Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent structure
Reexamination Certificate
2001-06-29
2003-08-12
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent structure
Reexamination Certificate
active
06605110
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to expandable endoprosthesis devices, generally called stents, which are adapted to be implanted into a patient's body lumen, such as a blood vessel, to maintain the patency thereof. These devices are particularly useful in the treatment and repair of blood vessels after a stenosis has been compressed by percutaneous transluminal coronary angioplasty (PTCA), percutaneous transluminal angioplasty (PTA), or removed by atherectomy, laser angioplasty or other means.
Several interventional treatment modalities are presently used for heart disease, including balloon and laser angioplasty, atherectomy, and by-pass surgery. In typical coronary balloon angioplasty procedures, a guiding catheter having a distal tip is percutaneously introduced through the femoral artery into the cardiovascular system of a patient using a conventional Seldinger technique and advanced within the cardiovascular system until the distal tip of the guiding catheter is seated in the ostium of a coronary artery. A guide wire is positioned within an inner lumen of a dilatation catheter and then both are advanced through the guiding catheter to the distal end thereof. The guide wire is first advanced out of the distal end of the guiding catheter into the patient's coronary vasculature until the distal end of the guidewire crosses a lesion to be dilated, then the dilatation catheter having an inflatable balloon on the distal portion thereof is advanced into the patient's coronary anatomy over the previously introduced guide wire until the balloon of the dilatation catheter is properly positioned across the lesion. Once in position across the lesion, the balloon is inflated to compress the plaque of the lesion against the inside of the artery wall and to otherwise expand the inner lumen of the artery. The balloon is then deflated so that blood flow can be resumed through the dilated artery and the dilatation catheter can be removed therefrom. Further details of dilatation catheters, guide wires, and devices associated therewith for angioplasty procedures can be found in U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lindquist); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622 (Samson, et al.); U.S. Pat. No. 4,554,929 (Samson, et al.); U.S. Pat. No. 4,616,652 (Simpson); U.S. Pat. No. 4,638,805 (Powell); U.S. Pat. No. 4,748,982 (Horzewski, et al.); U.S. Pat. No. 5,507,768 (Lau, et al.); U.S. Pat. No. 5,451,233 (Yock); and U.S. Pat. No. 5,458,651 (Klemm, et al.).
One problem that can occur during balloon angioplasty procedures is the formation of intimal flaps which can collapse and occlude the artery when the balloon is deflated at the end of the angioplasty procedure. Another problem characteristic of balloon angioplasty procedures is the large number of patients who are subject to restenosis in the treated artery. In the case of restenosis, the treated artery may again be subjected to balloon angioplasty or to other treatments such as by-pass surgery, if additional balloon angioplasty procedures are not warranted. However, in the event of a partial or total occlusion of a coronary artery by the collapse of a dissected arterial lining after the balloon is deflated, the patient may require immediate medical attention, particularly in the coronary arteries.
A focus of recent development work in the treatment of heart disease has been directed to endoprosthetic devices called stents. Stents are generally cylindrically shaped intravascular devices which are placed within an artery to hold it open. The device can be used to reduce the likelihood of restenosis and to maintain the patency of a blood vessel immediately after intravascular treatments. In some circumstances, they can also be used as the primary treatment device where they are expanded to dilate a stenosis and then left in place. Further details of stents can be found in U.S. Pat. No. 3,868,956 (Alfidi et al.); U.S. Pat. No. 4,512,338 (Balko et al.); U.S. Pat. No. 4,553,545 (Maass et al.); U.S. Pat. No. 4,733,665 (Palmaz); U.S. Pat. No. 4,762,128 (Rosenbluth); U.S. Pat. No. 4,800,882 (Gianturco); U.S. Pat. No. 4,856,516 (Hillstead); U.S. Pat. No. 4,886,062 (Wiktor); U.S. Pat. No. 5,421,955 (Lau); and U.S. Pat. No. 5,569,295 (Lam).
A variety of stent designs have been developed and include coiled wires in a variety of patterns that are expanded after being placed intraluminally on a balloon catheter; helically wound coiled springs manufactured from expandable heat sensitive metals; self-expanding stents inserted in a compressed state for deployment in a body lumen, and stents shaped in zig zag patterns. One of the difficulties encountered using prior art stents involve maintaining the radial rigidity needed to hold open a body lumen while at the same time maintaining the longitudinal flexibility of the stent to facilitate its delivery and accommodate the often tortuous path of the patient's vasculature. Generally, the greater the longitudinal flexibility of the stent, the easier and more safely it can be delivered to the implantation site.
Various means have been described to deliver and implant stents. One method frequently described for delivering of a stent to a desired intraluminal location includes mounting the stent on an expandable member, such as a balloon on a distal end of an intravascular catheter, advancing the catheter to the desired location within the patient's vascular system, inflating the balloon on the catheter to expand the stent into a permanent expanded condition. The expandable member is then deflated and the catheter is withdrawn, leaving the expanded stent within the blood vessel, holding open the passageway thereof. Other prior art stent delivery catheters used for implanting self-expanding stents include an inner member upon which the compressed or collapsed stent is mounted and an outer restraining sheath which is placed over the compressed stent to maintain it in its compressed state prior to deployment. When the stent is to be deployed in the body vessel, the outer restraining sheath is retracted in relation to the inner lumen to uncover the compressed stent, allowing the stent to move into its expanded condition for implantation in the patient.
Advancing the stent through a patient's vasculature, which can involve traversing sharp bends and other obstacles, may require the stent to be highly flexible. While it is beneficial if the area of treatment is located in a substantially straight portion of the patient's vasculature, often, the area of treatment is at a curved portion of the body vessel which can be problematic to the physician when implanting the device. Therefore, stent flexibility must permit the stent to be deployed in and conform to a tortuous section of a patient's vasculature. Moreover, once implanted, the stent should not attempt to straighten the curved vessel since this could possibly cause disruption in the normal flow of the blood through the vessel and could possibly result in restenosis occurring at that location. Additionally, visualization of the stent with a fluoroscope, which is currently the most widely used method of locating and positioning the stent during deployment, requires a stent with good radiopacity.
Different methods have been attempted to give stents high flexibility and radiopacity. By making stents out of relatively thin material, flexibility can be increased. However, the use of thin material can reduce the radiopacity of the stent, making it more difficult for the physician to visualize the stent. Conversely, the use of thicker material, which can promote radiopacity results in reduced stent flexibility, which can impair the deliverability of the stent. When the stent is made from a self-expanding material, such as nickel titanium, which has less radiopacity than a stainless steel stent, for example, the problem of visualizing the self-expanding stent can be further increased if thinner material is used to increase flexibility.
An early attempt at achieving a flexible st
Advanced Cardiovascular Systems Inc.
Fulwider Patton Lee & Utecht LLP
Jackson Suzette J.
Willse David H.
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