Abstract:
A first balloon catheter having a tip extends through the stem portion and first leg portion of a first expandable tubular member and a second balloon catheter having a tip through said stem portion and extends out of a branch aperture such that its tip is longer than that of the first balloon catheter. The first, expandable tubular member, first balloon catheter and second balloon catheter are delivered to a bifurcated vessel having a first lumen and a second lumen with the tip of the second balloon catheter leading the rest of the elements so that the tip of said second balloon catheter can be aligned with and enter into the second lumen before the first expandable tubular member and the tip of said first balloon catheter reach the area of said second lumen and interfere with the second balloon catheter.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a continuation-in-part of application Ser. No. 09/891,767, filed Jun. 26, 2001, which is a continuation of application Ser. No. 09/072,846, filed May 5, 1998, now Pat. No. 6,251,133, which is a continuation of application Ser. No. 09/049,842, filed Mar. 27, 1998, now Pat. No. 6,090,133, which is continuation of application Ser. No. 08/911,606, filed on Aug. 14, 1997, now Pat. No. 5,827,320, which is a continuation of application Ser. No. 08/841,702, filed on Apr. 30, 1997, now Pat. No. 5,755,735, which is a continuation of application Ser. No. 08/840,612, filed on Apr. 29, 1997, now U.S. Pat. No. 5,755,734, which is a division of application Ser. No. 08/642,297, filed May 3, 1996, now abandoned. This application is also a continuation-in-part of application Ser. No. 10/066,755, filed Feb. 6, 2002, which is a division of Ser. No. 09/575,957, filed May 23, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to stents, and more particularly methods of delivering a bifurcated stent.  
         BACKGROUND OF THE INVENTION  
         [0003]    Stents are well known in the art. They are typically formed of a cylindrical metal mesh, which can expand when pressure is internally applied. Alternatively, they can be formed of wire wrapped into a cylindrical shape or sheets of material formed into a cylindrical shape.  
           [0004]    Stents are devices that are usually implanted within bodily conduits including the vascular system to reinforce collapsing, partially occluded, weakened, or abnormally dilated sections of the blood vessel. Stents also have been successfully implanted in other areas, e.g., the urinary tract or the bile duct to reinforce such bodily conduits.  
           [0005]    U.S. Pat. No. 4,994,071 (MacGregor) discloses an expandable, bifurcating stent having a main cylindrical lattice formed from interconnected, flexible wire. Two additional cylindrical lattices, having smaller diameters than the main lattice, are similarly constructed. The main lattice includes a flexible wire interconnecting the main lattice to one of the additional lattices. A second flexible wire interconnects the main lattice to the other additional lattice. The flexible wires form backbones that extend axially along the length of the main lattice and along each of the additional lattices. One disadvantage of this bifurcating stent is the complex nature of the interconnection of the flexible wires forming the backbones with the loop structure of each lattice.  
           [0006]    Thus, embodiments described in the aforementioned U.S. Pat. No. 6,251,133 provide methods of making a stent which includes a first tubular member having a branch aperture. The tubular member may be inserted in a blood vessel, for example, with the branch aperture aligned with a side branch vessel. A second tubular member having a longitudinal bore may then be disposed and secured within the branch aperture of the first tubular member and, for example, extending into the branch vessel, with the longitudinal bore of the second tubular member in fluid communication with the longitudinal bore of the first tubular member.  
           [0007]    One delivery method of a bifurcated stent, such as the stents disclosed in U.S. Pat. No. 6,251,133, to the target area includes mounting the stent on two expandable balloons of the same length. Both expandable balloons are advanced toward the target site together, or are advanced individually in sequential order. One expandable balloon is to be disposed in the main vessel, and one the other is to be disposed in the side branch lumen of the bifurcated vessel. Typically, the side branch balloon is the same length or shorter than the main vessel balloon. Upon reaching the target area in the vessel, the main vessel becomes very crowded due to both balloons filling up the lumen of the main vessel. This causes the tip of the side branch balloon to be pressed against the main vessel, and causes difficulty in orienting the balloon into the side branch lumen, and hinders the ability of the side branch balloon to bend into the side branch vessel.  
