Abstract:
Apparatus, kits and methods for flaring an end of a stent that can then be placed within the ostium of a vessel are disclosed. Areas in which ostial stents with flared ends could be used may include, e.g., the left main artery, renal arteries, sub-clavian artery, right coronary artery, circumflex artery, et al.

Description:
RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Application No. 60/903,726, titled OSTIAL STENT PREFORMING APPARATUS, KITS AND METHODS, filed on Feb. 27, 2007. 
    
    
     The present invention relates generally to apparatus, kits and methods for modifying stents for ostial placement. 
     Angioplasty procedures are widely accepted for treatment of occluded arteries, the problem of restenosis following the angioplasty treatment is, however, a complication a patient must face. Restenosis is the reclosure or renarrowing of an artery following trauma caused by angioplasty to open an occluded portion of the artery. Renarrowing is also frequently caused by the elastic rebound of the arterial wall and/or by dissections in the vessel wall caused by the angioplasty procedure. To combat restenosis and maintain the patency of the vessel lumen, physicians implant tubular supports known as stents into surgically repaired vessels. 
     Stents are used to address restenosis in many patients. The stent is typically inserted by catheter into a vascular lumen at an easily accessible location, such as the brachial or femoral arteries, and then is advanced through the vasculature to the deployment site. The stent is initially maintained in a radially compressed or collapsed state to enable it to be maneuvered through the body lumen, and is mounted to a delivery system for advancement through a patient&#39;s vasculature to the deployment site. Once the stent has reached the stenotic site within a damaged vessel, and is ready for deployment, it is expanded by internal means or by means integral to the delivery system that are well known in the prior art. In its expanded state, the stent provides internal support for the vessel lumen and reduces the likelihood of the development of restenosis. 
     Placement of the stent within the vasculature can be especially challenging when the stenotic region is near the intersection of two vessels or is at the origin of a major vessel off the aorta. For example, the placement of a stent to repair a diseased vessel that is a branch vessel, such as the renal artery, near its ostium with a great vessel, such as the aorta, is particularly challenging because the stent must be securely and precisely positioned in an area that supports a heavy volume of blood flow without occluding the blood flow in either the branch vessel or the great vessel. Additionally, the angle created by the intersection of a main/great vessel and a branch vessel can lead to difficulties in precisely positioning the stent in the damaged branch vessel. Physicians often have difficulty aligning the stent to optimally repair the stenotic region of such a branch vessel, which leads to placement of the stent within the branch vessel such that a portion of the stent hangs out or extends into the main vessel. This can result in partial obstruction of the main vessel and can also make it difficult to reenter the branch vessel for repeat procedures in the future. Attempts to position a stent without any proximal overhang into the main vessel can often lead to the stent being positioned too deep inside the branch vessel, thereby incompletely covering the ostial narrowing. 
     Conventional stents are designed to repair areas of blood vessels that are generally located somewhere along the length of single elongated vessel, and as such, they are not sufficiently equipped to be reliably and securely placed at a site that has a substantially ostial location at an intersection. Use of such conventional stents in the vicinity of vessel intersections may lead to undesirable shifting of the stent within the vessel and deployment further downstream such that the ostium is left uncovered. 
     Some stents have incorporated various arrangements to assist in securing the expanded stent to the walls of the vessel lumen in a stenotic region. Examples of such arrangements include rounded protrusions, longitudinal rails, or tines configured to project in some manner from the tubular body of the stent itself and grip into the walls of the vessel lumen. Other designs also have proposed attachments of securing components to the ends of the stent&#39;s body, as opposed to the body itself. For example, flaps have been used to assist in securing the stent within a conventional vessel&#39;s stenotic region. 
     Flaring a portion of the stent has been used in the ostium of a bifurcated vessel or a smaller vessel branching off of a larger vessel. Flaring has, however, generally been performed on an ad hoc basis with minimal control over the length and other dimensions of the flared portion of the stent. 
