US20100274344A1 - Stent Delivery System Having Stent Securement Apparatus - Google Patents

Abstract

A system/assembly for delivery and deployment of an inflation expandable stent within a vessel, comprising a catheter having proximal and distal ends; a stent, inflation expandable from a delivery diameter to a deployment diameter, such that the delivery diameter is reduced from the deployment diameter for conforming the stent to the catheter, such that the stent, in its delivery diameter, is coaxially mounted on the catheter near the catheter distal end; an expandable inflation means coaxially mounted on the catheter axially within the stent, for expansion of the stent from the delivery diameter to the deployment diameter upon application of fluid deployment pressure to the inflation means; and a securement component coaxially mounted on the catheter, axially within the expandable inflation means, the securement component designed and adapted to provide a securement pressure to the stent in the delivery diameter to maintain the stent in position on the catheter during delivery to the deployment site.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• The present application is a continuation of U.S. Ser. No. 10/737,497, filed Dec. 16, 2003 and issued as U.S. Pat. No. 7,670,364, which is a continuation of U.S. Ser. No. 09/794,648, filed Feb. 27, 2001 and issued as U.S. Pat. No. 6,663,660, which is a continuation of U.S. Ser. No. 09/418,277, filed Oct. 14, 1999 and issued as U.S. Pat. No. 6,203,558, which is a continuation of U.S. Ser. No. 08/916,544, filed Aug. 22, 1997 and issued as U.S. Pat. No. 5,968,069, which is a Continuation-in part application based on U.S. Ser. No. 08/807,791, filed Feb. 28, 1997 and issued as U.S. Pat. No. 6,077,273, U.S. Ser. No. 08/702,150, filed Aug. 23, 1996 and issued as U.S. Pat. No. 6,007,543, U.S. Ser. No. 08/697,453, filed Aug. 23, 1996 abandoned, and U.S. Ser. No. 08/701,979, filed Aug. 23, 1996 and issued as U.S. Pat. No. 6,395,008, all of which are incorporated by reference in their entirety.
FIELD OF THE INVENTION
• This invention relates to an assembly and method for delivering and deploying an inflation expandable stent, particularly within a lumen of a body vessel. More specifically, this invention relates to stent securement devices most notably positioned between the balloon and the inner shaft of the catheter.
BACKGROUND OF THE INVENTION
• 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 general 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. 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 (also known as balloon expandable stents) are crimped to their reduced diameter about the delivery catheter, positioned at the deployment site, and then expanded to the vessel by diameter by fluid inflation of the balloon positioned between the stent and the delivery catheter. The present invention is particularly concerned with enhanced stent securement and safer stent loading in the delivery and deployment of balloon expandable stents.
• In angioplasty procedure, there may be restenosis of the artery, which either necessitates another angioplasty procedure, a surgical bi-pass procedure, or some method of repairing or strengthening the area. To prevent restenosis and strengthen the area, a physician can implant an intravascular prosthesis for maintaining vascular patency, i.e. a stent, inside the artery at the lesion. The stent is expanded to a larger diameter for placement in the vasculature, often by the balloon portion of the catheter. Stents delivered to a restricted coronary artery, expanded to a larger diameter as by a balloon catheter, and left in place in the artery at the site of a dilated lesion are shown in U.S. Pat. No. 4,740,207 to Kreamer; U.S. Pat. No. 5,007,926 to Derbyshire; U.S. Pat. No. 4,733,665 to Palmaz; U.S. Pat. No. 5,026,377 to Burton et al.; U.S. Pat. No. 5,158,548 to Lau et al.; U.S. Pat. No. 5,242,399 to Lau et al.; U.S. Pat. No. 5,344,426 to Lau et al.; U.S. Pat. No. 5,415,664 to Pinchuck; U.S. Pat. No. 5,453,090 to Martinez et al.; U.S. Pat. No. 4,950,227 to Savin; U.S. Pat. No. 5,403,341 to Solar; U.S. Pat. No. 5,108,416 to Ryan et al.; and European Patent Application No. 707837A1 to Scheiban, all of which are incorporated herein by reference. A stent particularly preferred for use with this invention is described in PCT Application No. 96/03092-A1, published 8 Feb. 1996, the content of which is incorporated herein by reference.
• In advancing a balloon 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. The stent, particularly its distal and proximal ends, are sometimes protected to prevent distortion of the stent, and minimize trauma to the vessel walls. Balloon expandable stent delivery and deployment assemblies are known which utilize restraining means that overlay the stent during delivery. U.S. Pat. No. 4,950,227 to Savin et al., relates to a balloon expandable stent delivery system in which a sleeve overlaps the distal or proximal margin (or both) of the stent during delivery. During inflation of the stent at the deployment site, the stent margins are freed of the protective sleeve(s) and the sleeves then collapse toward the delivery catheter for removal. A number of balloon expandable stent delivery and deployment assemblies do not use overlaying restraining members, such as the Savin sleeves, to position the stent for delivery. European Patent Application No. EP 055 3960A1 to Lau et al., uses an elastic sheath interspaced between the balloon and the stent. The sheath is said to act as a barrier to protect the balloon from the stent, allow uniform stent expansion, decrease balloon deflation time, prevent undesirable balloon flattening upon deflation and provide a friction substrate for the stent. The Lau sheath can be positioned on the inside or outside of the balloon. U.S. Pat. No. 5,409,495 to Osborne, similarly uses an elastic sleeve or sheath surrounding and in contact with the balloon for controlling the balloon radial expansion. In addition, Osborne is said to use restraining bands or a pair of balloons to achieve controllable stent expansion characteristics. U.S. Pat. No. 5,403,341 to Solar, relates to stent delivery and deployment assembly which uses a retaining sheath positioned about opposite ends of the compressed state. The retaining sheaths of Solar are adapted to tear under pressure as the stent is radially expanded, thus releasing the steno for 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 annular socket surrounding the balloon to position the stent during introduction to the deployment site. The content of all of these patents is incorporated herein by reference.
• In positioning a balloon expandable stent on the delivery catheter over the fluid expandable balloon, the stent must be smoothly and evenly crimped to closely conform to the overall profile of the catheter and the unexpanded balloon. It has been noted that, due to physical properties of the material used in manufacturing the stent (typically a shaped memory metal, such as stainless steel or Nitinol™) there is a certain amount of “recoil” of the stent despite the most careful and firm crimping. That is the stent evidences a tendency to slightly open up from the fully crimped position and once the crimping force has been released. For example, in the typical stent delivery and deployment assembly, if the stent has been fully crimped to a diameter of approximately 0.0035″, the stent has been observed to open up or recoil to approximately 0.0037″. This phenomenon has been characterized as “recoil crimping”. Due to recoil crimping to this slightly enlarged diameter, it can be understood that the stent tends to evidence a certain amount of looseness from its desired close adherence to the overall profile of the underlying catheter and balloon. That is, the stent tends to have a perceptible relatively slack fit in its mounted and crimped position. During delivery, the stent can thus tend to slip and dislocate from its desired position on the catheter or even become separate from the catheter, requiring further intervention by the physician.
• According to the present invention, a securement device is secured over the inner catheter beneath the balloon to compensate for the undesired looseness or slack that due to recoil crimping and to aid in securing the stent to the balloon, as well as protecting the balloon material from being sandwiched between the stent and any metal or protruding item which may be mounted on the inner shaft/guide wire lumen, for delivery of the stent. The securement devices secure the stent during tracking and delivery and provide a good friction fit to the stent and insure good contact between the stent and underlying balloon and catheter, instead of merely crimping the stent onto the balloon and the underlying catheter and relying on the bulk of the flaccid balloon to hold the stent on.
• The art referred to and/or described above is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. §1.56(a) exists.
SUMMARY OF THE INVENTION
• This invention concerns a catheter apparatus suitable for performing angioplasty and for delivery of stents to body cavities. In general, stents are prosthetic devices which can be positioned within a body cavity, for example, a blood vessel or in some other difficultly accessible place of the body of a living human or animal. The stent prosthesis is formed of a generally tubular body, the diameter of which can be decreased or increased. Stents are particularly useful for permanently widening a vessel which is either in a narrowed state, or internally supporting a vessel damaged by an aneurysm. Such stents are typically introduced into the body cavity by use of a catheter. The catheter is usually of the balloon catheter type in which the balloon is utilized to expand the stent, which is positioned over the balloon for delivery, to place it in a selected location in the body cavity. The present invention is particularly directed to improved arrangements for releasably attaching and securing the stent to the catheter to facilitate delivery thereof, specifically having a securement device within the balloon. The below identified embodiments all disclose improved means for securing the stent to the catheter during the delivery procedure.
• In certain embodiments the stent is held in place on the catheter by means of an enlarged mounting body carried within the balloon by the catheter shaft to which the stent and balloon are fitted. The stent is fitted over the balloon, as by crimping. According to the invention in some embodiments, the enlarged body is axially movable on the inner shaft of the catheter so that it can be retracted from the stent mounting area to provide a small profile for performing angioplasty. The catheter can then be withdrawn; the enlarged body can be moved into the stent mounting area; the stent can be mounted and the catheter can be re-inserted to implant the stent. In other embodiments, the enlarged body can be arranged to be reducible and enlargeable in size rather than being movable. Alternatively, the movable mounting body may be carried outside the balloon. A catheter of this type makes possible a method in which, before stent loading with the associated mounting body arranged to provide reduced diameter in the balloon region, the catheter may be used to dilate a lesion or the like. The catheter may be withdrawn and the mounting body may then be selectively manipulated to provide an enlarged diameter in the stent mounting region and a stent may be loaded onto the catheter. The catheter may be re-inserted to implant the stent. The catheter may be withdrawn or left in situ and the mounting body may be manipulated to provide reduced diameter again and the catheter may be used for any post-dilation desired. Also, the catheter may be used multiple times in the procedure for dilation and stent implantation.
• Another embodiment of the present invention is also an assembly for delivery and deployment of an inflation expandable stent within a vessel. The assembly comprises a catheter, an expandable tube component mounted on the catheter, an expandable balloon mounted on the catheter and encompassing the tube component, and a stent mounted on the balloon. The catheter has proximal and distal ends. The stent is inflation expandable from a delivery diameter to a deployment diameter. The delivery diameter is reduced from the deployment diameter for conforming the stent to the catheter. The stent, in its delivery diameter, is coaxially mounted on the catheter near the catheter distal end. The expandable balloon is coaxially mounted on the catheter axially within the stent. The balloon is designed and adapted for expansion of the stent from the delivery diameter to the deployment diameter upon application of fluid deployment pressure to the balloon. The expandable tube component is coaxially mounted on the catheter, axially within the expandable balloon. The tube components is designed and adapted for fluid expansion to provide a securement pressure to the stent in the delivery diameter to maintain the stent in position on the catheter during delivery to the deployment site. The expandable tube component is sized and constructed to be fluid expandable to no more than the delivery diameter. The tube component is essentially equal in length to the stent and the stent is positioned on the assembly essentially coextensive with the tube component.