         SUMMARY OF THE INVENTION  
         [0008]    Embodiments of the present invention solves these and other disadvantages of the prior art by providing a side branch balloon catheter whose tip leads the tip of the main vessel balloon catheter by few millimeters, so that the side branch balloon leads the delivery system while advancing towards the target area. The side branch balloon catheter reaches the target area first, allowing for greater freedom of the side branch balloon to bend into the aperture of the side branch vessel, due to less crowding of balloon catheter in the main vessel. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 shows a stem and first leg portion and a second leg portion used to form an embodiment of a bifurcated stent manufactured in accordance with this invention;  
         [0010]    [0010]FIG. 2 shows guide wires disposed in the trunk lumen and branch lumen to be treated;  
         [0011]    [0011]FIG. 3 shows the stem and first leg portion shown in FIG. 1 disposed on catheters and guide wires prior to introduction into the lumen to be treated;  
         [0012]    [0012]FIG. 4 shows the stem and first leg portion shown in FIG. 1 after it has been delivered to the bifurcation to be treated and prior to its expansion;  
         [0013]    [0013]FIG. 5 shows the second leg portion shown in FIG. 4 after it has been expanded;  
         [0014]    [0014]FIG. 6 shows expansion of the branch aperture;  
         [0015]    [0015]FIG. 7 shows the unexpanded second leg portion disposed in the branch aperture;  
         [0016]    [0016]FIG. 8 shows the expansion of the second leg portion shown in FIG. 7; and  
         [0017]    [0017]FIG. 9 shows the assembled bifurcated stent disposed in the bifurcated lumen to be treated. 
     
    
     DETAILED DESCRIPTION  
       [0018]    [0018]FIG. 1 is a general representation of one type of a stent with which the present invention may be used. The stent comprises two portions, which are deployed serially in two steps and assembled within the patient to form a bifurcated stent. FIG. 1 shows stem and first leg portion  110  provided with a longitudinal bore  131  and having a proximal end  115  defining a stem portion  125  and a distal end  120 . Second leg portion  140  is provided with a longitudinal bore  132  and has a proximal end  145  and a distal end  150 . Stem and first leg portion  110  and second leg portion  140  may be sized and patterned or etched as previously discussed. A branch aperture  135  is disposed between the proximal end  115  and the distal end  120  of stem and first leg portion  110 . The branch aperture  135  is sized to receive second leg portion  140  and is adapted to engage and secure the second leg portion  140  when it has been expanded within the branch aperture  135 . Second leg portion  140  is sized and adapted to engage and be secured into branch aperture  135  upon expansion.  
         [0019]    FIGS.  2  to  9  show how the bifurcated stent is assembled within a bifurcated lumen. As shown in FIGS.  2  to  9 , the area to be treated is a bifurcated lumen having a first or trunk lumen  190  and a second or branch lumen  195 . As shown in FIG. 2, a first guide wire  155  is introduced into the main lumen  190  and a second guide wire  156  is introduced into the branch lumen  195 .  
         [0020]    As shown in FIG. 3, a balloon expandable stem and first leg portion  110  of a bifurcated stent is disposed on the tip of a first balloon catheter  170  so that the balloon  175  is disposed within a longitudinal bore  131 . A second balloon catheter  171  is then introduced into longitudinal bore  131  of stem and first leg portion  110  and is advanced so that the balloon  176  is disposed within aperture  135 , with its tip extending further forward than the tip of the first balloon catheter  170 . As illustrated, the tip of balloon  176  leads the whole system. First catheter  170  is then mounted on first guide wire  155  and second catheter  171  is mounted on second guide wire  156 . The balloon lengths are selected in conventional fashion; the balloon  176  may be shorter or longer than the balloon  175 , so long as its tip is positioned so as to lead.  
         [0021]    As shown in FIG. 4, the unexpanded stem and first leg portion  110  is guided to the area to be treated so that first leg portion  130  is disposed within trunk lumen  190  and branch aperture  135  communicates with branch lumen  195 . Because the tip of balloon catheter leads the whole system, it is able to get into the side branch  195  before the rest of the system reaches the area. This greatly facilitates entry of the catheter into, and alignment of the branch aperture  135  with, the side branch  195 .  
