Stent deployment systems and methods

Abstract

A stent deployment system includes a catheter shaft, an expandable member mounted to the catheter shaft, and one or more stents or stent segments slidably positioned on the expandable member. The stent deployment system is adapted for deployment of stents or stent segments in very long lesions and in tapered and curved vessels. The stent deployment system facilitates slidable movement of a stent in a distal direction relative to the expandable member while inhibiting slidable movement in a proximal direction relative to the expandable member.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This application is a divisional of U.S. patent application Ser. No. 10 / 458,062 (Attorney Docket No. 021629-001800US), filed Jun. 9, 2003, the full disclosure of which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION [0002] In coronary artery disease, stenotic plaques form within the coronary arteries, restricting and in some cases completely blocking blood flow to the heart muscle. In recent years, a number of different catheter-based interventions have been developed to treat coronary artery disease, including percutaneous transluminal coronary angioplasty (PTCA) and stenting. PTCA involves the placement of an endovascular catheter into the diseased coronary artery and expanding a balloon within the stenotic lesion to dilate the lumen, thereby improving blood flow through the treated area. One drawback of PTCA has been the tendency in some cases for the coronary artery lumen to “restenose” following dil...

AI Technical Summary

Benefits of technology

[0009] In various embodiments, proximal and distal extremities may be tapered, stepped, non-tapered (constant diameter), or combinations thereof. The proximal and distal extremities may be contiguous with one another, or may be separated by a portion of the expandable member. Between the proximal and distal extremities, the expandable member may be non-tapered, tapered at a constant or variable slope, or it may include two or more cylindrical steps of decreasing diameter. Alternatively, the expandable member may include a combination of tapered sections and stepped sections, or tapered sections and non-tapered sections. The outer surface of the expandable member is preferably configured to allow the stent segments to be slidably advanced toward the distal end of the expandable member (or the expandable member slidably retracted proximally relative to the stent segments) when the expandable member is in an unexpanded condition. This enables the user to position the desired number of stent segments to be deployed over the expandable member, thereby facilitating in situ customization of stent length. Further, following deployment of a stent or series of stent segments, an additional stent or series of segments may then be slidably positioned on the expandable member for subsequent deployment.

[0013] In a preferred aspect of the invention, the expandable member is adapted to expand a first plurality of stent segments simultaneously while a second plurality of stent segments remains unexpanded. To accomplish this, the stent deployment system preferably includes a sheath slidably disposed over at least a proximal portion of the expandable member on which the second plurality of stent segments is disposed. The sheath is configured to restrain expansion of the proximal portion of the expandable member and the second plurality of stent segments when the distal portion of the expandable member is expanded. The sheath will have sufficient radial strength to resist expansion by the balloon as it is inflated. Preferably, the sheath has a metal braid or other reinforcement embedded in its wall.

Problems solved by technology

One drawback of PTCA has been the tendency in some cases for the coronary artery lumen to “restenose” following dilatation, wherein plaque reforms at the treatment site to narrow or block the lumen.

Even after stenting, however, some patients experience restenosis.

Current stents and stent deployment devices, however, are not well-suited to address these new potential applications for stents.

For example, current stents are designed for treating relatively short lesions, and often are not suitable for longer lesions through which the vessel may be curved, tapered or have other complex geometries.

Likewise, current stent deployment catheters function effectively to deliver stents of relatively short length in shorter vascular lesions, but they do not perform well in treating longer, tapered, and / or curved vessels.

For example in tapered vessels, current stent deployment catheters may fail to fully expand the stent at its proximal end, while potentially over-expanding the stent at its distal end.

Moreover, current stent and stent delivery technology is limited to deploying stents of predetermined length, requiring advance selection of a stent and associated catheter to match the lesion to be treated.

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