     SUMMARY OF THE INVENTION 
     The present invention provides apparatus, kits and methods for flaring an end of a stent that can then be placed within the ostium of a vessel. Areas in which ostial stents with flared ends could be used may include, e.g., the left main artery, renal arteries, sub-clavian artery, right coronary artery, circumflex artery, et al. 
     In one aspect, the present invention provides an apparatus for flaring a stent, the apparatus including a sterile body having a first end and a second end; a sterile bore formed through the body, the bore having a first opening at the first end and a second opening at the second end, wherein the bore has a first portion proximate the first end and a second portion proximate the second end, wherein the first portion and the second portion meet within the bore, and wherein the first portion has a flared diameter that decreases when moving from the first end towards the second end and the second portion has a substantially constant diameter; and a sterile clamp mechanism located proximate the second opening. 
     In other aspects, the apparatus may include one or more additional sterile bores formed through the body; wherein each of the additional bores has a first opening at the first end and a second opening at the second end, wherein the additional bore has a first portion proximate the first end and a second portion proximate the second end, wherein the first portion and the second portion meet within the bore, and wherein the first portion has a flared diameter that decreases when moving from the first end towards the second end and the second portion has a substantially constant diameter. 
     In another aspect, the present invention may provide an apparatus for flaring a stent, the apparatus including a sterile body having a first end and a second end; two or more sterile bores formed through the body, wherein each sterile bore of the two or more sterile bores includes: a first opening at the first end and a second opening at the second end; a first portion proximate the first end and a second portion proximate the second end, wherein the first portion and the second portion meet within the bore, and wherein the first portion comprises a flared diameter that decreases when moving from the first end towards the second end and the second portion comprises a substantially constant diameter; and a sterile clamp mechanism located proximate the second opening. 
     In various aspects, at least the second portion of the bore may be surrounded by a compression device adapted to compress a stent located within the second portion of the bore. The compression device may include a plurality of segments arranged around the second portion of the bore, an inflatable balloon, etc. 
     In another aspect, the present invention may provide a kit for flaring the end of an ostial stent, the kit including a sterile expandable stent and a sterile apparatus for flaring an end of the stent. The apparatus may include a body having a first end and a second end; a sterile bore formed through the body, the bore having a first opening at the first end and a second opening at the second end, wherein the bore has a first portion proximate the first end and a second portion proximate the second end, wherein the first portion and the second portion meet within the bore, and wherein the first portion has a flared diameter that decreases when moving from the first end towards the second end and the second portion has a substantially constant diameter; and a sterile clamp mechanism located proximate the second opening of the bore. The kit may further include a sterile expansion device sized for location within the first portion of the bore, wherein the expansion device is capable of flaring the end of the stent outward within the first portion of the bore. 
     The above summary is not intended to describe each embodiment or every implementation of the present invention. Rather, a more complete understanding of the invention will become apparent and appreciated by reference to the following Description of Exemplary Embodiments and claims in view of the accompanying figures of the drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWING 
       The present invention will be further described with reference to the figures of the drawing, wherein: 
         FIG. 1  is a perspective view of one body that includes a plurality of bores formed therethrough. 
         FIG. 2  is a cross-sectional view of one of the bores in the body of  FIG. 1 . 
         FIG. 3  is a view of  FIG. 2  with a stent located therein. 
         FIG. 4  is a view of  FIG. 3  with an expansion device in use to flare the end of the stent within the bore. 
         FIG. 5  depicts a stent after flaring. 
         FIG. 6  is a schematic diagram of one alternative design for a body that can be used in connection with the present invention. 
         FIG. 7  is a schematic diagram of another alternative design for a body that can be used in connection with the present invention. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     In the following detailed description of illustrative embodiments of the invention, reference is made to the accompanying figures of the drawing which form a part hereof, and in which are shown, by way of illustration, specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. 