         [0022]    Guide wire  156  facilitates the orientation of the branch aperture  135  with the branch lumen  195 . The size of the conventional catheters and balloons is not to scale and details well known to those skilled in the art have been omitted for clarity. In one embodiment, balloon  175  is inflated which causes the stem and first leg portion  110  to expand, as shown in FIG. 5, to secure it in the desired position. After expansion, the external wall of stem and first leg portion  110  would contact the interior walls of trunk lumen  190 ; however, a gap has been intentionally left for clarity. The balloon  175  on first catheter  170  is left inflated and the balloon  176  on second catheter  171  is then inflated to enlarge the branch aperture  135  as shown in FIG. 6. As the branch aperture  135  is enlarged a portion of the stent defining the branch aperture  135  is pushed outward to form a branch securing lip  180 .  
         [0023]    In this embodiment, balloons  175  and  176  are deflated, second catheter  171  is withdrawn, and second guide wire  156  is left in place in the branch lumen  195 . Second leg portion  140  is then applied to second catheter  171  so that balloon  176  is disposed in longitudinal bore  132  and second catheter  171  is then applied to second guide wire  156 . Second leg portion  140  is then guided to, and introduced into, the longitudinal bore  131  of the stem and first leg portion  110  and is advanced and passed through branch aperture  135  so that the distal end  150  of the second leg portion  140  protrudes into the branch lumen  195  and the proximal end  145  communicates with longitudinal bore  131 , as shown in FIG. 7. The balloon  176  on second catheter  171  is partially inflated and the balloon  175  on first catheter  170  is then partially inflated to a pressure substantially equal to the pressure in balloon  176 . Both balloons  175  and  176  are then simultaneously inflated to substantially equal pressures.  
         [0024]    As shown in FIG. 8, inflation of the balloon  176  on second catheter  171  causes second leg member  140  to expand so that its external walls engage and are secured to the area surrounding aperture  135 . Inflation of the balloon  175  on the first catheter  170  prevents stem and first leg portion  110  from collapsing when balloon  176  is inflated. After expansion, the external walls of second leg  140  would contact the inner wall of lumen  195 ; however, a gap has been intentionally left for clarity. The balloons  175  and  176  are deflated, catheters  170  and  171  and guide wires  155  and  156  are withdrawn, and the assembled bifurcated stent  160  is left in place as shown in FIG. 9.  
         [0025]    An alternative embodiment of a method of making a bifurcated stent comprises the steps of preparing a first expandable tubular member  110  having a proximal end  115  and a distal end  120  and a longitudinal bore  131  therethrough. The first tubular member  110  is provided with a branch aperture  135  disposed between the proximal end  115  and the distal end  120 . The branch aperture  135  communicates with the longitudinal bore  131  of the first expandable tubular member  110  and the aperture  135  is sized and adapted to receive and secure a second expandable tubular member  140 . The first expandable tubular member  110  is delivered to a bifurcated vessel having a first lumen  190  and a second lumen  195  so that the first expandable tubular member  110  is disposed within the first lumen  190  and the branch aperture  135  communicates with the second lumen  195 . The branch aperture  135  is aligned with the second lumen  195  and may be widened by first inflating the balloon  176  of FIG. 4. As specific applications dictate, the portion of the first expandable tubular member defining the branch aperture  135  may be adapted to form a branch securing lip when the branch aperture  135  is expanded a sufficient amount by inflating the balloon  176 .  
         [0026]    As shown in FIG. 5, the first expandable tubular member  110  is then expanded an amount sufficient to secure the first expandable tubular member  110  in the first lumen  190 . A second expandable tubular member  140  is prepared having a proximal end  145  and a distal end  150  having longitudinal bore  132  therethrough. The second expandable tubular member  140  is delivered into the branch aperture  135  so that the distal end  150  of the second expandable tubular member  140  is disposed within the second lumen  195  and the proximal end  145  of the second expandable tubular member  140  is disposed within the branch aperture  135  of the first tubular member  110  and so that the longitudinal bore  132  of the second expandable tubular member  140  is in fluid communication with the longitudinal bore  131  of the first longitudinal tubular member  110 . As shown in FIG. 6, the second expandable tubular member  140  is then expanded in an amount sufficient to secure the second expandable tubular member  140  within the second lumen  195  and within the branch aperture  135  of the first expandable tubular member  110 .  