• In another embodiment, this invention is a method for delivering and deploying a stent using an assembly as just described. A catheter is provided having proximal and distal ends. An expandable balloon is coaxially mounted on the catheter. An expandable tube component is coaxially mounted on the catheter, axially within the expandable balloon. The balloon and the tube component are each in an unexpanded condition. A stent is provided which is expandable from a delivery diameter to a deployment diameter. The stent, in a diameter greater than the delivery diameter, is mounted on the balloon. The stent is collapsed to the delivery diameter to conform to an overall profile of the catheter, the tube component and the balloon. The tube component is inflated to provide to the stent a securement pressure, to retain the stent on the assembly in the delivery diameter. The assembly is delivered to a deployment site. The balloon is inflated to expand the stent to its deployment diameter.
• An alternative embodiment of present invention is also an assembly for delivery and deployment of an inflation expandable stent within a vessel. The assembly comprises a catheter, an expandable balloon mounted on the catheter, a corrugated tubing mounted on the catheter beneath or within the balloon, and a stent mounted on the balloon. The catheter has proximal and distal ends. The stent is inflation expandable from a delivery diameter to a deployment diameter. The delivery diameter is reduced from the deployment diameter for conforming the stent to the catheter. The stent, in its delivery diameter, is coaxially mounted on the catheter near the catheter distal end. The expandable balloon is coaxially mounted on the catheter axially within the stent. The balloon is designed and adapted for expansion of the stent from the delivery diameter to the deployment diameter upon application of fluid deployment pressure to the balloon. The corrugated tubing is mounted and adhered coaxially onto the catheter and is situated between the balloon and the catheter itself When the stent is crimped and loaded onto the balloon, the balloon is situated therefore between the stent and the corrugated tubing. The tubing is preferably essentially equal to the length of the stent and the stent is positioned on the assembly essentially co-extensive with the tube component. The tubing on the catheter effectively holds the stent in place, takes up the slack due to recoil and protects the balloon material from being damaged during crimping.
• Still another embodiment of the present invention comprises an assembly for delivery and deployment of an inflation expandable stent. The assembly comprises a catheter having proximal and distal ends. An annular collar or the like is coaxially located on the catheter distal end. A fluid expandable balloon is coaxially mounted over the collar at the catheter distal end. The balloon is expandable from a contracted to an expanded state. A stent is coaxially mounted on the balloon. The stent is inflation expandable from a reduced to an enlarged condition, the reduced condition conforming the stent to the balloon, collar and catheter in the preferred embodiment. The stent has at least an end portion overlying the balloon. At least one cup is coaxially mounted on the catheter distal end. The cup has a first end portion which may overlie the stent end portion. The cup and collar are cooperatively constructed and arranged to retain the stent end portion on the catheter in the stent reduced condition when the balloon is in the contracted state. The balloon and catheter are cooperatively constructed and arranged to cause expansion of the balloon from the contracted to the expanded state to cause enlargement of the stent, including the stent end portion, from the reduced to the enlarged condition, and thereby release the stent end portion from the cup end portion. The cup may be axially spaced from the collar but preferably they are relatively close together. The second end portion of the cup may be fixed to the catheter. The cup may overlie at least a portion of the collar. The collar can be shaped as a single member with the catheter, that is integral with it or the collar may be a separate body mounted axially and positioned on the catheter. The collar may be a mounting ring or cylinder axially positioned between stent end portions under the stent and balloon. The collar may be a sheath under the stent and balloon.
• A further embodiment is also directed to improved arrangements for releasably attaching the stent to the catheter to facilitate delivery thereof. The stent is held in place on the catheter by means of an enlarged body carried by the catheter shaft within the balloon to which the stent and balloon are fitted, as by crimping in combination with one or more sleeves releasably overlying an end portion or portions of a stent and balloon.
BRIEF DESCRIPTION OF THE FIGURES
• FIG. 1 is an isometric view, a portion of which is enlarged and in longitudinal section, of a balloon catheter having a mounting body in a retracted position;
• FIG. 2 is an even more enlarged view in longitudinal cross-section of the distal end portion of the catheter ofFIG. 1;
• FIG. 3 is similar toFIG. 2 but showing the mounting body advanced to receive a stent mounted on the balloon;
• FIG. 4 is an enlarged cross-sectional view of the distal end portion of the catheter ofFIG. 1 similar to that of enlarged viewFIG. 3 but showing the balloon in an expanded condition along with the expanded stent;
• FIG. 5 is a schematic showing of a preferred mounting body carried by the catheter shaft within the balloon, the body being spirally cut to improve flexibility;
• FIG. 6 is a schematic showing in cross-section of another embodiment of the invention with a mounting body positioned to receive a stent but with a stent not yet mounted;
• FIG. 7 is a schematic showing of another embodiment of the invention;
• FIG. 8 is a schematic showing of a means for conveniently crimping the stent on the embodiment shown inFIG. 5;
• FIG. 9 is a schematic showing of yet another embodiment of the invention;
• FIG. 10 is a showing of another embodiment of a mounting body according to the invention;
• FIG. 11 is a schematic of an enlargeable mounting body which is not axially movable;
• FIG. 12 is a schematic of an alternate enlargeable mounting arrangement which is not axially movable;
• FIGS. 13 and 14 are schematic showings of yet another embodiment in which the axially movable mounting body is carried outside the balloon;
• FIGS. 15 and 16 are schematic showings of still yet another embodiment of the invention, and
• FIGS. 17 and 18 are modified versions of the embodiment shown inFIG. 11.
• FIGS. 19-21 are modified versions of the securement means of the present invention.
• FIG. 22 is a side profile section showing a balloon expandable stent delivery and deployment assembly, with the stent crimped to delivery diameter onto the balloon, the underlying inflating component and the catheter and with the inflating tube component inflated to securement pressure.
• FIG. 23 is a side profile section, similar toFIG. 22, with the balloon and the stent fully inflated to deployment diameter.
• FIG. 24 is a side profile section showing an alternative embodiment of a balloon expandable stent delivery and deployment assembly, having a tube component formed in several sections.
• FIGS. 25,26 and27 are cross-sectional views taken along lines4-4,5-5 and6-6 ofFIG. 24, respectively.
• FIG. 28 is a side profile section showing a balloon expandable stent delivery and deployment assembly, with the stent crimped to delivery diameter onto the balloon, the underlying tube component and the catheter.
• FIG. 29 is a side profile section, similar toFIG. 28, with the balloon and the stent fully inflated to deployment diameter.
• FIG. 30 is a perspective view of the corrugated tubing of the present invention.
• FIGS. 31-33 are side profile sections showing alternative embodiments of balloon expandable stent delivery and deployment assemblies, having the tubing component formed in a plurality of sections.
• FIGS. 34-35 are side profile sections showing alternative embodiments of the balloon expandable stent delivery and deployment assemblies, the tube component inflatable to add securement pressure.
• FIG. 36 is a side profile section showing a balloon expandable stent delivery and deployment assembly, with the stent crimped to delivery diameter onto the balloon, the underlying tube component and the catheter, and also having containment sleeves covering the ends of the stent.
• FIG. 37 is a side profile section showing a balloon expandable stent delivery and deployment assembly, with the stent crimped to delivery diameter onto the balloon, the underlying tube component and the catheter, and also having a pull-back wire attached to the tube component.
• FIG. 38 is a longitudinal cross-section of a stent delivery and deployment assembly of this invention showing a catheter with a collar mounted at the catheter distal end, an uninflated balloon mounted on the catheter over the collar, an unexpanded stent mounted on the balloon abutting the collar and a cup overlying the stent proximal end portion.
• FIG. 39 is a longitudinal cross-section of another stent delivery and deployment assembly of this invention showing a catheter with a collar mounted as a mounting ring at the catheter distal end, an uninflated balloon mounted on the catheter over the mounting ring, an unexpanded stent mounted on the balloon overlying the mounting ring and a cup overlying the stent proximal end portion; note that the collar is positioned closer to the cup than inFIG. 38.
• FIG. 40 is a longitudinal profile in partial cross-section of an assembly similar to that ofFIG. 38, with a bulge formed under the uninflated balloon at the catheter distal end.
• FIG. 41 is a longitudinal profile in partial cross-section of the assembly shown inFIG. 38 with the balloon inflated and the stent expanded, showing the cup end portion flared to release the stent.
• FIG. 42 is a longitudinal profile, similar toFIG. 41, showing the cup end portion rolled proximally to release the stent.
• FIG. 43 is a longitudinal profile of yet another stent delivery and deployment assembly of this invention, with the balloon mounted on the catheter, which has a collar formed as a tapered single enlarged piece on the catheter, an unexpanded stent mounted on the unexpanded balloon abutting the collar and a cylindrical sleeve overlying the stent proximal end portion.
• FIG. 44 is a longitudinal profile of the assembly ofFIG. 43 with the balloon inflated and the stent expanded, showing the sleeve moved proximally to release the stent.
• FIG. 45 is a side profile of still another stent delivery and deployment assembly of this invention with the uninflated balloon mounted on the catheter which has two collars formed integrally with the catheter, an unexpanded stent mounted on the balloon abutting the collar and a cylindrical cup overlying the stent proximal end portion and the underlying collar.
• FIG. 46 is a longitudinal profile of another stent delivery and deployment assembly of this invention with the uninflated balloon mounted on the catheter, an unexpanded stent mounted on the balloon, mounting a cylinder on the catheter and a pair of cups overlying the stent ends.
• FIG. 47 is an isometric view, a portion of which is enlarged and in longitudinal section, of a balloon catheter having a stent fixed to the catheter over the balloon;
• FIG. 48 is an even more enlarged view in longitudinal cross-section of the distal end portion of the catheter ofFIG. 47;
• FIG. 49 is a schematic showing of one form of retraction of the releasable sleeve upon expansion of the balloon;
• FIG. 50 is a schematic showing of another form of retraction of the releasable sleeve upon expansion of the balloon;
• FIG. 51 is yet another form of retraction of the releasable sleeve upon expansion of the balloon;
• FIG. 52 is a schematic showing of yet another form of retraction of the releasable sleeve upon expansion of the balloon;
