US20020038140A1

US20020038140A1 - Hybrid elastomer sleeve for stent delivery

Info

Publication number: US20020038140A1
Application number: US09/750,934
Authority: US
Inventors: Dachuan Yang; Paul Miller; Jan Seppala; Albert Chin; John Chen; Daniel Horn
Original assignee: Scimed Life Systems Inc
Current assignee: Boston Scientific Scimed Inc
Priority date: 2000-09-22
Filing date: 2000-12-29
Publication date: 2002-03-28
Also published as: JP2004508881A; US6805702B1; EP1339353A2; CA2421563A1; AU2001289106A1; US6554841B1; WO2002024110A3; WO2002024110A2

Abstract

A stent delivery system comprising a catheter. The catheter including a stent mounting region and a stent disposed thereabout. The stent having a distal end and a proximal end, and an unexpanded state and an expanded state. At least one stent retaining sleeve, having a first end and a second end, wherein the first end overlays an end of the stent when the stent is in the unexpanded state. The second end engaged to at least a portion of the catheter adjacent to the stent mounting region. The stent retaining sleeve(s) comprising a first material and at least one substantially longitudinally oriented fiber of a second material. The first material having a predetermined tensile modulus and the second material having a predetermined tensile modulus, wherein the predetermined tensile modulus of the second material is greater than that of the first material.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-In-Part application from U.S. application Ser. No. 09/668,496, filed Sep. 22, 2000, the entire contents of which is hereby incorporated by reference.[0001]

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to medical device delivery catheters in general, and specifically to balloon catheters for use in delivering a medical device such as a stent to a desired body location, such as in a blood vessel. More specifically, this invention relates to a stent retaining sock or sleeve composed of a generally elastic material, but which also includes at least one substantially longitudinally oriented fiber or filament which has a higher tensile modulus than the surrounding elastic material. The combination of the elastomeric sleeve material and reinforcing fiber(s) provides for a sleeve, which when mounted on a stent delivery balloon catheter, may be made to expand in the radial direction with limited or no elongation in the longitudinal direction.

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 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 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 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 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. 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 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.

Copending U.S. patent application Ser. No. 09/426,384 which was filed Oct. 26, 1999 and entitled Longitudinal Dimensional Stable Balloons, and which is incorporated in its entirety herein by reference describes material having longitudinally oriented fibers.

Copending U.S. patent application Ser. No. 09/407,836 which was filed on Sep. 28, 1999 and entitled Stent Securement 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 Ser. No. 09/407,836 the sleeves may be made up of a combination of polytetrafluoroethylene (PTFE) as well as one or more thermoplastic elastomers. Other references exist which disclose a variety of stent retaining sleeves.

A common problem which occurs in catheter assemblies is friction or adhesion between various parts which periodically come into contact with one another during the medical procedure. For instance, friction can occur between the guide catheter and guide wire, between the introducer sheath and the guide catheter, or between the guide catheter and the balloon catheter, for instance, and may increase the difficulty of insertion, cause loss of catheter placement, and result in discomfort to the patient or damage to the vasculature. In catheters equipped with stent retaining socks or sleeves, friction between the balloon and sleeve, and/or the stent and sleeve may also cause retraction of the sleeves to be made more difficult. It is therefore desirable to reduce the friction due to the sliding between the various parts of the catheter assemblies. Copending U.S. application Ser. No. 09/549,286 was filed Apr. 14, 2000 describes a reduced columnar strength stent retaining sleeve having a plurality of holes. The relatively reduced columnar and radial strength provided by the holes allows the sleeve to be retracted off of a stent without the need for lubricant.

Lubricants of many types have been used in conjunction with balloon catheters. Both hydrophilic and hydrophobic coatings and lubricants are well known in the catheter art. The present invention may be used in conjunction with any type of lubricious substance suitable for use with a stent delivery catheter, and is further directed to the application of the lubricious substance to the surface of a balloon cone and/or waste subsequent to stent mounting and sleeve placement onto the catheter.

Copending U.S. patent application Ser. No. 09/407,836 which was filed on Sep. 28, 1999 and entitled Stent Securement Sleeves and Optional Coatings and Methods of Use, provides for a stent delivery system having sleeves. In Ser. No. 09/407,836 the sleeves may be made up of a combination of polytetrafluoroethylene (hereinafter PTFE) as well as one or more thermoplastic elastomers. Copending U.S. patent application Ser. No. 09/427,805 filed Oct. 27, 1999, and entitled End Sleeve Coating for Stent Delivery, describes the use of stent retaining sleeves having lubricious coatings applied thereto. Copending U.S. patent application Ser. No. 09/273,520 filed Mar. 22, 1999, entitled Lubricated Sleeve Material For Stent Delivery likewise describes the use of stent retaining sleeves and lubricants.

