Devices and methods for controlling expandable prostheses during deployment

Abstract

Prosthesis delivery devices and methods are provided that enable precise control of prosthesis position during deployment. The prosthesis delivery devices may carry multiple prostheses and include deployment mechanisms for delivery of a selectable number of prostheses. Control mechanisms are provided in the prosthesis delivery devices that control either or both of the axial and rotational positions of the prostheses during deployment. This enables the deployment of multiple prostheses at a target site with precision and predictability, eliminating excessive spacing or overlap between prostheses. In particular embodiments, the prostheses of the invention are deployed in stenotic lesions in coronary or peripheral arteries or in other vascular locations.

Description

BACKGROUND OF THE INVENTION [0001] Stents are tubular prostheses designed for implantation in a vessel to maintain patency of the vessel lumen. Stents are used in various vessels throughout the body, including the coronary arteries, femoral arteries, iliac arteries, renal artery, carotid artery, vascular grafts, biliary ducts, trachea, and urethra, to name some examples. Stents are typically implanted by means of long and flexible delivery catheters that carry the stents in a compact, collapsed shape to the treatment site and then deploy the stents into the vessel. In some applications, balloon expandable stents are used. These stents are made of a malleable metal such as stainless steel or cobalt chromium and are expanded by means of a balloon on the tip of the delivery catheter to plastically deform the stent into contact with the vessel wall. In other applications, self-expanding stents are used. These are made of a resilient material that can be collapsed into a compact shape fo...

AI Technical Summary

Benefits of technology

[0013] In addition to controlling axial position of the stents relative to the delivery catheter and / or to each other during deployment, the control member of the delivery catheter is preferably configured to maintain rotational position of the prostheses relative to each other. This facilitates the delivery of stents having axially interleaving elements and prevents excessive spacing or overlap between such elements

Problems solved by technology

While self-expanding stents have demonstrated promise in various applications, such stents face a number of challenges.

One such challenge is that in some cases the disease in a vessel may be so extensive that a stent of very long length, e.g. 30-200 mm, is called for.

Currently available stents are typically less than 30 mm in length, and suffer from excessive stiffness if made longer.

Such stiffness is particularly problematic in peripheral vessels such as the femoral arteries, where limb movement requires a high degree of flexibility in any stent implanted in such vessels.

However, this approach has suffered from several drawbacks.

In order to place multiple stents, multiple catheters must be inserted, removed and exchanged, heightening risks, lengthening procedure time, raising costs, and causing excessive material waste.

In addition, the deployment of multiple stents end-to-end suffers from the inability to accurately control stent placement and the spacing between stents.

This results in overlap of adjacent stents and / or excessive space between stents, which is thought to lead to complications such as restenosis, the renarrowing of a vessel following stent placement.

With self-expanding stents the problem is particularly acute because as the stent is released from the catheter, its resiliency tends to cause it to eject or “watermelon seed” distally from the catheter tip by an unpredictable distance.

During such deployment, the stent may displace not only axially but rotationally relative to the delivery catheter resulting in inaccurate, uncontrollable, and unpredictable stent placement.

Interleaving stents or stent segments such as those disclosed in co-pending application Ser. No. 10 / 738,666, filed Dec. 16, 2003, which is incorporated herein by reference, present even greater challenges to conventional delivery systems.

Conventional delivery systems suffer from the inability to control both the axial and rotational positions of self-expanding stents as they are deployed.

Images