• FIG. 53 is a schematic showing of a modified shape for the releasable sleeve;
• FIG. 54 is a schematic showing in cross-section of another embodiment of the invention with a stent not yet mounted;
• FIG. 55 is a schematic showing of another embodiment of the invention; and
• FIG. 56 is a schematic showing of yet another embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
• The present invention relates to stent securement devices, most notably positioned between the balloon and the inner shaft of the catheter. Individual elements of the below disclosed embodiments are generally interchangeable if desired. Referring toFIGS. 1-4 an angioplasty and stent delivery catheter system generally indicated at10 includes a balloon catheter12 having aballoon14 on a distal end portion generally indicated at16.FIG. 1 shows a proximal portion of the catheter at12aand adistal portion12bin enlarged view.FIGS. 2 and 3 show thedistal end portion16 in an even more enlarged view. The illustrative catheter12 is of the type known as a rapid exchange or single operator catheter. However, other types of catheters may be used, such as over the wire and fixed wire types. Theballoon14 is fixed to the catheter12 by standard means. The balloon is shown in its contracted state in. Astent18 is fixed about the balloon by crimping thereto. The stent has a larger expanded diameter which is obtained when the balloon is expanded in the known manner. InFIGS. 1 and 2 catheter is shown prepared for performing angioplasty and inFIG. 3 it is prepared for stent implantation.
• InFIGS. 1 and 2, an axially movable mountingbody30 is shown in a position proximal to theend portion16 of the catheter where a stent may be mounted. The catheter includes at its proximal end a manifold, generally designated13, as is known in the art. The manifold includes an inflation port15 as is known in the art. Awire31 is attached tobody30 to enable remote (from the proximal catheter end) advancement and retraction of it axially oninner lumen26 over which it slides. In the retracted position shown inFIGS. 1 and 2, the catheter has a low profile for performing angioplasty.
• This position is a retracted position and is selected by operation of apull wire31. The retracted position of the mounting body may vary. To maximize the low profile of thedistal end16 of the catheter, the retracted position may be within the outer member24.
• After such a procedure, the balloon is deflated, the catheter is withdrawn and the mounting body is advanced by means ofwire31 to the stent mounting position shown inFIG. 3. Astent18 may then be fixed about the deflated balloon by crimping it thereto. The stent has a larger expanded diameter which is obtained when the balloon is again expanded in the known manner. That is, the stent is released from the catheter upon expansion of the balloon as shown inFIG. 4 to be placed in a vessel at the desired location. When the balloon is then again deflated, removal of the balloon and catheter may be accomplished, leaving the stent in place. Exemplary dimensions for the inner26 is a diameter of ½ mm and for body30 a diameter of ¾ mm.
• As is known in the art the balloon is either bonded at its ends by adhesive20 and22, respectively to the outer member24 of the catheter and to theinner member26 of the catheter in the manner as shown, or is made one-piece with the outer member as is known in the art. The catheter balloon may be inflated by fluid (gas or liquid) from an inflation port extending from a lumen28 (seen inFIGS. 2 and 3) contained in the catheter shaft and opening into the balloon as shown, or by other known arrangements, depending on the design of the catheter. The details and mechanics of balloon inflation and specific overall catheter construction will vary according to the particular design involved in any given instance, and are known in the art per se. Such details are only shown schematically herein. All variations are acceptable for use with this invention.
• Any balloon expandable stent may be used with this invention. Many are known in the art including plastic and metal stents. Some are more well known such as the stainless steel stent shown in U.S. Pat. No. 4,735,665; the wire stent shown in U.S. Pat. No. 4,950,227; another metal stent shown in European Patent Application EPO 707 837 A1 and that shown in U.S. Pat. No. 5,445,646, or U.S. Pat. No. 5,242,451. All of these patents are incorporated herein by reference. Also, shape memory metal stents may be used. As already indicated the stent of PCT Application 960 3092 A1 is particularly preferred.
• The stent is typically for example about 16 mm long, while the balloon may be 20 mm long for example. These dimensions, however, are merely representative for illustrative purposes only and are not meant to be limiting. The stent is positioned over the balloon portion of the dilatation catheter and gently crimped onto the balloon either by hand or with a tool such as a pliers or the like to be mounted for delivery as shown inFIG. 3. The crimping may be readily accomplished by the physician during the procedure.
• In accordance with this invention, mountingbody30, best seen inFIGS. 2 and 3, is included insideballoon14 to provide a cushion and/or substrate of enlarged diameter relative to the stent to support and hold the stent and secure it during crimping and the delivery procedure. The mounting body may be axially movable proximally or distally from the position shown inFIG. 3, proximally being preferred.
• In the embodiment shown inFIGS. 1-3, mountingbody30 is cylindrical in form and takes the shape of a sleeve axially and slidably carried oninner lumen26, providing an enlarged area or portion for receiving the balloon and stent when the latter is crimped to the balloon.Marker band34 may also be included on inner26 as shown. Any radiopaque material such as gold is useful for this purpose. Astop member36 of generally conical shape or any other shape may also be included on themarker band34 as shown to provide additional resistance to stent movement during delivery and to protect the leading edge of the stent during delivery. Polyethylene or the like is suitable for the stop member. Other marker arrangements and stop arrangements may be used as well.
• Although, the material of the mounting body may be hard, it is preferably of any deformable thermoplastic material, preferably an elastomer material and more preferably of a relatively resilient elastomer material, e.g., lower durometer silicone. A preferred deformable thermoplastic material is high density polyethylene (HDPE). A preferred lower durometer silicone is in the form of tubing. The deformation of the resilient material of the mounting body when the stent/balloon is crimped to it causes a radial outward force on the stent/balloon increasing the friction therebetween despite any recoil of the stent.
• During stent delivery, the balloon catheter is advanced through and positioned in a patient's vasculature so that the stent is adjacent to the portion of the vessel where treatment is to take place. The balloon is inflated to expand the stent to an enlarged diameter. When the stent has reached the desired diameter, the balloon is deflated so that the catheter may be removed leaving the stent in place.
• Another embodiment of the invention is shown inFIG. 5. In thisembodiment mounting body30 is a spiral cut elastomer or other suitable material, such as a rigid or flexible plastic, to provide separation for flexibility in that portion of the catheter, allowing more easy movement or tracking around bends. The spiral cut may be only partly through the mounting body or may be all the way through as shown in FIG.5. Also, whilestop member36 is shown at the distal end portion of the catheter in this embodiment, no stop member may be used.
• Another similar version is shown inFIG. 6 which includes a cylindrical mountingbody30 made up of a plurality of separate adjacent rings30aheld together bywire31 which extends therethrough as shown withstops29 to secure the rings together. Rings30amay be individual bodies carried on the sheath or bodies cut from a cylinder to partially separate them or fully separate them. Suitable arrangements may be made to wire31 at each end of thebody30 to hold the rings together, as shown.
• The embodiment shown inFIG. 7 includes another feature based on the geometry of the mounting body for further securing the stent upon crimping. This feature is referred to herein as “interlocking”. That is, the stent may be interlocked to the mount so that the stent cannot slide proximally or distally on the balloon unless it is deformed, such as by expansion. This can be seen by perusing the structure shown inFIG. 7 which includes the inner26 having a two-piece mounting body made up of spaced mountingbodies30aand30b.These bodies are connected to each other by connection means33 which may be a separate or integral cylindrical body of lesser diameter or may be one or two or more relatively rigid wire members as shown. The spacing betweenbodies30aand30ballows portions of thestent18 andballoon14 to be depressed or inserted between the bodies upon crimping of the stent thus forming an interlock against sliding of the stent axially or longitudinally before the stent is released.
• The interlock formation or crimping is readily accomplished by any suitable means such as a two-piece die40 shown inFIG. 8 or the like.
• FIG. 9 demonstrates that more than a two-piece mounting body arrangement may be used if desired. In this embodiment, the mounting body is comprised of three spacedinterconnected bodies30a,30band30con the inner26. Preferably in the embodiments ofFIGS. 7 and 9, the mounting bodies will be ring-like in shape or cylindrical in shape although other configurations will be readily apparent to those familiar with this art.
• Referring now toFIG. 10, another embodiment of a movable mountingbody30 is shown in the form of a rigid coil of plastic, metal or the like having acontrol wire31, preferably integral therewith. When in the metal form, the coil may be coated with a polymer such as polyethylene or PTFE or enclosed in a polymeric sheath of similar material. The coil may be slidably received on the inner26 similar in arrangement to that shown in the preceding Figures.
• As already indicated, an alternate arrangement may be used in which the mounting body, instead of being movable, is designed to be enlargeable and reducible or collapsible, while remaining in a fixed position in the stent mounting area of the catheter.FIGS. 11 and 12 are directed to such an arrangement.
• InFIG. 11, aninner balloon50 of smaller diameter thanouter balloon14 is mounted on the inner26.Balloon50 may have aseparate inflation conduit52 inside inner26, preferably including a valving arrangement54. Valve54 may be a one-way valve allowing only inflation ofballoon50 if desired. However, inner26 may serve as the inflation conduit as well. In addition to fully inflating the balloon,inner balloon50 may also be partially inflated.
• FIG. 19 shows a modification toFIG. 11 in which twoinner balloons50aand50bare included.FIG. 20 shows a modification in which two inflation valves54aand54bare included.
• FIG. 21 shows a full arrangement ofinner balloon50 in which asyringe120 is inserted into the distal end of theliner26 of the catheter. The syringe has at itsends blocks122 and124 to enable local pressurization of inner26 to inflateballoon50.
• FIGS. 17 and 18 show aninner balloon50 similar to the arrangement ofFIG. 11 but theballoon50 inFIG. 17 has a narrow center portion and wide ends to provide a mounting shape similar to that ofFIG. 7. InFIG. 17,balloon50 is inflated andballoon14 is partially inflated. InFIG. 18,balloon50 is inflated andballoon14 is uninflated ready for stent loading. Balloon material is preferably a polyethylene or urethane elastomer such as Tecoflex or Tecothane from Thermedics.
• Referring toFIG. 12, an alternate embodiment is shown in which the proximal portion of the inner26 is axially movable while the distal portion26bis fixed with respect to the catheter. In between portion26aand portion26bis acoil spring60 inside aflexible sheath62 of PTFE or the like. Portion26bof the inner is attached to balloon14 at the very distal end portion of the catheter. Portion26ais movable axially within the outer22. Thus, if26ais pushed in the distal direction and held to compresscoil60, the coil will enlarge in diameter to provide an enlarged mounting area for a stent. Twisting the inner to twist the coil will enhance enlargement. Alternatively,coil spring60 may be replaced by a braided element.