The entire content of all patents and applications listed within the present patent application are incorporated herein by reference.

BRIEF SUMMARY OF THE INVENTION

In at least one embodiment, the instant invention is directed to a medical device delivery system comprising a catheter assembly having a medical device receiving region and at least one retaining sleeve for retaining the medical device on the receiving region prior to delivery. An expandable medical device, such as a stent, is disposed about the medical device receiving region of the catheter assembly. At least one retaining sleeve is disposed about an end of the expandable medical device and at least a portion of the catheter assembly.

The at least one retaining sleeve comprises a first material and a second material. The first and second materials having a different tensile modulus, the second material being one or more substantially longitudinally oriented fibers or filaments of a predetermined material or combination of materials. The fiber material may overlay, be imbedded, co-extruded, woven, or otherwise placed into the matrix of the first material.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

A detailed description of the invention is hereafter described with specific reference being made to the drawings in which: [0018]
FIG. 1 is a perspective view of an embodiment of the invention; [0019]
FIG. 2 is a perspective view of an embodiment of the invention; [0020]
FIG. 3 is a perspective view of an embodiment of the invention; [0021]
FIG. 4 is a perspective view of an embodiment of the invention; [0022]
FIG. 5 is a perspective view of an embodiment of the invention; [0023]
FIG. 6 is across-sectional view of the embodiment of the invention shown in FIG. 5; [0024]
FIG. 7 is a perspective view of an embodiment of the invention; [0025]
FIG. 8 is a cross-sectional view of the embodiment of the invention shown in FIG. 7; [0026]
FIG. 9 is a perspective view of an embodiment of the invention; [0027]
FIG. 10 is a cross-sectional view of the embodiment of the invention shown in FIG.9; [0028]
FIG. 11 is a perspective view of an embodiment of the invention; and [0029]
FIG. 12 is a cross-sectional view of the embodiment of the invention shown in FIG. 11.[0030]

