Title of Invention

A MEDICAL CATHETER

Abstract This invention provides a medical catheter with a portion more flexible against sending in the tip portion than in the operator's end portion. The object is to provide catheter which can be easily introduced into a desired region. The medical catheter of this invention is especially useful for treating the constriction of a blood vessel or he constriction of a cardiac valve.
Full Text The present invention relates to a medical catheter, particularly a catheter to 3e inserted into a heart or a blood vessel.
BACKGROUND OF THE INVENTION
A medical catheter is inserted into a blood vessel, and pushed inward along the blood vessel, to let its tip portion reach the intended region. Then, a chemical material such as a contrast medium or drug is injected through the catheter. In the case of a catheter with a balloon at its tip portion, the balloon portion is forced in to reach the constriction of a blood vessel or the constriction of a cardiac valve, and is expanded to widen the constriction for treatment. In this way, a medical catheter must be inserted to let its tip reach the intended region through a blood vessel. However, a blood vessel with a lesion or a peripheral blood vessel is often curved three-dimensionally at small curvatures, and it is often difficult to let the tip portion of a catheter reach the intended region. If the catheter is forcibly inserted through a curved portion, the tip portion of the catheter may injure the blood vessel wall or the cardiac inner wall. Furthermore, in the case of a catheter with a balloon for treatment of a constricted cardiac valve, it is practiced that a pre-formed metallic stylet is inserted into the inner cavity of the balloon catheter to allow the insertion of the balloon into a constricted valve for opening- The medical catheter used for this purpose must be sufficiently soft at the shaft, but in order to push the catheter to insert the tip portion of the catheter into the intended region, and also in order to rotate it, the operator's end portion must be hard to some extent.
OBJECT OF THE INVENTION
The present invention has been completed to meet these requirements. The

object of the present invention is to provide a catheter with its tip portion kept flexible and its operator's end portion kept harder than the tip portion.
To achieve the above object, the present invention provides a medical catheter which is more flexible against bending in the tip portion than in the operator's end portion. Preferably, the portion more flexible against bending is 5 cm to 40 cm long from the tip and the flexural rigidity at the portion more flexible in the tip portion measured by a Tinius Olsen Stiffness tester is 10 g.cm to 100 g.cm in bending moment.
One of the preferable embodiments of this invention is a medical catheter made of a polymer containing a plasticizer, wherein the plasticizer content is smaller in the operator's end portion than in the more flexible portion.
Another preferable embodiments of the present invention is a catheter, wherein a balloon is provided in the tip portion.
Still another preferable embodiments of the present invention is a catheter, which is used for treating the constriction of a blood vessel or the constriction of a cardiac valve.
A preferable method for making the catheter of the present invention is to prepare a catheter tube with a flexible material containing a plasticizer and extract some amount of the plasticizer by a solvent in the operator's end portion. It is preferable to decrease the plasticizer by about 30 to 75 wt%.
Accordingly, the present invention provides a medical catheter with a flexible portion in the tip portion, wherein the flexural rigidity at the flexible portion in the tip portion measured by a Tinius Olsen Stiffness tester is 10 g. cm to 100 g. cm in bending moment, wherein the flexible portion in the tip portion is more flexible against bending than in the operator's end portion when measured by the Tinius Olsen Stiffness tester, and wherein a balloon is provided in the tip portion.
With reference to the accompanying drawings, in which
Fig. 1: Shows an example of the catheter of the present invention.
Fig. 2: Shows an example of a balloon catheter.
Meanings of symbols
1: catheter tube
2: connector

3 : balloon
4 : catheter shaft
5 : connector
DETAILED DESCRIPTION OF THE INVENTION
Difficult insertion of a medical catheter is experienced usually when the blood vessel is curved at a relatively small curvature, and if the tip portion is once successfully inserted, the subsequent insertion can be usually executed relatively smoothly. Therefore, in the present invention, the length of the flexible portion at the tip portion is preferably, though not limited to, 5 cm to 40 cm from the tip. Furthermore, the flexibility of the tip portion is preferably, though not limited to, 10 to 100 g-cm in bending moment when measured by a Tinus Olsen stiffness tester. On the other hand, the length of the operator's end portion is not limited either, but is preferably 20-110 cm for such reasons that after the tip portion of the catheter once successfully passes through a constricted or curved portion of the blood vessel, the catheter can be relatively easily pushed, and that if the flexible portion is too long, pushability is lowered, making catheter operation difficult. The flexibility is preferably 1 kg-cm or more.
There are various methods for making the tip portion flexible. Typical methods include connecting tubes different in flexibility, making the tip portion thin-walled, using a flexible material as a tube with the operator's end portion reinforced, using also a flexible material as a tube with the plasticizer decreased in the operator's end portion to keep the plasticizer content in the operator's end portion smaller for hardening the operator's end portion, and so on.
To connect tubes different in hardness, for example, a polyamide, teflon, polypropylene, etc. are available as hard materials, and polyurethane, polyethylene, etc. are available as soft materials.
As for the difference of thickness when the tip portion is made thin-walled, it is preferable to keep the thickness of the thin portion at 70 to 80% of that of the thick portion.