• Also, by providing different pitch over the length of the coil it can be made to enlarge more in some regions than in others. For example, if the coil windings are closer together in the center portions than in the end portions, when the coil undergoes compressing, the two end portions will enlarge in diameter more than the center portion to provide a mount similar to that ofFIG. 7.
• Referring now toFIGS. 13 and 14, another embodiment is shown which is alternative to the earlier described embodiments which are inside the balloon on the catheter. In this embodiment asheath80 is carried on the outside of the catheter.Sheath80 is elastomeric and is axially movable from a stent mounting position as shown inFIG. 14 to a position remote from the stent mounting position, such as the retracted position as shown inFIG. 13. In the position shown inFIG. 13,balloon14 may be inflated and deflated. In the position shown inFIG. 14,balloon14 will be deflated for low profile.Sheath80 when over the balloon as inFIG. 14 acts to increase the profile of the catheter to facilitate crimping a stent thereto during deployment of the stent,sheath80 will expand withballoon14 to facilitate inflation and during deflation the elastomer sheath will return to its original dimension. An elastomer material which is presently preferred is Tecothane, a trade name for a thermoplastic polyurethane available from Thermedics, Inc., of Woburn, Mass. It may be about 0.003 inches thick, for example.
• With respect toFIGS. 15 and 16, a further embodiment of the invention is shown in which inner26 carries a mountingbody30, the distal end100 of which is secured or fixably attached to inner26, as by any suitable adhesive. The remainder ofbody30 is slidable over inner26 as by the application of compression in the distal direction at the proximal end102. This may be accomplished by push wire104 which extends to the proximal end of the catheter for remote manipulation as is known in the art.
• Mountingbody30 is accordion folded with more widely spaced folds at the end portions106, than at the central portion108. Thus, as can be seen inFIG. 15, a relatively low profile is provided without compression for normal angioplasty use. When a stent is to be mounted (not shown), compression by means of push wire104 will result in a configuration of enlarged diameter ofbody30 as shown inFIG. 16 to provide a mount similar to that ofFIG. 7 in general configuration. If the spring is uniform over the body, it sill enlarge uniformly, similar to the inner balloon ofFIG. 11. The Figures are schematic in form but the concept can be readily appreciated.
• As an alternative to a folded construction, the body may be of braided construction to achieve the same operation.
• Also, this form ofbody30 may be inserted into a two piece inner26 similar to the arrangement shown inFIG. 12. In all of these arrangements, the accordion folded body material may be of any suitable polymer, such as polyethylene. For example, tubing having a wall thickness of about 0.002 inches may be used. The accordion folds or pleats may be readily formed in such tubing by means of a pressure mold containing spaced blades placed in a heated chamber.
• FIGS. 22-27 show embodiments wherein the inner securement device comprises an inner balloon beneath the outer catheter balloon, similar to above.FIGS. 22 and 23 illustrate a side profile section showing an inflation expandable stent delivery and deployment assembly generally designated110.Assembly110 includes a catheter comprised ofinner shafts112 and113 and an outer shaft115 of the coaxial type, an inflation expandable balloon114, an inflation tube component116 such as an inner balloon and inflationexpandable stent118. Any conventional type of catheter may be used, such as a catheter of the type generally used for PTA or PTCA angioplasty procedures, for prostate therapy, and TTS endoscopic catheters for gastrointestinal use. However, coaxial types as shown are most preferred. Theparticular catheter112 shown is formed of a biocompatible and hydrophilic compatible material, such as a lubricous polyimide or polyethylene. Other suitable materials for thecatheter112 include nylons, urethanes, and polypropylene materials compatible with coatings such as silicone and/or hydrophilic coatings. In addition to hydrophilic compatible materials, any biocompatible material may be used. For example, polyethylene or polypropylene can be coated with a hydrophilic material to render them hydrophilic compatible suitable catheters for use according to the present invention include a number of catheters available from SciMed Life Systems, Inc., Maple Grove, Minn., the assignee of the present invention, such as BANDI™, COBRA™, VIVA™, and VIVA PRIMO™ catheters.
• Inflatable tube component116 is fixed at its distal and proximal end toinner shaft112 and at its proximal end toinner shaft113 at a position to be encompassed within the distal and proximal ends of the outer balloon114. According to art-recognized convention, the length L-B of the balloon114 is defined as the length of the body portion of the balloon114, excluding theterminal cone sections120. As seen inFIG. 23, the body portion of the balloon114 is generally cylindrical when in its deployed or inflated condition. Tube component116 is illustrated as havingterminal sections122 which are more relatively vertical than thecone sections120 illustrated for the balloon114. However, it is to be understood that, according to the present invention, either of theterminal sections120,122 may be relatively cone shaped, relatively vertical or of any other configuration known to those of skill in this art. A preferred length L-T of the tube component116 is illustrated inFIGS. 22 and 23 as substantially equal to the length L-B of balloon114, and substantially equal to the length L-S ofstent112. However, according to the present invention,stent112 should be supported by the underlying tube component116 for a length sufficient to permit accomplishment of the stated purpose of the tube component116, when inflated, to provide-securement pressure forstent112 to maintainstent112 in position withassembly110 during delivery. It is also within the present invention for tube component116 to be slightly shorter thanstent112, for example, thedistal end119 ofstent112 may extend distally beyond the distal end121 of tube component116 (not shown), so that thedistal end119 of stent121 can be crimped over the distal end121 of tube component116 to prevent thedistal end119 ofstent112 from catching and tending to further open as it is maneuvered within a body vessel. As has been explained above, tube component116 is designed and constructed to be inflatable to no more than is necessary to compensate for recoil crimping ofstent112 and to closely accommodate (or even slightly over-stress) the delivery diameter ofstent112, taking into consideration the thickness of the intervening uninflated balloon114. Tube component116 is inflated through the opening(s)117 ofinner shaft112. Typically, tube component116 will have a wall thickness of about 0.0002-0.0007 inch and will be inflatable to no more than about 0.035.-0.045 inches.
• Inflating tube component116 may be formed of either compliant or non-compliant balloon materials. Compliant materials 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. Suitable materials include a copolymer polyolefin material available from E.I. DuPont de Nemours and Co. (Wilmington, Del.), under the trade name Surlyn™ Ionomer and a polyether block amide available under the trade name PEBAX™. 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.
• A balloon114 for use according to the present invention may be any conventional balloon for catheter delivery, such as a balloon of the type generally used for PTA and PTCA procedures. Typically, balloon114 is fixed at its distal end toinner shaft112 near the catheter-distal end and at its proximal end to outer shaft115. Balloon114 is larger in diameter than tube component116, because balloon114 must be able to expand to a larger diameter than tube component116. Balloon114 is inflatable through aninflation conduit123, i.e., the space between coaxialinner shaft113 and outer shaft115 of the catheter. The distal and proximal ends of balloon114 are shown inFIGS. 22 and 23 positioned exterior to the distal and proximal ends of tube component116, respectively, and of a length L-B generally equal to the length L-T of the tube component116. To be compatible with tube component116 illustrated inFIGS. 22 and 23 and described above, balloon114 is inflatable at deployment to about the diameter of the body vessel in which thestent118 is to be deployed. Balloon114 may be formed of a compliant or non-compliant material, of the types of compliant materials described herein above, such as polyethylene or any standard balloon material. Balloon114 typically has a wall thickness of about 0.0007-0.004 inch for example.
• A stent for use according to the present invention may be any conventional type of balloon expandable stent, including stents of the type used for PTA and PTCA angioplasty procedures, for prostate therapy, and TTS endoscopic catheters for gastrointestinal use. Suitable stent material is biocompatible stainless steel in the form of sheet metal, tube component wire or Nitinol. A preferred stent is described in PCT Application No. 960 3072 A1, published 8 Feb. 1996, the content of which is incorporated herein by reference. All such stents are well known in this art generally and additional examples are described in U.S. Pat. No. 5,507,768 to Lau et al.; in U.S. Pat. No. 5,458,615 to Klemm et al; in U.S. Pat. No. 5,226,889 to Sheiban; in U.S. Pat. No. 4,875,480 to Imbert; in U.S. Pat. No. 4,848,343 to Wallsten et al., and in U.S. Pat. No. 4,733,665 to Palmaz.Stent18 as shown inFIGS. 22 and 23 is positioned on balloon114, the underlying inflatable tube component116 and the distal end of the catheter. The length L-S ofstent118 is shown as essentially equal or slightly smaller than the length L-T of tube component116 and is positioned onassembly110 to be co-extensive with tube component116. In this position,stent118 is shown inFIG. 22 crimped to its delivery diameter D1, which is about 0.035-0.045 inch for example.
• As discussed above, despite the most careful and firm crimping ofstent118 to closely conform to the overall profile of the catheter unexpanded balloon114 and underlying inflatable tube component116, there is a certain amount of “recoil” ofstent118 or a tendency ofstent118 to slightly open from a desired hypothetical minimum crimped diameter. The actual minimum diameter achievable for fully crimpedstent118 onassembly110 is referred to as thestent118 delivery diameter D1. This tendency ofstent118 to open or recoil slightly when crimped onassembly10 has been characterized as “recoil crimping”. InFIG. 22, inflatable tube component116 is shown inflated to a diameter which is generally sufficient to compensate for any slack or looseness betweencrimped stent118 and the overall profile of the catheter, the unexpanded balloon114 and the underlying inflatable tube component116 due to recoil crimping.
• FIG. 23 illustrates a side profile section showing a stent delivery anddeployment assembly110 of this invention with balloon114 fluid inflated to its fully expanded position. As a result of the fluid inflation of the balloon114,stent118 has also been fully expanded to its deployment diameter D2 in which it can be deployed against the walls of a body vessel in which it is situated.
• Tube component116 may have a shape other than the cylindrical shape described and illustrated with regard to the embodiment shown inFIGS. 22 and 23. Further, the tube component may be comprised of more than one separately inflatable pouch. For example, as illustrated with regard toFIG. 24, the tube component of an alternative stent delivery and deployment assembly generally designated130 can be comprised of three separatelyinflatable pouches136,138,140. Thepouches136,138,140 are each separately inflatable through theirrespective inflation conduits137,139141, and each of thepouches136,138,140 can be inflatable to a different extent. The conduits are formed in the wall ofshaft132 as can be seen inFIGS. 25-27. The stent delivery anddeployment assembly130 ofFIG. 24 is also comprised of a catheter havinginner shaft132 andouter shaft135, aballoon134, with itsballoon inflation conduit139 and the balloonterminal cone sections144, and astent142. As has been explained above with reference toFIGS. 22 and 23,stent142 is crimped to closely conform to the overall profile of the catheter theunexpanded balloon134 and the underlyinginflatable pouches136,138,140. Even with the most careful and firm crimping, there is a certain amount of “recoil” of thestent142 or a tendency ofstent142 to slightly open from a desired hypothetical minimum diameter. InFIG. 24, the first136 and third140 pouches are inflated to a slightly larger size than thesecond pouch138. As discussed above, the inflation of thepouches136,138,140 to this configuration is generally sufficient to compensate for any slack or looseness between thecrimped stent142 and the overall profile of the catheter, theunexpanded balloon134 and the underlyinginflatable pouches136,138,140 due to recoil crimping. Oncepouches136,138140 have been inflated to the configuration shown inFIG. 24,stent142 is firmly secured against axial movement With regard toassembly130. The distal146 and proximal148 ends ofstent142 are protected from any possible unwanted contact with vessel walls during maneuvering, which helps to protect the vessel walls from abrasion and also helps to protect the ends146,148 ofstent142 from distortion. Additionally,stent142 may be of a length such that it fits overpouch140 andpouch136 as well as overpouch138.
