Title of Invention	AN AUTOMATIC DEVICE FOR USE IN A STRESS TEST SYSTEM
Abstract	This invention relates to an automatic stress test device. The device has a 12 channel amplifier adapted to be connected to the resistance network and with a 12 channel voltage to current converter connected to the outputs of the channel amplifier. A 12 channel band pass filter having a current to voltage converter connected to the outputs of said amplifier. A multiplexer is connected to the outputs of the band pass filter provided to digitize the signal received from the 12 channels simultaneously. An analog to digital converter adapted to be connected to the PC bus are connected to said multiplexer An IBM compatible PC having a high resolution video graphics adaptor (VGA) monitor is connected to the PC bus and a high resolution dot matrix printer or laser printer being provided to give the printed report in the graph form.

Title of Invention

AN AUTOMATIC DEVICE FOR USE IN A STRESS TEST SYSTEM

Abstract

This invention relates to an automatic stress test device. The device has a 12 channel amplifier adapted to be connected to the resistance network and with a 12 channel voltage to current converter connected to the outputs of the channel amplifier. A 12 channel band pass filter having a current to voltage converter connected to the outputs of said amplifier. A multiplexer is connected to the outputs of the band pass filter provided to digitize the signal received from the 12 channels simultaneously. An analog to digital converter adapted to be connected to the PC bus are connected to said multiplexer An IBM compatible PC having a high resolution video graphics adaptor (VGA) monitor is connected to the PC bus and a high resolution dot matrix printer or laser printer being provided to give the printed report in the graph form.

