the data
recorder-transmitter. The data recorder/transmitter can then be remotely interrogated by the
physician to evaluate hemodynamic performance. Alternately, the data recorder-transmitter can
automatically report to the physician unacceptable trends or levels of hemodynamic
performance, which could necessitate medical attention or changes in patient behavior.
With the DMVA device properly installed in the patient, and operating at an optimal
steady-state condition, all surgical procedures are completed and the patient is placed into
recovery in step 922. The condition of the patient and the performance of the DMVA device is
then monitored as an ongoing process, with further intervention or adjustment of DMVA
parameters made as required in step 924. Specific methods and apparatus to monitor the
cardiac performance and overall condition of the patient are well known and are described
elsewhere in this specification.
More detailed descriptions of Invention Aspect 4, which is directed to methods and
algorithms for specific feedback control of the DMVA Cup are now presented, with reference in
particular to Figures 5B.
Figure 5B is a flow chart of one specific algorithm for automatically adjusting the
function of an embodiment of the DMVA Cup. It is to be understood that this algorithm is one
example of many that are possible, which may be defined and selected according to the
particular patient and cardiac disorder for which DMVA assistance is indicated. For a better
understanding of the following description of algorithm 930 of Figure 5B, reference may also be
had to Figures IM, and 2A - 21, which were previously described in this specification. It is to
be understood that pressures provide in millimeters of mercury (Hg) are gage pressures, with
Ornm Hg being ambient atmospheric pressure.
Referring to Figure 5B and Figure 2C, method or algorithm 930 begins at the initiation
of systole with step 932, wherein delivery of drive fluid into cavity 119 of DMVA device 100
begins, at a delivery pressure of 20mm Hg. In step 934, blood is displaced from right ventricle
34. Blood volume and/or flow sensors, and imaging and/or other cardiac state sensors
described elsewhere in this specification provide data to the DMVA controller, enabling check
935. If the RV is less than 80% empty at 0.25 sec, the DMVA drive fluid pressure is increased
in step 936. The check is repeated in step 937, and the DMVA drive fluid pressure is again
increased in step 938. Blood displacement from the left ventricle begins, and the heart
transitions through the state shown in Figure 2D. A check 939 is made of the volume of the left
ventricle, and when the left ventricle is 80% empty, the DMVA drive fluid pressure is increased
to 114mm in step 940. Blood pressure is monitored and maintained to the completion of systole
in step 942 as shown in Figure 21.
Diastole is then initiated in step 944 by applying vacuum to the DMVA drive fluid at a
low level (e.g. -100mm Hg) for 0.5 seconds. Such vacuum is maintained until data input to the
DMVA controller indicates that the RV and LV are 90% refilled. The vacuum is then released
in step 948. In an optional step 950, the vacuum is sustained for a brief additional period in
order to adjust the size of the dilated heart to a slightly larger state.
A more detailed description of Invention Aspect 5, which is directed to Specific sensor
types and sensor locations is now presented with reference to Figures 6A - 13.
Figures 6A, 6B, and 6C are schematic representations of a sensor installed in a DMVA
Cup during systolic actuation, and Figure 7 is a schematic representation of a sensor installed in
a DMVA Cup during diastolic actuation. Figure 6A is a preferred embodiment of the present
invention, wherein sensor 1210 comprises an ultrasound probe(s) integrated directly and
permanently into DMVA Cup 103. In this embodiment, sensor 1210 collects the types of data
previously described in "Invention Aspect 2" during and following installation of the DMVA
Cup 103. Other aspects of DMVA Cup 103 of Figure 6A are similar to other DMVA Cups
described in this specification, and include shell 110; vacuum duct 111; liner 114 comprising
left portion 116 and right portion 118; liner inflation/deflation duct 120; working fluid as
indicated by phantom arrows 197 shown flowing into the space between shell 110 and liner
114, thereby inflating liner 114 and compressing heart 30; and seal 113. In Figure 6A, left
ventricle 32 and right ventricle 34 of heart 30 are shown in systolic actuation, as indicated by
bold arrows 196.
In the DMVA Cup 103 of Figure 6A, sensor 1210 is disposed within vacuum duct 111,
with it being understood that sufficient clearance is provided between sensor 1210 and the wall
of vacuum duct 111 to enable vacuum to be applied within Cup shell 110, thereby seating and
retaining heart 30 therein. In other embodiments, DMVA Cup 103 is provided with separate
attachment ports for sensor 1210 and for vacuum application. Sensor 1210 further comprises
cable 1214, which is used to link sensor transducer/receiver tip 1212 with externally located
receiver and/or control unit (not shown).
In operation, sensor 1210 provides an approximately conical field of view 1299 of heart
30, resulting from the propagation of ultrasound as indicated by arcs 1298, and the reflection of
such ultrasound back to tip 1212 by the objects within shell 112. Such reflected ultrasound is
used by data acquisition and analysis means to provide images of the DMVA Cup shell 110,
cavities 117 and 119, liner 114, and right and left ventricles 34 and 32 of heart 30. In particular,
ultrasonic probe 1210 enables the capturing, observation, and measurement of changes in LV
and RV geometry, LV and RV volume, relative RV/septal and LV/septal interactions, cupepicardial
interactions, and localized blood flow velocities in the ventricles, atria, and aorta, and
evaluations of these variables to achieve optimal DMVA drive settings under a variety of
physiologic conditions.
Reference may be had to the volume, pressure, and flow relationships of Figures 1A -
1M; and to the illustrations of proper DMVA assistance provided in Figures 2A - 2O; and to
the illustrations of improper DMVA assistance of Figures 2P - 2U. Sensor 1210 of DMVA
apparatus 103 of Figures 6A - 7 provides the capability of observation, measurement, and
acquisition of such data for the DMVA apparatus and for the heart assisted therein, over the
range of circumstances depicted in Figures 1A - 2U. The DMVA apparatus is further provided
with control capabilities to use such information to optimize the assistance to the heart, as will
be described subsequently in this specification.
Figure 7 is similar to Figure 6A except that DMVA Cup 103 and heart 30 are shown in
diastolic actuation. Working fluid is shown flowing completely out of the cavities 117 and 119
between shell 110 and liner 114 as indicated by arrows 195 and 194, thereby deflating liner 114,
and expanding heart 30, enabling left ventricle 32 and right ventricle 34 to fill with blood.
In yet another embodiment of the present invention depicted in Figure 6B, sensor 1210
is an ultrasound probe integrated directly and temporarily into the Cup to collect the same data
as described for Figure 6A, but further enabling the sensor 1210 to be removed following
verification of proper Cup installation and initial operation as indicated by arrow 1297.
Referring to Figure 6B, plug 1216 or other suitable sealing means, including self-sealing means
such as one-way valves, etc. is deployed from tip 1212 of sensor 1210, and used to prevent
fluids from passing into shell 110 after sensor 1210 is removed.
In yet another embodiment of the present invention depicted in Figure 6C, sensor tip
1212 of sensor 1210 is permanently installed within shell 112 of DMVA Cup 103, and an
electrical interface 1220 is connected to sensor 1210 by cable 1218. Electrical interface 1220 is
then connected to external instrumentation sensor control unit 1222 either percutaneously
through skin 52 such as with a puncture, or transcutaneously through skin 52 such as via
telemetry pulses 1224.
In a yet further embodiment of the present invention, the ultrasound image is not
provided by a single sensor such as sensor 1210, but is provided by one or more pairs of
individual piezoelectric crystals that are placed on either side of the heart, and utilize time-offlight
measurements and simple linear echo measurements to detect the position of tissue/fluid
interfaces relative to themselves. Referring to Figure 10A, any of the sensor elements 1262,
1264, 1266, 1272, and 1274 shown on the liner, or any of the sensor elements 1268, 1270, and
1278, shown on the shell, may be such piezoelectric crystals. These crystals may be used as
individual pairs, or in such two-dimensional or three-dimensional combinations to provide the
desired information relating to shape and movement of myocardial wall tissue and/or blood.
In yet another embodiment of the present invention (not shown) an external ultrasound
probe is used as above.
Referring again to Figures 6A and 7, in yet another embodiment of the present
invention, sensor 1210 is a magnetic resonance imaging (MRI) coil integrated directly and
permanently into the Cup shell 110. These embodiments enable the sensor to collect the types
of data outlined above in "Invention Aspect #2" during and following installation of the Cup on
the heart 30 of the patient. In various embodiments, MRI coil 1210 can be a receive only coil, a
transmit only coil, or a transmit and receive coil.
Referring again to Figure 6B, in yet another embodiment of the present invention, sensor
1210 is a MRI coil integrated directly and temporarily into the Cup to collect the same data as
described for Figure 6A, but further enabling the coil to be removed following verification of
proper Cup installation and initial operation as indicated by arrow 1297. Referring to Figure
6B, plug 1216 or other suitable sealing means, including self-sealing means such as one-way
valves, etc. is deployed from tip 1212 of sensor 1210, and used to prevent fluids from passing
into shell 110 after coil 1210 is removed.
Referring again to Figure 6C, in yet another embodiment of the present invention, MRI
coil 1210 is permanently installed within shell 112 of DMVA Cup 103 and an electrical
interface 1220 is connected to sensor 1210 by cable 1218. Electrical interface 1220 is then
connected to external instrumentation sensor control unit 1222 either percutaneously through
skin 52 such as with a puncture, or transcutaneously through skin 52 such as via telemetry
pulses 1224.
In yet another embodiment of the present invention (not shown) an external MRI coil is
used as in the foregoing description.
Figure 8 is a schematic representation of another embodiment of a DMVA Cup with an
MRI coil embedded therein. Referring to Figure 8, MRI coil 1230 or MRI coil 1240 can
alternately be integrated into wall 112 of the Cup 104. This embodiment is particularly
advantageous as the coil 1230/1240 completely encompasses the heart (not shown) enabling the
entire heart and DMVA Cup interior to be imaged with a coil that is very close to the heart.
Since the quality of the MR image increases with decreasing distance between the receive coil
and the tissues to be imaged, this design enables very high quality images of the heart to be
obtained due to the maximum signal produced in the coil. This maximum signal also enables
scan times to be reduced without compromising image quality, which is very important when
imaging the moving heart.
The quality of MR images is also dependent upon the strength of the static field used by
the MRI system. Higher field strength systems (e.g. 3.0 or 4.5 Tesla field strength) provide
greater image quality than lower field strength systems (e.g. 0.5 or 1.5 Tesla field strength).
However, the maximum signal provided by the MRI coil of the present invention enables
images to be obtained in lower strength with image quality equivalent to the quality of image
obtained in higher strength systems. This is particularly important since lower strength "open
MR" systems enable the physician to interact with patient during MRI, and these systems would
be one type of MRI system used to help guide the installation and assessment of the DMVA
Cup. The signal from embedded coil 1230/1240 can be obtained through a connection such the
type illustrated in Figure 6C, or through the use of external receive coils which monitor the
currents induced in embedded MRI coil 1230/1240. The latter approach offers the advantage of
being able to image the performance of the DMVA Cup and the heart in an MRI unit without
the need to physically access and connect to the implanted DMVA Cup. The ability to image
the DMVA Cup and heart using MRI is particularly important, since MRI is increasingly
becoming a preferred imaging modality for a variety of reasons. MRI provides superb soft
tissue contrast, and functional analysis capabilities. MRI requires no ionizing radiation or toxic
contrast agents and is not obstructed by the presence of bone. MRI is capable of providing
multi-plane images without repositioning the patient. The practice of MRI-guided surgery is
becoming more common, indicating that DMVA Cup installation and assessment under MRI
guidance is feasible.
Referring again to Figure 8, DMVA Cup 104 having an integrated MRI coil comprises
a typical shell 110 and liner 114. A ring-shaped MRI receiver coil 1230 is shown embedded in
the lower portion 124 of the wall 112 of shell 110 in a region that is relatively mechanically
stable during systolic and diastolic motion of the DMVA. Alternatively, MRI receiver coil 1240
is shown to be larger than coil 1230 and at a greater distance from the apex 126 of cup 104.
The larger diameter of alternative coil 1240 permits improved resolution of the MRI image.
Coil 1240 is surrounded by support ring 1242 that is molded as an extension of the shell 110
and that provides positioning of coil 1240 while at the same time isolates coil 1240 from the
flexure of shell 110 that occurs during systolic and diastolic motion of the DMVA Cup 104.
The choice of the diameter and location of the receiver coil (shown herein by two diameters and
locations depicted by 1230 and 1240) is made to optimize the depth of field and resolution
required by the MRI system, and may vary depending upon the type of MRI analysis being done
and the power of the system (e.g. 0.2 Tesla, 1.5 Tesla, or 3.0 Tesla).
Referring again to Figure 8, receiver coil 1230 or alternative receiver coil 1240 is
connected by wires 1232 to an amplifier 1234 that is positioned close to the receiver coil
1230/1240 and amplifies the MRI signal received by coil 1230 or 1240. The amplifier 1234 is
in turn connected by wires 1236 to an external MRI system 1238 that provides all of the signal
conditioning and data representation that will be used by the medical team to assess the
performance of the heart and performance of the DMVA system. Optionally, the MRI system
1238 may be connected directly to the DMVA drive unit 1310 via connection means 1239 (such
as e.g. a cable, or telemetry) in a manner that permits the drive unit 1310 to actively interpret
information coming from MRI system 1238 and use it to modify its operational parameters in
controlling the systolic and diastolic motion of DMVA Cup 104.
In yet another embodiment of the present invention, an external X-ray imaging
procedure, such as Conventional X-radiography or Computed Tomography, is used to collect
the following types of data during and following installation of the Cup: anatomical data, such
as motion of the heart wall, fit of the Cup to the heart; hemodynamic data, such as blood flow
rate, and/or blood pressure; and functional data, such as cardiac ejection fraction. Figure 9A
and Figure 9B are schematic representations of one embodiment of such an external X-ray
imaging procedure used to collect data on a patient and data on a DMVA Cup fitted therein.
Referring to Figure 9A, there is depicted a standard radiography or x-ray method and apparatus
that is used to image a part of the body, in this case the heart. Typically, for use with soft
tissues such as the heart, or fluids such as the blood, a contrast agent that preferentially absorbs
x-rays is used to accentuate the features under study. In Figure 9A, patient 90 is supported in a
stationary position, between x-ray source 1246 and an imaging plane 1248. The image at plane
1248 may be acquired by a traditional photographic process providing a single image, or may be
acquired by use of a fluoroscopic screen, providing an image that changes with movement of
the feature being imaged.
Figure 9B depicts a technique referred to as computed tomography (CT) and often
referred to as a "CAT Scan". In this technique, patient 90 is supported on a movable structure
1251 and passes through a circular opening 1252 in the scanning system. Multiple pairs of xray
sources 1254 and x-ray detectors 1256 are connected in a circular ring that spins around the
subject with its rotation shown by arrow 1296. Support structure 1251 moves slowly through
circular opening 1252 with motion shown by arrow 1295. The resulting information gathered
by multiple detectors 1256 is analyzed by a computer algorithm, and creates a three-dimensional
(3-D) image of the feature being imaged. While this 3-D image has substantially greater
information content than a simple planar x-ray, it should be noted that the time to create a single
3-D image will be at least on the order of a minute.
Figure 10A is a schematic representation of electrophysiological sensors and/or
electrodes integrated into a DMVA device, shown during systolic compression of a heart.
Referring to Figure 10A, electrical sensors 1262, 1264, 1266, 1272, and 1274 are placed on or
within liner 611 of Cup 105 to measure the electrophysiological signals produced by the heart
30. Sensor 1276 is placed on or within the external surfaces of Cup 105, or elsewhere on or
within the body, to provide a ground plane or reference electrical measurement for sensors 1262
- 1274, which are in contact with the heart 30. Alternately, sensors 1262 - 1274 may be placed
on or within the shell wall 112 of Cup 105, as indicated by sensors 1268, 1270, and 1278. In a
preferred embodiment of the present invention, electro-physiological signals are measured by
sensors 1262 - 1274 and are delivered to the DMVA device control unit (not shown), which in
turn directs the inflation and/or deflation of Cup liners 611 in a pre-determined synchronization
with the normal heart rhythm.
In an embodiment where the DMVA control unit device is positioned outside the body,
electro-physiological signals are delivered to the DMVA control device either percutaneously
through the skin such as with a puncture, or transcutaneously through the skin such as via
telemetry pulses.
In an embodiment where the DMVA control unit device is positioned inside the body,
electro-physiological signals are delivered to the DMVA control device through electrical
conductors (not shown), optical wave guides (not shown), such as fiber optic cables (not
shown), or via telemetry pulses.
In yet another embodiment of the present invention, electrical sensors 1262 - 1274 can
be cardiac pacing electrodes, electrical sensors, or both, placed on or within the liner 611 of Cup
105, or on or within shell wall 112 of Cup 105, for patients who require active management of
their cardiac disrhythmia. Electrodes and/or sensors 1262 - 1274 can be used without limitation
in the following ways:
1. Electrodes 1262 - 1274 may be connected to an implanted or external cardiac
pacemaker (not shown) for determining when a pacing pulse is required, and for
delivering this pulse(s) to the heart.
2. Electrodes 1262 - 1274 may be connected to the DMVA Control Unit to enable the
Control Unit to operate the DMVA device in desired synchrony or asynchrony with the
pacing pulses.
In yet another embodiment of the present invention, electrical sensors can be
cardioversion-defibrillation electrodes, electrical sensors, or both, placed on or within the Cup
liner or Cup wall, for patients at risk of fibrillation or unnatural heart rhythm. These electrodes
can be used without limitation in the following ways:
1. Electrodes 1262 - 1274 may be connected to an implanted cardioverter-defibrillator
(ICD) for determining when a cardioversion-defibrillation (CD) pulse is required, such
as the timing of cardioversion with compression (the synchronization of the delivered
energy with the appropriate timing of systolic compression and degree of systolic
compression), and for delivering this pulse.
2. Electrodes 1262 - 1274 may be connected to the DMVA Control Unit to enable the
Control Unit to operate the DMVA device in desired synchrony or asynchrony with the
delivered CD pulses.
In yet another embodiment of the present invention, a pacemaker (not shown) and/or
cardioverter-defibrillator (not shown) are integrated directly into the DMVA control device.
Figure 1 OB is a schematic representation of the electrophysiological sensors and the
liner of the DMVA device of Figure 10A. Referring to Figure 10B, DMVA Cup 106 comprises
an outer shell 160, with electrophysiological sensors or electrodes 1281 - 1287 embedded
within shell wall 162, or disposed on the inner surface thereof. Electrodes 1281 - 1.287 may be
used to excite cardiac tissue with an electrical pulse similar to a pacing pulse, a cardioversion
pulse sequence, or a defibrillating pulse sequence. Electrodes 1281 - 1287 may also be used
individually or in combination to sense cardiac electrical activity. The placement of such
multiple electrodes around the heart permits 3D analysis of cardiac electrical activity. Any
application of electrical stimulation may be done in a manner that has a net-zero DC current, in
order to eliminate electrolytic tissue damage. This feature of the present invention is important
to ensure the proper timing of compression with the stimulus for contraction to ensure that
DMVA Cup does the work of pumping blood.
Additionally, the array of electrodes 1281 - 1287 can be used to apply complex cyclic
three-dimensional electrical stimulation in a phased manner to heart tissues. Such stimulation
can be used to optimize synchronization of the natural rhythm of the heart with the DMVA
device, or to stimulate the heart slightly out of phase with the DMVA device in the use of a
training algorithm to be described subsequently.
In one embodiment electrodes 1281 - 1288 disposed on the inner surface of the Cup
shell wall 112 are small 'dots'. In another embodiment, electrodes 1281 - 1288 are larger
'patches'. In yet another embodiment, electrodes 1281 - 1288 are formed from a network of
filaments, or a combination of dots, patches, and/or filaments. Referring again to Figure 10B,
in one embodiment, electrodes 1281 - 1288 are joined by conductors 1289 to a common
electrical source such as e.g. conductive ring 1280. In another embodiment (not shown),
electrodes 1281 - 1288 are in electrical communication external to the Cup and/or patient by
individual wires or conductors. In such an embodiment, the DMVA Cup is capable of
functioning as an endocardia! pacemaker.
Electrodes 1281 - 1288, or electrodes in other configurations as previously described are
applied to the liner via adhesive, mechanical attachment, or by being co-molded on the internal
surface of the liner. Electrode material may be a biocompatible metal such as titanium or gold,
or it may be a conductive polymer such as polypyrrole, or a carbon-doped or metal-doped nonconductive
polymer, or a conductive paste containing a fine metal powder or other conductor.
In one embodiment, electrodes 1281 - 1288, and/or conductors 1289, and/or ring 1280 are
applied to the inner surface of Cup shell wall 162 by use of a direct circuit writing method and
apparatus, such as a MicroPen applicator manufactured by OhmCraft Incorporated of Honeoye
Falls, NY. Such an applicator is disclosed in United States patent 4,485,387 of Drumheller, the
disclosure of which is incorporated herein by reference. The use of this applicator to write
circuits and other electrical structures is described in e.g. United States patent 5,861,558 of Buhl
et al, "Strain Gauge and Method of Manufacture", the disclosure of which is incorporated herein
by reference. In a further embodiment, a protective overcoating is applied to such electrodes,
conductors, and ring, or to the entire inner surface of Cup shell 160.
In another embodiment electrodes 1281 - 1288, and/or conductors 1289, and/or ring
1280 are manufactured as an integral part of the Cup wall 162, and are electrically conductive
through the entire thickness of the Cup wall material. Electrodes 1281 - 1288 may take the
form of 'dots', 'patches', filaments, or a combination thereof.
In a further embodiment, Cup shell wall 162 is sufficiently porous and/or thin such that
electrical conduction will occur through an otherwise non-conductive shell wall material.
Depending upon the configuration of electrodes 1281 - 1288, the material, placement,
and the method of manufacture, electrical conductors/leads 1289 may be on the inner or outer
77
surface of the shell wall 162, or may be embedded therein. Leads 1289 may be made of
electrically conductive wire, or of an electrically conductive native polymer or a non-conductive
native polymer that is doped with carbon, metal, or other electrically conductive additive, or a
conductive paste containing a fine metal powder or other conductor, as previously described.
Leads 1289 may connect one or more electrodes individually or in combination. Leads may be
further coated or treated or shielded in order to prevent leakage of electrical current and to
minimize EMI interference with sensor signals. Such coatings and treatments are described e.g.,
in United States patent applications 10/384,288, and 10/369,429, the disclosures of which are
incorporated herein by reference.
In general, leads 1289 are collected in a region of the Cup shell 160 that minimizes
flexure of such leads 1289 and any adverse effect on the liner or on the heart. In the preferred
embodiment, leads 1289 are collected near the apex 161 of the Cup. A connector (not shown)
may be used to provide ease of Cup installation, but in one embodiment there is no connector
per se, in order to eliminate risk of circuit degradation or unintended cross-talk between
electrodes.
In another embodiment (not shown), operational data on the patient and on the
performance of the DMVA device is provided by externally positioned electrophysiological
sensors/electrodes. These sensors/electrodes can include without limitation skin mounted EKG
sensors and pacing electrodes, skin mounted cardioversion defibriallation (CD) sensors and
electrodes, or temporary pacing and CD leads such as percutaneously installed or
transesophageally delivered sensors and electrodes. These sensors and electrodes can be used
without limitation in the following ways:
1. Sensors and electrodes may be connected to an externally positioned cardiovertersdefibrillator
for determining when a CD pulse is required, and for delivering this pulse.
2. Sensors and electrodes may be connected to the DMVA Control Unit to enable the
Control Unit to operate the DMVA device in desired synchrony or asynchrony with the
delivered pacing and/or CD pulses.
Other arrangements of such electrodes will be apparent to those skilled in the art. Such
arrangements may include those performed in standard practice of electrocadiography, which is
described in Bronzino, J.D., The Biomedical Engineering Handbook, Second Edition, Volume I,
CRC Press, 2000, pp. 3 - 14 and 418 - 458; and in Essential Cardiology, Clive Rosendorf
M.D., ed., W.B. Saunders Co., 2001, pp. 23 - 699.
The purpose of any DMVA device is to maintain cardiac output. This output may be