• The method of using the stent delivery anddeployment assembly110 of this invention, as shown inFIGS. 22 and 23, is described as follows. Theassembly110 is constructed as described above.Stent118 is compressed or crimped onto balloon114, inflatable tube component116 and the catheter to a delivery diameter D1. This crimping can be done manually or with the aid of tooling specially designed for the purpose either by the physician or the manufacturer. In the crimped position, stent we closely conforms to the overall profile of balloon114, inflatable tube component116 and the catheter except for the slight slack or looseness due to recoil crimping. Tube component116 is fluid inflated to the extent necessary to compensate for this slack or looseness due to recoil crimping. The pressure of force required to inflate tube component116 to this extent is also referred to as securement pressure, i.e., the force or pressure needed to securestent112 in this position. It is to be noted that, since tube component116 is designed and constructed to be capable of fully expanding to no more than the size necessary to compensate for recoil crimping, there is no possibility ofstent112 expanding or beginning to open to a larger diameter. Thus, there is no hazard ofstent112 moving out of its position on the catheter during delivery or of becoming separated from the catheter within a body vessel. The catheter distal end is delivered by standard techniques to the deployment site within the body vessel of interest. At this point,stent112 is positioned as required by the physician and balloon114 is fluid inflated by standard technique to expand stent121 to its deployment diameter D2. During this expansion,stent112 is expanded to fill the body vessel. Following deployment ofstent112, balloon114 and optionally, tube component116 are deflated and theassembly110 is retracted proximally and withdrawn from the body. If required by the procedure, the site of entry to the body is appropriately closed.
• The method of using the stent delivery anddeployment assembly130 of this invention, as shown inFIG. 24, is similarly described. Theassembly130 is constructed as described above.Stent142 is compressed or crimped to closely conform to the overall profile ofballoon134,inflatable pouches136,138,140 and the catheter except for the slight slack or looseness due to recoil crimping.Pouches136,138,140 are each fluid inflated to the profile shown inFIG. 24 through separate fluid inflation conduits (not shown) to securement pressure to compensate for this slack or looseness and to securestent142 in this position. The overall configuration ofpouches136,138140 further serves to positionstent142 against axial dislocation during delivery. The catheter is delivered by standard techniques to the deployment site within the body vessel of interest. At this point,stent142 is positioned as required by the physician andballoon134 is fluid inflated by standard technique to expand and deploystent142. Following deployment ofstent142,balloon134 and, optionally,pouches136,138140 are deflated and theassembly130 is retracted proximally and withdrawn form the body. If required by the procedure, the site of entry to the body is appropriately closed.
• The inflation tube component provided by this invention maximizes stent securement force by optimizing the frictional force between the inflating tube component, the balloon wall and the internal diameter of the stent in its reduced crimped delivery diameter. The inflation tube component is more flexible than a solid sheath under the expandable balloon, and thus the entire assembly has greater flexibility. This invention has particular advantages for assemblies in which the stent is provided for use as pre-crimped to the balloon and underlying catheter, by increasing the shelf life of the pre-crimped assembly. The features and principles described for this invention are suitable for use with fixed wire, over-the-wire and single operator exchange assemblies.
• FIGS. 28-37 disclose still further embodiments of the securement device.FIGS. 28 and 29 illustrate a side profile section showing an inflation expandable stent delivery and deployment assembly, generally designated210.Assembly210 includes a catheter comprised ofinner shaft212 andouter shaft213 of the coaxial type and an optional retractable delivery shaft211 (typically called a guide catheter, shown retracted inFIG. 29, an inflationexpandable balloon214, a corrugated/ribbedstent securement device216,optional marker bands217 and an inflationexpandable stent218. Any conventional type of catheter may be used, such as a catheter of the type generally used for PTA or PTCA angioplasty procedures, for prostate therapy, and TTS endoscopic catheters for gastrointestinal use. However, coaxial types as show are most preferred. Theparticular catheters212 and213 shown are formed of a biocompatible and hydrophilic compatible material, such as a lubricous polyimide or poly ethylene. Other suitable materials for thecatheters212 and213 include nylons, urethanes, and polypropylene materials compatible with coatings such as silicone and/or hydrophilic coatings. In addition to hydrophilic compatible materials, any biocompatible material may be used. For example, polyethylene or polypropylene can be coated with a hydrophilic material to render them hydrophilic compatible. Suitable catheters for use according to the present invention include a number of catheters available from SciMed Life Systems, Inc., Maple Grove, Minn., the assignee of the present invention, such as BANDIT™, COBRA™, VIVA™, VIVA PRIMO™, MAXXUM™, MAXXUM ENERGY™ and RANGER™ catheters.
• Securement device216 is fixed at its distal and/or proximal ends toinner shaft212 at a position to be encompassed within the distal and proximal ends of theouter balloon214. According to art-recognized convention, the length L-B of theballoon214 is defined as the length of the body portion of theballoon214, excluding theterminal cone sections220. As seen inFIG. 29, the body portion of theballoon214 is generally cylindrical when in its deployed or inflated condition. Securement device/tube component16 is illustrated as havingterminal sections221,222. It is to be understood that, according to the present invention, either of theterminal sections220,222 may be relatively cone shaped, relatively vertical, relatively flat or of any other configuration known to those of skill in this art. A preferred length L-T of thetubing216 is illustrated inFIGS. 28 and 29 as substantially equal to the length L-B ofballoon214, and substantially equal to the length L-S ofstent218. However, according to the present invention,stent218 should be supported by theunderlying tube component216 for a length sufficient to permit accomplishment of the stated purpose of thetube component216, to provide a superior securement and protective surface forstent218 to maintainstent218 in position withassembly210 and to protect the balloon material during loading/crimping. It is also within the present invention for thetube component216 to be slightly shorter thanstent218, for example, thedistal end219 ofstent218 may extend distally beyond the distal end21 of tube component216 (not shown), so that the distal end19 ofstent18 can be crimped over thedistal end221 oftube component216 to prevent thedistal end221 ofstent218 from catching and tending to snag or further open as it is maneuvered within a body vessel. As has been explained above,tube component216 is designed and constricted to have enough flexibility and have enough volume to no more than is necessary to compensate for recoil crimping ofstent218 and to closely accommodate (or even slightly over stress) the delivery diameter ofstent218, taking into consideration the thickness of the interveninguninflated balloon214. Typically, thetube component216 will have a consistent frequency of ribs, but may also vary by having intermittent groups of ribs along the tubing.
• The balloon and the crimped stent slightly conform to the undulations of the tube component for greater securement, but this conformation is not illustrated.
• Tube component216 may be formed from a thermoplastic material, preferably a low modulus polymer, such as Surlyn™, Pebax and urethane. The device such as polypropylene, low density polyethylene (LDPE), high density polyethylene (HDPE), ethylene vinyl acetate (EVA), nylon, polyester and polyethylene terephthalate (“PET”), may be prepared through free blowing in a mold or inside a coil. Tubing is extruded with relatively thin walls and then free-blown in a mold, coil or other fixture to form the ribs/corrugation.
• Aballoon214 for use according to the present invention may be any conventional balloon for catheter delivery, such as a balloon of the type generally used for PTA and PTCA procedures. Typically,balloon214 is fixed at its distal end toinner shaft212 near the catheter distal end and at its proximal end toinner shaft212, near the distal end of theouter shaft213.Balloon214 is inflatable through an inflation conduit223, i.e., the space between coaxialinner shaft213 andouter shaft213 of the catheter. The distal and proximal ends ofballoon214 are shown inFIGS. 28 and 29 positioned exterior to the distal and proximal ends oftube component216, respectively, and of a length L-B generally equal to the length L-T of thetube component216. To be compatible with thetube component216 illustrated inFIGS. 28 and 29 and described above,balloon214 is inflatable at deployment to about the diameter of the body vessel in which thestent218 is to be deployed.Balloon214 may be formed of a compliant or non-compliant material, such as polyethylene or any standard balloon material. Compliant materials 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. Suitable materials include a copolymer polyolefin material available from E.I. DuPont de Nemours and Co. (Wilmington, Del.), under the trade name Surlyn™ Ionomer and a polyether block amide available under the trade name PEBAX™. Non-compliant materials include relatively rigid 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, or combinations thereof Theballoon214 typically has a wall thickness of about 0.0007-0.004 inch for example.
• A stent for use according to the present invention may be any conventional type of balloon expandable stent, including stents of the type used for PTA and PTCA angioplasty procedures, for prostate therapy, and TTS endoscopic catheters for gastrointestinal use. Suitable stent material is biocompatible stainless steel in the form of sheet metal, tube component wire or Nitinol. A preferred stent is described in PCT Application No. 960 3072 A1, published 8 Feb. 1996, the content of which is incorporated herein by reference. All such stents are well known in this art generally and additional examples are described in U.S. Pat. No. 5,507,768 to Lau et al.; in U.S. Pat. No.5,458,615 to Klemm et al.; in U.S. Pat. No. 5,226,899 to Sheiban; in U.S. Pat. No. 4,875,480 to Imbert; in U.S. Pat. No. 4,848,343 to Wallsten et al.; and in U.S. Pat. No. 4,733,665 to Palmaz.Stent218 as shown inFIGS. 28 and 29 is positioned onballoon214, which is over theunderlying tube component216, at the distal end of the catheter. The length L-S ofstent218 is shown as essentially equal or slightly smaller than the length L-T oftube component216 and is positioned onassembly210 to be coextensive withtube component216. In this position,stent218 is shown inFIG. 28 crimped to its delivery diameter D1, which is about 0.035-0.45 inch for example.
