Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-09-18
2003-01-07
Capossela, Ronald (Department: 3744)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S264000, C604S535000, C606S192000, C606S194000
Reexamination Certificate
active
06503223
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a balloon catheter suitably used as for example a balloon catheter for dilatation of blood vessels, more particularly relates to an improvement of a balloon catheter of a so-called monorail type.
BACKGROUND ART
In recent years, the trend in medical technology has been toward less invasive treatment. For example, stenosis of the coronary artery is increasingly being treated by vasodilation balloon catheters instead of the former coronary bypass surgery. This method of treatment has both economic advantages and lightens the load on the patient, so is increasingly growing in application. Along with this, balloon catheters are being required to be structured to enable dilatation of stenosis portions of the coronary artery more efficiently and simply than ever before.
As a method for treating stenosis portions in blood vessels, percutaneous transluminal coronary angioplasty (PTCA) is known. In this method, a balloon catheter is inserted into a blood vessel and the balloon unit is inflated so as to dilate the stenosis portion and thereby improve the flow of blood at the terminal side of the stenosis portion. As a balloon catheter used for this PTCA, there are an over-the-wire type balloon catheter and monorail type balloon catheter. In these types of balloon catheters, first the guidewire is made to pass through the stenosis portion in the blood vessel, then the balloon catheter is fed along the guidewire to the stenosis portion and the balloon unit inflated to dilate the stenosis portion. The stenosis portion must be dilated in stages so as not to damage the blood vessel. First, a balloon catheter with a small outside diameter balloon unit is inserted along the guidewire and then is exchanged with balloon catheters having successively larger outside diameter balloon units.
The over-the-wire type balloon catheter has a guidewire lumen formed over the entire length of the catheter tube. The guidewire is inserted along the lumen. The balloon unit is guided to the stenosis portion along this guidewire. After the dilatation of a blood vessel by a balloon catheter having a small outside diameter balloon unit, this is exchanged with a balloon catheter having a larger outside diameter balloon unit. At this time, the balloon catheter is pulled out along the guidewire, so the proximal end of the guidewire has to extend outside the body by at least the entire length of the catheter tube. If not, it is not possible to exchange a balloon catheter while leaving the distal end of the guidewire in the stenosis portion.
As opposed to this, in the monorail type balloon catheters disclosed in Japanese Unexamined Patent Publication (Kokai) No. 63-288167, U.S. Pat. No. 4,762,129, U.S. Pat. No. 5,061,273, or Japanese Unexamined Patent Publication (Kokai) No. 9-276411, an opening is formed in the middle of the catheter tube and a guidewire is guided from the opening through a guidewire insertion lumen to the distal end of the balloon unit. Due to this, in this type of balloon catheter, the length of the guidewire extending outside of the body for exchange of balloon catheters need only be slightly longer than the length from the opening to the distal end of the balloon. In this type, since the length of the guidewire can be shortened compared with the other type, the operability is excellent.
In the balloon catheters disclosed in the above publications, however, compared with the over-the-wire type, there was the problem of difficulty of insertion of the catheter into the blood vessel. As a method for dealing with this problem, a catheter tube where the distal end and proximal end of the catheter tube are comprised using different materials with different hardnesses and modulii of elasticity and these are joined to give a distal end with flexibility and a proximal end with rigidity has been reported. In this structure of a catheter tube, however, since the hardness changes sharply at the joined portion of the different materials, it is difficult to say that the operability is ideal. Further, since it is difficult to finish the joined portion completely smoothly, the catheter becomes difficult to insert into the blood vessel.
In the balloon catheter disclosed in U.S. Pat. No. 4,762,129, a dilatation use tubular member formed with a balloon inflation lumen and a wire use tubular member formed with a guidewire insertion lumen overlap over a predetermined distance along the axial direction. At the overlapped portion, the proximal end neck portion of the balloon unit is joined to cover part of the overlapped portion. In the balloon catheter disclosed in this publication, however, the outside diameter of the dilatation use tubular member becomes remarkably thinner compared with the portion overlapping the wire use tubular member, so there is the problem that kinks tend to occur.
Further, in the balloon catheter disclosed in U.S. Pat. No. 5,061,273, the dilatation use tubular member formed with the balloon inflation lumen and the wire use tubular member formed with the guidewire insertion lumen are overlapped across a predetermined distance along the axial direction at a position closer to the proximal end side than the proximal end of the balloon unit. Therefore, the outside diameter of the overlapped portion becomes larger and there is difficulty in the insertability of the balloon catheter. If the outside diameter of the dilatation use tubular member closer to the proximal end side than the overlapped portion is made smaller so as to reduce the outside diameter of the overlapped portion, there is also the problem that kinks tend to occur. Further, it is not possible to improve the strength of the proximal end neck portion of the balloon unit.
Further, in the balloon unit disclosed in Japanese Unexamined Patent Publication (Kokai) No. 9-276411, the ends of the two tubular members comprising the catheter tube are covered by separate tubular members, the outside diameters of those portions have thick step portions and there is difficulty in the insertability of the balloon catheter.
Further, in the technology disclosed in this publication, it is not possible to improve the strength of the proximal end neck portion of the balloon unit.
DISCLOSURE OF THE INVENTION
The present invention was made in consideration of this actual situation and has as its object the provision of a balloon catheter which is superior in insertability of the balloon catheter, improves the strength of the proximal end neck portion of the balloon unit, and is superior in resisting kinking.
To achieve the above object, the balloon catheter of the present invention comprises
a first tubular member in which at least one balloon lumen is formed inside along a longitudinal direction thereof;
a balloon unit which is communicated internally with the balloon lumen formed in the first tubular member and capable of being expanded by a fluid fed through that balloon lumen; and
a second tubular member extending axially inside the balloon unit and provided axially therein with at least one guidewire lumen;
a distal end of the balloon unit connected with a distal end of the second tubular member;
an overlapped portion formed by overlapping a proximal end of said second tubular member with a distal end of said first tubular member axially over a predetermined distance;
a neck portion of a proximal end side of said balloon unit directly or indirectly connected with at least part of said overlapped portion so as to cover at least part of said overlapped portion; and
a portion of an outside diameter smaller than an outside diameter of a proximal end of the first tubular member, which is formed on the distal end of said first tubular member.
That is, the balloon c at hater of the present invention has as its object to keep the increase of the outside diameter of the overlapped portion the minimum necessary, to prevent the outside diameter of that portion from becoming thicker in sharp increments, and to improve the insertability of the balloon catheter in a blood vessel etc. and is characterized by having a p
Kawabata Takashi
Miyata Shin'ichi
Sekido Akira
Uchiyama Masaru
Capossela Ronald
Nippon Zeon Co. Ltd.
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