characterized by stroke volume (the volume of blood expelled from the heart during each
systolic interval) and pressure at which this volume is delivered from the heart. In yet another
embodiment of the present invention, working fluid pressure and/or flow rate sensors are
integrated into the Cup and/or Cup drive assembly to collect data that can be used to control the
inflation/deflation of Cup liner, which in turn enables control of stroke volume and blood
pressure.
Figure 11 is a schematic representation of working fluid pressure and/or flow rate
sensors integrated into the Cup and the drive assembly thereof. Referring to Figure 11 DMVA
Cup 108 comprises fluid pressure sensors 1261, 1263, 1265, and 1267, which are placed
between the Cup shell 110 and liner 114 (pressure sensor 1261), and/or within the liner
inflation/deflation duct 322 (pressure sensors 1263 and 1267), and/or within the pump assembly
330 (pressure sensor 1265) used to pump DMVA working fluid indicated by arrows 399 from
within DMVA device control unit 1301. By measuring the pressure of DMVA working fluid
over time it is possible to infer the volume of working fluid delivered to Cup 108.
Alternately, the volume of working fluid delivered to Cup 108 can be measured directly
by placing a flow rate sensor(s) 1269 within liner inflation/deflation duct 322 to measure the
rate of flow of working fluid into or out of Cup 108 as indicated by arrows 399. Alternately, the
flow of working fluid into Cup 108 can be determined by calculating the volumetric
displacement of pump 330. In one embodiment wherein pump assembly 330 of DMVA device
108 comprises a piston pump, such volumetric displacement is determined by multiplying the
cross-sectional area of the bore 332 of pump cylinder 332 or of pump piston 334 by pump
stroke 336 due to piston driver 338. It is to be understood that similar means can be used to
determine volumetric displacement of other types of fluid pumping devices.
Sensor output from sensors 1261, 1263, 1265, and 1267, and/or other sensors described
previously or subsequently in this specification, is delivered to the DMVA device control unit
1301, which in turn directs the inflation and deflation of the Cup liner 114 as required to
provide the desired amount of cardiac output In one embodiment, ultrasound sensors as
described previously and shown in Figures 6A - 7 are used to monitor the LV/RV interactions,
geometric and volumetric changes throughout systolic and diastolic compression, heart
function, blood flow within the cardiac chambers, flow velocities and derived pressures across
all four of the heart's native valves. Information will be used to optimize DMVA action on the
heart, dictate weaning protocols and algorithms, etc. In another embodiment, fluid flow rate
sensors monitor the inflation and deflation volume of the liner(s), which correspond
respectively to the systolic output from and diastolic input to the heart. By controlling the total
volume of fluid pumped into and out of the liner(s), the DMVA is able to precisely control
stroke volume.
In other embodiments, blood pressure is controlled in a number of ways, including the
use of Cup working fluid flow rate sensors. The vascular structure of the body has a variable
resistance to blood flow as the body opens and closes resistance vessels depending upon a
variety of internal and external factors. Typically, resistance does not change much in a minute.
However, a sudden change such as e.g. a precipitous decrease in ambient temperature will
produce a very rapid change in resistance, due to such factors as the diameter, length, and
geometry of arteries, veins, etc. which restrict the flow of blood. Therefore increasing or
decreasing the rate of Cup liner inflation against this hemodynamic resistance will either
increase or decrease systolic blood pressure, respectively. Likewise, increasing or decreasing
the rate of Cup liner deflation against this hemodynamic resistance will either increase or
decrease diastolic blood pressure, respectively. Since the rate of flow of working fluid into the
Cup liner directly controls liner inflation and deflation, measurement and control of Cup
working fluid flow rate sensors can also be used to control blood pressure. In yet another
preferred embodiment, the Cup working fluid consists essentially of an electro-rheological fluid
(e.g. isotonic saline) that provides a unique and easily detectable flow rate signature.
In another embodiment, blood pressure is controlled by use of Cup working fluid
pressure sensors. Since Cup liner inflation or deflation is dependent upon the pressure at which
the working fluid is delivered to or removed from the liners, it is possible to use measurement
and control of DMVA working fluid pressure to control blood pressure. Specifically, the higher
or lower Cup liner inflation or deflation pressures can be used to control systolic or diastolic
blood pressure, respectively.
Figure 12 is a schematic representation of an alternate embodiment of working fluid
pressure sensors integrated into the Cup and Drive Assembly. Referring to Figure 12, in one
preferred embodiment, DMVA Cup comprises shell 210, liner 600, and seal 720. Shell 210 is
provided with a wall 212 comprising multiple chambers 214 and 216. In other embodiments
(not shown), shell wall 212 comprises three or more chambers. Such chambers 214 and 216
may be used to monitor pressure or flexure, or to apply pressure or other forms of modulation of
wall properties to wall 212, or a combination thereof.
In the embodiment depicted in Figure 12, the presumed use of the chambers is for
pressurization and pressure measurements. A first pressure sensor 1112 is disposed in chamber
214, and a second pressure sensor 1114 is disposed in chamber 216. In other embodiments (not
shown), there may be as many as 8 or 16 of these sensor positions depending on the approach
taken to modulate the behavior of the Shell and on the number of discrete chambers that exist.
Referring again to Figure 12, in the preferred embodiment depicted therein, liner 600
comprises an inner liner membrane 602 and an outer liner membrane 604, which are bonded to
each other at upper liner region 601 and lower liner region 603. Upper and lower liner regions
601 and 603 may be rolling diaphragm structures described previously in this specification.
Liner 600 is further provided with a pressure sensor 1116 disposed within the interstitial space
605 between inner liner membrane 602 and outer liner membrane 604 to monitor the pressure
therebetween. Interstitial space 605 may contain a gas or more preferably, an incompressible
fluid, thereby resulting in a fluid pressure- therein during operation of the DMVA Cup. This
pressure may be compared to other local pressures within the DMVA Cup to determine critical
operating conditions such as e.g., whether there may be a leak in one or both of liner
membranes 602 and 604. Sensor 1116 may also be used to monitor the pressure of a
therapeutic agent that may be applied through a permeable embodiment of inner liner membrane
602.
In one such embodiment (not shown) a circumferential cavity connects an external
source of pressurized therapeutic agent with a highly permeable center layer of the liner. In
another embodiment, the size, shape, and surface energy of the cavity wall are designed to
permit passive capillary movement of therapeutic agent from an external source to a highly
permeable center layer of the liner. In a third embodiment, the same approach is taken, but with
an active valve between the external source and the cavity, in order to control flow of
therapeutic agent. In a fourth embodiment the size, shape, and surface energy of the cavity wall
are designed to permit passive capillary movement of therapeutic agent from an external source
to the highly permeable center layer of the liner, but the relative surface energy of the wall
surface is controllable by external means in order to modulate flow of therapeutic agent.
In the embodiment depicted in Figure 12, it will also be apparent that liner membrane
602 and liner membrane 604 may be provided as two separated functioning liners, so that they
function as redundant liners. In the event that one liner were to fail in operation of the DMVA
apparatus, the other liner would continue to function. This capability is considered to be an
important safety and reliability feature of the present invention.
In the embodiment depicted in Figure 12, DMVA Cup 109 may be further provided with
several additional pressure sensors disposed within Cup shell 210. Sensor 1118 is disposed in
cavity 310, in order to measure the working pressure of the DMVA drive fluid contained therein
during systolic and diastolic actuation by the DMVA Cup. Sensor 1120 is disposed on the
surface of inner liner 602 or in proximity thereto in order to measure the pressure between inner
liner 602 and the wall of the heart (not shown). Sensor 1122 is disposed within a cavity 129
formed between seal 720 and heart surface 45, in order to measure pressure in proximity to seal
720, thereby enabling measurement of the effectiveness of seal 720.
In the embodiment depicted in Figure 12, DMVA Cup 109 may be further provided with
several additional pressure sensors disposed within the vacuum system 350 and/or fluid drive
system 360. Sensor 1124 is disposed within vacuum system 350, or alternatively within
vacuum duct 220, or both, in order to measure the vacuum applied to the Cup shell 210. Sensor
1126 is disposed within DMVA fluid drive system 360, or alternatively within drive fluid
supply duct 211, or both, in order to measure the pressure and vacuum applied to the liner 600
during systolic and diastolic actuation, respectively. In the instance where sensors are provided
in both locations, additional parameters such as frictional line losses, cardiac performance
conditions, the phase of systolic/diastolic cycle, and/or system malfunction may be measured
and/or detected.
In one embodiment the Cup controller receives pressure data from sensors 1112 - 1126
depicted in Figure 12. The control algorithm monitors absolute pressure levels and pressure
ratios against a table of acceptable values. In another embodiment the Controller inputs the
above pressure data to a Cup performance-monitoring algorithm to monitor appropriate Cup
performance. In yet another embodiment the Controller inputs the above pressure data to the
Cup control algorithm, which monitors Cup performance, and when one or more performance
parameters approaches or exceeds a limit, the algorithm applies compensation to the drive
system, or to other output devices such as e.g., cardiac electrodes, to correct the fault. For
example, if sensor 1122 indicates a minor loss of integrity of seal 720, the applied negative
pressure from vacuum system 350 may be increased, and/or measures may be taken (see e.g.,
Figures 19A - 19C) to increase the force of the seal against the heart wall.
Figure 13 is a schematic representation of several embodiments of position sensing
means for detection of the position of the liner of the DMVA apparatus during operation.
Referring to Figure 13, DMVA Cup 151 comprises shell 230, liner 690, and controller 1310.
Liner 690 is depicted in two positions: in dotted line in a more inward position, e.g. at the end
of systole or beginning of diastole; and in solid line in a more outward position, e.g. at the end
of diastole or beginning of systole. Controller 1310 provides power for sensor operation, signal
conditioning for sensor signals, and may provide analog-to-digital (A/D) conversion and/or
software analysis. The logical outputs of sensors (to be described) are used to monitor Cup
performance, monitor for Cup failures, and/or adapt Cup operation to other parameters, using
sensor data as part of the algorithm input.
In the embodiment depicted in Figure 13, DMVA Cup 151 is provided with several
position detecting sensor means disposed within Cup shell 230. Sensor 1130 is a Hall Effect
sensor comprising a small magnetic slug 1132 disposed on the outer surface 692 of liner 690,
and a magnetic proximity pickup 1134 disposed on the inner surface 234 of shell 230, and
further comprising a feedthrough conductor 235 passing through shell wall 232. In an alternate
embodiment, magnetic proximity pickup 1136 is disposed on the outer surface 236 of shell 230,
or embedded therein. Sensor 1130 detects the relative position of liner 690 with respect to shell
230 via the well known Hall Effect principle, and provides a signal correlating with such
position to controller 1310 via wires 1138.
In another embodiment depicted in Figure 13, DMVA Cup 151 is provided with an
optical reflective sensor 1140 comprising a light source and photodetector 1142, and a reflective
surface 1144 joined to the outer surface 692 of liner 690. In this embodiment, the sensor 1140
is of the type that transmits a diverging bundle of light from source 1142, and receives and
detects this light after it reflects off surface 1144. It can be seen from Figure 13 that as the
distance between the source/detector 1142 and the reflective surface 1144 increases (e.g.
movement from 690 in solid line to 690 in dotted line), the diverging bundle of light will
expand accordingly. Thus if the light receptor area of the detector 1142 is fixed, the amount of
light will vary approximately as the inverse square of the distance, and the distance from shell
wall 232 to liner 690 can be inferred. Sensor 1140 is connected to controller 1310 by cable
1148. In one embodiment, cable 1148 comprises optical fiber. In another embodiment, cable
1148 comprises electrical wires.
In another embodiment depicted in Figure 13, DMVA Cup 151 is provided with an
optical transmission sensor 1150 comprising a light source and photodetector 1152, and a
reflective surface 1154 joined to the outer surface 692 of liner 690. In this embodiment the
sensor 1150 is of the type that transmits light in a relatively collimated bundle, so that inversesquare
losses are minimal. In this embodiment, the DMVA working drive fluid is an optical
element in the light path and has an optical density chosen to match the working characteristics
of the transmission sensor 1150. The drive fluid may contain a dissolved dye that attenuates
light at some wavelength of interest, i.e. that is detectable by detector 1152. As path length
increases, sensor output decreases and thus the distance from shell wall 232 to liner 690 can be
inferred. Sensor 1150 is connected to controller 1310 by cable 1158. In one embodiment, cable
1158 comprises optical fiber. In another embodiment, cable 1158 comprises electrical wires.
In another embodiment depicted in Figure 13, DMVA Cup 151 is provided with an
inductive coil sensor 1160 comprising an active inductive coil 1162 disposed near the surface
236 of shell wall 232 or embedded therein, and a passive inductive coil 1164 joined to the outer
surface 692 of liner 690. In this embodiment active inductive coil 1162 cooperates across space
with passive inductive coil 1164 in a manner that results in a change in the effective LRC circuit
(within controller 1310 and connected to sensor 1160 by wires 1168), as the distance between
active coil 1162 and passive coil 1164 changes.
In yet another embodiment of the present invention (not shown), blood pressure and/or
blood flow rate sensors located in the patient's circulatory system are used to provide data to the
DMVA control system, or the physician, for use in controlling and operating the DMVA Cup.
Such sensors may include, but are not necessarily limited to a catheter (such as a Swan-Ganz
catheter) located in the patient's right atrium, right ventricle, or pulmonary artery.
Alternatively, sensors can also be located within the descending aorta (measuring the pressure
and/or flow rate of blood delivered from the left ventricle), or the right atrium or superior vena
cava (measuring the pressure and/or flow rate of blood delivered to the right ventricle). Sensor
measurements are fed back to the DMVA control unit, which in turn regulates Cup liner
inflation and deflation to maintain desired blood pressure and flow rate, as previously described.
It is to be understood that additional sensors could be installed in the Cup assembly, or
elsewhere within the body, and connected to the control unit. These sensors would include
without limitation sensors for measuring tissue oxygenation (i.e. detection of ischemic tissues
particularly tissues undergoing silent ischemia), blood oxygenation, tissue temperature, or other
physiological parameters. Additional physiological data obtained by conventional measurement
means that could be used to control Cup operation include without limitation respiratory rate
and body physical motion.
A more detailed description of Invention Aspect 6, which is directed to imaging contrast
agents incorporated into critical components of the Cup to enhance the images obtained thereof
is now presented with reference in particular to Figure 14. In yet another embodiment of the
present invention, ultrasonic contrast agents are utilized without limitation according to the
following descriptions.
In one embodiment, ultrasonic contrast agents are added to the surface of or imbibed
into the liner of the Cup, making the thin liner much easier to visualize under ultrasonic
imaging. Enhancing the liner image is critical to assess fit of the liner to the heart. One example
of a suitable ultrasonic contrast agent is to ultrasound is ECHO-COAT® ultrasound echogenic
coating from STS Biopolymers of Rochester NY. The thin, polymeric nature and very high
ultrasonic contrast of this material lends itself well to the polymeric nature of the Cup and Cup
liner. It is to be understood that any other component of the DMVA device could also be
treated with ultrasonic contrast agent to enhance its image profile.
In another embodiment, ultrasonic contrast agents are incorporated into the working
fluids used to inflate and deflate the Cup liners, to help visualize liner inflation and deflation
performance. In yet another embodiment, ultrasonic contrast agents can also be incorporated
into the blood flowing into and around the heart.
In similar embodiments of this particular invention (not shown), MRI contrast agents are
utilized without limitation according to the following descriptions.
In one embodiment, MRI contrast agents are added to the surface of or imbibed into the
liner of the Cup, making the thin liner much easier to visualize under magnetic resonance
imaging. Enhancing the liner image is critical to assess proper fit of the liner to the heart. One
example of a suitable MRI contrast agent is gadolinium. The thin and very high MR contrast of
this material, and its ability to be easily attached to or imbibed into the polymeric Cup and Cup
liner make this material a desirable choice. It is to be understood that any other component of
the DMVA device could also be treated with MRI contrast agent to enhance its image profile.
In another embodiment, MRI contrast agents can be incorporated into the working fluids
used to inflate and deflate the Cup liners, to help visualize liner inflation and deflation
performance. In yet another embodiment, MRI contrast agents can also be incorporated into the
blood flowing into and around the heart.
One example of an MRI contrast agent includes nano-particulate particles, including
nano-magnetic particles. Nano-magnetic particles can be applied as thin-films (typically on the
order of one micron in thickness) to objects to make them more visible under MRI. These
85
particles act by temporarily storing MRI RF energy and re-radiating this energy away once the
RF field is turned off, similarly to the way that the hydrogen nuclei (i.e. protons) in tissues
behave. However, the nano-magnetric coatings have a relaxation time (similar to the spinlattice
relaxation time of a proton), i.e. the time it takes for the nano-magnetic particles to
release the energy obtained from the RF pulse back to their surroundings in order to return to
their equilibrium state, that is different from that of body tissues, thereby enabling the nanomagnetic
coating to be visualized under MRI. Such a coating can be applied on or within the
surfaces of the DMVA device, such as the surface or interior of the liners, to enable these
components or features to be visualized under MRI. Such nano-magnetic coatings and
materials are described e.g., in United States patent applications 10/384,288, and 10/369,429,
the disclosures of which are incorporated herein by reference.
In a similar embodiment of this particular invention (not shown), radiopaque (i.e. X-ray)
contrast agents are utilized without limitation according to the following descriptions.
In one embodiment, radiopaque contrast agents are added to the surface of or imbibed
into the liner of the Cup, making the thin liner much easier to visualize under ultrasonic
imaging. Enhancing the liner image is critical to assess proper fit of the liner to the heart. One
example of a suitable radiopaque contrast agent is Omnipaque™, a non-ionic aqueous solution
of iohexol, N,N' - Bis(2,3-dihydroxypropyl)-5-[N-(2,3-dihydroxypropyl)-acetamido]-2,4,6-
triiodo-isophthalamide made by the Amersham Health Corporation of Princeton, NJ. The very
high X-ray contrast of this material, and its ability to be easily attached to or imbibed into the
polymeric Cup and Cup liner make this material a desirable choice. It is to be understood that
any other component of the DMVA device could also be treated with a radiopaque contrast
agent to enhance its image profile.
In another embodiment, radiopaque contrast agents can be incorporated into the working
fluids used to inflate and deflate the Cup liners, to help visualize liner inflation and deflation
performance. In yet another embodiment, radiopaque contrast agents can also be incorporated
into the blood flowing into and around the heart.
Figure 14 is a schematic representation of Cup with imaging contrast agents applied to
critical Cup components where contrast agents may be used to help define points or surfaces
that are important in monitoring the function of the DMVA. Such contrast agents may be
specific to x-ray (e.g. iodine compounds), to MRI (e.g. gadolinium compounds), to ultrasound
(e.g. ECHO-COAT® ultrasound echogenic coating) or any other contrast agent that is suited to
improve the resolution of an imaging modality used to determine the performance of the
DMVA system by monitoring the shape of the cup and/or the shape of the myocardial surface.
Referring to Figure 14, DMVA Cup 150 comprises shell 110 and liner 114 that define a
lumen or cavity 310 that surrounds the lower half of the heart (not shown). Upon sequential
application of positive and negative hydrostatic pressure to lumen 310, systolic and diastolic
performance of the heart (respectively) are enhanced.
A contrast agent such as described above is applied to the inner surface 201 of the shell
110 in order to enhance imaging of the shell wall. A contrast agent is also applied to the outer
surface 613 of liner 114 in order to enhance imaging thereof. Alternatively, the latter contrast
agent may be applied to the inner surface of liner 114, but the use of the outer surface 613 may
be preferred in order to avoid potential biocompatibility issues. Imaging of liner surface 613
provides measurements of the shape of the exterior of the heart itself. By monitoring this shape
over time, the performance of the heart under DMVA assist may be analyzed. In a similar
manner, imaging of both the liner surface 613 and the shell surface 201 provides measurements
of the volume contained in lumen 310; this may also be monitored in order to analyze the
performance of the heart under DMVA assist.
Most imaging techniques benefit from the use of reference points, comprising the same
image enhancing materials as described above, that are used to offset drift in the imaging
system electronics, or shifts in alignment of the object being imaged that would otherwise
degrade the accuracy of measurement by the imaging technique. In the embodiment shown,
multiple reference points 203 are shown in one possible position at the upper periphery of the
cup shell 110. Alternatively, or additionally, one or more reference points 205 near the apex of
the cup shell 110 may be employed to provide further information for purposes of referencing
the imaging system during use. These reference points 203 and 205 may be in other locations,
and may be extended as linear or surface elements in order to optimize the referencing process
for a specific imaging method.
A more detailed description of embodiments of the present invention pertaining to
Invention Aspect 3 (DMVA feedback control parameters), Invention Aspect 4 (DMVA
feedback control methods and algorithms), Invention Aspect 9 (Sensor data recording and
analysis capabilities), and Invention Aspect 10 (Specific device performance measures
appropriate for sensing) is now presented with reference to Figures 6A - 15,26 and 27.
Figure 15 is a schematic diagram of an overall control system with performance
feedback, for operation and control of the DMVA apparatus. Referring to Figure 15, DMVA
Cup 109 of Figure 12 is connected to a fluid drive system 300 and a control system 1300. It is
to be understood that many other embodiments of DMVA Cups as described in this
specification may be substituted for DMVA Cup 109. DMVA Cup 109 comprises shell 210,
liner 600, seal 720, and a plurality of sensors connected to control system 1300 by connection
lines. It is to be understood that as used herein, lines are meant to be connection means used to
place sensors in communication with control system 1330, and may comprise any of the
following: tubing, sleeving, insulation, conducting wires, wires shielded by sleeves or coatings,
optical fibers, telemetrically transmitted radio frequency or other electromagnetic or sonic
signals, and combinations thereof.
DMVA Cup 109 further comprises seal sensor 1122 connected via line 1123; upper
cavity pressure sensor 1112 connected via line 1113; lower cavity pressure sensor 1114
connected via line 1115; drive fluid lumen/cavity pressure sensor 1118 connected via line 1119;
and internal pressure sensor 1120 connected via a line (not shown). Vacuum port 211 of
DMVA Cup 109 is connected to drive system vacuum pump 302 by line 301. Fluid drive port
220 of DMVA Cup 109 is connected to drive system DMVA fluid drive pump 304 by line 303.
In an embodiment wherein seal 720 is an active seal, as in active seal 820 of Figure 19A or
active seal 770 of Figure 20, seal 720 is connected to drive system seal actuator 306 by line 305.
In a further embodiment, DMVA Cup 109 further comprises cardiac sensor 1260
connected to control system 1300 via line 1261, which may be any of a variety of electrical,
optical, chemical, or other sensors that directly measure some parameter associated with cardiac
performance and/or cardiac tissue status. In addition to sensors traditionally used for these
purposes, this embodiment provides for measurement of blood components such as CRP (CReactive
Protein, an indicator of tissue damage due to trauma or overwork) or Lactate (an
indicator of muscle fatigue), or other markers that can be used to determine the level of stress in
cardiac tissue, the degree of healing of damaged cardiac tissue, the degree of regeneration of
cardiac tissue, or a combination of these. Cardiac sensor 1260 may also be used to measure the
presence or concentration of a therapeutic agent. Cardiac sensor 1260 is connected to control
system 1300 via line 1261.
In the preferred embodiment, control system 1300 comprises numerous subsystems and
subcomponents, including microcontroller 1302 connected to programmable logic controller
1304 via interconnect line 1305, and connected to external transceiver 1306 via interconnect