• As discussed above, despite the most careful and firm crimping ofstent218 to closely conform to the overall profile of the catheterunexpanded balloon214 andunderlying tube component216, there is a certain amount of “recoil” ofstent218 or a tendency ofstent218 to slightly open from a desired hypothetical minimum crimped diameter. The actual minimum diameter achievable for fully crimpedstent218 onassembly210 is referred to asstent218 delivery diameter D1. This tendency ofstent218 to open or recoil slightly when crimped onassembly210 has been characterized as “recoil crimping”. InFIG. 28,tube component216 is shown inflated to a diameter which is generally sufficient to compensate for any slack or looseness betweencrimped stent218 and the overall profile of the catheter, theunexpanded balloon214 and theunderlying tube component216 due to recoil crimping.
• FIG. 29 illustrates a side profile section showing a stent delivery anddeployment assembly210 of this invention withballoon214 fluid inflated to its fully expanded position. As a result of the fluid inflation of theballoon214,stent218 has also been fully expanded to its deployment diameter D2 in which it can be deployed against the walls of a body vessel in which it is situated.
• FIG. 30 illustrates the preferred configuration of thetube component216. The tube component has a plurality of ribs230 and is configured in a corrugated or accordion fashion. The ends of thetube component216,222 and221, are substantially rib-free so as to provide a flat surface to receive an adhesive and thereby bond to theinner shaft212. Preferable adhesives include cyanoacrylates such as Loctite 4061/4011 or urethanes, such as H. B. Fuller 3507/3506. The tube component may also be heat bonded to the inner shaft. The ribs may vary in frequency and spacing.
• Tube component216 may have different configurations in other embodiments, as shown inFIGS. 31-33. Thetube component216 may be comprised of more that one piece of corrugated tubing (FIG. 31), a smaller single piece (FIG. 32) or one single piece of tubing sectioned into a plurality of ribbed sections, wherein the tubing is adhered to theinner shaft212 in more than two locations (FIG. 33).
• FIG. 31 shows two pieces oftubing component216a,216b.Both pieces are adhered toinner shaft212 at adhesion points232.FIG. 32 discloses an embodiment which comprises one smaller piece oftube component216 which is adhered toinner shaft212 at adhesion points232.FIG. 33 discloses an embodiment which comprises onetube component216 which has interrupted ribbedsections234 adhered to theinner shaft212.
• FIGS. 34 and 35 illustrate an alternative embodiment in which the tubing component is inflatable to increase the securement pressure on the inside ofballoon214 when the stent is crimped onto the balloon so as to negated additional recoiling. The full expansion of thetube component216 should only be slightly greater than the diameter of the inside of theballoon214 when thestent218 is fully crimped onto theballoon214.
• InFIG. 34, the inflating fluid comes through theguide wire lumen212 under pressure from the proximal end or the distal end of theguide wire lumen212, preferably via a syringe, and fills thetubing component216 through a one-way valve247 (preferably resisting up to about 4 atm) in theinner catheter212.
• InFIG. 35, thetubing component216 is inflated via anadditional lumen242 which extends from the proximal end of the catheter along the guide wire lumen240, much the same as any inflating lumen incorporated to inflate a balloon.
• In an alternative embodiment, as shown inFIG. 36, socks orsleeves251 may be incorporated to stretch over the ends of the stent to prevent snagging and to secure the stent onto the balloon. Such sleeves are demonstrated in U.S. application Ser. Nos. 08/702,149, filed Aug. 23, 1996, and Ser. No. 08/701,979, filed Aug. 23, 1996, which are incorporated in their entirety herein by reference.
• In still another embodiment, as shown inFIG. 37, thetubing component216 is slidable axially along theinner shaft212 and is connected to aretracting wire250 such that the tubing component may be retracted into theouter shaft213 after the balloon has been inflated to reduce the profile of theballoon214 when the catheter is removed. The tubing component, since it is not adhered to theinner shaft212 in this embodiment, should fit tightly enough on the inner shaft to stay in place, but not too tightly so that it may be retracted by pulling on theretracting wire250.
• The method of using the stent delivery anddeployment assembly210 of this invention, as shown inFIGS. 1 and 2, is described as follows. Theassembly210 is constructed as described above.Stent218 is compressed or crimped ontoballoon214,tube component216 and the catheter to a delivery diameter D1. This crimping can be done manually or with the aid of tooling specifically designed for the purpose either by the physician or the manufacturer. In the crimped position,stent218 closely conforms to the overall profile ofballoon214,tube component216 and the catheter except for the slight slack or looseness due to recoil crimping.Tube component216 is flexible enough to slightly collapse during crimping and rebound to the extent necessary to compensate for the slack or looseness due to recoil crimping, thus securing the stent. As a result, the stent does not move out of its position on the catheter during delivery or become separated from the catheter within a body vessel. The catheter distal end is delivered by standard techniques to the deployment site within the body vessel of interest. At this point,stent218 is positioned as required by the physician andballoon214 is fluid inflated by standard technique to expandstent218 to its deployment diameter D2. During this expansion,stent218 is expanded to fill the body vessel. Following deployment ofstent218,balloon214 is deflated and the assembly is retracted proximally and withdrawn from the body. If required by the procedure, the site of entry to the body is appropriately closed.
• The tube component provided by this invention increases stent securement force by increasing the frictional force between the tube component, the balloon wall and the internal diameter of the stent in its reduced crimped delivery diameter. The tube component is more flexible than a solid sheath under the expandable balloon, and thus the entire assembly has greater flexibility. This invention has particular advantages for assemblies in which the stent is provided for use as pre-crimped to the balloon and underlying catheter, by increasing the shelf life of the pre-crimped assembly. The tube component also protects the balloon material during crimping by acting as a buffer between the balloon material and whatever may be mounted on the inner shaft, such asmarker bands217. The features and principles described for this invention are suitable for use with fixed wire, over-the-wire and single operator exchange assemblies.
• FIGS. 38-46 disclose alternative embodiments of the securement device.FIG. 38 shows a stent delivery and deployment assembly generally designated310. Acatheter312 has acollar314 coaxially mounted at the catheterdistal end portion316. Anuninflated balloon318 is coaxially mounted oncatheter312 overcollar314. Anunexpanded stent320 is coaxially mounted on theballoon318 abutting but not overlyingcollar314. Acup322 coaxially overlies the stentproximal end portion324.Cup322 may be elastomeric or rigid, preferably elastomeric.Cup322 is over-expanded over thestent320, so that recoil of thecup322 is sufficient to securestent320 in place and prevent it from being pulled off of theassembly310 distally or proximally asassembly310 is delivered to a deployment site in a body vessel.Cup322 also protects the proximal end ofstent324 from inadvertently catching on anatomical structures or other things during maneuvering within the body or during loading and other handling. The ends of the stent may axially protrude and should be protected during maneuvering ofstent320 to keepstent20 onassembly310 in its contracted configuration and to maintain the structural integrity ofstent320.Collar314 abuts the stentdistal end326 without underlyingstent320. The position ofcup322overlying stent320 and containingstent320 againstcollar314 increases the securementforce maintaining stent320 in its axial and radial position on catheter12.FIG. 40 is similar toFIG. 38, showing abulge28 beneath theuninflated balloon318 at catheterdistal end316.
• Any of the various types of known stents may be used in the delivery system of this invention, even self-expanding stents which are partly balloon-expandable may be used, the balloon initiating release of the stent and/or finally seating the stent after self-expansion. However, ordinary balloon expandable stents are preferred and aforenoted.
• FIG. 39 shows another stent delivery and deployment assembly generally designated330. Acatheter332 has a collar coaxially mounted as a mountingring334 on the catheter. Anuninflated balloon338 is coaxially mounted oncatheter332 over mountingring334. Anunexpanded stent340 is coaxially mounted onballoon338 overlying the mountingring34. Acup342 overlies the stentproximal end portion344 to secure thestent340 in place and prevent it from being pulled off ofassembly330 distally or proximally, asassembly330 is delivered to a deployment site in a body vessel.Cup342 also protects the proximal end ofstent40 from inadvertently catching on anatomical structures during maneuvering within the body. The position ofcup342overlying stent340 together with the closer positioning of mountingring334 as compared toFIG. 38 increases the securementforce maintaining stent340 in its axial and radial position oncatheter342. The closer the mountingring334 is positioned tocup342 the more securely the stent is held in place and interlocked between this cup and ring. When used in conjunction with mountingring334,cup342 will also prevent the stentproximal segment344 from opening up, i.e., increasing its diameter, and will keep thestent340 locked onto the mountingring334. This will preventstent340 from moving on the catheter distally as well as proximally. This cup does not have to be an elastomer, but may be sufficiently rigid to prevent thestent340 from expanding.
• Cups322,342 ofFIGS. 38-40release stents320,340 whenballoons318,338 are inflated during deployment.Cups322,342 can, for example, flare radially outward as illustrated with reference toFIG. 41, roll axially away fromstents320,340 as illustrated with reference toFIG. 42, or slide axially away fromstents320,340 as illustrated with reference toFIGS. 43 and 44. Also, the cups may be formed with axial areas of weakness which split on balloon inflation, as described in the aforenoted Savin patent.
• FIG. 41 shows an assembly generally designated310 as shown inFIGS. 38 and 36 withballoon318 inflated andstent320 expanded, showing thecup322 end portion flared to releasestent320. As noted above,cup322 may be elastomeric or rigid. The dimension L is short enough and the material ofcup322 is sufficiently elastic so thatcup322 flares out and is no longer in contact withstent320 whenballoon318 is inflated and thestent320 expanded for deployment.
• FIG. 42 shows an assembly generally designated310, as shown in FIGS.
• 38 and36, withballoon318 inflated andstent320 expanded, showingcup322 end portion rolled proximally to release thestent320. As noted above, thecup322 may be elastomeric to facilitate rolling. The cup may also accordion or bunch up on itself to release the stent.
• FIGS. 43 and 44 show yet another stent delivery and deployment assembly generally designated350. Thecatheter352 has acoaxial collar354 formed integrally withcatheter352 at the catheterdistal end356. Aballoon358 is coaxially mounted oncatheter352, overlyingcollar354. InFIG. 43,balloon358 is coaxially mounted oncatheter352, overlyingcollar354. InFIG. 43,balloon358 is shown as uninflated, with anunexpanded stent360 mounted onballoon358abutting collar354, and a cylindrical cup in the form ofsleeve362 overlying the stentproximal end portion364.FIG. 44 shows theassembly350 ofFIG. 43 withballoon358 inflated andstent360 released and expanded.Sleeve362 is designed, constructed and adapted so that, asballoon358 andstent360 are enlarged, thesleeve portion366 gathers or moves proximally to releasestent360. The increasing angle of theballoon358 cone (the tapered end sections of balloon358) duringinflation push sleeve362 axially away fromstent360. This can be done by shapingsleeve362 with preformed accordion pleats368.Sleeve362 may also be formed so that the portion detaining (that is, abutting or overlying)stent360 is of thicker or more rigid material than the portion ofsleeve362 axially distant fromstent360. Materials which may be used to provide the foregoing function are silicones, urethanes and the like as well as other elastomers, for example. A rigid sleeve carried on the catheter for sliding movement may also be used. Sleeves may be included at the proximal and distal end of the stent.