DETAILED DESCRIPTION OF THE INVENTION

As may be seen in FIG. 1, the present invention may be embodied in a stent delivery catheter, indicated generally at [0031] 10. Catheter 10, includes a stent mounting region 12, the stent mounting region 12 may be an inflatable portion of the catheter or may be a separate balloon mounted to the catheter shaft 14. The balloon 12 may have an unexpanded state and an expanded state. A stent 16, disposed about the stent mounting region 12 may be delivered when the balloon 12 is expanded to the expanded state.
The [0032] stent 16 includes a proximal end 18 and a distal end 20. In the embodiment shown a stent retaining sleeve 22 overlies at least a portion of each end 18 and 20. As is known in the art, when the balloon 12 and stent 16 are expanded to their expanded state, the ends of the stent retaining sleeves will often likewise expand and may also be configured to retract off of the stent ends. In the present invention, the sleeves 22 have a unique construction which allows a first portion 24 of the sleeve which overlies the stent 16 to attain a radial expansion of up to or exceeding 400 percent. The second portion 26 of the sleeve 22 is disposed about and is engaged to a portion of the catheter shaft 14 adjacent to the balloon 12. Because the second portion 26 is not typically subjected to an expansive force its radial expansion is minimal. When the sleeve is expanded, the sleeve undergoes minimal or no increase in length.
As [0033] stent 16 is expanded, the stent ends 18 and 20 will eventually be drawn from underneath the stent retaining sleeves 22. The present sleeves 22 may expand to nearly the same extent as the balloon 12 thereby ensuring the position of the stent 16 on the catheter 14. By providing a sleeve 22 which may control the time of the release of the stent 16 during the expansion procedure, the present invention ensures that the stent is delivered in an extremely accurate and consistent manner.
The [0034] sleeves 22 are capable of expanding in the manner described as a result of their unique construction. As previously indicated, the sleeves 22 are constructed from at least two materials having different tensile modulus characteristics. The first material 30 is formed into a generally tubular body 32 which provides the sleeve with its shape. The second material 34 is embodied in at least one substantially longitudinally oriented fiber or filament 36.
The first material may be any elastic material known. Preferably the durometer hardness of the first material is between [0035] 40A and 100A. The second material 34 may be any material that when presented as one or more longitudinally oriented fibers has a tensile modulus greater than that of the first material.
In the embodiment shown in FIG. 1, the [0036] fiber 36 may extend substantially across the longitudinal length of the sleeve 22, the material 34 of fiber 36 will tend to provide a greater restriction on longitudinal expansion compared to radial expansion of the sleeve as has been previously described.
The [0037] first material 30 may be selected from one or more of the following substances: polyurethane-polyether polymers, such as Tecothane™ 1074A available from Thermedics, Inc.; polyester-polyurethanes, such as Pellethane™ 2103-70A sold by Dow Chemical; polyether-polyurethanes, such as Estane™ 5703P sold by BF Goodrich; polyether block amides, such as Pebax™ 2533 available from Elf Atochem; and styrene-butadien-styrene triblock copolymers such as Kraton™ D1101 sold by Shell Chemical company. Other materials which may also be used in the production of the first material 30 include, but are not limited to styrenic block copolymers, polyurethanes, silicone rubber, natural rubber, copolyesters, polyamides, EPDM rubber/polyolefin, nitril rubber/PVC, fluoroelastomers, butyl rubber, epichlorohydrin, and any combinations thereof.
The [0038] second material 34 may be selected from one or more of the following substances: metal, glass, carbon, and/or polymers.
Where the [0039] material 34 includes a polymer, such polymer materials may be a liquid crystal polymer (LCP) such as VECTRA™ LKX 1107, 1111, polyetheretherketone (PEEK) material, and PPS. Other materials may also be utilized as the fibril component of the present invention. Such substances include aromatic nylon, rigid polyurethane, polyester, copolyester, polyester blends, polyester/polyurethane blends, PEEK, PPS, fluoropolymer and so on.
Fiber(s) [0040] 36 may also include one or more of the following substances: polyurethane-polyether polymers, such as Tecothane™ 1055D or 1065D both of which are available from Thermedics, Inc.; polyether-polyurethanes, such as Estane™ 58237 sold by BF Goodrich; polyether block amides, such as Pebax™ 7233 or 6333 both of which are available from Elf Atochem. Other materials which may also be used in the production of the second material 34 include, but are not limited to: polyolefins, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene polymers, polyacrylonitrile, polyacrylate, vinyl acetate polymer, cellulose plastics, polyurethanes, polyethylene terephthalate, polyacetal, polyethers, polycarbonates, polyamides, polyphenylene sulfide, polyarylethersulfones, polyaryletherketones, polytetrafluoroethylene, and any combinations thereof.
Other materials which may be suitable for use in forming fiber(s) [0041] 36 include Nylon, Kevlar™, polyethyleneterephthalate (PET), stainless steel, NITINOL and others.
The various materials which may be used to form the fiber or [0042] fibers 36 as depicted in the various figures may be combined with the first material 24 in a wide variety of manners and configurations. The material 34 may combine one or more of the materials described above into a fiber 36 such as is shown. Alternatively, the fiber 36 may be a combination of one or more materials woven together, or a single continuous shaft of material or materials, such as a filament or wire of one or more of the materials 34 mentioned above. Other configurations may also be provided, some of which are described in greater detail below.