line 1307. Control system 1300 is in communication with patient 90 via transceived signal
1309 (such as e.g. a patient alert signal) and via line 1311. Control system 1300 is in
communication with physician 92 via transceived signal 1313 (such as e.g. a physician alert
signal) and via line 1315. Drive fluid pump 304 is in communication with controller 1300 via
line 311. Vacuum pump 302 is in communication with controller 1300 via line 309. Seal
actuator 306 is in communication with controller 1300 via line 307.
In a further embodiment, vacuum port 211, DMVA drive fluid port 220, and various
sensor lines 305, 1113, 1115, 1119, and 1123 are integrated into a single multi-conduit, multiwire
connecting cable preferably entering the Cup shell 220 near the apex 161 (see Figure 10B)
of the Cup. Internal individual passageways are provided in the Cup shell wall for distribution
of the various sensor wires and fluid passageways.
In yet a further embodiment, the line or lines connected to the DMVA cup are provided
with a coating of an anti-infection agent and/or an anti-inflammatory agent. Descriptions of
suitable agents may be found at e.g., "Preventing Complications of Intravenous Catheterization"
New England Journal of Medicine, March 20, 2003, 1123. In addition, at http://link.springerny.
com/linkyservice/joumals/00284/bibs/33nlpl.html, there is described a a hydrogel/silver
coating that reduces adherence of E-coli (hydrogel effect) and reduces growth (silver); at
http://www.infectioncontroltoday.com/articles/291feat3.html there is described several
antimicrobial surface treatments such as chlorhexidine-silver sulfadiazine, minocycline, and
rifampin, as well as silver compounds (chloride or oxide). Those skilled in the art will be aware
of a variety of such anti-infection and anti-inflammatory agents, each having specific beneficial
properties, and each that may be used individually or in combination.
With such a comprehensive fluid drive system 300 and control system 1300 interfaced
with DMVA Cup 109, it will be apparent that a wide range of data acquisition, and Cup control
and operating algorithms are possible. Further embodiments of the DMVA Cup of the present
invention are directed to advanced control and use of such Cup device in cardiac regeneration.
Figure 26 is a schematic diagram of an overall control system with performance feedback, for
operation and control of the DMVA apparatus; and Figure 27 is a schematic diagram of a
DMVA control system, including the relationships between algorithms, input data, and output
data for operation and control of a DMVA apparatus in the practice or cardiac regeneration.
Referring to Figure 26, Cup controller 1300 operates DMVA Cup 100. There is further
provided a data interface 1400 to which sensor data from DMVA Cup 100 is provided, and
from which signal conditioned and/or analyzed data is provided as input to a treatment
algorithm 1510. Such algorithm may be formulated by a human (e.g. patient 90 or physician
92) based upon intuition, experience, and physical sensation, as well as data from data interface
1400; or such algorithm may be formulated by a computer within Cup controller 1300, or other
artificial intelligence device. In either instance, algorithm 1510 may be provided with
additional input from external data input source 1599, materials input source 1598, and/or
power input source 1597.
Algorithm 1510, in combination with various embodiments of the DMVA Cup
described in this specification, may be designed to provide the heart with and/or assist the heart
in biochemical regeneration, and/or cardiac training, and/or therapeutic recovery, as will be
presently described and shown in Figure 27.
The accepted practice of treating congestive heart failure (CHF) and other degenerative
cardiac diseases has in the past been to attempt to slow the progress of disease (e.g. drug
therapies and multi-chamber heart pacing), to compensate for the disease (e.g. restricted life
style, oxygen support, mechanical ventricular assist devices), or in some cases to replace the
diseased heart. The inability of the heart to recover from its diseased state, and the resulting
inevitability of physical decline, morbidity, and death, have for some time been reluctantly
accepted by the medical community, and society at large.
Recent parallel advances in cardiac medicine and in regenerative medicine have led
some researchers to speculate as to whether some of the effects of CHF might be even more
effectively delayed or compensated by use of regenerative medical treatment on the heart itself.
However, the working premise of the instant invention goes well beyond the improved
outcomes that are predicted based on results from prior art approaches. It is proposed that the
entire course of CHF may in many cases be made totally reversible, and that an individual
treated under the process of this invention may recover completely from CHF.
The aspects of this approach include the following:
- An improved device and method for mechanical ventricular assist that is used to
support life functions, and to permit the heart to operate in a low-stress environment.
- A comprehensive historical information set relating to the individual, and to large
populations of individuals with similar circumstance.
- An exhaustive set of electronic, physical, and bio/chemical sensor measurements.
- An array of treatment options, including physical, electromagnetic, chemical, and
regenerative cellular techniques.
- A treatment algorithm that draws all of the above aspects together in a control system
that is knowledge-based and adaptive.
First Order Algorithm Elements
For the purpose of this disclosure, a first-order control algorithm element is defined as
one that uses a single input to modify a single output, based on a predetermined mathematical
relationship. For a system having 'n inputs that are one-for-one related to outputs, the control
algorithm is simple, having (n) elements that may be updated on a sequential or parallel basis.
For a system comprising 'n' inputs and 'm' outputs, and where there is no one-for-one
relationship, the maximum set of elements will be (m) x (n). While in theory these elements
could be updated on a sequential or parallel basis, it becomes obvious that for any other than an
extremely simple and linear system, the order and frequency of update will have a significant
impact on the response of the system. The variability coming from this approach, especially if
used to control a biological process, will result in an indeterminate result.
Second Order Algorithm Elements
For the purpose of this disclosure, a second-order control algorithm element is defined
as one that uses multiple inputs to modify a single output, based on a predetermined
relationship. In the case of 'n' inputs and 'm' outputs, each of the control elements will be far
more complex, but there will be only (m) elements and the algorithm will be far more robust,
especially if used to control a biological process.
Algorithm Updating and Adaptation Process
The biological process that the algorithm of this invention is intended to control is not
the human heart, per se. The biological process this algorithm is intended to control is the
healing of the heart, and the recovery from a degenerative cardiac disease such as congestive
failure.
Thus, the cardiac regenerative algorithm or 'treatment algorithm' will not be one that is
based on a premise of norms, stability, and control limits. Rather, the treatment algorithm of
this invention will be based on a premise of gradual migration of a large set of parameters from
a state of disease to a state of health. Each of these states, 'disease' and 'health', have a number
of parameters each of which may vary over a range of values over time. In addition, the pathway
from disease to health will vary from individual to individual. Thus for the purpose of creating
an algorithm to guide the system in a manner that effectively moves this individual's heart from
a diseased state to a healthy state, a fixed set of control equations will not suffice. What is
required is an adaptive algorithm that continually updates itself, having 'knowledge' of a variety
of pathways from disease to health that results from 1) generalized demographic information,
used in combination with 2) detailed historical information on the individual, and 3) frequent
pathway analysis and correction.
Algorithm Fail safes
Given the adaptive nature of the treatment algorithm, there is an increased possibility of
'traps' along the particular pathway that is being followed. The term 'trap' refers to a local
optimum that precludes movement of the algorithm to the global optimum solution for the
individual. In some cases a pathway trap may stall the process of healing, and in others it may
have even more serious negative consequences. Thus the treatment algorithm also has failsafe
measures built into it that monitor its progress and if a trapping situation is sensed, corrective
actions and/or alarms can be activated.
Core Treatment Algorithm Model
Referring to Figure 27, the core treatment algorithm model 1520 is essentially an
adaptive, knowledge-based, software control algorithm, set at its initialization point and
intended for use across the entire range of working scenarios. By analogy it is "right out of the
box - batteries not installed" and must be set up by the attending physician for use with the
specific individual.
The core treatment algorithm model 1520 may be updated from time to time, at a
number of levels. However, the updating of the core model should not be confused with the
behavior of a working algorithm 1540 that is constantly modifying its set points based on a
variety of inputs. The working algorithm 1540 is intended to adapt to changes in patient state,
to take advantage of information relating to a large population of patients in order to predict
some aspects of patient response to therapy, to accept changes in control parameters from the
attending physician, and to monitor its own performance. However, all of these aspects of the
working algorithm 1540 are based on protocols in the core algorithm model that are fixed.
These core algorithm protocols may only be changed upon a version update that is beyond
access to the patient or the physician.
Physician Inputs and Outputs 1524 are provided for use in the working algorithm.
Inputs are provided such that the attending physician will be presented with an interactive
software program that does the following:
- Prompts the physician with input questions
- Guarantees a comprehensive set of data on the specific patient.
- Challenges the physician in cases where data elements may be in conflict.
- Crosschecks inputs against patient record databases as a second failsafe.
- May suggest multiple treatment pathways based on access to a broader knowledgebased
cardiac treatment database.
Outputs are provided such that feedback to the physician will be timed to match level of
urgency:
- Regular status updates on patient condition and response to the chosen treatment.
- Advance warning if any patient condition parameter is approaching a control limit.
- Immediate warning via telemetry if any control limit is exceeded.
Algorithm Adaptation
The working algorithm 1540 is intended to adapt based on the following sets of
conditions and inputs for algorithm adaptation 1530:
Initialization:
- Initial choices for treatment and for alarm limits made by the attending physician.
- Patient history 1532 for the individual.
- Demographic information 1534 across a large population of similar patients.
Long-term:
- Response to therapy 1536.
- Update to core treatment model (only upon version change and with physician
involvement).
The algorithm adaptation process 1530 has the following characteristics:
- It is a fixed routine that is part of the core model, so its behavior may only be changed
by a version change to the core model.
- It accepts inputs listed above and modifies the working algorithm 1540 accordingly.
Working Algorithm
The working algorithm 1540 uses real-time inputs to control real-time operation of the
therapeutic device. Inputs include:
- Electrophysiological measurements 1542.
- Bio/chemical measurements 1544.
- Physical measurements 1546.
- Imaging measurements 1547.
- Patient inputs 1548.
- Failsafe limit alarm 1549.
The working algorithm controls the following aspects of therapeutic device function:
- Mechanical assist 1551, via the Heart Cup 100 (see Figure 26).
-Use of artificial blood components 1552 that act to enhance the effectiveness of oxygen
and carbon dioxide exchange well beyond that of natural blood.
- Standard electrical cardiac pacing 1553, with single- or multiple-chamber leads.
- Advanced electromagnetic therapy 1554.
- Interval training 1555, used to periodically stress the heart as in athletic conditioning.
- Bio/chemical therapeutic agents 1556 applied topically via the Heart Cup, or into the
bloodstream.
- Regenerative medical agents 1557, including tissue scaffold materials, biochemical
materials, stem cell and/or other cellular components, and electrical stimulation of
tissue regeneration.
The working algorithm 1540 is fixed in its behavior over short periods between updates
from the algorithm adaptation process 1530. However, the working algorithm 1540 is a
complex, second-order control system that not only uses in the inputs listed above, but also
analyzes the relationships between those inputs and is able to react in a non-linear fashion.
Patient Inputs & Outputs 1548
The patient will be provided with an input/output device that permits entry of
information that may improve the effectiveness of the treatment. Examples of inputs include
the following:
- Information relating to planned physical activity or rest - this may be used to influence
the scheduling of training-related portions of the treatment algorithm.
- Information related to timing and content of meals - metabolic information may be
useful in predicting cardiac response, and in some cases the drugs used by the treatment
algorithm may be contraindicated in combination with some foods.
The I/O device permits communication output to the patient. Examples of outputs
include the following:
- The same information being sent to the physician.
- Confirmation of, or challenge to, information input by the individual.
- Suggested actions that extend the effectiveness of the treatment algorithm, relating to
physical activity, rest, or other factors.
Parameter Monitor, Failsafe Limit Monitor, and Alarm 1549
This ("Failsafe") subroutine acts as a secondary safety feature, providing redundant
measures to ensure the safety of the patient. It is not a redundant controller and does not affect
the operation of the primary working algorithm. Rather, it has a baseline set of parameter
limits, and parameter-to-parameter limits that can be modified by the physician at the outset.
During initialization of the system, the failsafe algorithm 1549 (as modified by the physician) is
compared against the working algorithm 1540 (as modified by the physician, and by input of
patient history and demographic information) to determine if there are operational
inconsistencies. Once the overall system is initialized and started, the failsafe algorithm 1549
monitors the control outputs of the working algorithm 1540 on a real-time basis and reacts to
both limits that are exceeded, and trends in performance that are approaching limits in a manner
that is inconsistent with nominal operation. It then provides an appropriate warning or alarm
output to the physician and/or patient, as appropriate.
External Data
Individual Patient History 1532: Patient history input 1532 is a set of numerical values
that describe or quantify a variety of prior aspects of the individual patient preceding the
implementation of the DMVA apparatus, the specific cardiac disease being treated, and other
health-related factors that may be important to proper operation of the working algorithm 1540,
and especially as the interval training 1555 aspects are utilized. Typical elements in patient
history include the following: history of cardiac disease conditions such as pulmonary
hypertension, systemic hypertension, dilated cardiomyopathy, congestive heart failure, and
myocardial infarction; hereditary factors; smoking or substance abuse; and history of other large
organ diseases.
Demographic Information 1534: Any individual patient, healthy or unhealthy, provides
opportunity for retrospective analysis of their responses to disease and to treatment (physical,
bio/chemical, electromechanical, etc.). But the individual patient history provides only the
opportunity for retrospective analysis, and no opportunity for predictive analysis. A database of
demographic information, i.e. predictive numerical parameters, provides the opportunity for
prediction of the individual patient's response to the above stimuli by comparison to others with
similar conditions and an analysis of the outcomes from specific pathways chosen in treatment.
The kinds of demographic information useful to the working algorithm include information
such as age, race/ethnicity, and gender.
Therapeutic Response 1536: Input parameters shown in Figure 27 by indicia 1542,
1544, 1546, and 1547 are measurements made by individual sensors or groups of sensors,
indicating the value of a specific parameter in real time. These parameters are used by the
working algorithm 1540 in its real time control of system function. In aggregate, they may be
analyzed along with other inputs, such as physician observations and patient observations, to
create a set of factors that correlate to the general state of health of the patient, of the
cardiovascular system, and individual subcomponents of the heart such as regions of tissue that
may have been damaged during a myocardial infarction, or a particular part of the circulatory
system of the heart itself.
The therapeutic response factors 1536 are used as inputs to the algorithm adaptation
process 1530 as a means of indicating the recent and longer-term effectiveness of the working
algorithm 1540 (as currently configured) to stabilize, heal, and/or regenerate the heart. Use of
these therapeutic response factors along with patient history and demographic information, are
analyzed by the algorithm adaptation process 1530 to either continue or modify the current
working algorithm 1540.
The therapeutic response function 1536 may also periodically provide status and trend
data to the physician and/or the patient, as appropriate.
Internal Data
Electrophysiology input 1542 includes one-dimensional data 1571, two-dimensionaldimensional
data 1572, and three-dimensional data 1573. One-dimensional data 1571 entails
typical electrophysiological signals such as are used in controlling pacemakers and cardiodefibrillators.
These are typically point measurements made by sensors that contact cardiac
tissue at specific parts. With regard to two-dimensional data 1572, the electrophysiology of
heart function is not a set of distinct traditional nerve pathways connecting a set of points in the
heart tissue. Rather, it involves a wave front that propagates through the tissue in a very
complex way. By making electrophysiological measurements at multiple distributed surface
sites (and conversely providing the opportunity for pacing the heart at these multiple sites),
more information may be collected regarding the state of tissue at specific locations within the
heart. This information may be key to application of regenerative therapies and specifically to
the use of "training" regimens. See, for example, United States patent 5,674,259, "Multifocal
leadless apical cardiac pacemaker," the disclosure of which is incorporated herein by reference.
With regard to three-dimensional data, reference may be had to, "When Time Breaks Down -
The Three-Dimensional Dynamics of Electrochemical Waves and Cardiac Arrhythmias",
Arthur T. Winfree, Princeton University Press, ISBN 0-691-02402-2, the disclosure of which is
incorporated herein by reference.
Bio/Chemical Markers 1544
Lactate 1574: Lactate is well known as a marker for muscle fatigue. It may be
measured directly via a chemical analysis of blood. It may also be measured by spectroscopic
means. If the latter approach is taken it may also be measured directly in cardiac tissue thus
providing a feedback mechanism for the degree of stress involved in a cardiac muscle training
regimen.
C-Reactive Protein 1575: CRP is produced in the liver in response to inflammation
and/or tissue damage. The biochemical pathway resulting in an increase in CRP concentration
appears to be somewhat complex. Thus it is unlikely to find a precursor molecule at the heart
that would be an early indicator of cardiac tissue damage due to excess physical exertion, or
some other form of impending damage to the heart.
POa 1576: Concentration of oxygen and carbon dioxide in arteries, capillaries, and
veins supporting cardiac tissue may be an important indication of tissue health, and the ability
of the heart to do effective pumping work.
PCO2 1577: See above for PO2.
As stated previously, the present invention avoids the production of stress forces within
the heart muscle by applying forces to the heart that are perpendicular to the surface of the heart,
while also ensuring that the magnitude of the difference between adjacent forces is very small.
In other words, the application of the force to the heart is substantially uniform, taken over a
distance scale that is relevant to the imposition of significant (i.e. traumatic) shear stress on the
heart muscle. In particular, the applied force is uniform circumferentially, i.e. around the heart,
such that the heart is compressed to form a core shape with a substantially circular cardiac core
diameter as previously described. Each of these features eliminates the formation of shear
forces within the heart muscle, which leads to bruising damage to the heart tissue which leads to
muscle fatigue and potentially failure of the heart. The DMVA device of the present invention
is thus atraumatic with respect to the heart.
Specific features of the present invention which provide these capabilities include the
following:
A. Near-Isotropic liner material
Liner materials that are near-isotropic will expand uniformly from internal pressure or
vacuum applied by the internal working fluid. This uniform expansion or contraction prevents
"less stiff portions of the liner from "ballooning" into the heart tissue and creating higher
forces on the heart tissue, relative to "more stiff' adjacent portions of the liner, which would
cause shear stresses throughout the heart wall and bruising of heart tissue, which would
ultimately lead to damage to the heart tissue. Over time, this damage could lead to total failure
of the heart.
In addition, some materials either stiffen after being flexed or stretched ("strain
hardening"), or weaken after flex or stretch (strain softening). In metals, this results from
changes in grain structure, and in elastomers, it results from changes in polymer chain bonds.
Optimal materials for the DMVA Cup liner and shell are "strain neutral", and maintain original
properties after repeated cyclic loadings. The near-isotropic and strain neutral liner avoids this
problem by enabling all areas of the liner to expand at the same rate and preventing areas of the
liner from "ballooning" into the myocardium and creating shear stresses within the heart tissue.
Furthermore, isotropic materials allow the heart to be actuated (compressed and dilated) in a
manner dictated by the tissue characteristics, and pressure points are minimized as the material
does not fold or bend in a non-uniform fashion. In one embodiment, a suitable near-isotropic
and strain neutral elastic material is a heat curable liquid silicone rubber sold.by the NuSil
Technology Company, of Carpenteria, CA.
B. Fatigue-resistant liner material
Fatigue of the liner material would create a "weak spot" such as described above, and
result in shear within the heart tissue. Liner materials that are fatigue-resistant ensure that the
liner will avoid "weak spots" and prevent a difference in forces from being applied to the heart
tissue and the shear stresses that such differences create.
C. Dynamic Cup shell structure and material.
The compliant nature of the preferred Cup shell of the present invention results in the
constantly adaptation of the shape thereof in response both to the actuating forces applied to the
heart and changes in the heart's size and/or shape. This characteristic contributes to decreased
ventricular trauma, ease of application as the housing can be deformed to fit through small
incisions, and important dynamic conformational changes that constantly respond to the heart's
changing shape.
The housing (shell) of the device is constructed of a flexible material that has
appropriate compliance and elastic properties that allow it to absorb the systolic and diastolic
actuating forces in a manner that somewhat buffers the effect of the liner on the heart. The
unique qualities of this housing lessen the risk for inadvertent excessive forces to be applied to
the heart at any time of the cycle. The shell conforms to the dynamic changes in the right and
left ventricles throughout compression and relaxation cycles as well as overall, ongoing changes
related to variances in heart size over time which occur as a consequence of continued
mechanical actuation and related "remodeling" effects on the heart.
In one embodiment, the Cup shell consists essentially of the aforementioned liquid
silicone rubber polymer having a wall thickness of between about 2 millimeters and about 8
millimeters. It is preferable to form the Cup shell with walls as thin as possible white retaining
the desired dynamic capabilities.
D. Liner design improvements:
In another embodiment, the requirement for an isotropic or near-isotropic material is
greatly reduced or eliminated by the provision of a liner that applies a uniform force to the heart
without undergoing elastic deformation, one such a liner is a rolling diaphragm liner that is
deployed against ventricle walls of the heart by a progressive rolling action, as described
previously in this specification and shown in Figures 4A - 4C.
2. Absence of Surface Abrasion
The Cup liner described above creates a near-zero shear stress or minimum-slip
condition at liner-myocardium interface, similar to the "rolling interface" that exists between
mechanical gears. This no-slip condition minimizes or eliminates abrasion of the heart tissue,
which over time can result in serious damage to the heart tissue.
Figure 16A is a schematic representation of a further embodiment of the DMVA
apparatus of the present invention, comprising an integrated seal and liner with a rolling
diaphragm. This embodiment demonstrates the concept of making the shell and the liner as
separate, precisely molded components, and bonding them together in a secondary process using
fixtures to locate and clamp them. Referring to Figures 16A, DMVA apparatus 101 comprises
shell 110, depicted therein as a simple thick-walled cup-shaped structure. For sake of simplicity
of illustration, no attempt is made to show ports or other features in shell ItO. In other
embodiments, shell 110 may have variable thickness and/or variable material in both vertical
and circumferential sectors in order to provide desired mechanical properties. In a further
embodiment, shell 110 comprises a core of non-biocompatible material with an outer layer of
biocompatible material.
Referring again to Figures 16A, DMVA apparatus 101 further comprises integral liner
and seal assembly 530 joined to Cup shell 110. Integral liner and seal assembly 530 is formed
of a unitary piece, preferably by a molding process, such as e.g., by an injection molding or
compression molding technique, or by pre-molding the seal and bond area features thereof via