• FIG. 45 shows still another stent delivery and deployment assembly generally designated370. Acatheter372 has twocollars374 formed integrally withcatheter372 and spaced from each other on the catheter distal end portion. Aballoon378 is coaxially mounted on thecatheter372, overlying thecollars374. Theballoon378 is shown as uninflated with anunexpanded stent380 mounted onballoon378 abutting both of thecollars374. It can be seen that the distance between thecollars374 is to be chosen to closely accommodatestent380 in its fully contracted position about theballoon378 andunderlying catheter372. Acup382 overlies the stentproximal end portion384 and the underlyingproximal collar374.Cup382 will deploy duringballoon378 inflation in the manner described above with reference toFIGS. 41-44.
• FIG. 46 shows even another stent delivery and deployment assembly generally designated390. Theuninflated balloon398 is shown coaxially mounted on acatheter392 at the catheter distal end portion. An unexpanded stent400 is coaxially mounted onballoon398. A pair of cups402 overlap the ends of the stent400 ends. A mounting cylinder404 is carried by thecatheter shaft392.
• The Figure also illustrates cups at both ends of the stent, an arrangement which may be used in all the foregoing embodiments.
• The cups or sleeves used in the various embodiments of this invention can be of elastomeric or rigid material to contain one or both ends of the stent. In preferred embodiments of this invention the cups are used in conjunction with one or more stent collars positioned under the balloon. The collar may be formed as a ring, to abut the end of the stent, to lie under the stent and the intervening balloon, or as a cylinder, to lie under essentially the entire length of the stent and the intervening balloon. The stent detainment according to the present invention offers increased stent securement, particularly on pre-mounted delivery systems. The cups and sleeves illustrated in the various embodiments of this invention can be secured to the catheter, as by adhesive or thermal bonding, or they may be sliding cups or sleeves. When the cups are freely sliding on the catheter, they should always be used directly over a collar so that there is a friction fit between the cup and the stent.
• A method for delivering and deploying a stent using an assembly according to the present invention is described as follows: A catheter is provided as described above with reference to any ofFIGS. 38-40,43 and45. At least one collar is coaxially mounted at the catheter distal end. As discussed above, the collar may be a separate element affixed to the catheter or the collar and catheter may be formed together as a single element. The collar may be positioned abutting an end of the stent. The collar may be a mounting ring, may be positioned under the stent or underlying the balloon. The collar may be a cylinder essentially coextensive in length with the stent and underlying the balloon. A fluid expandable balloon is coaxially mounted over the collar on the catheter distal end. A stent is provided which is inflation expandable from a reduced to an enlarged condition. The stent, in its reduced condition, is coaxially mounted on the balloon so that at least an end portion of the stent overlies the balloon. A cup is provided which has first and second end portions. The cup is in an expanded form and also has a retracted form. The expanded cup is coaxially mounted on the catheter at the distal end portion so that the cup first end portion detains the stent end portion. The cup first end portion detains the stent end portion by overlying the stent end portion, or by closely accommodating the stent against the collar without overlying the stent end portion. The cup is then contracted about the catheter and the stent end portion to fix the stent to the catheter. The cup and collar cooperate to retain the stent on the catheter in its reduced condition. The assembly is then maneuvered by the physician through a body vessel by methods known per se to reach a pre-selected deployment site. The surgeon can determine when the assembly has reached the deployment site by means which are themselves known per se. For example, the assembly may be provided with radiopaque marking bands at either end of the stent, or the cups or the collars or both may be made of radiopaque material. Once the surgeon determines that the stent has been correctly positioned at the desired site, the balloon is inflated to expand the stent to its enlarged condition. Inflation of the balloon expands the stent and the stent is released from the cup or cups. As has been discussed above, the cups may deploy to release the stent in a number of ways, dependant on the construction and materials of the cup or cups. The cup may flare or enlarge radially following the increasing angle of the balloon cones. The cup may roll axially away from the stent. The portion of the cup axially distant from the stent may accordion back on itself The cup may slide axially. The cup may accordion or buckle. If the cup is not fixed to the catheter, but is freely slidable on the catheter, the cup may slide axially away from the stent. After deployment of the stent, the balloon, according to previously known procedures, is deflated and the assembly is withdrawn proximally from the body vessel. Any incision made to allow access from the assembly is appropriately closed.
• FIGS. 47-56 illustrated alternative embodiments of securement devices. Referring toFIGS. 47 and 48 a stent delivery system generally indicated at410 includes a balloon catheter412 having aballoon414 on a distal end portion generally indicated at416.FIG. 47 shows a proximal portion of the catheter at412aand a distal portion412bin enlarged view.FIG. 48 shows the distal end portion416 in an even more enlarged view. The illustrative catheter412 is of the type known as an over the wire catheter. However, other types of catheters may be used, such as rapid exchange/single operator exchange and fixed wire types. Theballoon414 is fixed to the catheter412 by standard means. The balloon is shown in its contracted state inFIGS. 47 and 48. Astent418 is fixed about the balloon by crimping it thereto. The stent has a larger expanded diameter which is obtained when the balloon is expanded in the known manner. That is, the stent is released from the catheter upon expansion of the balloon when placed in a vessel. When the balloon is then deflated, removal of the balloon and catheter may be accomplished while leaving the stent in place.
• As is known in the art the balloon is either bonded at its ends by adhesive420 and422, respectively to theouter member424 of the catheter and to theinner member426 of the catheter in the manner as shown, or is made one-piece with the outer member as is known in the art. The catheter balloon may be inflated by fluid (gas or liquid) from an inflation port extending from alumen428 contained in the catheter shaft and opening into the balloon as shown, or by other known arrangements, depending on the design of the catheter. The details and mechanics of balloon inflation and specific overall catheter construction will vary according to the particular design involved in any given instance, and are known in the art per se. All variations are acceptable for use with this invention.
• Any balloon expandable stent may be used with this invention. Many are known in the art including plastic and metal stents. Some are more well known such as the stainless steel stent shown in U.S. Pat. No. 4,735,665; the wire stent shown in U.S. Pat. No. 4,950,227; another metal stent shown in European Patent Application No. EPO 707 837 A1 and that shown in U.S. Pat. No. 5,445,646. All of these patents are incorporated herein by reference. Also, shape memory metal stents may be used. As already indicated the stent of PCT Application 960 3092 A1 is particularly preferred.
• The stent is typically about 16 mm long, while the balloon may be 20 mm long. These dimensions, however, are merely representative for illustrative purposes only and are not meant to be limiting. The stent is positioned over the balloon portion of the dilatation catheter and gently crimped onto the balloon either by hand or with a tool such as a pliers or the like to be mounted for delivery as shown inFIGS. 47 and 48. The crimping may be accomplished by either the manufacturer or the physician.
• In accordance with one embodiment of this invention, a mountingbodies430, seen inFIGS. 47 and 48 are included insideballoon414 to provide a cushion and/or substrate of enlarged diameter relative to the shaft to support and hold the stent and secure it during crimping and the delivery procedure. The mounting bodies are preferably located in the body portion of the balloon.
• In the embodiment shown, mountingbodies430 are ring-like in form and are mounted oninner lumen426, providing an enlarged area or portion for receiving the balloon and stent when the latter is crimped. Marker bands432 and434 may also be included on inner426 as shown. Any radiopaque material such as gold is useful for this purpose. Although, the material of the mounting bodies may be hard, it is preferably of any thermoplastic elastomer having elastic or deformable properties, more preferably of a relatively resilient elastomer material, e.g., silicone, preferably a lower durometer silicone, or polyurethane, such as Tecothane 1055D. A deformable thermoplastic material such as high density polyethylene (HDPE) may be used. Any deformation of resilient material of the mounting body when the stent/balloon is crimped to it causes a radial outward force on the stent/balloon increasing the friction therebetween despite a recoil of the stent.
• The stent is also fixed in position by two overlying retainingsleeves436 and438.Sleeves436 and438 are formed of polyurethane, preferably Tecothane 1055D, and are axially fixed on catheter412 byadhesive plugs440 and442 of urethane adhesive. The plugs of adhesive may be tapered to the catheter as shown to facilitate movement of the catheter in a vessel. The sleeves overlap the marginal end portions ofstent418 as shown.
• A lubricating solution such as silicone fluid may be used betweenballoon414 andsleeves436 and438 and thereon to facilitate release ofstent418 from the sleeves.
• During delivery, the balloon catheter is advanced through and positioned in a patient's vasculature so that the stent is adjacent to the portion of the vessel where treatment is to take place. The balloon is inflated to expand the stent to an enlarged diameter. At this time, expansion of the balloon causes the end margin of the sleeves to slide axially from over the stent thereby releasing the ends of the stent from the catheter. Various forms of retraction ofsleeves436 and438 are shown inFIGS. 49-52. These figures illustrate the configuration of thesleeves436 and438 in their retracted state after theballoon414 has been fully expanded. Only thedistal sleeve438 is shown.FIG. 49 illustrates the preferably retraction configuration. To promote easier retraction sleeves are coated with silicone. The sleeves are preferably adhered to theouter shaft424 and theinner shaft426 atpoint440,442, but may be adhered further up thewaste441 of the balloon. The retraction configurations may be controlled by either pre-creasing the sleeves or adhering the sleeve to a point further up on the waist of the balloon. The sleeves have a tendency of folding at a pre-fold crease or at the point of adherence. A preferred cone angle of 45.degree. for the balloon is shown inFIG. 52, which shows an expandedballoon414 and retractedsleeves436,438. When the stent has reached the desired diameter, the balloon is deflated so that the catheter may be removed leaving the stent in place.
• A modified439 sleeve configuration is shown inFIG. 53 in stepped form43 having a large diameter at444 in onesection446 and a small diameter445 in a second section450.
• FIGS. 54-56 show alternative embodiments of the invention. Specifically, alternative positioning and number of mountingbodies430. These figures show an unexpanded balloon having the mountedbodies430 within the balloon. They are meant to illustrate essentially the same structure as shown inFIG. 448 differing only in the number and positioning of the mountedbodies430. In the embodiment shown inFIG. 54, the ring-like mounting body430 is singular. Another similar version is shown inFIG. 55 which includes three ring-like mountingbodies430. The embodiment shown inFIG. 56 includes four ring-like mountingbodies430.
• It should be understood that the various elements and materials of all embodiments could be utilized in each of the other embodiments, if desired.
• 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.