Full Text	This invention relates to an automatic device for use in a stress test system. The stress test is conducted on heart patients or probable heart patients. The patients are subjected to a standard protocol of graded exercise programme and a tread mill is available for this purpose to walk and run. The stress test system is used to acquire, monitor, analyse and document the electrocardiogram (ECG) of the person. The existing stress test systems generally comprise of a 12 channel amplifier, 12 channel filter, A/D converter, a host processor with necessary Input/output devices. The existing stress test system can be broadly classified into two category. The first category of the stress test system are those in which the computer is a dedicated system. These systems use dedicated integrated circuits (ICs) for amplification, filtering, A/D conversion and use high speed digital signal processor (s) with its own input/output devices. These systems are expensive due to customised ICs. The host computer of the system is dedicated to the stress test analysis and is not available for any other application. This limits the utility of the host computer. Further this type of system has the limitation that it cannot be used for acquiring other bio-medical signals, such as EEG (Electro EncepheloGram) EMG (ElectroMyoGram). In the second type of stress test system, the host computerised any IBM compatible PC and the amplifier, filter, A/D converter are dedicated components. A Co-processor/ digital signal processor is also used to process (acquire, display, store, document) ECG signal for stress test. In this type of system, host computer is available for any other application. The cost of these system, as compared to first-type of system described in preceding para, is also relatively lower. However, these type of systems like the first type of systems have also the limitation that these can not be ased for acquiring other bio-medical signals such as EEG, EMG. The primary object of the present invention is to propose an improved low-cost automatic stress device to obviate the above disadvantages. Another object of the present invention is to provide a stress test device, which can simultaneously acquire, display, store and document the ECG, without use of fast DSP (digital signal processor) or without use of a co-processor. Yet another object of the present invention is to provide a stress test which can be used as a general purpose data acquisition system with on-line display, for acquiring EEG, EMG and speach signals with little or no-modifications. Still another object of the present invention is to provide a stress test device in which host computer besides stress test analysis, is available for other applications, thereby enhancing the utility of the host computer. A further object of this invention is to provide an automatic stress test device capable to be used for the diagnosis of the disease like arrhythmia, with addition of co-processor boards which can access data-lines already provided in the system. Yet another object of this invention is to provide the stress test device provided with DC-DC conveter which draws the power from PC power supply and supplies isolated and regulated power to all circuits of the stress test system. According to this invention there is provided an automatic device for use in a stress test system comprising a 12 channel amplifier adapted to be connected to the resistance network and with a 12 channel voltage to current converter connected to the outputs of the channel amplifier, a 12 channel band pass filter having a current to voltage conveter connected to the outputs of said amplifier, a multiplexer connected to the outputs of said filter being provided to digitize the signal received from said 12 channels simultaneously, an analog to digital converter adapted to be connected to the PC bus being connected to said multiplexer. In accordance with this invention the amplifier consists of 12 amplifier circuits to amplify the 12 Lead/ signals received from the network of the ECG... . A volt to current converter is connected to the output of the amplifier to convert the signals. A band pass filter having a current to Voltage converter connected the inputs thereof is connected to said amplifier to remove the base line drift and muscle noise. A multiplexer having a timing and control circuit connected therewith, is connected to the band pass filter generate timing and channel selection signals. An opto isolator is connected to the output of said multiflexer so as to isolate the patient from the PC and its power supply so as to provide safety to the patient against leakage of cutrent. An analoge to digital converter is connected to the output of the isolator for digitising the signals to be transfered to the PC-Bus by DMA (Direct Memory Assess) controller circuit of the PC, A DC-DC converter is provided to draw the power from PC power supply so as to supply isolated, regulated power supply to all the analog circuits. Further another DC-DC converter is provided so as to convert PC power supply into isolated and regulated supply to supply the same to 12 channel amplifier and voltage to current convertor. The ECG signal contains noise from sources such as muscle noise, RF signals and AC supply. The signal rides on a base line drift due to improper contact. The subject is moving in this system and hence the signal is prone to motion artifacts. Therefore the ECG data are acquired in twelve channels, and acquisition is simultaneous. The frequencies of interest are of 0.05Hz to 100 Hz. The voltage is of the order of a few mV and hence sufficient amplification is done. The parameters to be monitored are ST shift and heart rate. These parameters are computed continuously and therefore, the processor time is used optimally. Further, the display is on a graph and to scale. An automatic stress test system according to a preferred embodiment is herein described and illustrated in the accompanying drawings where-in: Fig 1: shows the schematic of the stress test device. Fig 2: shows the points on the body where electrodes are fixed. Fig. 3: shows the block diagram and flow chart of the device. Referring to the drawings particularly Fig.2, electrodes are connected to positions RA,LA, RL, LL, VI, to V6 on the body of the patient. The voltage are picked up using clips and cables connected to resistance network 1 to derive the 12 channels of the amplifier 2 of the ECG. Signals are amplified by 12 channel amplifier 2. These signals are converted into current by voltage to current converter 3 connected to said amplifier 2. The resistance network 1, 12 channel amplifier 2 and converter 3 are housed in a single portable box 4. A current to voltage converter 7 is connected to the output of said converter 3 and the current signal flows through current to voltage converter 7. The voltage is then passed through 12 channel Band Pass Filter 8 connected to the converter 7 and provided to remove the base line drift and muscle noise (0.05 to 100 Hz). Timing and control circuit 9 is connected to the multiplexer 10 to generates timing and channel selection signals which are input to the multiplexer 10. The multiplexer selects one channel, at a time at the rate of 240 samples/sec/channel and transmit the selected channel to the opto-isolator 11 connected therewith. The opto-isolator 11 isolates patients from the PC and its power supply. This is done to ensure the safety of Patient against leakage of current. An analog to digital converter 12 is connected to the out-put of the isolater 11 to digitise the signals and the data is made available fortransfer to PC-RAM at the PC-BUS 6. The data is transferred to PC-RAM by DMA (Direct Memory Access) controller circuit (not shown) of the PC. A DC-DC converter 13 is connected to the PC power supply so as to draw power from PC power supply and to supply isolated, regualted power supply to all the components 9-12 as mention herein above. The components 9-13 are housed in a housing 5 which is disposed inside the DC Bus 6. Another DC-DC converter 14 is provided with the PC so as to convert PC power supply into isolated and regulated supply and supplies the power to resistance network 1, amplifire 2 and converter 3. The amplification factors have been carefully selected to give the best signal to noise ratio. DC-DC converter noise and PC-SMPS (Switched Mode Power Supply) noise have been completely isolated from the signal. The stress test system is driven by the following software package consisting of following modules. (a) data acquisition software (using DMA technique) for DMA controller of PC which is programmed to transfer data in to PC-RAM without hampering the working of PC. Due to this software only 2% of the PC CPU time is used for data transfer. (b) display software to display any selected 4 channels out of the 12 channels that are acquired, online with the acquisition. Display software to display clock, heart rate and ST shift in all 12 leads online with acquisition. (c) data analysis software to detect QRS complex, compute heart rate, and ST shift in all leads online with acquisition. (d) data storage to store all 12 channels online with acquisition. (e) pseudo-online printing software to generate the image of the ECG in memory and to print on the printer. (f) a supervisor programme that is totally interactive and user friendly to carry out the stress test using the above modules. WE CLAIM: 1. An automatic device for use in a stress test system comprising a 12 channel amplifier adapted to be connected to the resistance network and with a 12 channel voltage to current converter connected to the outputs of the channel amplifier, a 12 channel band pass filter having a current to voltage converter connected to the outputs of said amplifier, a multiplexer connected to the outputs of said filter being provided to digitize the signal received from said 12 channels simultaneously, an analog to digital converter adapted to be connected to the PC bus being connected to said multiplexer. 2. An automatic device as claimed in claim 1 wherein said multiplexer has a timer and control circuit connected to a set of inputs of said multiplexer. 3. An automatic device for use in a stress test system substantially as herein described and illustrated.