injection molding, then placing such piece in an insert mold such that the thin liner sections may
be molded and bonded thereto simultaneously.
Assembly 530 comprises seal 720, upper rolling diaphragm section 520, liner membrane
540, and lower rolling diaphragm section 570. In the preferred embodiment, seal 720 is formed
with a structure similar to seal 730 of Figure ISA, which is described subsequently in this
specification. Seal 720 preferably comprises base 722, tapered section 724, tip 726, and surface
728, which is formed to mate with corresponding upper edge 115 of Cup shell 110. Surface 728
of assembly 530 is joined to Cup shell 110 by suitable means such as e.g., adhesive, as
described subsequently in this specification for the joining of lower joint region of liner 510 to
Cup shell 110 and shown in Figure 19B. In the preferred embodiment, surface 728 of assembly
530 is joined to upper edge 115 of Cup shell 110, while transition section 532 of assembly 530
is not joined to shell 110. Thus in a manner similar to that described subsequently and shown in
Figure 16B, assembly 530 is free to flex at transition section 532 as indicated by bi-directional
arrow 198, thereby distributing bending stress over transition section 532. It is noted that
Figure 19A depicts an alternate embodiment comprising a transition section 533 for distributing
stress in assembly 530 according to the same general principles.
In one embodiment, rolling diaphragm liner is directly bonded to DMVA Cup shell wall
112 at upper section 520 and lower section 570 thereof. Figure 16B depicts one embodiment of
such a bond between liner 510 and Cup shell wall 112 at lower joint region 514 therebetween.
Referring to Figure 16B, shell wall 112 is provided with a groove 130 having surfaces 132 and
134 in shell wall 112, formed preferably during the shell manufacturing process such as e.g.,
molding, or less preferably, by a secondary operation such as e.g., milling or etching. Lower
rolling diaphragm section 570 of liner 510 is provided with a rim 572 having surfaces 574 and
576, which are formed to mate with corresponding surfaces 132 and 134 of groove 130 of Cup
shell wall 112. In one embodiment (not shown), during the manufacturing process, an adhesive
is dispensed such that a thin film of adhesive is formed in the interstice between rim 572 and
groove 130, thereby bonding lower joint region 514 of liner 510 to Cup shell wall 112.
In the preferred embodiment, surfaces 576 and 134 are bonded, while surfaces 574 and
132 are not bonded. With such a structure, rim 572 of lower rolling diaphragm section 570 is
free to flex as indicated by arrow 199 when liner membrane 540 is displaced outwardly and
inwardly, thereby widely distributing stress within lower rolling diaphragm section 570, such
that fatigue of the material thereof is greatly diminished. Thus the safety, reliability and
longevity of the DMVA device 101 are significantly enhanced.
It is known that sudden changes in cross-section of components that undergo repetitive
bending result in stress-concentrations that reduce fatigue life of such components. A number
of approaches are traditionally taken to effect stress relief, but one of the simplest is a gradual
change in section. Thus it can be seen that there is a continuous, gradual thinning of the liner
material in the progression from the rim 572, from surface 576 upwardly to the portion thereof
bounded by surface 574, an on through transition section 578 to liner membrane 540 in order to
achieve such a reduction in stress concentration.
Other means of bonding liner 510 to shell wall 112 will be suitable and will be apparent
to those skilled in the art, with the exact choice of means depending upon the particular material
selections for Cup shell 110 and liner 510. One example of a material suited for both shell 110
and liner 510 is MED4850 Liquid Silicone Rubber. One example of an adhesive well suited for
bonding elements consisting essentially of this material is MED 1-4213. Both of these materials
are products of the NuSil Technology Company of Carpenteria, CA.
Figure I7D - 17H are detailed views of alternate embodiments of rolling diaphragm
liners of the DMVA apparatus, particularly showing the bonds between such rolling diaphragm
liners and the cup shell. Figures I7A, 17B, and 17C depict liner attachments having simple
designs that will result in shear stress in the surface tissue of the heart, and are thus less
preferred. However, such designs demonstrate one aspect that should be considered, i.e. a
gradual shape transition from liner 610 or 620, (which moves during systole and diastole) and
shell 110 (which moves far less). Thus; sharp edges and shape transitions in the liner that act as
stress concentrators are to be avoided. In the embodiments of Figure 17B and 17C, liner 620
comprises a tapered unbonded transition section 622, which reduces in thickness to a thin
section forming liner membrane 624. The DMVA device of Figure 17C is further provided
with a shell 110 having a recess 121, so that during diastolic actuation, liner 620 can flex
beyond a 180 degree angle as indicated by dotted line 193. Liner 620 may even be displaced
such that unbonded transition section 622 is contiguous with recess 121 of shell 110 at the
completion of diastole.
Figure 17D depicts an embodiment of a rolling diaphragm 630 comprising bonded rim
631, unbonded tapered transition section 632, rolling bend 633, and liner membrane section
639. In this embodiment, single bend 633 is used to minimize the motion of the heart wall (not
shown) relative to liner 630; however, this design will still result in relatively high bending
stress in the material of liner 630 at bend 633.
Figure 17E depicts another embodiment of a rolling diaphragm provided with two folds
or bends. Referring to Figure 17E, rolling diaphragm 640 comprises bonded rim 641, unbonded
tapered transition section 642, first rolling bend 643, second rolling bend 644, and liner
membrane section 649. The presence of two bends 643 and 644, along with a larger recess 122
in shell 110, further reduces tissue shear stress and liner material fatigue.
Figure 17F depicts another embodiment of a rolling diaphragm provided with three
bends. Referring to Figure 17F, rolling diaphragm 650 comprises bonded rim 651, short
tapered transition section 652, first elbow bend 653, first U bend 654, second elbow bend 655,
and liner membrane section 659. Figure 17G depicts yet another embodiment of a rolling
diaphragm provided with a plurality of stress-relieving bends. Referring to Figure 17G, rolling
diaphragm 660 comprises bonded rim 661, short tapered transition section 662, first elbow bend
663, first U bend 664, second U bend 665, third U bend 666, second elbow bend 667, fourth U
bend 668, and liner membrane section 669. The presence of multiple bends in these
embodiments further reduces tissue shear stress and liner material fatigue.
Figure 17H depicts yet another embodiment of a rolling diaphragm provided with a
plurality of stress-relieving bends and with an active seal, rather than a passive "self-bailer" or
"check valve" seal. Referring to Figure 17H, rolling diaphragm 670 comprises bonded rim 671,
riser section 672, riser bend 673, tapered transition section 674, first elbow bend 675, first U
bend 676, second U bend 677, third U bend 678, second elbow bend 679, fourth U bend 680,
and liner membrane section 681. The presence of multiple bends in these embodiments further
reduces tissue shear stress and liner material fatigue. Rolling diaphragm 670 further comprises
seal 685 comprised of base 686, tapered section 687, and tip 688.
Arrows 682, 683, 689, and 684 indicate the linkage between motion of liner membrane
681 and seal 685 during systole and diastole that results from pressurization of the cavity 123
between shell 110 and liner 670 with DMVA drive fluid. During systole, liner membrane
moves as indicated by arrow 683, and seal 685 moves as indicated by arrow 684; such that
during systole, seal 685 is relatively looser on the heart (not shown). During diastole, liner
membrane 681 moves as indicated by arrow 682, and seal 685 moves as indicated by arrow 689;
such that during diastole, seal 685 is relatively tighter on the heart. Thus the "self-bailing"
efficiency of active seal 685 is improved. This effect results directly from the shapes,
dimensions and materials chosen for liner/seal 670. It will be apparent to those skilled in the art
that there are many variants of liner seal 670 with regard to material thicknesses and bend
configurations comprising at least one bend that will achieve the same result, i.e. the linkage
102
between motion of liner membrane 681 and seal 685 as indicated by arrows 682, 683, 689, and
684, an that such variants are to be considered within the scope of the present invention.
Figure ISA - 18C are detailed views of alternate embodiments of several DMVA cup
seals, in which the free shape, initial installed shape, partially recovered shape, and final
position are shown. Referring to Figure ISA, obtuse seal 730 comprises structural base 732,
which is joined to shell 112 of DMVA Cup 100 (see e.g., Figure 4A). Obtuse seal 730 further
comprises a tapered midsection 734, which tapers to an apex or tip 736. Tip 736 of seal 730 is
tapered to a very thin section terminating at a distinct edge, thus conforming to the details of
heart surface effectively. In a further embodiment, the overall shape of the seal annulus is not
perfectly circular, but instead seal 730 is molded or formed to adapt to the non-circular shape of
the heart at this vertical position near the atrio-ventricular groove of the heart.
Referring again in particular to the upper portion of Figure ISA, labeled F.S., seal 730 is
depicted in the free state (F.S.). When seal 730 is in the free state, tapered midsection 734 and
apex 736 are generally disposed at an obtuse angle with respect to surface 731 of structural base
732. Seal 730 is shown as inwardly-facing, in order to maximize the "self-bailing" properties
associated with diastolic and systolic movement of the Cup and the Heart. By self bailing, it is
meant that the action of seal 730 against the heart surface is intended to act like a check valve,
encouraging any trapped fluid to be easily pushed out during systole, and discouraging any
external fluid from entering during diastole. The seal-to-heart interface is maintained partly by
sh'ape and elastic forces, and partly by hydrostatic pressure on the outer surface of seal 730. In a
further embodiment (not shown), seal 730 further comprises an internal core section having
different material and physical properties than the outer surface, and may or may not be
biocompatible.
When the DMVA Cup is to be installed upon a heart, the Cup is slipped over the heart,
such that heart tissue 39 is placed in sliding contact with seal 730. During installation (D.I.),
seal 730 bends at midsection 734, and apex 736 is displaced downwardly by the downward
sliding action of heart tissue 39 indicated by arrow 99, as indicated in the second part of the
sequence labeled D.I.
As the heart is slipped into the DMVA Cup, and the portion of maximum girth of the
heart passes seal 730, seal 730 begins to recoil in the tapered midsection 734, thereby drawing
apex 736 upwardly as indicated by arrow 98. The third graphic of Figure ISA, labeled P.R.,
shows such a partial recovery of seal 730. When the heart is fully seated and retained in the
DMVA Cup, and the recoiling action of seal 730 is complete, seal 730 is in final position (P.P.),
as shown in the final graphic of Figure ISA. The recoil of seal 730 may occur spontaneously
during installation; or it may occur by some manual manipulation thereof; or it may occur after
several cardiac cycles that "work" the heart in the Cup, thereby facilitating the flexure and
recoiling of seal 730.
Seal 730 is configured such that apex 736 is in tension against heart tissue 39. In
addition to such tension, the pressure differential that is present between the outside and inside
of the Cup wall during diastole further enhances engagement and sealing contact between heart
tissue 39 and seal 730. As a result of such tension and engagement, after seal 730 has been thus
engaged with the heart for a period of time, tissue ingrowth occurs, such that apex 736 becomes
embedded in heart tissue 39, as indicated by apex 737 shown in phantom in Figure ISA.
Seal 730 is preferably formed of a deformable elastic polymer. In one embodiment, seal
730 is made of a silicone polymer known commercially as Silastic, or Liquid Silicone Rubber.
One example of a material suited for seal 730 is MED4850 Liquid Silicone Rubber. One
example of an adhesive well suited for bonding elements consisting essentially of this material
is MED 1-4213. Both of these materials are products of the NuSil Technology Company, of
Carpenteria, CA.
In a further embodiment, seal 730 is provided with a coating of a biocompatible thin
film to facilitate such ingrowth and adhesion of tissue.
Figure 1 SB is a cross sectional view of a perpendicular seal, the geometry of which is
similar to the prior art design of Anstadt. Referring to Figure 18B, perpendicular seal 740
comprises surface 741, and structural base 742, which is joined to shell 112 of DMVA Cup 100
(see e.g., Figure 4A). Perpendicular seal 740 further comprises a tapered midsection 744, which
tapers to an apex or tip 746. Referring in particular to the upper portion of Figure 18B, labeled
F.S., seal 740 is depicted in the free state (F.S.). When seal 740 is in the free state, tapered
midsection 744 and apex 746 are generally disposed perpendicular to surface 741 of structural
base 742. In the remaining views of seal 740 of Figure 18B, there are depicted in descending
sequence views of seal 740 during installation (D.I.), partially recovered (P.R.), and in final
position (F.P.). The manner in which the DMVA Cup comprising seal 740 is fitted to a heart is
as described previously and shown in Figure 18A.
Seal 740 is a less-preferred design, compared to seal 730 of Figure 18A. Seal 740
provides substantially the same wiping action and spring-back during installation as described
for seal 730, but seal 740 is more dependent upon elastic force than upon hydrostatic loading
104
during diastole in order to maintain a good seal to the heart, as compared with seal 730. Seal
740 is more likely to trap minor amounts of fluid within the DMVA Cup, thus being less
effective as a 'self-bailer'. This condition may require that an active vacuum pump be used to
maintain negative pressure within the Cup during diastole, for a DMVA Cup comprising seal
740.
Figure 18C is a cross sectional view of a seal that is 'self-bailing' during operation, and
that is actively retained during installation to keep it out of contact with the heart wall, thus
minimizing possible tissue damage thereto. Referring to Figure 18C, self-bailing seal 750
comprises surface 751, and structural base 752, which is joined to shell 110 of DMVA Cup 100
(see e.g., Figure 4A). Self-bailing seal 750 further comprises a tapered midsection 754, which
tapers to an apex or tip 756. Referring in particular to the upper portion of Figure 18C, labeled
F.S., seal 750 is depicted in the free state (F.S.). In the next view down in Figure 18C, seal 750
is depicted during installation (D.I.)- It can be seen that seal 750 is bent outwardly and
downwardly approximately 180 degrees along tapered section 754, such that during installation
of the DMVA Cup on the heart, seal 750 does not contact the heart, thereby eliminating the risk
of any damage to heart tissue by seal 750.
In the next view down in Figure 18C, seal 750 is depicted in a state of partial recovery
(P.R.). It can be seen that the apex 756 of seal 750 has been released, and that apex 756 of seal
750 is snapping upwardly and inwardly as indicated by arrow 799, to engage with heart tissue
39 (see Figure ISA). Subsequently, seal 750 achieves final position (F.P.) against the heart
tissue 39 as shown in Figure 18A.
In one embodiment (not shown), seal 750 is provided with water soluble adhesive
applied to surface 753, which temporarily bonds surface 753 to the outer surface of shell 110 of
the DMVA Cup 100 (see e.g., Figure 4A). Apex 756 is retained during installation, and upon
exposure to bodily fluid, such adhesive dissolves, thereby releasing apex 756 as shown in the
P.R. and F.P. states in Figure 18C. In another embodiment (not shown), seal 750 is provided
with an active physical feature such as a tear-away strip to release apex 756.
In yet another embodiment depicted in Figure 20, the seal is provided with a passive
physical feature such as a ring at the apex of the seal that is disposed in a corresponding groove
in wall 112 of Cup shell 110. Referring to Figure 20, passive release seal 760 seal comprises
structural base 762, which is joined to shell 112 of DMVA Cup 100 (see e.g., Figure 4A).
Passive release seal 760 further comprises a tapered midsection 764, which tapers to an apex or
tip 766, to which is joined an elastic ring 768. During installation (graphic D.I. of Figure 20),
ring 768 is disposed in a corresponding groove 125 that is formed in Cup shell wall 110, so that
seal 760 does not contact the heart, thereby eliminating the risk of any damage to heart tissue by
seal 760. After the heart is fully seated in the DMVA cup, ring 768 is rolled or stretched out of
groove 125, so that apex 766 of seal 760 snaps upwardly and inwardly during recovery (P.R.) as
indicated by arrow 799, to engage with heart tissue 39 (see Figure 18A). Subsequently, seal 760
achieves final position (P.P.) against the heart tissue 39 as shown in Figure ISA. In one
embodiment, in order to reduce the effect of a relatively large cross-section at apex 766 of seal
760, and the resulting inelasticity of seal 760, ring 768 may be segmented (not shown). The
retention properties of ring 768 will remain, and seal 760 will be far more elastic.
Figure 20 further depicts an embodiment of an active seal similar to the seal of Figure
18C, further comprising an active release mechanism, which is used to temporarily restrain the
seal during Cup installation and which is activated when the DMVA apparatus is installed on
the heart. Referring to Figure 20, active release seal 770 further comprises cavity or annulus
772. During installation (see the graphic of Figure 20 labeled D.I.), air within annulus 772 is
displaced, or actively evacuated, out of a port (not shown) provided in annulus 772. After the
heart is fully seated in the DMVA cup, annulus 772 is inflated with positive pressure such that
ring 768 is displaced out of groove 125. Apex 766 of seal 760 snaps upwardly and inwardly
during recovery (P.R.) as indicated by arrow 799, to engage with heart tissue 39 (see Figure
18A). Subsequently, seal 770 achieves final position (F.P.) against the heart tissue 39 as shown
in Figure 18A.
In a further embodiment, annulus 772 is filled with a fluid containing a therapeutic drug
or other therapeutic agent, and the material of seal 770 is permeable to such drug or agent, or
provided with microscopic pores for the passage of the drug therethrough, so that the drug may
be delivered directly to the heart. Such therapeutic agents include but are not limited to antiinflammatory
agents, gene therapy agents, gene transfer agents, stem cells, chemo-attractants,
cell regeneration agents, ventricular remodeling agents, anti-infection agents, tumor
suppressants, tissue and/or cell engineering agents, imaging contrast agents, tissue staining
agents, nutrients, and mixtures thereof.
Figure 19A is a cross-sectional view of an active seal by which the DMVA apparatus
more firmly engages the heart, and Figure 19B and 19C are detailed cross-sectional views of the
active seal of Figure 19A, shown in the passive and active states, respectively. Referring to
Figure 19A, active seal 820 comprises structural base 822, tapered neck 824, cavity 826
106
disposed between inner wall 828 and outer wall 830, and tip 832. Referring to Figures 19B and
19C, it can be seen that cavity 836 may be pressurized through a port into such cavity that is
connected to a fluid pressure source.
With proper choice of the shape of active seal 820 with respect to the heart to which the
DMVA Cup is fitted, to the shape and size of cavity 826, and to the relative thickness and
elastic moduli of inner wall 828 and outer wall 830 of cavity 826, pressurization of cavity 826
may be used to force seal 820 inwardly against the heart wall (not shown). In one embodiment,
this pressurization is timed to coincide with action of the Cup so that seal 820 is relatively
relaxed during systole and relatively tight during diastole.
Figure 21A is a cross-sectional view of a passive seal comprising a release mechanism
that is deployed when the DMVA apparatus is installed on the heart, shown prior to engagement
and sealing thereto; and Figure 21B is a cross-sectional view of the passive sea! of Figure 21 A,
shown in the free and the engaged/sealed state. Referring to Figures 21A and 2IB, passive seal
