Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2001-02-07
2002-09-17
Derakshani, Philippe (Department: 3752)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
Reexamination Certificate
active
06451005
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a catheter which is used by inserting it into a blood vessel or the like.
In recent years, the use of the catheter is popular to treat lesion of a blood vessel because the catheter has a very low degree of a surgical stress.
In using the catheter, the catheter is required to have a high operability because it is necessary to insert it into a blood vessel having a fine and complicated pattern at a high speed and with a reliable selectivity.
It is also demanded that the catheter has a small diameter, i,e., has a possible smallest outer diameter, with a certain inner diameter secured to widen the selection range of an insertion portion in the human body, reduce the burden of a patient, and improve an insertion operability.
A micro-catheter is used to administer or inject medicines, thrombus substances to be used in an operation which is called embolization to be performed in a blood vessel or a contrast medium to a desired portion in internal organs (liver) such as brain and belly to diagnose and treat the desired portion. It is necessary to advance the micro-catheter inside a peripheral blood vessel narrow, branching, and zigzag and having a diameter less than 3 mm and introduce it into the desired portion selectively. In recent years, owing to medical progress, it is necessary to inject medicines, thrombus substances or a contrast medium to diagnose and treat the desired portion by inserting the micro-catheter to a peripheral blood vessel having a diameter as small as less than 1 mm. Therefore, there is a demand for development of the catheter which can be inserted into such a narrow blood vessel.
The operability of the catheter will be described below. The catheter is required to have pressing performance of reliably transmitting a pressing force applied by an operator to advance the catheter inside a blood vessel to the front end thereof from the rear end thereof; torque transmission performance of transmitting a rotational force applied to the rear end of the catheter to its front end; follow-up performance of progressing smoothly and reliably inside the curved blood vessel along a guide wire; and kink resistance of being not bent at a portion where the blood vessel is curved or bent after the guide wire is pulled out from the catheter at the desired portion. The catheter is also required to have safety that the tip of the catheter does not damage the inner wall of the blood vessel.
The catheter is also required to have pressure resistance to prevent it from bursting even when a contrast medium or the like is injected thereinto at a high pressure.
It is known that to obtain the pressing performance and the torque transmission performance, the part of the catheter except the front end thereof is composed of a comparatively hard material. It is also known that to obtain the follow-up performance and the safety, the front end of the catheter is composed of a comparatively soft material.
In particular, it is demanded that to obtain high follow-up performance, a region having a length of about 5 mm rearward from the front end of the catheter is flexible (low in rigidity) and bendable.
However, in the case where the front end of the catheter is composed of the comparatively flexible material, it is difficult to allow the front end of the catheter to have high kink resistance and pressure resistance. That is, it is difficult for the conventional art to allow the catheter to have all of these characteristics at the same time. The case where a contrast medium or the like is injected into a blood vessel or the like at a high pressure is described below. Normally, a high pressure is applied to the rear end of the catheter. Thus it is important that the catheter has an appropriate pressure resistance at its rear end. If a lumen at the front end of the catheter is clogged with the contrast medium for some reason, a high pressure is applied to the front end of the catheter. As a result, there is a possibility that the catheter bursts at the front end thereof. Accordingly, the catheter is demanded to have a pressure resistance, at its front end, equal to that at its rear end.
To confirm the position of the front end of the catheter under X-ray fluoroscopy, there is commercially available a catheter having a radiopaque marker consisting of a radiopaque cylindrical band made of platinum or the like or a radiopaque coil, made of platinum or the like, wound with adjacent windings in contact with each other. The radiopaque marker is installed at a position spaced about 1 mm apart from the front end of the catheter. However, because the radiopaque marker is made of a material having a high rigidity, the radiopaque marker reduces the flexibility and follow-performance at the front end of the catheter. The front end of a micro-catheter is very small in its diameter and very flexible to allow it to advance it inside a very narrow blood vessel branching and zigzag complicatedly. Thus, the radiopaque marker having a length of only 1 mm considerably reduces the flexibility of the catheter at a region about 5 mm apart from the front end thereof, thus sacrificing the operability of the catheter.
It is an object of the present invention to provide a catheter having high pressing performance, follow-up performance, and kink resistance. It is another object of the present invention to provide a catheter bendable and high in follow-up performance, with a front end thereof having high kink resistance and pressure resistance. It is still another object of the present invention to provide a catheter having a construction allowing its diameter to be small so that it is suitably used as a micro-catheter.
SUMMARY OF THE INVENTION
The object of this invention is to provide a catheter that has a flexible tubular body and a reinforcing coil embedded in a wall of said body, wherein said catheter has an outer diameter not larger than 1.5 mm at a front end thereof, said body has a first region disposed within a range of 1-30 mm from said front end of said catheter and a second region nearer to a rear end of said catheter than said first region; said coil extends from a position inside said first region to said second region; a part of said coil disposed in said second region is wound at long winding pitches; and a winding pitch of a part of said coil disposed in said first region is shorter than that of the part of the coil disposed in said second region and becomes shorter gradually or stepwise toward said front end of said catheter, whereby a rigidity of said catheter is lower in said first region than in said second region.
Further, the object of this invention is to provide a catheter that has a flexible tubular body and a reinforcing coil embedded in a wall of said body, wherein said catheter has an outer diameter not larger than 1.5 mm at a front end thereof, a front end of said coil is located within 1-30 mm apart from a front end of said body; a winding pitch of a part of said coil disposed within 1-30 mm apart from said front end of said body becomes shorter gradually or stepwise toward said front end of said catheter.
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patent: 5662622 (1997-09-01), Gore et al.
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patent: 5782809 (1998-07-01), Umeno et al.
patent: 5827242 (1998-10-01), Follmer et al.
patent: 5851203 (1998-12-01), Van Muiden
patent: 6258080 (2001-07-01), Samson
patent: 0 622 385 (1995-07-01), None
patent: 9-94296 (1997-04-01), None
patent: 97/17998 (1997-06-01), None
Mihara Nobuaki
Saitou Takehiko
Burns Doane , Swecker, Mathis LLP
Derakshani Philippe
Terumo Kabushiki Kaisha
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