Full Text

This invention relates to an automatic device for use in a stress test system.
The stress test is conducted on heart patients or probable heart patients. The patients are subjected to a standard protocol of graded exercise programme and a tread mill is available for this purpose to walk and run. The stress test system is used to acquire, monitor, analyse and document the electrocardiogram (ECG) of the person.
The existing stress test systems generally comprise of a 12 channel amplifier, 12 channel filter, A/D converter, a host processor with necessary Input/output devices. The existing stress test system can be broadly classified into two category. The first category of the stress test system are those in which the computer is a dedicated system. These systems use dedicated integrated circuits (ICs) for amplification, filtering, A/D conversion and use high speed digital signal processor (s) with its own input/output devices. These systems are expensive due to customised ICs. The host computer of the system is dedicated to the stress test analysis and is not available for any other application. This limits the utility of the host computer. Further this type of system has the limitation that it cannot be used for acquiring other bio-medical signals, such as EEG (Electro EncepheloGram) EMG (ElectroMyoGram).
In the second type of stress test system, the host computerised any IBM compatible PC and the amplifier, filter, A/D converter are dedicated components. A Co-processor/ digital signal processor is also used to process (acquire, display, store, document) ECG signal for stress test. In this type of system, host computer is available for any other application. The cost of these system, as compared to first-type of system described in preceding para, is also relatively lower. However, these type of systems like the first type of systems have also the limitation that these can not be ased for acquiring other bio-medical signals such as EEG, EMG.
The primary object of the present invention is to propose an improved low-cost automatic stress device to obviate the above disadvantages.
Another object of the present invention is to provide a stress test device, which can simultaneously acquire, display, store and document the ECG, without use of fast DSP (digital signal processor) or without use of a co-processor.
Yet another object of the present invention is to provide a stress test which can be used as a general purpose data acquisition system with on-line display, for acquiring EEG, EMG and speach signals with little or no-modifications.
Still another object of the present invention is to provide a stress test device in which host computer besides stress test analysis, is available for other applications, thereby enhancing the utility of the host computer.
A further object of this invention is to provide an automatic stress test device capable to be used for the diagnosis of the disease like arrhythmia, with addition of co-processor boards which can access data-lines already provided in the system.
Yet another object of this invention is to provide the stress test device provided with DC-DC conveter which draws the power from PC power supply and supplies isolated and regulated power to all circuits of the stress test system.
According to this invention there is provided an automatic device for use in a stress test system comprising a 12 channel amplifier adapted to be connected to the resistance network and with a 12 channel voltage to current converter connected to the outputs of the channel amplifier, a 12 channel band pass filter having a current to voltage conveter connected to the outputs of said amplifier, a multiplexer connected to the outputs of said filter being provided to digitize the signal received from said 12 channels simultaneously, an analog to digital converter adapted to be connected to the PC bus being connected to said multiplexer.
In accordance with this invention the amplifier consists of 12 amplifier circuits to amplify the 12 Lead/ signals received from the network of the ECG... . A volt to current converter is connected to the output of the
amplifier to convert the signals. A band pass filter having a current to Voltage converter connected the inputs
thereof is connected to said amplifier to remove the
base line drift and muscle noise. A multiplexer having
a timing and control circuit connected therewith, is connected to the band pass filter generate timing and channel
selection signals. An opto isolator is connected to the
output of said multiflexer so as to isolate the patient
from the PC and its power supply so as to provide
safety to the patient against leakage of cutrent. An
analoge to digital converter is connected to the output
of the isolator for digitising the signals to be
transfered to the PC-Bus by DMA (Direct Memory Assess)
controller circuit of the PC, A DC-DC converter is
provided to draw the power from PC power supply so as
to supply isolated, regulated power supply to all the
analog circuits. Further another DC-DC converter is
provided so as to convert PC power supply into isolated
and regulated supply to supply the same to 12 channel
amplifier and voltage to current convertor.
The ECG signal contains noise from sources such as muscle noise, RF signals and AC supply. The signal rides on a base line drift due to improper contact. The subject is moving in this system and hence the signal is prone to motion artifacts. Therefore the ECG data are acquired in twelve channels, and acquisition is simultaneous. The frequencies of interest are of 0.05Hz to 100 Hz. The voltage is of the order of a few mV and hence sufficient amplification is done. The parameters to be monitored are ST shift and heart rate. These parameters are computed continuously and therefore, the processor time is used optimally. Further, the display is on a graph and to scale.
An automatic stress test system according to a preferred embodiment is herein described and illustrated in the accompanying drawings where-in:
Fig 1: shows the schematic of the stress test
device.
Fig 2: shows the points on the body where electrodes
are fixed.
Fig. 3: shows the block diagram and flow chart of the
device. Referring to the drawings particularly Fig.2, electrodes are connected to positions RA,LA, RL, LL, VI, to V6 on the body of the patient. The voltage are picked
up using clips and cables connected to resistance network 1 to derive the 12 channels of the amplifier 2 of the ECG. Signals are amplified by 12 channel amplifier 2. These signals are converted into current by voltage to current converter 3 connected to said amplifier 2. The resistance network 1, 12 channel amplifier 2 and converter 3 are housed in a single portable box 4. A current to voltage converter 7 is connected to the output of said converter 3 and the current signal flows through current to voltage converter 7. The voltage is then passed through 12 channel Band Pass Filter 8 connected to the converter 7 and provided to remove the base line drift and muscle noise (0.05 to 100 Hz). Timing and control circuit 9 is connected to the multiplexer 10 to generates timing and channel selection signals which are input to the multiplexer 10. The multiplexer selects one channel, at a time at the rate of 240 samples/sec/channel and transmit the selected channel to the opto-isolator 11 connected therewith. The opto-isolator 11 isolates patients from the PC and its power supply. This is done to ensure the safety of Patient against leakage of current. An analog to digital converter 12 is connected to the out-put of the isolater 11 to digitise the signals and the data is made available fortransfer to PC-RAM at the PC-BUS 6. The data is
transferred to PC-RAM by DMA (Direct Memory Access)
controller circuit (not shown) of the PC. A
DC-DC converter 13 is connected to the PC power supply
so as to draw power from PC power supply and to supply
isolated, regualted power supply to all the components
9-12 as mention herein above. The components 9-13 are
housed in a housing 5 which is disposed inside the
DC Bus 6. Another DC-DC converter 14 is provided
with the PC so as to convert PC power supply into isolated and regulated supply and supplies the power to resistance network 1, amplifire 2 and converter 3.
The amplification factors have been carefully selected to give the best signal to noise ratio. DC-DC converter noise and PC-SMPS (Switched Mode Power Supply) noise have been completely isolated from the signal. The stress test system is driven by the following software package consisting of following modules.
(a) data acquisition software (using DMA technique) for DMA controller of PC which is programmed to transfer data in to PC-RAM without hampering the working of PC. Due to this software only 2% of the PC CPU time is used for data transfer.
(b) display software to display any selected 4
channels out of the 12 channels that are acquired, online with the acquisition. Display software to display clock, heart rate and ST shift in all 12 leads online with acquisition.
(c) data analysis software to detect QRS complex,
compute heart rate, and ST shift in all leads online with acquisition.
(d) data storage to store all 12 channels online with
acquisition.
(e) pseudo-online printing software to generate
the image of the ECG in memory and to print on the
printer.
(f) a supervisor programme that is totally interactive
and user friendly to carry out the stress test using the above modules.