840 comprises structural base 842, tapered neck 844, and ring 848 bonded, formed, or otherwise
disposed proximate to tip 846. In the embodiment of the DMVA Cup 107 depicted in Figures
2A and 21B, passive seal 840 is integrated with liner 510, in a manner similar to that of
integrated liner and seal assembly 530 shown in Figure 16A and previously described in this
specification. Passive seal 840 is also similar to passive seal 660 of Figure 20, previously
described in this specification.
Referring again to Figure 21 A, during installation, ring 848 rs engaged with and retained
within retention groove 125 during the entire installation procedure. Upon the first systolic
action of the Cup 107, the working drive fluid expands the space 127 between the shell 112 and
liner membrane 540, stretching upper rolling diaphragm section 520 and causing the ring 848 to
be released from the retention groove 125. This action causes seal 840 to move from the
configuration shown in Figure 21A to the working position shown in Figure 21B.
Figure 22A is a cross-sectional view of one embodiment of a liner and seal of the
DMVA apparatus, comprising locally specialized materials and/or textures; and Figure 22B is a
detailed cross-sectional view of one liner of the DMVA apparatus of Figure 22A. Referring to
Figures 22A and 22B, DMVA Cup 152 comprises shell 110, and integral liner and seal
assembly 850 comprised of seal 851 and liner 852. Alternatively, the liner and seal may be
configured as depicted in various other Figures shown and described herein.
In various embodiments, liner 852 is further specialized, in terms of material, surface
texture, surface lubricity, elasticity and fatigue resistance, and either inducement or inhibition of
tissue in-growth. These forms of specialization may be localized in specific areas of the liner.
In one embodiment, upper liner region 853 and lower liner region 854 are shaped to optimize
fatigue resistance and to minimize local and general shear stress in the heart, both at the heart
wall surface and within the cardiac muscle, as described previously in this specification. Since
the design of a rolling diaphragm will likely result in some rubbing contact between layers of
the same material, the core material - or a coating applied thereto - is chosen to optimize the
wear characteristics thereof. Thus, for example, a coating of a fluoropolymer such as
polytetrafluoroethylene may be applied to regions 853 and 854.
Liner membrane 855 is the region of liner 852 that is in constant physical contact with
the heart. Depending upon whether the specific Cup 850 is indicated for acute or chronic use,
the liner membrane 855 may be provided with a particular surface texture, topically applied
materials, or imbibed materials, to either enhance or inhibit tissue in-growth into the surface
thereof. In one embodiment depicted in Figure 22B, liner membrane 855 is provided as a
multilayer structure, comprising an inner layer 856, at least one center layer 857, and an inner
layer 858, wherein such topically applied materials or imbibed or diffused or impregnated
materials are provided within one or more of such layers to benefit the heart. Such beneficial
materials may include, but are not limited to anti-inflammatory agents, gene therapy agents,
gene transfer agents, stem cells, chemo-attractants, cell regeneration agents, ventricular
remodeling agents, anti-infection agents, tumor suppressants, tissue and/or cell-engineering
agents, imaging contrast agents, tissue staining agents, nutrients, and mixtures thereof
In a further embodiment, a surface texture 859 is provided on the outer surface of inner
layer 858 to enhance tissue in-growth into the surface thereof. Such a surface texture may be
created by the primary manufacturing process (e.g. injection molding), by a secondary
mechanical process (e.g. abrasion, scoring, extrusion, or calendaring), by a chemical process
(e.g. etching or solvent softening), by plasma treatment, by a direct writing device, or by a
combination of these and other processes.
Referring again to Figure 22A, seal 851 may or may not be designed to encourage tissue
in-growth thereto, depending upon the expected term of use of the Cup in a specific patient and
for a specific disease state. Factors that affect tissue in-growth are texture, topical compounds
(applied at time of installation), and imbibed compounds (gradually eluted to work over time).
108 '
The seal section 851 of assembly 850 also is provided with specific mechanical and surface
characteristics to optimize its sealing and 'self-bailing' performance.
Referring yet again to Figure 22B it may be seen that if outer liner layer 856 is
impermeable, if center liner layer 857 is highly porous, and if inner liner layer 858 is porous, but
substantially less porous that center liner layer 857, the construction of the overall liner 855 is
such that fluid may be ported into it at a convenient location, and that liquid will be uniformly
applied to any material that is adjacent to the inner surface of the liner. Thus the liner may be
used to actively apply topical therapeutic compounds under processor control. One or more
topical compounds including but not limited to anti-inflammatory agents, gene therapy agents,
gene transfer agents, stem cells, chemo-attractants, cell regeneration agents, ventricular
remodeling agents, anti-infection agents, tumor suppressants, tissue and/or cell engineering
agents, imaging contrast agents, tissue staining agents, nutrients, and mixtures thereof may be
applied by this method, either separately or in sequence. The control of delivery of these
materials may be coordinated with other forms of cardiac therapy.
Figure 23A is a cross-sectional view of another embodiment of the DMVA apparatus,
further comprising means for disengagement of the seal thereof that is attached to the heart; and
Figures 23B and 23C are detailed cross-sectional views of embodiments of detachable seals of
the DMVA apparatus of Figure 23A. Referring to Figure 23A, DMVA Cup 153 comprises
shell 240, integral liner and seal assembly 850 comprised of seal 860 and liner 852.
Alternatively, the liner and seal may be configured as depicted in various other Figures shown
and described herein.
DMVA Cup shell 240 comprises a cup-shaped wall 242, drive fluid port 220 in
communication with cavity 310, and vacuum port 211. Drive fluid port 220 connects the cavity
310 between shell 240 and liner 852 with a local or remote fluid drive subsystem 360 that
pumps drive fluid to act on the heart (not shown) through liner membrane 855. Drive fluid port
220 also provides access for internal pressure measurements. Port 220 may be a simple tube
accessing the lumen in one place, or alternately may have a network of small channels that
provides uniform flow to all areas of the cavity 310. Cross-section and internal shape changes
may be optimized to minimize friction losses in order to maximize Cup energy efficiency.
Vacuum port 211 connects the internal cavity 128 of the Cup shell 240 to a local or
remote vacuum subsystem 350 that may be used to generate negative differential pressure
("vacuum") between the interior 128 and exterior of the Cup 153 in order to retain the Cup 153
on the heart (not shown). Some Cup and seal designs may not require vacuum at all. Other
Cup and seal designs used for acute applications may use a vacuum pump as part of vacuum
system 360. In one embodiment, the pump is a bi-directional pump 352, the pumping action of
which can be alternated between pressure and vacuum, so that the Cup 153 can be easily
removed from the patient. Pump 352 is connected to DMVA drive unit or controller 1310 (see
Figure 13) via wires 354.
Yet other Cup and seal designs may require vacuum during and shortly following
installation, but make use of tissue in-growth for long-term retention. In this last case vacuum
port 211 may be disconnected from its vacuum source at a time when retentive vacuum is no
longer needed to secure the Cup 153 on the heart. In some circumstances, where applied
vacuum is not used for either installation or retention, where tissue in-growth either does not
occur or can be countered for reasons of Cup removal, and where the innate negative pressure
created by the 'self-bailing' nature of the Cup seal 860 makes Cup removal difficult or
impossible, a valve 356 connected to controller 1310 by wiring 358 provides for active venting
of vacuum from the Cup interior at the time of Cup removal.
In another embodiment, vacuum system 350 comprises vacuum pump 360 connected to
vacuum port 211 of Cup shell 240 through valve 362. Valve 362 is preferably a three way
valve, with a first position closing off flow.into/out of vacuum port 211, a second position
allowing flow from vacuum port 211 to pump 360, and a third position venting port 211 to the
external atmosphere. Pump 360 is connected to DMVA drive unit or controller 1310 via wires
364, and valve 362 is connected to DMVA drive unit or controller 1310 via wires 366.
In a further embodiment, means are provided in the DMVA apparatus for enhanced
aspiration of fluid from any volumes formed between the heart and the liner or between the
heart and the interior surface of the Cup shell wall. Referring to Figure 2L, it can be seen that
when cavitation occurs, and there is a volume 51 and/or 53 of fluid between the heart 30 and the
Cup liner 116/118, such fluid must be forced out past seal 113, or alternatively, aspirated by
vacuum out of vacuum port 111. There is, however, a possibility that the apex 38 of the heart
30 will occlude port 111 when subjected to a strong vacuum, and prevent the flow of fluid from
volume 51 and/or 53 out of port 111.
In such a circumstance, one means of enhancing aspiration of such fluid out of volumes
51 and/or 53 is to provide drainage grooves 142 on the interior wall of the Cup shell 110 near
vacuum port 111. Such grooves are preferably disposed radially from port 111, with the
number of aspiration grooves preferably being between four and twelve. In a further
embodiment, a grating or screen is provided or formed integrally in shell 110 at the entry of port
111 to prevent the apex of the heart from being sucked into port 111 and deformed. Such a
similar use of drainage grooves and a grating in a batch fluid delivery device is described at
column 7 lines 46-61 of United States patent 5,205,722, the disclosure of which is
incorporated herein by reference. In yet a further embodiment, a plurality of raised ribs are
provided disposed radially outwardly from vacuum port 111 on the inner surface of Cup shell
110, which prevent the occlusion of port 111 by apex 38 of heart 30, thereby achieving
substantially the same result as the grooves 142 of Figure 2L.
In a further embodiment (not shown), aspiration ports are provided within the Cup shell
wall, preferably disposed either in proximity to port 111, and/or in proximity to seal 113. Such
ports are connected within cup shell 110 either to vacuum port 111, or to another vacuum port
(not shown) provided for aspiration. In another embodiment, such aspiration ports are provided
in a seal comprising a cavity, such as seal 820 of Figure 19A, or seal 770 of Figure 20. Such
aspiration ports are disposed between the cavity and the inner surface of the tapered midsection
of such seal that is in contact with the heart. In a further embodiment, aspiration grooves may
be provided on such inner surface of such seal, as described previously. In yet a further
embodiment, the inner surface of the liner of the DMVA device that is in contact with the heart
is provided with a texture that facilitates aspiration, such as grooves, ribs, or other texture that
provides fluid passageways during such contact.
Figures 23B and 23C are detailed cross-sectional views of embodiments of detachable
seals of the DMVA apparatus of Figure 23 A.^Referring to Figure 33B, in one embodiment, seal
860 comprises a tear away feature 861, enabling the surgeon to easily separate the distal portion
of the seal comprised of taper 862 and tip 863 from the base 864 of seal 860, thereby facilitating
Cup removal. Tear away feature may be a notch, a cord, or a wire, or another linear feature that
tears the seal 860 sufficiently to permit removal of the Cup 153.
Referring to Figure 23C, in another embodiment, seal 860 comprises a separation
section 865, separable by a feature 866 in seal 860 that permits non-mechanical action to
separate the tip of the Seal from the body of the Cup. Examples of feature 866 include a section
that is electrically conductive and melts sufficiently to separate, or a small channel that provides
access to a biocompatible fluid that causes an adhesive material to part the Seal from the body
of the Cup.
Referring to Figure 23A, in another embodiment, feature 861 of Figure 23B and/or
feature 866 of Figure 23C are provided at upper liner region 853 and lower liner region 854 of
liner 850 of DMVA Cup 153, thereby rendering liner 850 of DMVA Cup detachable at such
time when Cup 153 is removed from the patient. In such a situation, liner 580 is preferably
made of a biocompatible material or provided with a surface coating thereof that promotes
ingrowth and permanent attachment to the surface of the heart (not shown). Liner 850 is further
provided with properties and/or materials that can continue to provide benefit to the heart,
including but not limited to providing beneficial mechanical properties such as limiting enddiastolic
volumes (i.e. a "girdle effect"); and/or continued delivery of pharmacologic therapies
to the myocardium such as drugs gene therapies, and the like.
Figure 24 is a cross-sectional side view of one embodiment of a DMVA cup formed
with a hollow wall structure comprised of alternating structural ribs and cavities disposed in
horizontal planes. Prior art devices similar to the DMVA Cup of the present invention
typically comprise an outer shell that is either rigid or highly flexible. There are advantages to
having a Cup shell that may be more easily compressed during installation, that may have a
level of rigidity that can be adjusted on a one-time basis or on an on-going basis, or that has
specialized rebound characteristics during systolic and diastolic action, thus enhancing the
performance of the Cup and the heart itself.
Referring to Figure 24, DMVA Cup 154 is provided with a hollow wall assembly
approach to designing and manufacturing the Cup shell 250 having the above advantages and
also permitting individual shell 250 assembly components to have relatively thin wall sections,
thus optimizing the uniformity of injection molding techniques-and- reducing cycle ^time of
injection molding manufacturing processes for shell 250. By using finite element modeling
(FEM) techniques, shell 250 can be designed such that the shell assembly and the overall Cup
154 have virtually any combination of strength and flexibility that is desired, and such that the
flexibility of shell 250 is 'tuned' to specific needs in specific areas. Stress and fatigue behavior
can also be predicted.
Referring again to Figure 24, DMVA Cup 154 comprises shell assembly 250, and
integrated liner and seal assembly 850 comprised of seal 851 and liner 852. Shell assembly 250
comprises an inner shell 251, a shell outer wall 261, and a shell inner wall 271. Inner shell
preferably comprises a series of hollow cavities 252 interspersed with a series of latitudinal ribs
or fins 253 joining shell inner wall 271 to shell outer wall 261. Such ribs provide beam strength
in the assembled shell 250, and also provide multiple individual chambers that may or may not
be filled or pressurized, and that have external edges that are bonded to shell outer wall 261 and
112
shell inner wall 271. Provision is made for uniform wall thickness so that an injection molding
process can be very precise and repeatable; and provision is also made for location features and
bonding features that facilitate assembly, both of which are described presently. In addition, the
hollow shell construction permits the Cup 154 to be compressed to a greater extent during
installation, thus minimizing surgical trauma.
Referring again to Figure 24, shell outer wall 261 comprises an upper section 262, and a
lower section 266. Upper section 262 generally has a thin ring shape, designed to have
reasonable mold release characteristics and to have a geometry that makes final assembly and
bonding relatively simple. Lower section 266 generally has a hemispherical shape, also
designed to have reasonable mold release characteristics and to have a geometry that makes
final assembly and bonding relatively simple. Shell inner wall 271 is preferably provided with a
thickness of between about 0.060 inch thick and 0.150 inch thick at the largest diameter 272
thereof, with the same shape and surface characteristics as those for a solid-wall shell described
previously. The shape of the inner shell 271 is provided to also have reasonable mold release
characteristics (assuming an elastic material) and to have a geometry that makes final assembly
and bonding relatively simple.
Upper section 262 of shell outer wall 261 is joined to lower section 266 of outer shell
wall 261 at bond area 265. Inner shell wall 271 is joined to outer shell wall 261 at upper bond
area 269, at lower bond area 270, and at the contact surfaces between ribs 253 and inner shell
wall 271 and outer shell wall 261. Several alignment features 263, 264, and 267 are provided
on inner'shell wall 271 and outer shell wall 261 to facilitate alignment thereof prior to and
during bonding therebetween.
Figure 25A is a cross-sectional top view of another embodiment of a DMVA apparatus
formed with a hollow wall structure comprised of alternating structural ribs and cavities
disposed in longitudinal planes; and Figure 25B is a detailed cross-sectional top view of a
structural joint between a rib and an outer shell of the DMVA apparatus of Figure 25A.
Referring to Figure 25A, shell 280 comprises a first outer wall segment 282 forming
approximately a first half of the outer wall of shell 280, and a second outer wall segment (not
shown) forming the corresponding second half of the outer wall of shell 280. Shell 280 further
comprises an inner shell wall 284, and a series of longitudinal ribs 286 interspersed with a
series of cavities 287. Longitudinal ribs 286 are joined to the inner surface of outer wall
segment 282, and to the inner surface of the corresponding outer wall segment half not shown,
and to the outer surface of inner shell wall 284, in a manner similar to that described previously
and shown in Figure 24. Although in Figure 25A outer wall segment 282 is shown separated
from ribs 286, in use, outer wall segment 282 is joined to ribs 286 as indicated by arrows 299.
It is to be noted that in this embodiment, the outer wall segments 282 and the corresponding one
not shown are parted in the vertical plane rather than the horizontal plane (as in shell 250 of
Figure 24). This design provides two identical components rather than an upper and lower
component that are different, thereby reducing manufacturing costs.
Shell 280 is preferably provided with attachment features to ensure a strong bond
between the subcomponents thereof. Referring to Figure 25B, outer wall segments 282 and 283
are provided with joining gussets 288 and 289, respectively, within which is nested and joined
rib 286. Such a construction ensures a strong bond between outer wall segments 282 and 283,
rib 286, and inner shell wall 284.
Figure 28 is a cross-sectional view of another embodiment of a DMVA apparatus,
further comprising an implantable pump used to drive systolic and diastolic actuation of the
DMVA Cup and heart therein. Referring to Figure 28, DMVA apparatus 156 comprises Cup
shell 170 to which is joined liner 530 and seal 720. Apparatus 156 further comprises pump
assembly 410 joined to Cup shell 170 by conduit 402. Pump assembly 410 delivers DMVA
drive fluid to and from cavity 310 of-DMVA apparatus 156 through hollow conduit 402,
thereby displacing liner membrane 540 and performing systolic and diastolic actuation of the
heart (riot shown) as described previously.
Pump assembly 410 may be any suitable pumping mechanism, which is designed to
alternatingly deliver a fluid outwardly through conduit 402 as indicated by arrow 498, and
withdraw a fluid inwardly through conduit 402 as indicated by arrow 499. In one embodiment,
the DMVA drive fluid delivered and withdrawn into cavity 310 of DMVA apparatus 156 is a
compressible fluid, i.e. a gas such as e.g., air. In another embodiment, the DMVA drive fluid is
an incompressible liquid.
In the preferred embodiment, pump assembly 410 comprises a reciprocating pump, such
as a piston pump comprising a reciprocating piston, or a diaphragm purnp comprising a
reciprocating diaphragm. Such a reciprocating pump is preferable, because such a pump
inherently comprises a fluid reservoir 412 contained within a housing 414, and a reciprocating
element 416 driven by reciprocating drive means 418, as indicated by bi-directional arrow 497.