     A variety of documents describe the advancement and placement of stents within vessels, including the advancement and placement of ostial stents. See, e.g., U.S. Patent Application Publication Nos. US 2002/0077691 (Nachtigall); US 2002/0091434 (Chambers); US 2004/0111143 (Fischell et al.); etc.—as well as U.S. Pat. No. 5,607,444 (Lam); U.S. Pat. No. 5,749,890 (Shaknovich); etc. 
     The stents that can be used in connection with the present invention may include, e.g., any conventional stent that can be deformed to include a flared end suitable for ostial placement. In many instances, such stents may be made of metallic materials, although other deformable materials may also be used to manufacture the stents. 
       FIG. 1  depicts one apparatus that may be used to flare the ends of stents. 
     The apparatus includes a body  10  having a first end  12  and a second end  14 . Bores  20   a ,  20   b , and  20   c  are depicted as being formed through the body  10 . Each of the bores  20   a ,  20   b , and  20   c  includes a first opening in the first end  12  and a second opening (not shown) in the second end  14  of the body  10 . 
     Although the body  10  is depicted with three bores formed therethrough, the bodies used in connection with the present invention may alternatively include as few as one bore, two bores, or more than three bores. 
       FIG. 2  is a cross-sectional view of bore  20   a . The bore  20   a  includes a first portion  26   a  and a second portion  28   a . The first portion  26   a  preferably has a flared diameter that is largest at the opening  22   a  and decreases when moving from the first end  12  towards the second end  14  of the body  10 . The flared shape of the first portion  26   a  may preferably have a generally circular shape, although other cross-sectional shapes are also possible. Also, although the bore  20   a  includes a second opening  24   a  distal from the flared first portion  26   a , the bores used in connection with the present invention may alternatively be closed at the distal end. 
     The first portion  26   a  of the bore  20   a  meets the second portion  28   a  of the bore  20   a  within the body  10 . At the junction between the first portion  26   a  and the second portion  28   a , the diameters of the two portions are preferably equal. While the first portion  26   a  preferably tapers as depicted in  FIG. 2 , the second portion  28   a  may preferably have a substantially constant diameter. In some embodiments, however, the shape of the second portion  28   a  may differ. For example, the second portion may have a shape that is complementary to a stent to be inserted therein. 
     It may be preferred that the first portion  26   a  of the bore  20   a  be limited to a length of, e.g., less than half of the overall length of the bore  20   a  between the first end  12  and the second end  14 . As an alternative manner of characterizing the length of the flared first portion  26   a , it may be preferred that the flared first portion  26   a  have a length (measured between the first end  12  and the second end  14 ) of 5 millimeters (mm) or less, or even 2 mm or less. 
       FIG. 3  is a view of the bore  20   a  of  FIG. 2  with a stent  40  located therein. The stent  40  is preferably positioned on a delivery catheter  50 , with the catheter  50  located over a guidewire  60 . The guidewire  60  may preferably extend out of the distal opening  24   a  of the bore  20   a  such that it protrudes from the second end  14  of the body  10  as depicted. When properly positioned, it may be preferred that the proximal end  42  of the stent  40  be generally even with the first end  12  of the body  10 . 
     Also depicted in  FIG. 3  is an optional clamp mechanism  30  positioned to retain the guidewire  60  or any other component extending out of the distal end  24   a  of the bore  20   a . It may be preferred that the clamp  30  prevent the guidewire  60  (and associated catheter  50  located thereon) from pulling back into the bore  20   a  during expansion of the stent  40  to provide a flared end as discussed herein. The clamp  30  may take any form capable of retaining the guidewire  60  in position in the bore  20   a  by, e.g., compressing the guidewire, etc. 
       FIG. 4  depicts the components of  FIG. 3  in which an expandable member  56  (e.g., a balloon, etc.) in the catheter  50  is expanded to force the portion of the stent  40  located within the flared first portion  26   a  of the bore  20   a  outwardly to conform to the shape of the flared first portion  26   a . It is preferred that the expansion of the stent  40  be such that the proximal end portion  46  of the stent  40  is plastically deformed such that when the stent  40  is deployed within a vessel, the proximal end of the stent  40  exhibits a flared end to assist in retention of the stent  40  in the ostium in which it is deployed. 
