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CROSS-REFERENCE TO RELATED
STATEMENT REGARDING FEDERALLY
BACKGROUND OF THE INVENTION
1. Field Of The Invention
This invention relates to a medical device delivery systems, namely catheter mounted stent delivery systems. More particularly, the present invention is directed to socks or sleeves used to retain a stent on a stent delivery catheter. The present invention provides for one or more stent end retaining sleeves having a double wall construction. The double wall construction allows the sleeve(s) to be readily and completely retracted off the stent ends during a stent delivery procedure while retaining an extremely low profile relative to the catheter. In at least one embodiment of the invention the double wall sleeve(s) may be characterized as a tube folded over upon itself to form a continuous loop, wherein a portion of the folded over tube overlies an end of the stent and a portion of the tube is engaged to the catheter shaft. The tube may be retracted off of the stent in a number of ways. The tube may be constructed to roll, slide, or other wise retract away from the stent when the stent expands during delivery. The sleeve may be used singly or in pairs with either self-expanding or balloon expandable stents. In the case of a self expanding stent, one or more sleeves may be utilized in conjunction with one or more retractable sheaths. The sleeve(s) may be provided in a variety of lengths to provide partial to full stent coverage. Other inventive aspects and embodiments of the present end retaining sleeves will be made apparent below.
2. Description Of The Related Art
Stents and stent delivery assemblies are utilized in a number of medical procedures and situations, and as such their structure and function are well known. A stent is a generally cylindrical prosthesis introduced via a catheter into a lumen of a body vessel in a configuration having a generally reduced diameter and then expanded to the diameter of the vessel. In its expanded configuration, the stent supports and reinforces the vessel walls while maintaining the vessel in an open, unobstructed condition.
Both self-expanding and inflation expandable stents are well known and widely available in a variety of designs and configurations. Self-expanding stents must be maintained under positive external pressure in order to maintain their reduced diameter configuration during delivery of the stent to its deployment site. Inflation expandable stents may be crimped to their reduced diameter about the delivery catheter, maneuvered to the deployment site, and expanded to the vessel diameter by fluid inflation of a balloon positioned on the delivery catheter. The present invention is particularly concerned with delivery and deployment of inflation expandable stents, although it is generally applicable to self-expanding stents when used with balloon catheters.
In advancing an inflation expandable stent through a body vessel to the deployment site, there are a number of important considerations. The stent must be able to securely
maintain its axial position on the delivery catheter, without translocating proximally or distally, and especially without becoming separated from the catheter. The stent, particularly its distal and proximal ends, must be protected to prevent
5 distortion of the stent and to prevent abrasion and/or reduce trauma of the vessel walls.
Inflation expandable stent delivery and deployment assemblies are known which utilize restraining means that overlie the stent during delivery. U.S. Pat. No. 4,950,227 to
1° Savin et al,relates to an expandable stent delivery system in which a sleeve overlaps the distal or proximal margin (or both) of the stent during delivery. That patent discloses a stent delivery system in which a catheter carries, on its distal end portion, a stent which is held in place around the catheter
15 prior to and during percutaneous delivery by means of one and preferably two sleeves. The sleeves are positioned around the catheter with one end portion attached thereto and overlap an end portion(s) of the stent to hold it in place on the catheter in a contracted condition. Each sleeve is
20 elastomeric in nature so as to stretch and release the stent when it expands for implantation. The stent is expandable by means of the expandable balloon on the catheter. During expansion of the stent at the deployment site, the stent margins are freed of the protective sleeve(s). U.S. Pat. No.
25 5,403,341 to Solar, relates to a stent delivery and deployment assembly which uses retaining sheaths positioned about opposite ends of the compressed stent. The retaining sheaths of Solar are adapted to tear under pressure as the stent is radially expanded, thus releasing the stent from
30 engagement with the sheaths. U.S. Pat. No. 5,108,416 to Ryan et al., describes a stent introducer system which uses one or two flexible end caps and an annular socket surrounding the balloon to position the stent during introduction to the deployment site.
35 Copending U.S. patent application Ser. No. 09/407,836 which was filed on Sep. 28, 1999 and entitled Stent Securemerit Sleeves and Optional Coatings and Methods of Use, and which is incorporated in its entirety herein by reference, also provides for a stent delivery system having sleeves. In
40 09/407,836 the sleeves may be made up of a combination of polytetrafluoroethylene (hereinafter PTFE) as well as one or more thermoplastic elastomers. Other references exist which disclose a variety of stent retaining sleeves.
45 The entire content of all patents and applications listed within the present patent application are incorporated herein by reference.
BRIEF SUMMARY OF THE INVENTION
50 This invention provides for one or more low profile double walled stent retaining sleeves which may be readily and fully retracted from a stent during stent delivery. The rolling retractable sleeves of the present invention improve over the prior art by providing a unique sleeve(s) which is
55 designed to completely retract off of the stent during the stent delivery procedure. The present sleeve(s) are doublewalled providing the sleeve(s) with the ability to roll and/or are otherwise retracted off of the stent ends by moving, such as by rolling, away from the stent mounting region or
go balloon along the catheter shaft. The ability of a sleeve to rollingly retract off of the stent allows the sleeve to retain its general shape and low profile throughout the stent delivery procedure.
In at least one embodiment of the invention the inside 65 surfaces of the walls of the double walled sleeve may be lubricious in nature, have a lubricious coating thereon, or define a space which may contain a lubricant. The double
walled structure of the sleeves allows each sleeve to be rollingly retracted completely off of a stent during stent delivery and avoids an accordion or wrinkled sleeve profile subsequent to stent delivery. The sleeves may be comprised of a combination of materials to provide the sleeves with a 5 variety of characteristics such as those described in detail below.
