Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
1999-10-21
2001-05-29
Mendez, Manuel (Department: 3763)
Surgery
Instruments
Internal pressure applicator
C604S096010
Reexamination Certificate
active
06238408
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates to a balloon-tip catheter, and particularly to a balloon-tip catheter having a balloon high in strength, excellent in flexibility, processability, shapeability, retention of shape, stability and fusion-bonding ability to a catheter. The balloon-tip catheter according to the present invention is particularly suitable for use as a balloon-tip catheter for dilation for dilating a living organ or coeloma such as a vessel.
2. Background Art
A balloon-tip catheter is a tube provided with a balloon on its tip, and the balloon may be inflated or deflated without drawing out the catheter after insertion thereof. When the balloon-tip catheter is inserted into a vessel to inflate the balloon, the inflated balloon is propelled by blood, so that the catheter is easily passed through the vessel. A vessel, through which the blood freely flows when the balloon is deflated, may also be occluded by inflating the balloon.
Balloon-tip catheters are used in, for example, {circle around (1)} arterial embolization and thrombectomy, {circle around (2)} venous thrombectomy, {circle around (3)} dilation of a constricted artery, {circle around (4)} vascular embolization and vascular occlusion, {circle around (5)} removal of foreign matter in a vessel, etc., and are classified into, for example, balloon-tip catheters for arterial thrombectomy, balloon-tip catheters for occlusion, balloon-tip catheters for vasodilation, etc. according to the respective uses and application sites thereof.
In recent years, medical techniques have trended toward low invasive treatment against the human body. Among the balloon-tip catheters, an application range of the balloon-tip catheters for dilation for dilating living organs or coelomae has expanded in keeping with that. In general, the balloon-tip catheters for dilation have a structure that a balloon
2
is arranged in the vicinity of the tip of a catheter
1
as illustrated in FIG.
1
. The balloon
2
may be inflated by introducing a gas under pressure into the balloon
2
through an opening provided in the catheter
1
or deflated by drawing the gas out of the balloon
2
. The catheter
1
is generally equipped with various parts such as a side arm adapter
3
and an adapter
4
.
In order to dilate a constricted artery, the outside of the body is first connected to an artery to be dilated by means of a vessel puncturing device called a sheath introducer under local anesthesia, a sheath serving as a passageway of a catheter is inserted into the artery, and a fine catheter is put in the artery through the sheath. A pressure-resistant balloon-tip catheter for dilation is then inserted into the constricted part, and the balloon is inflated, thereby pressing the hypertrophic tunica intima causing atheromatous degeneration against the tunica externa to dilate the lumen. This method is called percutaneous transluminal artery angioplasty and yields satisfactory results. The method is applied to, for example, a coronary artery, a renal artery, an external iliac artery, a femoral artery, etc. This treating method can greatly relieve patient's stress and also has an economical advantage. Accordingly, the constriction of a coronary artery or the like is often treated by a vasodilative operation making use of a balloon-tip catheter for vasodilation in place of a coronary artery bypass operation or the like previously performed.
The application range of the balloon-tip catheters for dilation is expanded making good use of their merits. Correspondingly, the balloon-tip catheters for dilation are also required to have high properties. The balloon-tip catheters for dilation are required, for example, {circle around (1)} to be able to treat the constriction of a peripheral coronary artery, {circle around (2)} to easily insert into a curved vessel, {circle around (3)} to have a strong dilation pressure, and to {circle around (4)} safely dilate a vessel.
More specifically, (1) it is required to be able to treat the constriction of a more peripheral coronary artery than before using a balloon-tip catheter for vasodilation. In order to meet this requirement, formation of a balloon of low profile (reduction in the projected area of the balloon in a longitudinal direction) is required. Therefore, a balloon of thinner wall and higher strength than before is required. (2) Cases of an intravascular operation, in which a balloon-tip catheter for dilation is inserted into a curved vessel, increase. In order to insert the catheter into the curved vessel with ease, the balloon is required to be flexible and have trackability. (3) A stent is often left in a coeloma for support during anastomosis or after the anastomosis, or ensuring the communication of the coeloma easy to constrict. In keeping with that, the balloon is required to have a stronger dilation pressure. (4) As the intravascular operation is frequently performed, it is required to be able to safely dilate a vessel using a balloon-tip catheter for dilation. In order to meet this requirement, the balloon is required to have a compliance (i.e., rate of change in the diameter of the balloon inflated to the dilation pressure of the balloon) within a proper range and high breaking strength.
Polyethylene resins have heretofore been principally used as materials of the balloon-tip catheters for dilation because they are comparatively good in processability and balance among their properties. However, the polyethylene resins heretofore used have involved a problem that they cannot fully meet the requirements as the requirement level against the properties of the balloon-tip catheters for dilation is heightened. The conventional balloon made of low density polyethylene (LDPE) is insufficient in both strength and flexibility. Even when a linear low density polyethylene (LLDPE) is used in place of LDPE, its improving effect on strength is a little, and only a balloon poor in flexibility can be obtained. Even when a balloon made of a polyethylene resin is crosslinked by electron beam crosslinking, water crosslinking or the like, any balloon excellent in balance among strength, flexibility, compliance upon inflation of the balloon, etc. cannot be obtained.
The balloon-tip catheter for dilation is shaped into a fixed form that a balloon is wound around a catheter in order to facilitate its insertion into and extraction from a coeloma such as a vessel, and the fixed form is often retained while the balloon is deflated under reduced pressure. However, the balloon made of the conventional polyethylene resin has been insufficient in shapeability and retention of shape. Balloons making use of a polyamide resin or polyester resin have also been known. However, it is difficult to obtain a balloon excellent in balance between strength and compliance.
As described above, various resin materials have heretofore been investigated as materials for forming a balloon of a balloon-tip catheter for dilation. However, there has not been yet obtained any material which can meet the above-described properties highly required.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a balloon-tip catheter having a balloon which is high in strength, excellent in flexibility, easy to shape the balloon when it is folded, good in setting ability, has a compliance within a proper range when it is inflated, and moreover is excellent in processability, retention of shape and fusion-bonding ability to a catheter.
The present inventors have carried out an extensive investigation with a view toward overcoming the above-described problems involved in the prior art. As a result, it has been found that a polyolefin obtained by polymerization using a metallocene catalyst is used, thereby obtaining a balloon-tip catheter having good various properties. It has also been found that when an ethylene-&agr;-olefin copolymer having specific physical properties is selectively used as the polyolefin, a balloon-tip catheter, which can fully satisfied such highly required properties as described above and
Kawabata Takashi
Sakai Koichi
Uchiyama Masaru
Dinsmore & Shohl LLP
Mendez Manuel
Nippon Zeon Co. Ltd.
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