         [0027]    In one particular embodiment, a first guide wire  155  is delivered into the first lumen  190  of a bifurcated vessel having a first lumen  190  and a second lumen  195  and a second guide wire  156  is delivered into the second lumen  195  of the bifurcated vessel. A first expandable tubular member  110  is prepared having a proximal end  115  and a distal end  120  and a longitudinal bore  131  therethrough. The first expandable tubular member  110  is provided with a branch aperture  135  disposed between the proximal end  115  and the distal end  120 . The branch aperture  135  communicates with the longitudinal bore  131  and the branch aperture  135  is sized and adapted to receive and secure a second expandable tubular member  140 . The first expandable tubular member  110  is mounted on a first balloon catheter  170  and the first balloon catheter  170  is mounted on the first guide wire  155 .  
         [0028]    The first expandable tubular member  110  is delivered to the first lumen  190  of the bifurcated vessel so that the first expandable tubular member  110  is disposed within the first lumen  190  and the branch aperture communicates  135  with the second lumen  195 . A second balloon catheter  171  is mounted on the second guide wire  156  and the balloon portion  176  of the second balloon catheter  171  is delivered into the side-branch aperture  135 . In accordance with the present invention, both balloons may be inserted through the stem portion of the tubular member and delivered to the bifurcated vessel simultaneously. As explained previously, the tip of balloon catheter  171  leads the whole system, permitting it to be more easily aligned with and inserted in the branch lumen  195 .  
         [0029]    The second balloon catheter  171  is inflated to align the branch aperture  135  with the second lumen  195 . It may additionally be inflated sufficiently to widen the branch aperture  135 . The first balloon catheter  170  may then be inflated to expand the first expandable member  110  in an amount sufficient to secure the first expandable member  110  in the first lumen  190 . The first  170  and second  171  balloon catheters are deflated and the second balloon catheter  171  is removed.  
         [0030]    A second expandable tubular member  140  is prepared having a proximal end  145  and a distal end  150  having longitudinal bore  132  therethrough. The second expandable tubular member  140  is mounted on the second balloon catheter  171 . The second expandable tubular member  140 , mounted on the second balloon catheter  171 , is delivered into the branch aperture  135  so that the distal end  150  of the second expandable tubular member  140  is disposed within the second lumen  195  and the proximal end  145  of the second expandable tubular member  140  is disposed within the branch aperture  135  of the first tubular member  110  and so that the longitudinal bore  132  of the second expandable tubular member  140  is in fluid communication with the longitudinal bore  131  of the first longitudinal member  110 . The first balloon catheter  170  may be inflated. The second balloon catheter  171  is inflated to expand the second expandable tubular member  140  in an amount sufficient to secure the second expandable tubular member  140  within the second lumen  195  and within the branch aperture  135 .  
         [0031]    As specific applications dictate, the portion of the first tubular stent  110  defining the side branch aperture  135  may be adapted to form a branch securing lip when the branch aperture  135  is expanded a sufficient amount. In one embodiment, the first balloon catheter  170  is inflated before the second balloon catheter  171  is inflated and the first balloon catheter  170  is left inflated until the second expandable tubular member  140  is secured within the branch aperture  135  by the second balloon catheter  171 . In another embodiment, the first balloon catheter  170  and the second balloon catheter  171  are inflated simultaneously.  
         [0032]    The stent with which the methods of the present invention may be used can be of any construction that provides first expandable tubular member  110  having a proximal end  115  and a distal end  120  and a longitudinal bore  131  therethrough, with a branch aperture  135  disposed between the proximal end  115  and the distal end  120  communicating with the longitudinal bore  131  of the first expandable tubular member  110  and aperture  135  is sized and adapted to receive and secure a second expandable tubular member  140 . Exemplary embodiments of structures which meet this requirement and the method of making them are disclosed in U.S. application Ser. No. 09/575,957, particularly in FIGS.  22  to  34 . The disclosure of Ser. No. 09/575,957 is hereby incorporated by reference in its entirety.