Metal working – Means to assemble or disassemble – To apply or remove a resilient article
Reexamination Certificate
1998-02-26
2001-03-20
Watson, Robert C. (Department: 3723)
Metal working
Means to assemble or disassemble
To apply or remove a resilient article
C029S234000, C029S268000, C029S270000, C029S282000, C029S283500, C081S003430, C081S064000
Reexamination Certificate
active
06202272
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a stent crimping device of the type that will enable the user to crimp a stent onto the distal end of a balloon dilatation catheter assembly, for example of the kind used in a typical percutaneous transluminal coronary angioplasty (PTCA) procedure.
2. Description of the Related Art
In a typical PTCA procedure, for compressing lesion plaque against the artery wall to dilate the artery lumen, a guiding catheter is percutaneously introduced into the cardiovascular system of a patient through the brachial or femoral arteries and advanced through the vasculature until the distal end is in the ostium. A guidewire and a dilatation catheter having a balloon on the distal end are introduced through the guiding catheter with the guidewire sliding within the dilatation catheter. The guidewire is first advanced out of the guiding catheter into the patient's coronary vasculature, and the dilatation catheter is advanced over the previously advanced guidewire until the dilatation balloon is properly positioned across the lesion. Once in position across the lesion, a flexible, expandable, preformed balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures to radially compress the atherosclerotic plaque of the lesion against the inside of the artery wall and thereby dilate the lumen of the artery. The balloon is then deflated to a small profile, so that the dilatation catheter can be withdrawn from the patient's vasculature and blood flow resumed through the dilated artery. While this procedure is typical, it is not the only method used in angioplasty.
In angioplasty procedures of the kind referenced above, a restenosis of the artery may develop over several months, which may require another angioplasty procedure, a surgical bypass operation, or some method of repairing or strengthening the area. To reduce the chance of the development of restenosis and strengthen the area, a physician can implant an intravascular prosthesis for maintaining vascular patency, typically called a stent. A stent is a device used to hold tissue in place in a vessel or to provide a support for a vessel to hold it open so that blood flows freely. A variety of devices are known in the art for use as stents, including expandable tubular members, in a variety of patterns, that are able to be crimped onto a balloon catheter, and expanded after being positioned intraluminally on the balloon catheter, and that retain their expanded form. Typically, the stent is loaded and crimped onto the balloon portion of the catheter, and advanced to a location inside the artery at the lesion. The stent is then expanded to a larger diameter, by the balloon portion of the catheter, to implant the stent in the artery at the lesion.
However, if the stent is not tightly crimped onto the catheter balloon portion, when the catheter is advanced in the patient's vasculature the stent may move or even slide off the catheter balloon portion in the coronary artery prior to expansion, and may block the flow of blood, requiring procedures to remove the stent.
In procedures where the stent is placed over the balloon portion of the catheter, the stent must be crimped onto the balloon portion to prevent the stent from sliding off the catheter when the catheter is advanced in the patient's vasculature. In the past this crimping was often done by hand, which does not provide optimum results due to the uneven force being applied, resulting in non-uniform crimps. In addition, it was difficult to judge when a uniform and reliable crimp had been applied. Though some tools, such as ordinary pliers, have been used to apply the stent, these tools have not been entirely adequate in achieving a uniform crimp. Moreover, an unevenly crimped stent may result in an unevenly expanded stent in the vessel or artery, which is undesirable.
SUMMARY OF THE INVENTION
This invention is directed to a vascular prosthesis crimping device which enables substantially uniform and tight crimping of a stent onto a catheter balloon portion, to better secure the stent onto the catheter for delivery of the stent through the patient's vasculature.
The present invention attempts to solve several problems associated with crimping stents onto balloon catheters.
In an exemplary embodiment of the present invention, the stent crimping device includes a compressible and resiliently expandable loop portion (e.g., mylar, nylon, nickel-titanium (NiTi), polymide) in the tip of a hand tool (or mechanical device such a a pneumatic cylinder), connected to the distal end of jaw portions of the hand tool. The loop portion is compressible radially inwardly by the application of compressive force to the hand tool by the user, to substantially uniformly and tightly crimp the stent onto the balloon catheter assembly. The loop portion is further expandable upon release by the user of the compressive force applied to the hand tool, to enable the loop portion to resiliently expand for enabling another stent and balloon catheter assembly to be supported therein for crimping.
The device enables the stent to be crimped onto the distal end of a balloon catheter substantially uniformly and tightly, reducing the risk that the stent may slide off the catheter balloon portion. It is further easy to use in performing the stent crimping procedure. It also enables the crimping procedure to be repeatably performed on stent and balloon catheter assemblies with substantially repeatable crimping force applied thereto.
These and other advantages of the invention will become more apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 698492 (1902-04-01), Hart
patent: 5295420 (1994-03-01), Grimes
patent: 5920975 (1999-07-01), Morales
patent: 5931851 (1999-08-01), Morales
Advanced Cardiovascular Systems Inc.
Fulwider Patton Lee & Utecht LLP
Watson Robert C.
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