In addition, the manner in which the fiber(s) [0043] 36 are combined with the first material 24 may also vary. The fiber(s) 36 may be co-extruded with the first material 24. The fiber(s) 36 may be imbedded into the first material 24, or may be placed over the first material 24. The fiber(s) may also be woven into the matrix of the first material 24.
The above examples of the first and [0044] second materials 30 and 34 or the configurations of fiber(s) 36 or the various manners in which the fiber(s) 36 and first material 24 may be joined, are in no way exhaustive of the potential substances or combinations of substances which may be used. The present invention is directed to a sleeve composed of any materials which have the respective tensile modulus qualities previously described for the respective materials 30 and 34.
As may be seen in the various figures, the present invention may be embodied in a variety of manners. For instance, in the embodiment shown in FIG. 1 the [0045] catheter 10 is seen with a pair of sleeves 22 each of which have a single longitudinally parallel fiber 36. The fiber 36 may be a wire, or filament of material placed onto a surface of the body 32.
As may be seen in FIG. 2, the sleeve(s) [0046] 22 may include a plurality of fibers. The fibers 36 may be arranged in any manner desired, for example, in FIGS. 5 and 6 the sleeve 22 includes a plurality of fibers 36 having a variety of lengths. As may best be seen in FIGS. 5 and 6, the fibers 36 do not need to extend the entire length of the sleeve 22. The fibers 36 may have significantly reduced lengths when compared to that of the sleeve 22. In addition the fibers 36 may be positioned in a uniform manner relative to one another about the circumference 40 of the sleeve 22 such as may be seen in FIGS. 7-12, or the fibers 36 may be randomly distributed such as is illustrated in FIGS. 5 and 6.
In FIG. 3 an embodiment of the invention is shown wherein the [0047] sleeves 22 have fibers 36 which are tapered. Each fiber 36 has a first end 42 and a second end 44. The first end corresponds to the portion 24 of the sleeve 22 which overlies the end of the stent 16 and the second end 44 corresponds to the portion 26 of the sleeve 22 which is engaged to the catheter shaft 14. The second end 44 has a predetermined width which is greater than and tapers to the predetermined width of the first end 42. By providing the portion 26 of the sleeve 22 with a proportionally stronger second material 34 than the first portion 24, the second portion will have a greater resistance to expansion and will therefor remain engaged to the shaft 14 through out most of the stent delivery procedure. At the same time the comparatively reduced amount of second material 34 at or near the first portion of the sleeve 22, will allow the first portion 24 to more readily and fully expand according to the expansion characteristics of the first material 30, as previously described.
FIGS. [0048] 4-6 show additional configurations of the fiber 36 as it may be embodied on a sleeve 22 design. FIG. 4 shows a sleeve 22 which includes a plurality of fibers 36 having a sinusoidal configuration. FIGS. 5 and 6, shows a sleeve 22 having fibers 36 with a variety of lengths and configurations. Other arrangements may also be provided.
As previously discussed the [0049] fibers 36 may be applied to or combined with the body 32 in a variety of manners. For instance where the second material 34 is a coating, the fiber(s) 36 may be directly applied to a surface of the sleeve 22, in any of the patterns or configurations discussed thus far. In the embodiments shown in FIGS. 7-12 a variety of additional fiber 36 and body 32 arrangements are shown.
In FIGS. 7 and 8, the [0050] sleeve 22 has a predetermined thickness 48. The body 32 and fibers 36 which make up the sleeve 22 have the same uniform thickness 48 through out the entire sleeve 22. Such an arrangement may be possible by forming the sleeve 22 directly via a co-extrusion process, or by bonding uniformly thick pieces of alternating materials together.
In FIGS. 9 and 10 an embodiment of the [0051] sleeve 22 is shown wherein the fibers 36 are raised relative to the thickness 48 of the body 32. While the thickness of the fibers 36 may be the same or different than that of the body 32, the fibers have a raised appearance because they are positioned in longitudinal grooves 50 positioned longitudinally about the circumference 40 of the sleeve 22. Such a ‘raised fiber’ may provide for fiber(s) of greater hardness which in turn provides for greater sleeve stiffness. In the embodiment shown in FIGS. 11 and 12, the grooves 50 are also present but the fibers 36 are not raised thereby providing the entire sleeve 22 with a uniform thickness as well as a reduced profile relative to the fiber configurations shown in FIGS. 9 and 10.
It should also be noted that the [0052] fibers 36 such as are depicted in FIGS. 9-12 may be raised relative to the inside of the sleeve, such that the fibers 36 extend radially inward relative to the thickness 48 of the body 32.
In alternative embodiments, notably those utilized specifically for delivery of a self expanding stent, a retractable sheath (not shown) such as are known in the art, may be employed to overlay the stent. In such embodiments a single sleeve or two sleeves such have been shown and described may be employed to retain the self-expanding stent in place. When the sheath is retracted the stent will expand causing the sleeve(s) to retract. [0053]
In addition to being directed to the embodiments described above and claimed below, the present invention is further directed to embodiments having different combinations of the features described above and claimed below. As such, the invention is also directed to other embodiments having any other possible combination of the dependent features claimed below. [0054]
The above examples and disclosure are intended to be illustrative and not exhaustive. These examples and description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto. [0055]

