Surgery – Instruments – Means for inserting or removing conduit within body
Reexamination Certificate
1999-08-06
2001-07-03
Mancene, Gene (Department: 3732)
Surgery
Instruments
Means for inserting or removing conduit within body
C606S195000
Reexamination Certificate
active
06254611
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a stent delivery catheter system, such as the kind used in percutaneous transluminal coronary angioplasty (PTCA) procedures. More particularly, it relates to a stent delivery catheter employing a retractable sheath which slidingly seals with the catheter.
BACKGROUND OF THE INVENTION
In typical PTCA procedures, a guiding catheter is percutaneously introduced into the cardiovascular system of a patient and advanced through the aorta until the distal end is in the ostium of the desired coronary artery. Using fluoroscopy, a guide wire is then advanced through the guiding catheter and across the site to be treated in the coronary artery. An over the wire (OTW) balloon catheter is advanced over the guide wire to the treatment site. The balloon is then expanded to reopen the artery. The OTW catheter may have a guide wire lumen which is as long as the catheter or it may be a rapid exchange catheter wherein the guide wire lumen is substantially shorter than the catheter. Alternatively, a fixed wire balloon may be used. This device features a guide wire which is affixed to the catheter and cannot be removed.
To help prevent arterial closure, repair dissection, or prevent restenosis, a physician can implant an intravascular prosthesis, or a stent, for maintaining vascular patency inside the artery at the lesion. The stent may either be a self-expanding stent or a balloon expandable stent. For the latter type, the stent is often delivered on a balloon and the balloon is used to expand the stent. The self-expanding stents may be made of shape memory materials such as nitinol or constructed of regular metals but of a design which exhibits self expansion characteristics.
In certain known stent delivery catheters, a stent and an optional balloon are positioned at the distal end of the catheter, around a core lumen. The stent and balloon are held down and covered by a sheath or sleeve. When the distal portion is in its desired location of the targeted vessel the sheath or sleeve is retracted in a proximal direction on the catheter to expose the stent. After the sheath is removed, the stent is free to self-expand or be expanded with a balloon.
In a stent deployment system which utilizes a retractable sheath one problem which is encountered is the interaction of the sheath and guide catheter upon retraction. The traditional way of dealing with this is to make the retractable sheath long enough so that it will be contained in the guide catheter at all times. This increases system profile, reduces flexibility and creates excess friction upon sheath retraction.
Another problem encountered when using a retractable sheath relates to catheter preparation. This involves flushing the system with fluid to ensure no air remains in the delivery device and maintaining the fluid filled state to prevent air from entering the system before inserting it into the vasculature of the patient.
SUMMARY OF THE INVENTION
The present invention provides an improved stent delivery system. The stent delivery system comprises in a preferred embodiment, a catheter having a proximal outer shaft and a stent receiving portion adapted to receive a stent near the distal end of the catheter, a retractable distal sheath concentrically arranged around the stent receiving portion and a pull back means operatively connected to the distal sheath. The catheter is further arranged so that the retractable sheath or a member connected thereto is pulled into the proximal outer shaft of the catheter during retraction of the distal sheath thereby freeing the loaded stent. The inclusion of the retractable sheath maintains a reduced system profile and provides good flexibility.
In the preferred embodiment of the invention the basic components of the stent delivery system consist of a stent sheath, i.e., a cover means surrounding the stent at least in part but preferably fully, a pull wire arrangement or other pull back means, such as a hydraulic or screw arrangement or other means, a manifold with a slide mechanism, a catheter having a non-compressible inner shaft, an outer shaft, and two radiopaque marker bands. The stent is introduced to the body housed in a polymer sheath. The sheath is operatively connected to the manifold by a stainless steel pull wire or the like. The manifold contains a slide mechanism. Deployment is achieved by actuating the slide mechanism to retract the stent sheath thereby releasing the stent from the sheath. A non-compressible inner shaft creates a lumen for guide wire passage and fluid delivery. A multi-component outer shaft receives the sliding sheath interiorly while maintaining a fluid path between the manifold and sheath. Two radiopaque marker bands rest underneath the stent. The marker bands are spaced to match the length of the stent providing a visual guide for accurate placement and deployment.
The multi-component outer shaft preferably consists of a Polyimide stainless steel composite tube, a high density polyethylene (HDPE) proximal slide sheath, a distal HDPE dual lumen tube, and a HDPE stent sheath. The proximal slide sheath is bonded to the distal end of the composite outer tube. The stent sheath is bonded to the distal end of the dual lumen tube to form a retractable sheath means. The proximal slide sheath is sized in correspondence with the distal dual lumen tube to form a seal with the dual lumen tube. The proximal end of the dual lumen tube slides into the distal end of the proximal slide sheath to absorb the length of the stent means which is retracted when the stent sheath is moved to release the stent. Together, the dual lumen tube and the stent sheath form a retractable sheath means which is received interiorly of the outer body portion of the catheter, such as the outer shaft. This contrasts with other methods where a distal segment slides over the proximal segment or collapses to absorb a length of a retracting member.
The proximal slide sheath is stationary and is in effect an extension of the outer shaft. The distal dual lumen slides into the proximal slide sheath. The ledge formed by the outside diameter growth between the two shafts remains stationary in the anatomy once tracked to the lesion. Therefore, the ledge will not engage the anatomy during deployment. In the prior art, anatomy engagement with a sheath sliding over the proximal shaft is a distinct possibility, especially on a bend.
The distal segment's profile will be smaller with an “into” length change according to this invention compared to an “over” length change. A “collapsing” design requires a profile growth during deployment and can present a nonuniform profile when pulling the shaft back into the guide catheter.
The length of the absorbing member is minimized with an “into” or “over” design versus a “collapsing” design. Since a collapsing tube requires space even in it's collapsed position, the ratio between the required shaft length change and the absorbing member will never be one to one. The collapsing shaft's longer absorption member exposes the pull wire to buckle over a longer length. The axial length change in the pull wire caused by buckling could cause unintended stent deployment.
The inventive delivery system solves the problem of catheter preparation, maintaining the prepared condition of the system, and preventing fluid from leaking out by providing a sliding seal which forms a seal between the proximal end of the retractable sheath and the catheter body. The sliding seal maintains the prepared state and allows elimination of full length sheaths such as Imbert U.S. Pat. No. 4,875,480 without using the collapsible sheath technique of U.S. Pat. No. 5,534,007.
Other objects, features, embodiments and characteristics of the present invention, as well as the methods of operation and functions for the related elements of the structure, and the combination of parts and economics of manufacture, will become more apparent upon consideration of the following description with reference to the accompanying drawings, all of which form a part of this specific
Mancene Gene
Philogene Pedro
Sci-Med Life Systems, Inc.
Vidas, Arrett & Steinkra
LandOfFree
Stent deployment catheter with midshaft seal does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Stent deployment catheter with midshaft seal, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stent deployment catheter with midshaft seal will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2537950