Such a reciprocating pump assembly does not require a separate fluid reservoir and valving
means to switch the direction of fluid flow, and can thus be made as a very compact assembly.
In the preferred embodiment, reciprocating drive means 418 comprises a linear actuator
that is capable of providing bi-directional linear motion. Such a linear actuator may be any of a
variety of linear actuator devices, including but not limited to a standard alternating current or
direct current continuous or stepper type electric motor engaged with the following: a ball-screw
or other rotational-to-Iinear mechanism, a rack and pinion, a cam linkage, a four bar or other
linkage, a crankshaft, or a hydraulic or pneumatic power source. Alternatively, such linear
actuator may comprise an electrical solenoid; an inchworm drive using piezoelectric,
electrostrictive, or other short-range linear power source; an electrostrictive or electroactive
polymer artificial muscle (EPAM) such as e.g., a silicone EPAM or a polyurethane EPAM; or a
skeletal muscle affixed to reciprocating element 416, sustained by an artificial capillary bed, and
driven by an electrical stimulus. For a detailed description of EPAMs, reference may be had to
SPE Proceedings Volume 3669, Smart Structures and Materials 1999: Electroactive Polymer
Actuators and Devices, and in particular, paper 3669-01, Electroactive polymer' actuators and
devices by S.G. Wax et al, the disclosure of which is incorporated herein by reference. Actuator
shaft 417 connects any of these actuator devices to reciprocating element 416.
Alternatively, reciprocating drive means 418 may comprise a camshaft engaged directly
with reciprocating element 416, as described in United States patent 5,368,451 of Hammond,
the disclosure of which is incorporated herein by reference. Such camshaft driven reciprocating
means may further include fneahs to vary the timing and duration of the reciprocation thereof,
as is practiced in providing variable reciprocation of objects such as e.g., automotive engine
valves. Such variable timing enables the programming and control of a wide range of systolic
and diastolic actuation conditions as described previously in this specification. In yet another
embodiment, reciprocating drive means 418 may be hydraulic and may comprise a closed loop
reciprocating fluid system as described in United States patent 5,205,722 of Hammond, the
disclosure of which is incorporated herein by reference. Such a reciprocating fluid system may
be coupled to reciprocating element 416, or it may be coupled directly to conduit 402, thereby
directly reciprocating liner 530 in systolic and diastolic actuation.
Referring again to Figure 28, and in the preferred embodiment depicted therein, pump
assembly 410 comprises a reciprocating pump comprised of a diaphragm 420 joined at an inner
perimeter 422 thereof to a cylindrical plate reciprocating element 416, and at an outer perimeter
424 thereof to housing 414. In one embodiment, diaphragm 420 is an elastic diaphragm. In the
preferred embodiment depicted in Figure 28, diaphragm 420 is a rolling diaphragm, operating in
a manner similar to, and with the same advantages of the rolling diaphragm Cup liners
described previously in this specification. Such a rolling diaphragm is also preferred, as it
eliminates the need for seals that may wear or leak over time. Reciprocating element 416 serves
to provide a rigid attachment for interior perimeter 422 of rolling diaphragm 420, and an
attachment point for the actuator shaft 417. It will be apparent that other embodiments may use
variations on diaphragm designs, bellows pump designs, or piston/seal pump designs in order to
move the DMVA drive fluid.
Referring again to Figure 28, and in the preferred embodiment depicted therein, rolling
diaphragm 420 comprises a cylindrical flexible polymer membrane that provides a moving seal
between DMVA drive fluid in cavity 412 and a secondary fluid contained in cavity 426. The
material and thickness of diaphragm 420 are chosen to be compatible with both fluids, and to
have excellent fatigue resistance over the expected working life of the DMVA apparatus 156.
In a further embodiment (not shown), diaphragm 420 is joined to reciprocating plate 416 and to
housing 414 with annular shaped attachments, which minimize bending fatigue.
In the preferred embodiment, the secondary fluid contained in cavity 426 is preferably a
gas, either at a neutral pressure, or at negative pressure with respect to the implant environment.
As reciprocating plate 416 displaces the DMVA drive fluid in cavity 412, thereby displacing
liner membrane 540, the secondary fluid in cavity 426 will undergo expansion. This will
require increased force on actuator shaft 417 during systole, but will also provide useful force
during diastole to pull DMVA drive fluid back through conduit 402, thus pulling the liner 540
and expanding the heart (not shown). In this embodiment the use of positive or negative
pressure in the secondary fluid in cavity 426 is somewhat immaterial, since the compressible
nature of the gas will not affect the energy efficiency of the cyclic process. However, in order to
keep physical forces and resulting wear to a minimum, the pressure is best selected to be about
neutral (physiologic pressure) at the center of the stroke of the actuator shaft 417. In another
less preferred embodiment not shown, cavity 426 containing the secondary fluid may be
'vented' to the interior of the body of the patient, but contained within an expandable envelope,
fluid bag, or other sealed collection means.
Referring again to Figure 28, in one embodiment of DMVA assembly 156, Cup shell
170 and pump housing 414 are molded as a compact unitary part, joined by a short length of
conduit 402, and preferably further reinforced by attachment web 174, or other suitable
reinforcement means. Attachment web 174 thus provides a semi-rigid attachment between the
pump housing 414 and the Cup shell 170, permitting reliable physical connection and
compliance therebetween, as is necessary in an implanted device of this size. Such a compact
assembly enables the implantability of the entire DMVA apparatus 156 solely within the
thoracic region of the body.
In another embodiment (not shown), DMVA apparatus comprises a longer flexible
conduit 402, thus providing greater separation of pump assembly 410 from Cup shell 170, so
that pump assembly 410 may be implanted at a more distal location within the body. In either
instance, DMVA apparatus 156 is provide as an assembly that is entirely implantable within the
body. In another embodiment, conduit 402 is provided with a biocidal anti-infection and/or
anti-inflammatory coating as described previously in this specification.
In a further embodiment (not shown), pump assembly 410 of DMVA apparatus 156 is
provided with means to heat or cool the DMVA drive fluid contained within cavity 412. Such
means provides the DMVA apparatus with the capability of using chilled DMVA drive fluid to
cool the heart and the blood pumped therefrom, and hence to also cool the brain and other
organs during resuscitation efforts. Such cooling is a well-established method to significantly
extend the period that the brain can withstand anoxia, and is thus uniquely suited to the use of
the DMVA apparatus and method of resuscitation. Accordingly, such a capability may greatly
enhance the clinical effectiveness in acute resuscitations using the DMVA apparatus of the
present invention.
It will be apparent that pump housing 414 provides structural support for elements
contained therein, such as piston/reciprocating element 416, diaphragm 420, seals not shown,
motor and/or linear actuator or other reciprocating means 4] 8, and any sensors (not shown). In
addition, pump housing 414 must be secured to Cup shell wall 172 in a manner that guarantees
reliable operation under physiologic conditions and under physical exercise, and obviously must
be biocompatible. The diameter of pump housing 414 and the linear travel of reciprocating
element 416 are selected to provide sufficient volume so as to displace a large heart in a normal
manner. In the preferred embodiment, the typical displacement volume of pump assembly 410,
defined approximately by the cross sectional area of reciprocating element 416 times the stroke
length of reciprocating element 416, will be on the order of 150 to 250 cubic centimeters.
Figure 29 is a cross-sectional view of another embodiment of a DMVA apparatus,
further comprising an implantable phase change pump used to drive systolic and diastolic
actuation of the DMVA Cup and heart therein. Referring to Figure 29, DMVA apparatus 157
comprises Cup shell 180 to which is joined liner 114 and a seal (not shown), as described
previously in this specification. Apparatus 157 further comprises pump assembly 430 joined to
Cup shell 180 by conduit 404. Pump assembly 430 delivers DMVA drive fluid to and from
cavity 119 of DMVA apparatus 157 through hollow conduit 404, thereby displacing liner 114
and performing systolic and diastolic actuation of the heart (not shown) as described previously.
In the embodiment depicted in Figure 29, pump assembly 430 is a phase change or flash
pump, which is designed to altematingly deliver a fluid outwardly and inwardly through conduit
404 as indicated by bi-directional arrow 496. The term "flash" refers to the rapid "flashing" or
"flash evaporation" of a liquid phase into a vapor phase. In the preferred embodiment, pump
assembly 430 comprises a housing 434 containing a reservoir 432 and a reciprocating element
436. Housing 434 and reciprocating element 436 are preferably cylindrical, with rolling
diaphragm 440 being joined to reciprocating element 436 and housing 434, as described
previously for pump assembly 410 of Figure 28.
Referring again to Figure 29, housing 434 of pump assembly 430 further comprises a
heat sink 435 having a plurality of internal fins 437 and a plurality of external fins 439. Heat
sink 435 is either integrally formed as part of housing 434, or contained therein. Housing 434
further contains an array of resistive filaments 438 consisting essentially of fine wire or another
suitable material that increases in temperature when conducting electrical current. Resistive
filaments 438 are preferably interspersed with internal fins 437 as shown in Figure 29.
Resistive filaments 438 are connected to implanted controller 450 by control line 452.
Implanted Battery 460 provides electrical power to controller 450 via line 454.
Pump assembly 430 further comprises a valve 431 disposed in conduit 404 between
pump housing 434 and Cup shell 180, and connected to controller 450 via line 456. DMVA
apparatus further comprises a pressure sensor 1118 disposed in cavity 119, and connected to
controller 450 via line 458.
Implanted battery 460 is preferably a rechargeable battery, and is provided with
recharging means 470. In one embodiment, recharging means 470 comprises an internal
inductive coil 471 connected directly to implanted battery 460, or connected through controller
450 via line 451 as indicated in Figure 29. As also indicated in Figure 29, inductive coil 471 is
preferably implanted subcutaneously within the patient, with arrow 495 indicating the space
within the body cavity of the patient, and arrow 494 indicating the space external to the patient.
Recharging means 470 further comprises external inductive coil 473 connected to external
controller 480 via line 474. External battery or battery pack 482 is connected to external coil
473 through controller 480 via line 476. In a further embodiment, external controller 480 is in
communication with remote transceiver 490, as indicated by bi-directional arrow 493. Remote
transceiver 490 comprises a modem connection or other suitable means that enables controller
480 to communicate bidirectionally with a physician or others.
In operation, pump assembly 430 operates on the principle of fluid phase change from
liquid to gas, and from gas to liquid. A flash pump fluid having a low boiling point and high
vapor pressure is contained in cavity 446, and is alternatingly boiled and condensed. Boiling of
fluid in cavity 446 produces an expanding pressurized vapor that flows through conduit 404 and
displaces liner 114 in systolic actuation; condensation of fluid in cavity 446 results in the
withdrawal of vapor from conduit 404 and the retraction of liner 114 in diastolic actuation, with
the effects of boiling and condensation being indicated by bi-directional arrow 496. Valve 431
is controlled by controller 450 to adjust the volume and flow rate of the vapor as it flows
between pump cavity 432 and Cup cavity 119.
The pump fluid in cavity 446 is chosen to have a boiling point (or flash point) slightly
above physiologic temperature. One fluid that has appropriate thermodynamic properties is
ethyl bromide (CjHsBr), with a boiling point at 1 atm of 38.4 degrees Centigrade (°C), and
having a vapor pressure of 2 atm at 60.2°C. Since the positive pressure needed in order to
displace the DMVA drive fluid to provide systolic blood pressure is on the order of 0.17 atm
(-125mm Hg), a temperature rise of 3.7°C above its 38.4°C boiling point will be sufficient to
drive liner 114 in systolic actuation.
To perform the boilingportion of the cycle (systolic actuation), electrical current is
supplied from controller 450 to resistive filaments 438, thereby rapidly heating such filaments,
preferably to a temperature of about 39°C. Pump fluid immediately surrounding filaments 438
instantaneously flashes to vapor at a pressure sufficient to displace liner 114 in systolic
actuation. The condensation portion of the cycle (diastolic actuation) is performed
subsequently, when electrical current through filaments 438 is ceased. Fins 437 and 439 rapidly
conduct heat from the liquid and vapor within cavity 446, resulting in rapid withdrawal and
condensation of the vapor within cavity 119, such that diastolic actuation is achieved. By
proper selection of size and spacing of both fins 437 and 439, and filaments 438, this
thermodynamic cycle can be made to occur extremely quickly, and can be controlled by valve
431 or by modulating electrical current input to the filaments 438, or a combination of both.
Properties, requirements, materials, and/or characteristics of various components of
pump assembly 430 will now be described.
Referring again to Figure 29, fins 437 and 439 are preferably metal fins, consisting
essentially of a material (e.g. aluminum or copper) that has very high thermal conductivity and
relatively high heat capacity. Fins 437 are spaced apart so as to provide very rapid cooling of
the pump fluid, but far enough apart so the cooling effect thereof does not prevent the flashover
of the pump fluid into gas upon heating by the filaments 438. Because fins 439 are exposed to
the internal body cavity of the patient, such fins 439 must be biocompatible or be coated with a
biocompatible film. In one embodiment, pump housing 434 may comprise part or all of the
external heat sink 435, depending upon the efficiency of the thermal circuit and on the overall
cooling demands of the pump assembly 430. It should also be understood that exposure to a
temperature of 39 degrees Centigrade does not pose a risk to tissues. In a heat sink design of
even modest energy efficiency, such tissues in contact with pump assembly 430 are exposed to a
temperature only slightly higher than 37 degrees Centigrade during pump operation.
In the preferred embodiment, filaments 438 are preferably formed of fine wire or other
resistive material. Such material is chosen to have a negative thermal coefficient of electrical
resistivity, thus permitting uniform heating of the entire filament length, irrespective of minor
fluctuations in cross-section that would otherwise result in non-uniform heating along the length
thereof.
Some liquid-vapor flashing fluid materials with appropriate thermodynamic properties
(e.g. ethyl bromide) are not biocompatible and may also permeate materials such as silastic and
other flexible polymers. Accordingly, a barrier to such material coming in contact with the liner
and shell of the DMVA Cup h provided by reciprocating element 436 disposed between the
pump fluid cavity 446 and DMVA drive fluid reservoir 432. It will be apparent that
reciprocating element must be made of a material that is impermeable and insoluble to the
pump fluid and the DMVA drive fluid. In circumstances where the liquid-vapor flashing fluid
material is biocompatible and does not permeate Cup materials, the flash pump may be used to
directly reciprocate the liner 114 of the apparatus 157.
Conduit 404 between the cup shell 170 and the pump assembly 430 may be either short
(as shown) or longer, depending upon the preferred placement of pump assembly 430. It will be
apparent that the cup shell 180 must surround the subject heart, but a location chosen for the
pump assembly 430 will be based on a comfortable body cavity that has heat-sink properties, on
proximity to the cup shell 180 (to minimize friction losses in conduit 404) and on proximity to
battery 460, recharging means 470, and controller 450. In general, pump assembly 430 is
designed to be comfortably implanted and to be biocompatible. The overall size for a pump
assembly 430 that delivers a DMVA drive fluid volume of 250 cubic centimeters is preferably
on the order of 600 to 800 cubic centimeters.
Another factor to be considered is the amount of thermal energy that is dissipated into
the patient having an implanted flash pump 430. Simply put, any device that provides energy to
physically pump the heart via a heart cup or other related assist device will, in addition to the
physical pumping of blood, dissipate mechanical and/or electrical energy that is used in the
operation thereof. The end result is a modest amount of thermal energy or heat that must be
dissipated by the body. While use of the physical phenomenon of liquid flashing into gas gives
the impression of substantial heating, such is not the case, as condensation of the vapor in the
diastolic portion of the cycle occurs at near-physiologic temperature. Accordingly, a flash pump
may be designed to have the same or better energy efficiency as a mechanical pump, thus
requiring the same amount of body heat dissipation, or less.
In operation, small rechargeable battery 460 is used to continue operation of DMVA
Cup 157 during periods when the primary external battery pack 482 is being replaced, or when
emergency backup power is required due to malfunction. In one embodiment, DMVA
apparatus comprises two redundant batteries 482 for increased reliability. External battery pack
482 is preferably a rechargeable lithium battery pack, which typically has up to 80% capacity
after 500 charge/discharge cycle. Such a battery pack 482 weighing approximately 5 Ib has the
capacity to store sufficient energy for operation of DMVA apparatus 157 over a full day.
Battery pack 482 may be conveniently recharged during sleep cycle or at other times.
In operation, implanted inductive charging coil 471 is used to power DMVA apparatus
157 and to keep implanted battery 460 charged. Implanted inductive charging coil 471 is
preferably placed subcutaneously, with such coil 471 inductively coupled to external coil 473.
Coils 473 and 471 must transfer approximately 10 - 25 watts of electrical power, depending
upon overall system efficiency and upon the degree of patient dependence on DMVA apparatus
157.
In operation, implanted controller 450 performs multiple control functions as follows:
overall power management for the implanted part of the system, particularly pump assembly
430; real time control of the operation DMVA Cup 157, based on programming and on sensor
data; and control of DMVA fluid pressure delivered to cavity 310 during each systotic/diastolic
cycle. External controller 480 performs multiple control functions as follows: overall power
management for the DMVA system 157; output control data, other information, and alarms to
remote transceiver 490; and control of the recharging process for primary battery pack 482.
It will be apparent that the entire power supply and control system of DMVA apparatus
157 can be used in a like manner to power and control the DMVA apparatus 156 of Figure 28.
It will be further apparent that other power sources would be suitable to power DMVA
apparatus 156 of Figure 28 and 157 of Figure 29, including but not limited to a kinetic power
source, a piezoelectric power source, an electrostrictive power source, a thermal power source,
and the like.
It is, therefore, apparent that there has been provided, in accordance with the present
invention, a method and apparatus for Direct Mechanical Ventricular Assist (DMVA). While
this invention has been described in conjunction with preferred embodiments thereof, it is
evident that many alternatives, modifications, and variations will be apparent to those skilled in
the art. Accordingly, it is intended to embrace all such alternatives, modifications and
variations that fall within the spirit and broad scope of the appended claims.