For using a flexible material as a tube with a reinforcing layer provided on the inner or outer surface or in the wall of the operator's end portion, for example, stainless steel wires can be used for reinforcement only in the operator's end portion.
When a flexible material containing a plasticizer is used as a tube, it is preferable to extract some amount of the plasticizer by a solvent in the operator's end portion. It is preferable to decrease the plasticizer by about 30 to 75 wt%.
The catheter of the present invention is preferably used with a balloon installed at the tip portion, and the balloon can be made of a polyester, polyarnide, polyethylene or latex, etc.
Embodiments of the catheter of the present invention are described below in reference to drawings. Fig. 1 shows a general catheter to be inserted into a heart or blood vessel for injecting a chemical solution, etc. Symbol 1 denotes a catheter tube, and 2, a connector. Fig. 2 shows a balloon catheter to have its balloon inserted in the constricted portion of a blood vessel or the constricted portion of a cardiac valve for expanding the balloon for treatment. Symbol 3 denotes a balloon, 4, a catheter shaft, and 5, a connector. The tip portion of the catheter shaft is flexible.
The catheter of the present invention can be preferably used for treating the constriction, etc. of a blood vessel or cardiac valve.
EXAMPLE 1
In a balloon catheter (Fig. 2), in which a double catheter tube consisting of a hollow polyvinyl chloride (PVC) outer tube and an inner PVC tube coaxially arranged in the hollow portion of the outer tube was provided with a balloon at its tip portion and a connector at the operator's end portion, both the outer and inner tubes had their plasticizer extracted by methanol in the operator's end portion beyond the tip portion of about 10 to 20 cm, to be hardened.
The outer tube was extracted at 60°C for about 6 hours, and was dried and furthermore treated at 60 °C for further 6 hours, and the inner tube had its plasticizer extracted at 60°C for about 3 hours, to remove about 60% of the plasticizer, for producing a balloon catheter with its operator's end portion kept harder than the tip

portion. The tip portion had a flexibility suitable (about 40 g-cm in bending moment when measured by a Tinius Olsen stiffness tester) for being pushed through a heart or blood vessel, and the operator's end portion had sufficient hardness (1.0 to 2.0 kg-cm) for catheter operation.
EFFECT OF THE INVENTION
The present invention can provide a catheter with its tip portion kept soft and its operator1 s end portion kept harder than the tip portion, hence capable of being easily introduced into a desired region.


WE CLAIM:
1. A medical catheter with a flexible portion in the tip portion, wherein the flexural rigidity at the flexible portion in the tip portion measured by a Tinius Olsen Stiffness tester is 10 g. cm to 100 g. cm in bending moment, wherein the flexible portion in the tip portion is more flexible against bending than in the operator's end portion when measured by the Tinius Olsen Stiffness tester, and wherein a balloon is provided in the tip portion.
2. The medical catheter, as claimed in claim 1, wherein the flexible portion in the tip portion is 5 cm to 40 cm long from the tip,
3. The medical catheter, as claimed in claim 1, wherein tubes different in hardness are connected.
4. The medical catheter, as claimed in claim 1, wherein the wall thickness of the tube in the flexible portion in the tip portion is thinner than that in the operator's end portion.
5. The medical catheter, as claimed in claim 1, wherein a reinforcing layer is provided on the inner or outer surface or in the wall of the tube.
6. The medical catheter made of a polymer containing a plasticizer, as claimed in 1, wherein the plasticizer content is smaller in the operator's end portion than in the flexible portion in the tip portion.
7. The medical catheter, as claimed in claim 1, which is made of polyvinyl chloride or polyvinylidene chloride.

8. The method for making a medical catheter as claimed in claim 1 wherein a catheter
tube with a flexible material containing a plasticizer is prepared and some amount of
the plasticizer is extracted by a solvent in the operator's end portion.
9. A medical catheter substantially as herein described with reference to the
accompanying drawings.


Documents:

1688-mas-1997-abstract.pdf

1688-mas-1997-claims.pdf

1688-mas-1997-correspondence others.pdf

1688-mas-1997-correspondence po.pdf

1688-mas-1997-description complete.pdf

1688-mas-1997-drawings.pdf

1688-mas-1997-form 1.pdf

1688-mas-1997-form 3.pdf

1688-mas-1997-form 4.pdf

1688-mas-97 abstract-duplicate.pdf

1688-mas-97 claims-duplicate.pdf

1688-mas-97 description (complete)-duplicate.pdf

1688-mas-97 drawings-duplicate.pdf


Patent Number 228473
Indian Patent Application Number 1688/MAS/1997
PG Journal Number 10/2009
Publication Date 06-Mar-2009
Grant Date 05-Feb-2009
Date of Filing 28-Jul-1997
Name of Patentee TORAY INDUSTRIES, INC
Applicant Address 2-1, MUROMACHI 2-CHOME, NIHONBASHI, CHUO-KU, TOKYO 103,
Inventors:
# Inventor's Name Inventor's Address
1 MICHIHARU SHIOTA TORAY ISHIYAMA RYO NO. 521, 2-272-24, KOKUBU, OTSU-SHI, SHIGA-KEN, 520,
2 OSAMU KAWANAMI TORAY FUKAZAWA-RYO, NO. 202, 7-2-20, FUKAZAWA, SETAGAYA-KU, TOKYO 158,
3 YOSHIHARU YAMASAKI 3-23, 3, KITAOJI, OTSU-SHI, SHIGA-KEN, 520,
PCT International Classification Number A61M25/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA