Abstract:
An expandable stent for percutaneous procedures comprises a tubular structure disposed about a longitudinal axis and a plurality of fingers. The plurality of fingers, upon expansion of the stent, extends from the tubular structure about a second longitudinal axis which is angularly offset from the first longitudinal axis. At least one of the plurality of fingers has a length that is greater than that of the other fingers.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of U.S. application Ser. No. 10/288,621 filed Nov. 5, 2002 and issued as U.S. Pat. No. 7,326,242, the entire contents of which are hereby expressly incorporated by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0003]    Stents, grafts, stent-grafts, vena cava filters and similar implantable medical devices, collectively referred to hereinafter as stents, are radially expandable endoprostheses which are typically intravascular implants capable of being implanted transluminally and enlarged radially after being introduced percutaneously. Stents may be implanted in a variety of body lumens or vessels such as within the vascular system, urinary tracts, bile ducts, fallopian tubes, coronary vessels, secondary vessels, etc. Stents may be used to reinforce body vessels and to prevent restenosis following angioplasty in the vascular system. They may be self-expanding, expanded by an internal radial force, such as when mounted on a balloon, or a combination of self-expanding and balloon expandable. 
         [0004]    Within the vasculature it is not uncommon for stenoses to form at a vessel bifurcation. A bifurcation is an area of the vasculature or other portion of the body where a first (or parent) vessel is bifurcated into two or more tubular component vessels. Where a stenotic lesion or lesions form at such a bifurcation, the lesion(s) can affect only one of the vessels (i.e., either of the tubular component vessels or the parent vessel) two of the vessels, or all three vessels. 
         [0005]    Many of the bifurcated stents that have been disclosed are deployed by two balloons. A first balloon expands the main section of the stent and a second balloon expands the branch. 
         [0006]    In spite of the many bifurcated stents that have been disclosed, there remains a need for innovative bifurcated stents which may be deployed using a single balloon for the main section and an alternate mechanism for the side branch. There also remains a need for bifurcated stents with innovative designs in the region of the bifurcation to provide adequate coverage of the carina. 
         [0007]    All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety. Without limiting the scope of the invention, a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below. 
         [0008]    A brief abstract of the technical disclosure in the specification is provided as well for the purposes of complying with 37 C.F.R. 1.72. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    In one embodiment, the invention is directed to an expandable stent having a tubular structure which is disposed about a first longitudinal axis and a plurality of fingers which, upon expansion of the stent, extend from the tubular structure about a second longitudinal axis. The second longitudinal axis is angularly offset from the first longitudinal axis. At least one of the plurality of fingers has a length that is greater than that of the other fingers. In the unexpanded state the fingers may lie substantially on the surface of the stent. 
         [0010]    Desirably, the fingers are disposed about an opening of the stent. The fingers and the opening define a crown. 
         [0011]    Another embodiment of the invention is directed to a stent with a crown having fingers in which one portion of the crown has fingers that have a shorter average length than the average length of fingers on another portion of the crown. 
         [0012]    Another embodiment of the invention is directed to a stent with a crown having fingers in which the proximal portion of the crown has fingers with a longer average length than the average length of fingers on the distal portion of the crown. 
         [0013]    Another embodiment of the invention is directed to a stent with a crown having fingers in which the proximal portion of the crown has fingers with a shorter average length than the average length of fingers on the proximal portion of the crown. 
         [0014]    Another embodiment of the invention is directed to a stent in an unexpanded condition with a crown. The fingers on a more distal portion of the crown extend proximally in such a way that a portion of at least one finger on the distal portion is proximal to a portion of at least one finger on the proximal portion of the crown which extend distally such that the fingers overlap one another. Another embodiment is directed to fingers that are interlaced with one another. 
         [0015]    Another embodiment of the invention is directed to a stent with a crown having fingers with a length between 10.0 and 0.5 mm; desirably between 7.0 and 1.0 mm; and more desirably between 5.5 and 1.5 mm. 
         [0016]    Another embodiment of the invention is directed to a stent with a crown having fingers in which the fingers have varying lengths. 
         [0017]    Another embodiment is directed to a stent with a crown that begins opening into the secondary lumen before the main body of the stent is fully deployed. 
         [0018]    A further embodiment of the invention is directed to a bifurcated stent comprising a first tubular component and a second tubular component. The first tubular component has a longitudinal axis, and the second tubular component has a longitudinal axis angularly offset relative to the first longitudinal axis. The second tubular component extends from the first tubular component. The second tubular component has a plurality of fingers with at least one of the plurality of fingers having a length that is greater than that of the other fingers. 
         [0019]    Another embodiment is directed to a bifurcated stent having a tubular structure with a first longitudinal axis and fingers extending therefrom. The fingers are positioned about a second longitudinal axis wherein at least one finger is longer than an adjacent finger. Desirably, the fingers are disposed about an opening. 
         [0020]    Another embodiment is directed to a catheter for delivery of a stent. The catheter comprises an apparatus for expanding a crown of the stent. The apparatus has a pushing device with a proximal end region and a distal end region. The proximal end region corresponds to a proximal end of a catheter, and the distal end region is constructed and arranged to be positioned adjacent to the stent to expand the crown members when the pushing device is advanced. 
         [0021]    The pushing device may be a rod or hypotube. 
         [0022]    In another embodiment, the catheter comprises a balloon, and the stent is disposed about a portion of the balloon. At least a portion of the distal end region of the pushing device is fixedly attached to the balloon at a region of attachment with the distal end of the pushing device having flexible spaced portions proximal to the region of attachment such that when a distal force is applied to the pushing device the spaced portions bend outwardly from the pushing device thereby engaging the crown members of the crown to expand the crown. 
         [0023]    In another embodiment the catheter comprises a balloon, and the stent is disposed about a portion of the balloon. The distal end of the pushing device includes a two member cantilever mechanism. A first member extends substantially parallel to a longitudinal axis of the catheter, and a second member extends proximally at an oblique angle from a region of attachment at the distal end of the first member. The first member and the second member are fixedly attached one to the other at a joining region. The joining region is fixedly engaged to the balloon with the distal end region of the pushing device extending between the first member and the second member. When the pushing device is advanced, the second member rotatingly engages the plurality of crown members to expand the crown. 
         [0024]    Another embodiment is directed to a catheter wherein the pushing device includes a ring portion. The ring has a first portion and a second portion. The first portion being positioned proximal to the distal end region, and the second portion is positioned distal to the distal end region of pushing device. The ring portion rotatingly engages the plurality of crown members to expand the crown. 
         [0025]    Another embodiment is directed to a catheter wherein the pushing device includes a plurality of web-like strands. The plurality of web-like strands is constructed and arranged to engage the plurality of crown members when the pushing device is advanced in a distal direction to a first predetermined distance. When the pushing device is advanced to a second predetermined distance, the plurality of web-like strands pulls the crown members to expand the crown. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0026]    A detailed description of the invention is hereafter described with specific reference being made to the following drawings. 
           [0027]      FIG. 1  is a side view of a stent with a crown. 
           [0028]      FIG. 1   a  is a side view of a stent with the crown expanded. 
           [0029]      FIG. 2  is a cross-sectional view of an expanded stent with the asymmetrical crown fingers of the crown extended into a lumen. 
           [0030]      FIG. 2   a  is a cross-sectional view of an expanded stent with the asymmetrical fingers of the crown extended and engaging a stent in a secondary lumen. 
           [0031]      FIG. 3  is a cross-sectional view of an expanded stent with the equal-length fingers of the crown extended and engaging only a portion of the stent in the secondary lumen while leaving a gap on one side. 
           [0032]      FIG. 3  is a cross-sectional view of an expanded stent with the equal-length fingers of the crown extended and engaging the stent in the secondary lumen while overlapping a portion of the stent in the secondary lumen. 
           [0033]      FIG. 4   a  is a cross-sectional view of a stent with a crown in which the fingers overlap. 
           [0034]      FIG. 4   b  is a cross-sectional view of a stent with a crown in which the fingers are interlaced. 
           [0035]      FIG. 5   a  is a cross-sectional view of a partially deployed stent with a crown in which the fingers are opening towards the secondary lumen. 
           [0036]      FIG. 5   b  is a cross-sectional view of a fully deployed stent with a crown in which the fingers extend into the secondary lumen to engage another stent. 
           [0037]      FIG. 5   a  is a cross-sectional view of a partially deployed stent with a crown in which the fingers are opening towards the secondary lumen. 
           [0038]      FIG. 6  is a side view of a stent with a crown and the stent deployment apparatus. 
           [0039]      FIG. 7  is a perspective view of a possible push tip design. 
           [0040]      FIG. 7   a  is a view through a secondary lumen of the end view of the push tip. 
           [0041]      FIG. 8  is a cross-sectional view of a possible push plate design. 
           [0042]      FIG. 8   a  is a cross-sectional view of the end view of the push plate. 
           [0043]      FIG. 9  is a cross-sectional view of a possible push plate design utilizing a ring. 
           [0044]      FIG. 9   a  is a view through a secondary lumen of the end view of the push plate. 
           [0045]      FIG. 10  is a perspective view of a possible push tip design having a fixed region and a distal end with spaced portions. 
           [0046]      FIG. 10   a  is a perspective view of a possible push tip design in which distal force is applied and the distal spaced portions bend flaring outward. 
           [0047]      FIG. 10   b  is an end view through a secondary lumen of a possible push tip design in which the distal spaced portions are fully flared. 
           [0048]      FIG. 11  is a side view of a stent with a crown and the stent deployment apparatus wherein the push tip is pulling the fingers outward. 
           [0049]      FIG. 11   a  is a close-up view of the push tip with the pull wires engaging the crown fingers outward. 
           [0050]      FIG. 11   b  is a side view of a stent with a crown and the stent deployment apparatus inside a body lumen wherein the push tip is pulling the fingers outward into a secondary lumen. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0051]    While this invention may be embodied in many different forms, there are described in detail herein specific embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. 
         [0052]    As discussed above, the present invention is directed to a variety of bifurcated stents. The embodiments disclosed herein may be balloon expandable, self-expanding, or hybrid stents. 
         [0053]    A first embodiment of the invention is depicted in  FIG. 1 , wherein a stent, indicated generally at  10 , is shown. The stent  10  can be self-expandable, balloon expandable or a hybrid and has a proximal end  14  and a distal end  16 . Positioned between the distal and proximal ends of the stent  10  is a crown  20 . The crown  20 , having a distal portion  21  and a proximal portion  22 , is defined by a cell opening  23  about which fingers  24  are positioned. Upon expansion these fingers may extend into a bifurcation. As seen in  FIG. 1 , the fingers  24  may vary in length and the majority of the fingers  24  extend longitudinally in either a distal or proximal direction from the crown with some fingers  24  extending at an angle that is not longitudinal. However, for purposes of this embodiment, those fingers  24  that extend with a longitudinal component will be considered to be on a distal portion  21  of the crown  20  if a component of its extension from the crown  23  is in a proximal direction and will be considered on a proximal portion  22  of the crown  20  if a component of its extension from the crown  23  is in a distal direction. The distally extending fingers  24  are generally longer than the proximally extending fingers  24 . 
         [0054]      FIG. 1   a  illustrates an embodiment of the invention in which the fingers  24  positioned on crown  20  are in an expanded state. Among other things, the combination of longer and shorter fingers  24  is designed to provide better carina coverage. A desirable embodiment would have fingers  24  that decrease in length from the proximal to the distal end of the crown  20 , and for that matter, from the distal to the proximal end of the crown  20 . A more desirable embodiment would have a decrease of similar increments in the length of the fingers  24 . 
         [0055]      FIG. 2  is a cross-sectional side view of an expanded stent  10  positioned at a bifurcation. The stent  10  includes crown  20  having longer fingers  24   a  and shorter fingers  24   b  which extend into the secondary lumen of the bifurcation. As illustrated in  FIG. 2 , shorter fingers  24   b  are located at the carina  26  of the bifurcation. The longer fingers  24   a  and shorter fingers  24   b  are designed to extend in such a way that support is provided at the bifurcation, and as illustrated in  FIG. 2   a , when attachment to another stent  100  in the secondary lumen is desired, there is no gap in coverage. 
         [0056]      FIGS. 3 and 3   a  illustrate two cases with lesser coverages.  FIG. 3  depicts a bifurcation in which the fingers  24  of the stent  10  are of a short equal length. The stent  100  in the secondary lumen can only engage the fingers  24  at one location. Thus a portion of the secondary lumen at the bifurcation remains uncovered.  FIG. 3   a  depicts a bifurcation in which the fingers  24  of the stent  10  are long but of equal length. In this example, the fingers  24  extend into the secondary lumen at the bifurcation. However, coverage is again not full because to obtain full coverage, it is necessary to overlap one portion of the fingers  24  with the stent  100  in the secondary lumen. 
         [0057]      FIG. 4   a  illustrates a stent  10  with a crown  20 . The fingers  24  of the crown  20  overlap. In this embodiment the fingers  24  extending proximally overlap those extending distally.  FIG. 4   b  illustrates a stent  10  with a crown  20 . The fingers  24  of the crown  20  are interlaced. 