Claims

1. A stent delivery system comprising:

a catheter including a stent mounting region;

a stent disposed about the stent mounting region of the catheter, the stent having a distal end and a proximal end, the stent further having a unexpanded state and an expanded state, and

at least one stent retaining sleeve, the at least one stent retaining sleeve having a first end and a second end, the first end overlying an end of the stent when the stent is in the unexpanded state, the second end engaged to at least a portion of the catheter adjacent to the stent mounting region, the at least one stent retaining sleeve comprising a first material and at least one substantially longitudinally oriented fiber of a second material, the first material having a first predetermined tensile modulus and the second material having a second predetermined tensile modulus, the second predetermined tensile modulus being greater than that of the first predetermined tensile modulus.

2. The stent delivery catheter of claim 1, the at least one substantially longitudinally oriented fiber of a second material further comprising a plurality of substantially longitudinally oriented fibers.

3. The stent delivery catheter of claim 1 wherein the at least one substantially longitudinally oriented fiber of a second material further comprises a first portion and a second portion, the first portion having a first predetermined width, and the second portion having a second predetermined width, the first predetermined width being less than the second predetermined width, the first portion substantially oriented toward the first end of the at least one stent retaining sleeve and the second portion substantially oriented toward the second end of the at least one stent retaining sleeve. The first predetermined width tapering to the second predetermined width.

4. The stent delivery catheter of claim 3 wherein the first predetermined width is 30 zero.

5. The stent delivery catheter of claim 1 wherein the at least one substantially longitudinally oriented fiber of a second material is characterized as being substantially sinusoidal in shape.

6. The stent delivery catheter of claim 1 wherein the first material and the at least one substantially longitudinally oriented fiber of a second material are co-extruded.

7. The stent delivery catheter of claim 1 wherein the substantially longitudinally oriented fiber of a second material is a wire, the wire engaged to the first material of the at least one stent retaining sleeve.

8. The stent delivery catheter of claim 1 wherein the substantially longitudinally oriented fiber of a second material is at least partially compose of a polymer.

9. The stent delivery catheter of claim 1, the at least one stent retaining sleeve having a predetermined thickness and the first material having at least one groove, the at least one groove having a predetermined thickness less than the predetermined thickness of the at least one stent retaining sleeve, at least one substantially longitudinally oriented fiber of a second material positioned within the at least one groove.

10. The stent delivery system of claim 1 wherein the first material has a predetermined thickness and the at least one substantially longitudinally oriented fiber of a second material has a predetermined thickness, wherein the predetermined thickness of the first material and the predetermined thickness of the at least one substantially longitudinally oriented fiber of a second material are the same.

11. The stent delivery system of claim 2, the at least one stent retaining sleeve further comprising a circumference, the plurality of substantially longitudinally oriented fibers being uniformly spaced apart about a the circumference.

12. The stent delivery catheter of claim 2, the at least one stent retaining sleeve further comprising a circumference, the plurality of substantially longitudinally oriented fibers are randomly dispersed about the circumference.

13. The stent delivery system of claim 1 wherein the first material is constructed from at least one member of the group consisting of: styrenic block copolymers, polyurethanes, silicone rubber, natural rubber, copolyesters, polyamides, EPDM rubber/polyolefin, nitril rubber/PVC, fluoroelastomers, butyl rubber, epichlorohydrin, and any combinations thereof.

14. The stent delivery system of claim 1 wherein the at least one substantially longitudinally oriented fiber of a second material is constructed from at least one member of the group consisting of: liquid crystal polymers, polyolefins, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene polymers, polyacrylonitrile, polyacrylate, vinyl acetate polymer, cellulose plastics, polyurethanes, polyethylene terephthalate, polyacetal, polyethers, polycarbonates, polyamides, polyphenylene sulfide, polyarylethersulfones, polyaryletherketones, polytetrafluoroethylene, polyethyleneterephthalate, nylon, metal, carbon, glass and any combinations thereof.

15. The stent delivery catheter of claim 1,

the first end of the at least one stent retaining sleeve having an unexpanded diameter and an expanded diameter, the expanded diameter of the first end being up to approximately 400 percent greater than the unexpanded diameter;

whereby when the balloon is expanded from the unexpanded state to the expanded state the unexpanded diameters of the first end of the at least one stent retaining sleeve is increased by up to approximately 400 percent to the expanded diameter.

16. A stent retaining sleeve for retaining stent ends on a balloon catheter comprising:

a tubular member composed of a first material and at least one substantially longitudinally oriented fiber of a second material, wherein the first material has a predetermined tensile modulus and the second material has a predetermined tensile modulus, the predetermined tensile modulus of the second material being greater than the predetermined tensile modulus of the first material;

the tubular member having a first end and a second end, the first end constructed and arranged to overlay an end of a stent, the second end constructed and arranged to be in contact with at least a portion of a catheter;

the first end of the tubular member having an unexpanded diameter and an expanded diameter whereby when the balloon catheter is expanded the unexpanded diameter increases by up to 400 percent to the expanded diameter.

17. The stent retaining sleeve of claim 16, the sleeve having an unexpanded length and an expanded length, the unexpanded length being substantially the same as the expanded length.