BRIEF DESCRIPTION OF THE SEVERAL
VIEWS OF THE DRAWINGS 10
A detailed description of the invention is hereafter described with specific reference being made to the drawings in which:
FIG. 1 is a side view of an embodiment of the invention;
FIG. 2 is a side view of another embodiment of the invention;
FIG. 3 is a side view of another embodiment of the invention;
FIG. 4 is a side view of another embodiment of the 20 invention;
FIG. 5 is a side view of the embodiment shown in FIG. 4, shown subsequent to stent delivery;
FIG. 6 is a side view of another embodiment of the ^ invention;
FIG. 7 is a side view of the embodiment shown in FIG. 6 wherein the protective sheath has been retracted;
FIG. 8 is a side view of another embodiment of the invention; 30
FIG. 9 is a side view of the embodiment shown in FIG. 8 wherein the protective sheath has been retracted;
FIG. 10 is a side view of another embodiment of the invention;
FIG. 11 is a side view of another embodiment of the invention; and
FIG. 12 is a side view of another embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
As previously discussed, the present invention is directed to one or more double walled stent retaining sleeves. In FIG. I a pair of stent retaining sleeves, indicated generally at 10, 45 are shown. The individual sleeves 10, are composed of a tubular double walled member 12. The double walled member 12 may be characterized as having a an inside layer 14 and an outside layer 16, wherein the inside layer 14 and the outside layer 16 are bonded together to be continuous with 50 one another. The double walled member 12 is formed by folding or everting one of the layers, such as the inside layer 14, back upon itself to form the other layer, such as outside layer 16.
The double walled member 12 when utilized with the 55 stent delivery system 30, such as may be seen in the embodiments shown in FIGS. 3-9, provides such the system 30 with stent retaining sleeves 10 which may be retracted completely off of the stent 32 during a stent delivery procedure. As may best be seen in FIG. 5, in at least one of 60 the embodiments discussed herein, the double walled construction of the sleeves 10 provides the sleeves with the ability to roll off of the balloon or stent mounting region 34 of the catheter 36 during stent delivery.
The sleeves 10 may be constructed to rollingly retract 65 when subjected to a predetermined outwardly acting force. In the case of a self-expanding stent, such as may be seen in
FIGS. 6-9, when the sheath 33 is retracted off of the stent 32 by pulling the sheath 33 proximally via a pull back member 35, the stent 32 will exert an outwardly acting radial force against the sleeves 10. As may be seen in FIGS. 7 and 9, the force supplied by the stent 32 will cause the sleeve(s) 10 to retract off of the stent.
In the embodiment shown in FIGS. 8 and 9 a single sleeve 10 is used to overlay only one end of the stent 32. As with any embodiment of the present invention, the sleeve 10 may be configured to have a wide variety of lengths so as to provide for a variable extent of stent coverage. The sleeve 10 may even extend over the length of the entire stent 32. However, in the embodiment shown, the sleeve 10 overlays the distal stent end 48 while the sheath 33 overlays the proximal end 50. When the sheath 33 is retracted via the pull back member 35 the proximal end 50 is released resulting in a momentary flaring of the proximal end 50 as the it begins to expand. As the proximal end 50 expands the sleeve 10 will retract off of the distal end 48 thereby allowing the distal end 48 to expand with the proximal end 50.
In the embodiments shown in FIGS. 6-9 the stent mounting region 34 may be an unexpanding portion of the catheter 36 or it may be expandable as previously discussed.
In an embodiment where the sleeves 10 are utilized with a balloon expandable stent 32, such as may be seen in the embodiments shown in FIGS. 3-5, the force supplied by the expanding balloon 34 which causes the stent 32 to expand, will likewise trigger the retraction of the sleeves 10 off of the stent 32. In the case of a balloon expandable stent, the force exerted by the balloon 34 will typically be 6 atmospheres or less.
Depending on several variables including: the materials used to make the sleeves, the materials used to make the catheter/balloon, and the type of engagement between the catheter and each sleeve; the sleeve(s) 10 may be configured to retract off of the stent 32 in a variety of manners.
The balloon 34 may be constructed of compliant materials, noncompliant materials or a combination thereof. The balloon 34 may be composed of compliant materials which include low pressure, relatively soft or flexible polymeric materials, such as thermoplastic polymers, thermoplastic elastomers, polyethylene (high density, low density, intermediate density, linear low density), various co-polymers and blends of polyethylene, ionomers, polyesters, polyurethanes, polycarbonates, polyamides, poly-vinyl chloride, acrylonitrile-butadiene-styrene copolymers, polyether-polyester copolymers, and polyetherpolyamide copolymers. Other suitable materials include a copolymer polyolefin material available from E.I. DuPont de Nemours and Co. (Wilmington, Del.), under the trade name SURLYNTM Ionomer and a polyether block amide available under the trade name PEBAXTM. Non-compliant materials include relatively rigid of stiff high pressure polymeric materials, such as thermoplastic polymers and thermoset polymeric materials, poly(ethylene terephthalate) (commonly referred to as PET), polyimide, thermoplastic polyimide, polyamides, polyesters, polycarbonates, polyphenylene sulfides, polypropylene and rigid polyurethanes.
Depending on the composition of the balloon 34 and the resulting extent of the frictional engagement between the balloon 34 and the sleeve 10, the sleeves 10 may be configured to roll, slide, "snap" off, or otherwise retract in any manner or combination of manners such as is know in the art. An additional benefit provided for by the sleeves 10 of the present invention, is that the sleeves 10 may be fully