Intravascular stent

Details Intravascular stent Intravascular stent

2000-12-21

2003-09-30

McDermott, Corrine (Department: 3738)

Prosthesis (i.e., artificial body members), parts thereof, or ai

Arterial prosthesis

Stent structure

C623S001160

Reexamination Certificate

active

06626935

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to devices for the treatment of heart disease and particularly to endo-arterial prostheses, which are commonly called stents. More particularly, the invention relates to stents incorporating flexible joints in the structure thereof that enable the stents to bend inside a patient's vasculature.
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 and advanced 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 guide wire 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.), which are hereby incorporated herein in their entirety by reference thereto.
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), which are hereby incorporated herein in their entirety by reference thereto.
One method and system developed for delivering stents to desired locations within the patient's body lumen involves crimping a stent about an expandable member, such as a balloon on the distal end of a catheter, advancing the catheter through the patient's vascular system until the stent is in the desired location within a blood vessel, and then inflating the expandable member on the catheter to expand the stent within the blood vessel. The expandable member is then deflated and the catheter withdrawn, leaving the expanded stent within the blood vessel, holding open the passageway thereof.
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. Stent flexibility also permits the stent to be deployed in and conform to a tortuous section of a patient's vasculature. Additionally, visualizing the stent with a fluoroscope, which is currently the most widely used method of stent visualization during stent 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, which can make it difficult for a physician or technician to visualize the stent. Conversely, the use of thicker material, which promotes radiopacity, can reduce stent flexibility and resultantly impair the deliverability of the stent.
An early attempt at achieving a flexible stent with good radiopacity characteristics involved providing a stent of a base material with good flexibility and strength but relatively low radiopacity, and then adding a thin layer of a highly-radiopaque material, such as gold, to the stent. This approach, which required the use of two separate materials, involved a relatively complicated process in applying the radiopaque material to the stent. Additionally, the use of multiple materials can complicate use and deployment of the stent, particularly where the different materials have different material characteristics, such as different strengths, different biocompatibility, or different responses to temperature changes.
Another approach was to provide a stent with substantially thicker portions at each end. Such an approach provided a stent with highly radiopaque ends, so that a physician could easily view the stent ends during stent delivery.
What has been needed and heretofore unavailable is an improved means of providing a stent with high flexibility, strength, and radiopacity. The present invention satisfies this need.
SUMMARY OF THE INVENTION
This invention relates to devices for the treatment of heart disease and particularly to endo-arterial prostheses, which are commonly called stents. More particularly, the invention relates to stents incorporating flexible joints in the structure thereof enabling the stents to easily bend to conform to a patient's vasculature.
Present day expandable stent designs incorporate portions that flex or otherwise deform during insertion of the stent into a patient's vasculature. Similarly, there are also portions of the stent that remain more stable (i.e., less deformed) during insertion.
It will be appreciated that as a stent advanced along a circuitous path in a coronary artery, it flexes about it longitudinal axis in order to navigate curves in the patient's vasculature. In this invention, when the stent is flexed while passing through the bends in an artery, some portions of the stent will flex substantially while other portions, remain less deformed. Thus, the stent has highly flexible portions and more stable (i.e., less deformed) portions that function a

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