Stent delivery system and method of manufacturing same

Abstract

Stent delivery system and method of manufacturing same. In one embodiment, the stent delivery system comprises an inner catheter. A handle is disposed at the proximal end of the inner catheter, and an enlarged tip is disposed at the distal end thereof. A stent engaging sleeve coaxially surrounds and is secured to a portion of the inner catheter proximally contiguous to the tip. The stent engaging sleeve is used to frictionally engage a stent mounted thereover in such a way as to prevent the stent, during deployment, from sliding proximally relative to the inner catheter. The system additionally comprises a self-expandable stent of the type comprising a knitted mesh of nitinol wire flexible in both the radial and longitudinal axes. The stent is mounted over the stent engaging sleeve in a longitudinally stretched state and is maintained, until deployment, in the stretched state by a stent restraining sleeve. The stent restraining sleeve, which coaxially surrounds the stent and is appropriately sized to maintain the stent in its stretched state, is a braided tube formed directly over the stent. The system also includes an outer catheter that surrounds much of the distal end of the inner catheter up to its tip, the outer catheter being adapted for axial movement relative to the inner catheter. The distal end of the outer catheter, which is mechanically coupled to the distal end of the stent for axial movement, is provided with an increased inner diameter to accommodate those components positioned between the inner and outer catheters. To facilitate the advancement of the outer catheter over the stent restraining sleeve during the assembly of the system, the outer catheter is fabricated with a longitudinal split extending proximally from its distal end. After the outer catheter has been positioned over the stent restraining sleeve, the split is sealed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a continuation of U.S. patent application Ser. No. 10 / 790,607, filed Mar. 1, 2004, which in turn is a continuation of U.S. patent application Ser. No. 09 / 767,212, filed Jan. 22, 2001, now U.S. Pat. No. 6,699,274, both of which are incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] The present invention relates generally to medical stents (hereinafter “stents”) and relates more particularly to stent delivery systems. [0003] A stent is a tubular endoprosthesis placed within a body lumen to maintain its patency. For example, a stent may be used to maintain the patency of an esophagus or other passageway occluded by a tumor or of a blood vessel constricted by plaque. Most stents fall into one of the following two classes: (i) balloon-expandable stents; and (ii) self-expandable stents. Generally speaking, a stent delivery system includes the stent and some means for positioning and fixing the stent...

AI Technical Summary

Benefits of technology

[0014] It is still another object of the present invention to provide a stent delivery system that has a minimal number of parts, that can be mass-produced, that is easy to manufacture and that is easy to use.

Problems solved by technology

Although the above-described coaxial tube delivery system is well-suited for many types of self-expandable stents, such a delivery system is not particularly well-suited for those self-expandable stents that have limited axial strength, such as the Strecker stent—a knitted nitinol wire stent disclosed in U.S. Pat. No. 5,366,504 and commercially available from Boston Scientific Corporation, Natick, Mass.

This is because such stents are often unable to resist becoming axially compressed during assembly of the coaxial tube delivery system, when the distal end of the outer catheter must be drawn across the stent, and / or during deployment of the coaxial tube delivery system, when the distal end of the outer catheter must be withdrawn across the stent.

Unfortunately, the manufacture of the aforementioned crocheted cord delivery system is typically performed manually and can be quite taxing physically as a great deal of strength is required to tightly stretch the stent down on the catheter while crocheting the cord around the stent.

Another problem with the foregoing system is that, during deployment, the crocheted cord does not always unravel correctly and completely.

Images