WE CLAIM:
1. A cardiac assist device comprising:
a cup configured to encompass, and to seal and conform to said heart from atrio-ventricular groove to apex throughout systolic and diastolic actuation by imposing negative pressure between said cup and said heart, said cup having a compliant exterior wall attached to a compliant interior liner forming a continuous annular cavity between said wall and said liner, wherein the liner comprises a tapered unbonded transition section reducing in thickness to a thin section forming the liner adjacent a liner portion attached to the wall;
a drive system in closed fluid communication with said cavity to effect displacement of said cavity;
a sensor measuring at least one parameter; and
a control system in communication with said drive system and with said sensor.
2. The device as claimed in claim 1, wherein data imported into the control system corresponds to fluid pressure within said annular cavity.
3. The device as claimed in claim 1, wherein said sensor detects one or more of: device operational data; anatomical data; hemodynamic data; electrophysiological data; biochemical/biological data; acoustical data; tissue characteristic data; temperature data; optical data; and/or device mechanical data.
4. The device as claimed in claim 3, further comprising one or more sensors remote to said cup.
5. The device as claimed in claim 4, wherein one or more sensors is an electrophysiological sensor positioned externally on said patient.
6. The device as claimed in claim 1, wherein said sensor guides installation of the device and/or assesses cardiac performance under the influence of the device.
7. The device as claimed in claim 1, wherein said sensor collects data relating to liner conformation to, and contact with, an exterior surface of the heart corresponding to the right and/or left ventricles throughout systolic and diastolic actuation.
8. The device as claimed in claim 1, wherein said sensor collects data relating to fit of the cup on the heart.
9. The device as claimed in claim I, wherein the compliant exterior wall and compliant interior liner are the same material.
10. The device as claimed in claim 9, wherein the wall and liner material is a strain neutral material that retains isotropic or near-isotropic properties after repeated cyclic loadings.
11. The device as claimed in claim 9, wherein the wall and liner material is a heat curable liquid silicone rubber.
12. The device as claimed in claim 9, wherein the compliant exterior wall has a wall thickness between about 2 millimeters and about 8 millimeters.
13. The device as claimed in claim 9, wherein the liner is a rolling diaphragm liner.
14. The device as claimed in claim 13, wherein the exterior wall and interior liner are joined through an integral liner and seal assembly.
15. The device as claimed in claim 14, wherein the seal of the integral liner and seal assembly is the same material as wall and liner.
16. The device as claimed in claim 1, wherein the liner portion attached to the wall is configured to mate with a recess in said wall.
17. The device as claimed in claim 1, wherein said at least one parameter is a therapeutic response factor.
18. The device as claimed in claim 1, wherein said at least one parameter is an electrophysiological parameter.
19. The device as claimed in claim 1, wherein said at least one parameter is a three-dimensional data array of electrophysiological parameters.
20. The device as claimed in claim 1, wherein said at least one parameter is a biochemical marker.
21. The device as claimed in claim 20, wherein said biochemical marker is selected from the group consisting of lactate, C-reactive protein, oxygen, and carbon dioxide.
22. The device as claimed in claim 1, wherein said at least one parameter is blood pressure.
23. The device as claimed in claim 1, wherein' said at least one parameter is blood flow velocity.
24. The device as claimed in claim 1, wherein said at least one parameter is cardiac ejection fraction.
25. The device as claimed in claim 1, wherein said at least one parameter is inferred from ultrasonic image data.
26. The device as claimed in claim 25, wherein said at least one parameter inferred from ultrasonic image data is right ventricle volume.
27. The device as claimed in claim 25, wherein said at least one parameter inferred from ultrasonic image data is left ventricle volume.
28. The device as claimed in claim 1, wherein said at least one parameter is inferred from magnetic resonance image data.
29. The device as claimed in claim 28, wherein said at least one parameter inferred from magnetic resonance image data is right ventricle volume.
30. The device as claimed in claim 28, wherein said at least one parameter inferred from magnetic resonance image data is left ventricle volume.
31. The device of claim 1, wherein said at least one parameter is a numerical values that quantifies a prior aspect of said patient
32. The device of claim 1, wherein said at least one parameter is predictive parameter of said patient.
33. A cardiac assist device comprising:
a cup having a compliant exterior wall joined to a compliant interior rolling diaphragm liner continuously along two circumferential lines forming a continuous annular cavity said wall and said liner, wherein the liner comprises a tapered unbonded transition section reducing in thickness to a thin section, said cup configured to encompass, and to seal and conform to said heart from apex to atrioventricular groove throughout systolic and diastolic actuation by imposing negative pressure between said cup and said heart; and
a drive system in closed fluid communication with said cavity to effect displacement of said cavity;
a sensor; and
a control system in communication with said drive system and with said sensor.
34. The device as claimed in claim 33, wherein data imported into the control
system corresponds to fluid pressure within said annular cavity.
35. The device as claimed in claim 33, wherein said sensor detects one or more of: device operational data; anatomical data; hemodynamic data; electrophysiological data; biochemical/biological data; acoustical data; tissue characteristic data; temperature data; optical data; and/or device mechanical data.
36. The device as claimed in claim 33, further comprising one or more sensors remote to said cup.
37. The device as claimed in claim 36, wherein one or more sensors is an electrophysiological sensor positioned externally on said patient.
38. The device as claimed in claim 33, wherein said sensor collects data relating to fit of the cup on the heart.
39. The device as claimed in claim 33, wherein said sensor collects data relating to liner conformation and contact with the heart surface throughout systolic and diastolic actuation.
40. The device as claimed in claim 33, wherein said sensor collects data relating to pump function of the heart under the influence of the device.
41. The device as claimed in claim 33, wherein the exterior wall and interior rolling diaphragm liner are joined through an integral liner and seal assembly.
42. The device as claimed in claim 33, wherein the seal is the same material as wall and liner.
43. The device as claimed in claim 33, wherein the liner portion attached to the exterior wall is configured to fit in a recess within said wall.