WE CLAIM:
1. An automatic device for use in a stress test system comprising a 12 channel amplifier adapted to be connected to the resistance network and with a 12 channel voltage to current converter connected to the outputs of the channel amplifier, a 12 channel band pass filter having a current to voltage converter connected to the outputs of said amplifier, a multiplexer connected to the outputs of said filter being provided to digitize the signal received from said 12 channels simultaneously, an analog to digital converter adapted to be connected to the PC bus being connected to said multiplexer.
2. An automatic device as claimed in claim 1 wherein said multiplexer has a timer and control circuit connected to a set of inputs of said multiplexer.
3. An automatic device for use in a stress test system substantially as herein described and illustrated.

Documents:

100-del-1995-abstract.pdf

100-del-1995-claims.pdf

100-del-1995-correspondence-others.pdf

100-del-1995-correspondence-po.pdf

100-del-1995-description (complete).pdf

100-del-1995-drawings.pdf

100-del-1995-form-1.pdf

100-del-1995-form-2.pdf

100-del-1995-form-3.pdf

100-del-1995-form-4.pdf

100-del-1995-form-5.pdf

100-del-1995-form-6.pdf

100-del-1995-form-7.pdf

100-del-1995-form-9.pdf

100-del-1995-gpa.pdf

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Patent Number

190623

Indian Patent Application Number

100/DEL/1995

PG Journal Number

31/2009

Publication Date

31-Jul-2009

Grant Date

16-Mar-2004

Date of Filing

25-Apr-1995

Name of Patentee

CHIEF CONTROLLER, RESEARCH & DEVELOPMENT

Applicant Address

B-341 SENA BHAWAN, DHQ P.O.NEW DELHI-110011,INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	DR.THALAKKOTTUR LAZAR MATHEW	Bio-Engineering and Electromedical Laboratory (DEBEL), Post Bag No.9326, C.V.Raman Nagar, Bangalore-93
2	SHRI CHINNA KONDA KRISHNAMOORTHY DWARAKANATH	SCIENTIST 'C' DEBEL, BANGALORE-560093, INDIA

PCT International Classification Number

G11C11/00; G01R31/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA