Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent combined with surgical delivery system
Reexamination Certificate
2001-03-27
2003-09-16
Isabella, David J (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent combined with surgical delivery system
Reexamination Certificate
active
06620191
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 catheter assemblies for releasably securing the stent to the catheter during delivery through a body lumen.
Several interventional treatment modalities are presently used for heart disease including balloon and laser angioplasty, atherectomy and by-pass surgery. In typical balloon angioplasty procedures, a guiding catheter having a performed distal tip is percutaneously introduced through the femoral artery into the cardiovascular system of a patient in a conventional Seldinger technique and advanced within the cardiovascular system until the distal tip of the guiding catheter is seated in the ostium.
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, which is made of relatively inelastic materials, is inflated to a predetermined size with radiopaque liquid at relatively high pressure (e.g., greater than 4 atmospheres) to press the arteriosclerotic 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 which 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 which 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 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 prevent 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.
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 implanted within the blood vessel, holding open the passageway thereof.
However, retaining the position of the stent in the proper location on the expandable member while advancing the catheter through the body lumen has been found to be difficult. If the stent is dislodged from or moved on the expandable member the system will not correctly deliver the stent into the body lumen. This would require repeating the procedure. This delays insertion of the stent into the body lumen which may adversely affect the patient's health.
Different methods have been attempted to maintain the position of the stent on the expandable member. One such method involves a protective sheath surrounding the catheter and stent assembly, which is retracted prior to inflation of the expandable member. The use of the sheath, however, increases the profile of the catheter assembly which must traverse narrow vessels. It would be an improvement to use a technique which does not increase the overall profile of the catheter assembly.
Another method has been to remove the friction reducing coating on the expandable member in the location of the stent thereby allowing the catheter assembly's pre-coated surface to hold the stent in frictional contact. This method has not proven highly efficient in maintaining the stent in the desired location.
Still another method involves application of high pressure to force the inflation balloon into gripping contact with gaps or openings between struts in the stent wall. Should the gaps between stent struts be relatively small, however, such a method may have limitations. Other methods require heat to flow balloon material into the gaps or a balloon coating.
What has been needed is a reliable and convenient means of maintaining a stent in a desired location on a stent delivery system without substantially increasing the overall profile of the catheter assembly. The present invention satisfies this need.
SUMMARY OF THE INVENTION
This invention is directed to an improvement in stent delivery systems for releasably securing a stent onto an expandable member of a catheter. The improvement of this invention includes placing deformable material between the outer surface of the expandable member and the stent coaxally disposed thereon. The deformable material is affixed to an expandable member, such as a dilatation balloon and is sufficiently compliant to be deformed by compressive engagement with the stent. The material sandwiched between the expandable member and the stent is compressed projecting a portion of the material adjacent the stent into a physical stop that impedes lateral movement of the stent relative to the balloon during travel to the target site. The deformable material may be an adhesive or a curable compound in a cured or uncured state. The affixed material may be brought into releasably secure contact with the stent by closing the stent inwardly toward, and into engagement with, the underlying expandable member, expanding the expandable member outwardly toward, and into engagement with, the stent, or both. Compressing the stent toward the balloon may include crimping the stent. Once at the target site, the stent is expanded by way of inflation of the expandable member. Any adhesive contact between the stent and the expandable member is broken and the stent is expanded to its implanted diameter. The expandable member is deflated and withdrawn from the patent leaving the stent implanted in a body lumen, such as a coronary artery.
The deformable material is applied to the outer surface of the balloon followed by the coaxial mounting of the stent thereover. In the adhesive form, the deformable material can be ap
Advanced Cardiovascular Systems Inc.
Fulwider Patton Lee & Utecht LLP
Isabella David J
Landrem Kamrin
LandOfFree
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