Documents:

89-DELNP-2006-Abstract (19-10-2009).pdf

89-delnp-2006-abstract.pdf

89-DELNP-2006-Claims-(19-10-2009).pdf

89-delnp-2006-claims.pdf

89-DELNP-2006-Correspondence-Others (19-10-2009).pdf

89-DELNP-2006-Correspondence-Others (23-10-2009).pdf

89-DELNP-2006-Correspondence-Others.pdf

89-DELNP-2006-Description (Complete)- (19-10-2009).pdf

89-delnp-2006-description (complete).pdf

89-DELNP-2006-Drawings (19-10-2009).pdf

89-delnp-2006-drawings.pdf

89-delnp-2006-form-1.pdf

89-delnp-2006-form-13 (19-10-2009).pdf

89-DELNP-2006-Form-18.pdf

89-DELNP-2006-Form-2 (19-10-2009).pdf

89-delnp-2006-form-2.pdf

89-DELNP-2006-Form-3 (19-10-2009).pdf

89-delnp-2006-form-3.pdf

89-delnp-2006-form-5.pdf

89-DELNP-2006-GPA (19-10-2009).pdf

89-delnp-2006-gpa.pdf

89-delnp-2006-pct-101.pdf

89-delnp-2006-pct-210.pdf

89-delnp-2006-pct-220.pdf

89-delnp-2006-pct-237.pdf

89-delnp-2006-pct-301.pdf

89-delnp-2006-pct-304.pdf

89-delnp-2006-pct-308.pdf

89-delnp-2006-pct-332.pdf

89-delnp-2006-pct-401.pdf

89-delnp-2006-pct-402.pdf

89-DELNP-2006-Petition-137 (19-10-2009).pdf

89-DELNP-2006-Petition-138-(19-10-2009).pdf


Patent Number 239097
Indian Patent Application Number 89/DELNP/2006
PG Journal Number 11/2010
Publication Date 12-Mar-2010
Grant Date 05-Mar-2010
Date of Filing 05-Jan-2006
Name of Patentee ADVANCED RESUSCITATION LLC
Applicant Address SUITE 215, 150 LUCIUS GORDON DRIVE, WEST HENRIETTA, NEW YORK 14586, USA.
Inventors:
# Inventor's Name Inventor's Address
1 MARK P. ANSTADT 501 SYLVANDALE DRIVE DAYTON, OHIO 45419, USA.
2 GEORGE L. ANSTADT 6495 EAST AGENBROAD ROAD, TIPP CITY, OHIO 45371, USA.
3 STUART MACDONALD 4663 EAST LAKE ROAD, PULTENEYVILLE, NEW YORK 14538, USA.
4 JEFFREY L. HELFER 17 CAPTAINS COVE LANE, WEBSTER, NEW YORK 14580, USA.
5 GEORGE W. ANSTADT 19 RUSTIC PINES, PITTSFORD, NEW YORK 14534, USA.
PCT International Classification Number A61F
PCT International Application Number PCT/US2004/020605
PCT International Filing date 2004-06-25
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/607,434 2003-06-26 U.S.A.