     Although the bores may include first portions that have a flared diameter as described herein, in some apparatus, kits and methods, the bore(s) may not include a flared portion. A stent inserted into a bore that does not include a flared portion may still be flared by leaving a portion of the stent protruding out of the bore, such that expansion of, e.g., a balloon located within the stent, causes the unconstrained portion of the stent (i.e., the portion outside of the bore) to expand and deform into a flared shape. The unconstrained portion of the stent protruding out of the bore may be adjusted by the practitioner to provide the desired flared shape and length. 
       FIG. 5  depicts the stent  40  outside of the bore. The proximal end portion  46  preferably includes a flared shape that will advantageously promote proper placement and retention of the stent  40  in an ostium. The flared portion of the stent  40  may be reduced in diameter by, e.g., a sheath placed over the stent during delivery to a site. Removal of the sheath before final placement will preferably result in the stent  40  resuming its flared configuration to assist in proper placement and retention. The remainder of the stent  40  may preferably have a uniform diameter (or some other selected shape). The residual flare in the stent  40  after deployment and expansion to its reference size within a vessel is likely to be minimal. 
       FIG. 6  is a schematic diagram of an alternative body  110  in which a bore  120  is located. The body  110  is provided in the form of multiple segments  116  arranged around the bore  120 . Although the depicted body  110  includes four such segments  116 , it will be understood that it could alternatively include as few as two or three segments or five or more segments. The segments  116  may be provided as one form of a compression device and may preferably be urged towards the center of the bore  120  during use such that the portion of a stent located in the bore  120  can be deformed outwardly to form a flared portion as described herein while the reminder of the stent is compressed to preferably prevent or limit any expansion. 
       FIG. 7  depicts another alternative embodiment of a body  210  in which the second portion  228  of the bore  220  is surrounded by a compression device in the form of one or more balloons  229  (or other expandable member). The first portion  226  of the bore  220  preferably has a flared shape as discussed herein. In use, the balloon within a catheter may be expanded to force the portion of a stent located on the catheter outwardly within the flared first portion  226  to form a flared end on the stent. During such expansion, it may be preferred that the one or more balloons  229  positioned around the remainder of the stent be pressurized such that the portion of the stent located therein is compressed such that it is not expanded. 
     In a system such as that depicted in  FIG. 7 , it may be desirable that the pressure within the one or more balloons  229  be greater than the pressure within a balloon used to expand the portion of the stent in the flared first portion  226  of the bore  220 . By maintaining such a pressure relationship between the balloon acting on the interior of the stent and the compression device acting on the exterior of the stent, expansion of the balloon located within the stent (which is urging the stent outward) would be contained by the greater pressure of the one or more balloons  229  acting on the exterior of the stent—thus preferably preventing (or severely limiting) expansion of the stent outside of the flared first portion  226  of the bore  220 . 
     It may be preferred that all components of the apparatus and kits used in connection with the present invention be sterile as supplied such that their introduction into a sterile environment does not compromise the sterility of that environment. Sterilization of the components may be accomplished by any suitable technique or combination of techniques. 
     The terms “comprises” and variations thereof do not have a limiting meaning where these terms appear in the accompanying description and claims. Moreover, “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably herein. 
     The complete disclosure of the patents, patent documents, and publications cited in the present application are incorporated by reference in their entirety as if each were individually incorporated. 
     Illustrative embodiments of this invention are discussed and reference has been made to possible variations within the scope of this invention. These and other variations and modifications in the invention will be apparent to those skilled in the art without departing from the scope of the invention, and it should be understood that this invention is not limited to the illustrative embodiments set forth herein. Accordingly, the invention is to be limited only by the claims provided below and equivalents thereof.