         [0058]      FIG. 5   a  illustrates a stent  10 , with a crown  20  that has longer fingers on the distal portion of the crown  20 , inside a body lumen at the point of the bifurcation. In this embodiment the fingers  24  of the crown  20  begin to open before the main body of the stent  10  is fully deployed. Typically, treated bifurcations have a lumen opening 2.0 mm or greater. While the fingers can be of a length up to about 10.0 mm, for a finger  24  to flip into the bifurcated secondary lumen it is sometimes beneficial to limit the length of the finger  24  to about 1.5 mm to account for any misalignment in the placement of the stent  10 . Because the fingers  24  must clear the walls of the carina of the secondary lumen, designing the crown  20  to begin opening before stent  10  is fully deployed allows the length of the fingers  24  to be longer than if the fingers  24  were extended into the secondary lumen after the full deployment of the stent  10 . The fingers  24  can begin opening within the primary lumen before full deployment and thus have extra room in which to clear the apexes of the carina.  FIG. 5   b  depicts the stent of  FIG. 5   a  after full deployment. As shown, the distal portion of the carina has very good coverage. Here a second stent  100  is present in the secondary lumen. 
         [0059]      FIG. 6  illustrates an apparatus  28  for deploying a stent  10  with a crown  20  at a bifurcation. Though this can be done in a self expanding stent, a balloon  40  is shown with the apparatus  28 . The stent  10  is guided along guidewire  50 . A pushing device  30 , with a push plate tip  35 , is located alongside the catheter and balloon  40  and extends under the stent  10  to the crown portion  20  of the stent  10 . The pushing device  30  is guided by a guidewire  55 . In one embodiment of the pushing device, as shown in  FIG. 7 , pushing device  30  includes a push plate  30   a  with a tip  35 . In this embodiment the push plate  30  is guided along guidewire  55  and pushed forward through the crown  20 . The push plate  30   a  forces the fingers outwardly and into the secondary lumen.  FIG. 7   a  illustrates the view through the secondary lumen after the push plate  30   a  has been pushed through. 
         [0060]      FIG. 8  illustrates another embodiment. Here the pushing device  30  includes an engaging mechanism  60  which is moveably disposed between the balloon  40  and push plate  30   b . The mechanism  60  includes a longitudinal member  68  which extends along at least a portion of balloon  40  and includes a cantilever member  62 . Upon distal movement along the longitudinal member  68 , the push plate  30   b  engages and rotates the cantilever member  62  about a pivot position  65 . As the cantilever member  62  rotates, it engages the crown portion  20  of the stent  10  and opens the crown portion.  FIG. 8   a  illustrates the end result of this movement. 
         [0061]      FIG. 9  illustrates another embodiment in which a ring  27  is attached to the push device  30 . The distal end of the ring  27  comes into contact with crown  20  and thereby rotates the proximal end of the ring so as to engage and force outward the fingers of the crown  20 . In  FIG. 9   a  a view through the secondary lumen is shown. The ring  27  has fully engaged the fingers and extended them into the lumen  29 . 
         [0062]    Another embodiment is illustrated in  FIG. 10 . Here the pushing device  30  is a tube or rod in which the distal end is hollow and has spaced openings  31  around the distal end. Between each of these openings  31   a  strip  33  of flexible material is extant. As shown in  FIG. 10   a , when distal movement is applied to the pushing device  30 , the strips  33  bend outward under a compressive force created due to the end of the tube or rod having a fixed region of attachment  37  fixedly attached to the balloon or to an embodiment of the longitudinal member  68  of  FIG. 8 . As the strips  33  flare outward, the fingers are contacted and forced outward into the secondary lumen  29 .  FIG. 10   b  illustrates the end result of this movement. 
         [0063]    In  FIGS. 11 and 11   a  another embodiment is illustrated. Here, a pushing device  30  includes web-like strands  43 . When distal motion is applied to the device  30 , the distal portion of device  30  will pass through the crown  40  and the strands  43  will engage the fingers  24  of the crown  40 . In this manner a pulling motion is applied to the fingers  24  to deploy them.  FIG. 11   b  illustrates a device that pulls the fingers  24  to deploy them within a body lumen  70 . The web-like strands  43  break free from the fingers  24  when a certain distance is traveled. This can be done using a number of materials. One embodiment includes biophilial materials that break upon a designed-for tension. Another embodiment incorporates a material that acts in the manner of hook and loop material. 
         [0064]    The above disclosure is intended to be illustrative and not exhaustive. This 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 claims where the term “comprising” means “including, but not limited to”. 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. 
         [0065]    Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim  1  should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below.