Claims (20)

1. A system/assembly for delivery and deployment of an inflation expandable stent within a vessel, comprising: a catheter having proximal and distal ends; a stent, inflation expandable from a delivery diameter to a deployment diameter, such that the delivery diameter is reduced from the deployment diameter for conforming the stent to the catheter, such that the stent, in its delivery diameter, is coaxially mounted on the catheter near the catheter distal end; an expandable inflation means coaxially mounted on the catheter axially within the stent, for expansion of the stent from the delivery diameter to the deployment diameter upon application of fluid deployment pressure to the inflation means; and a securement component coaxially mounted on the catheter, axially within the expandable inflation means, the securement component designed and adapted to provide a securement pressure to the stent in the delivery diameter to maintain the stent in position on the catheter during delivery to the deployment site.

2. The system ofclaim 1, the catheter having a shaft and the expandable inflatable means associated therewith at a distal part of the shaft and including mounting and retaining means for receiving the stent on the expandable means for radial expansion of the stent, the mounting and retaining means being associated with the inflatable means and being constructed and arranged for selectively providing an enlarged mounting body for receiving the stent.

3. The system ofclaim 2 wherein the mounting body is inside the inflatable means.

4. The system ofclaim 2 wherein the mounting body is outside the inflatable means.

5. The system ofclaim 2, the inflatable means being a balloon, wherein the mounting body is carried by the catheter and is axially movable between the stent mounting position associated with the balloon and a position removed from the stent mounting position.

6. The system ofclaim 1, the catheter having a shaft, the expandable inflatable means being associated therewith at a distal part of the shaft and including mounting and retaining means for receiving a stent on the expandable inflatable means and for radial expansion of the stent upon inflation of the inflatable means, the mounting and retaining means including at least one mounting body carried on and surrounding the shaft inside the inflatable means whereby the diameter of the shaft and inflatable portion may be increased at the distal part of the shaft for facilitating the mounting and retaining of the stent.

7. The delivery system ofclaim 6 wherein the mounting body is axially movable with respect to the inside shaft, and including means for moving the mounting body.

8. The stent delivery system ofclaim 7 wherein the mounting body is of a material which resiliently deforms under radial pressure.

9. The stent delivery system ofclaim 8 wherein the material comprises HDPE or silicone.

10. The stent delivery system ofclaim 7 wherein the mounting body configuration includes at least one separation whereby the flexibility of the body and catheter is increased.

11. The stent delivery system ofclaim 10 wherein the separation is in the form of a spiral.

12. The stent delivery system ofclaim 7 wherein the mounting body is positionable to receive a stent and a stent is crimped to the mounting and retaining means over the balloon for delivery.

13. The stent delivery system ofclaim 6 including a stop positioned at the distal end portion of the inflatable means and carried by the shaft inside the inflatable means.

14. The stent delivery system ofclaim 6 including at least one marker band.

15. The stent delivery system ofclaim 6 wherein the inflatable means comprises a balloon.

16. The stent delivery system ofclaim 6 including a stop positioned at the distal end of the catheter and carried by the shaft inside the inflatable means.

17. The stent delivery system ofclaim 6 wherein the mounting body is in a fixed position and is adapted and arranged to enlarge in diameter to receive a stent.

18. The stent delivery system ofclaim 17 wherein the mounting body is a second inflatable means inside the first inflatable means, the inner one being shaped to have wide end portions and a narrow center portion.

19. The stent delivery system ofclaim 17 wherein the mounting body is a coil-like structure adapted and arranged to be compressed and the proximal portion of the inside shaft is connected thereto for compressing the structure to enlarge its diameter.

20. The system ofclaim 17 wherein the mounting body is a sleeve including radial accordion like pleats extending over at least a portion of its length, the distal end being secured to the inside shaft and a means for compressing the body from its proximal end and attached thereto.

Images