Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-11-12
2001-09-11
Seidel, Richard K. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S916000, C606S194000
Reexamination Certificate
active
06287277
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is directed to the formation of inflatable members and particularly to inflatable balloons for dilatation catheters used in angioplasty procedures, commonly referred to as percutaneous transluminal coronary angioplasty (PTCA).
In a typical PTCA procedure a dilatation balloon catheter is advanced over a guidewire to a desired location within the patient's coronary anatomy where the balloon of the dilatation catheter is properly positioned within the stenosis to be dilated. The balloon is then inflated to a predetermined size with radiopaque liquid at relatively high pressures which can generally range from 4-20 atmospheres to dilate the stenosed region of the diseased artery. One or more inflations may be needed to effectively dilate the stenosis. The catheter may then be withdrawn from the stenosis or advanced further into the patient's coronary anatomy to dilate additional stenoses.
The catheters used to insert stents into a patient's blood vessel are very similar to the catheters employed for angioplasty. The stent is mounted onto the balloon of the catheter in a contracted or otherwise unexpanded state, the catheter with the stent is advanced through the patient's vasculature until the balloon and stent thereon are disposed within a desired region of the patient's vasculature, such as a coronary artery. The balloon is inflated to expand the stent into position within the desired region of the patient's blood vessel.
Presently used balloons are formed of a polymer such as polyethylene terephthalate (PET), polyethylene (PE), nylon and the like. The strength requirements for balloons whether for dilatation and stent delivery has tended to increase over the years. But it has become more difficult with conventional manufacturing procedures to form high strength balloons with thin walls of uniform thicknesses without pin holes. Typical procedures involve blowing of a tubular parison, usually within a mold having an interior surface corresponding to the desired inflated shape of the balloon.
Dilatation balloons of non-standard shapes, such as bifurcated balloons shown in U.S. Pat. No. 4,456,000, are difficult to manufacture without seams, flow lines, flash or other defects. What has been needed and heretofore unavailable is a method of forming balloons having high strength, thin walls and low incidence of pin holes and in a variety of shapes and sizes without the prior defects. The present invention satisfies these and other needs.
SUMMARY OF THE INVENTION
The present invention is directed to a method of forming a thin walled high strength balloon for dilatation, stent delivery and implacement and the like, which has little incidence of pin holes and which is without seams, flow lines, flash or other defects.
In one presently preferred embodiment of the invention, a balloon is formed by deposition of a thermoplastic polymeric material or thermoplastic elastomeric material onto a mandrel of desired shape in a vacuum or low pressure environment and preferably under cover of an inert or non-reactive gas such as argon, nitrogen and the like. The mandrel has an exterior shape which corresponds to the desired inflated shape of the balloon. One presently preferred method of depositing the polymeric material onto the mandrel is radio frequency (RF) sputtering. Another method is plasma coating. Other vacuum or vapor deposition methods may also be employed to deposit polymeric material onto a mandrel to form a balloon. Suitable polymeric materials which may be vacuum deposited onto a mandrel to form a balloon include conventional dilatation balloon materials such as polyethylene, polyvinyl chloride, polyethylene terephthalate, nylon and other polyamides and zinc and sodium ionomers (e.g. Surlyn). Balloons formed of other less conventional materials such as polypropylene, polyimide, various fluoropolymers and proprietary polymeric materials such as Parylene and Parylast which are available from Advanced Surface Technology, Inc. of Billerica, Mass., may also be made with the method of the invention. Blends of polymeric materials are also suitable for deposition. Composite balloons and other catheter parts with separate layers of different polymeric materials may also be formed by the vacuum deposition of the polymeric materials. For example, a first component such as a balloon can be formed in the manner of the invention, and then be assembled with a suitable inner tubular member and catheter shaft. After the assembly, the balloon can be first coated in the manner of the invention with a suitable material such as Parylene and then Parylast is applied to further secure the balloon to the catheter shaft.
Generally, the vacuum deposition is conducted within a chamber that has a vacuum level of about 10
−2
to about 10
−10
torr, preferably about 10
−3
to about
10
−6
Torr. The gas cover is preferably argon for RF sputtering and nitrogen for plasma deposition. Other relatively inert or otherwise non-reactive gases may likewise be employed in this regard.
The balloon of the invention can be formed with a wall thickness which is uniform and accurate. Wall thicknesses between about 0.3 to over 2 mils (0.008-0.05 mm) and typically from 0.5 to about 1.5 mils (0.013-0.038 mm) can be readily formed with variations from 0.05 to 0.3 mils (0.0013-0.008 mm), typically about 0.1 to about 0.2 mils (0.0025-0.005 mm). Moreover, the balloon is essentially pin hole free and has no seams, flow lines, flash or other defects. The method of the invention is particularly adaptable to the manufacture of balloon shapes other than conventional cylindrical working sections with tapered ends, e.g. multi-furcated balloons, i.e. balloons with multiple distal portions which extend distally a angles from one another. These and other advantages of the invention will become more apparent from the following detailed description of the invention, when taken in conjunction with the accompanying exemplary drawings.
REFERENCES:
patent: 4248224 (1981-02-01), Jones
patent: 4309994 (1982-01-01), Grunwald
patent: 4413989 (1983-11-01), Schjeldahl et al.
patent: 4456000 (1984-06-01), Schjeldahl et al.
patent: 4743327 (1988-05-01), Dehaan et al.
patent: 4952357 (1990-08-01), Euteneuer
patent: 4994071 (1991-02-01), MacGregor
patent: 5613980 (1997-03-01), Clauhan
patent: 5669924 (1997-09-01), Shaknovich
patent: 5720735 (1998-02-01), Dorros
patent: 5749825 (1998-05-01), Fischell et al.
patent: 347 023 (1989-03-01), None
patent: 97/16217 (1997-05-01), None
Advanced Cardiovascular Systems Inc.
Heller Ehrman White & McAuliffe
Rodriguez Cris
Seidel Richard K.
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