Abstract:
A vascular implant includes a scaffold and a tubing in covering relating to the scaffold. Preferably, the tubing completely covers or encases the scaffold interior surface and exterior surface to leave no portion of the scaffold exposed. Methods for constructing includes pulling tubing through a scaffold and folding at least a portion of the tubing over at least one of the ends of the scaffold. Methods for using an implant include performing coronary vessel bypass procedures or forming blood flow paths in a blood vessel utilizing constructions described herein.

Description:
TECHNICAL FIELD  
         [0001]    This disclosure relates to vascular implants, methods of making, and methods of using.  
         BACKGROUND  
         [0002]    U.S. Pat. No. 5,944,019, issued Aug. 31, 1999, teaches an implant for defining a blood flow conduit directly from a chamber of the heart to a lumen of a coronary vessel. An embodiment disclosed in this patent teaches an L-shaped implant in the form of a rigid conduit having one leg sized to be received within a lumen of a coronary artery and a second leg sized to pass through the myocardium and extend into the left ventricle of the heart. As disclosed in the &#39;019 patent, the conduit is rigid and remains open for blood flow to pass through the conduit during both systole and diastole. The conduit penetrates into the left ventricle in order to prevent tissue growth and occlusions over an opening of the conduit. U.S. Pat. No. 5,944,019 is incorporated by reference herein.  
           [0003]    U.S. Pat. No. 5,984,956, issued Nov. 16, 1999, discloses an implant with an enhanced fixation structure. The enhanced fixation structure includes a fabric surrounding at least a portion of the conduit to facilitate tissue growth on the exterior of the implant. U.S. Pat. No. 5,984,956 is incorporated herein by reference. U.S. Pat. No. 6,029,672 issued Feb. 29, 2000 teaches procedures and tools for placing a conduit. U.S. Pat. No. 6,029,672 is incorporated herein by reference.  
           [0004]    Improvements in implants continue to be desirable.  
         SUMMARY  
         [0005]    In one aspect, a vascular implant is provided that includes a scaffold and a tubing in covering relation to the scaffold. Preferably, the scaffold completely embeds the scaffold.  
           [0006]    In another aspect, a method of making a vascular implant is provided. The method includes completely covering a scaffold interior surface and exterior surface with a tubing.  
           [0007]    In another aspect, a method for performing a coronary vessel bypass procedure is provided. The method includes forming a blood flow path from a heart chamber directly to a coronary vessel by placing a conduit in a heart wall between the chamber and the vessel. The conduit includes tubing completely lining both an interior surface of the conduit and an exterior surface of the conduit. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a side sectional view of one embodiment of an implant shown in place in a human heart wall with the implant establishing a direct blood flow path from a heart chamber to a coronary vessel, constructed according to principles of this disclosure;  
         [0009]    [0009]FIG. 2 is a cross-sectional view of the embodiment of the implant shown in FIG. 1 in one step of constructing the implant;  
         [0010]    [0010]FIG. 3 is a cross-sectional view of the implant shown in FIG. 2 during another step of making the implant;  
         [0011]    [0011]FIG. 4 is a cross-sectional view of the implant shown in FIGS. 2 and 3 in another step of making the implant;  
         [0012]    [0012]FIG. 5 is a side sectional view of a second embodiment of an implant shown in place in a human blood vessel, constructed according to principles of this disclosure;  
         [0013]    [0013]FIG. 6 is a cross-sectional view of the embodiment of the implant shown in FIG. 5 during one step of constructing the implant;  
         [0014]    [0014]FIG. 7 is a cross-sectional view of the implant shown in FIG. 6, during another step of constructing the implant;  
         [0015]    [0015]FIG. 8 is a cross-sectional view of the implant shown in FIGS. 6 and 7 during another step for constructing the implant;  
         [0016]    [0016]FIG. 9 is a cross-sectional view of the implant shown in FIGS.  6 - 8  and including an optional cuff;  
         [0017]    [0017]FIG. 10 is a cross-sectional view of another embodiment of an implant shown during one step for constructing the implant;  
         [0018]    [0018]FIG. 11 is a cross-sectional view of the implant shown in FIG. 10, during another step for constructing the implant; and  
         [0019]    [0019]FIG. 12 is a cross-sectional view of the implant shown in FIGS. 10 and 11 in a final step for constructing the implant. 
     
    
     DETAILED DESCRIPTION  
       [0020]    With initial reference to FIG. 1, an implant is shown generally at  10 . The implant  10  includes a composite of a hollow, rigid conduit  12 . The conduit  12  includes a wall  14  defining an outer surface  16  and a hollow interior  18 . In preferred embodiments, the wall  14  has a circular cross-section, forming a tube or cylinder  20 . The conduit  12  includes a first portion  24 , preferably corresponding to a vessel or vasculature portion, and a second portion  26 , generally corresponding to a myocardial portion. The conduit  12  includes an open first end  28  that is defined by the vascular portion  24 . The conduit  12  also includes an open second end  30  that is defined by the myocardial portion  26 .  
         [0021]    In FIG. 1, a cross-section of the myocardium  32  of a human heart is shown. As can be seen in FIG. 1, in preferred embodiments, the first portion  24  is dimensioned to be received within a lumen  34  of a coronary vasculature  36 . As used herein, the term “vasculature” refers to veins or arteries. Note that the vasculature  36  resides exterior of the myocardium  32 . The second portion  26  is dimensioned to extend from the vasculature  36  through the myocardium  32  and into a heart chamber  38 . In preferred implementations, the heart chamber  38  will be the left ventricle  40 . As can be seen in FIG. 1, the conduit  12  defines a blood flow pathway  42  within the interior  18  between the open first end  28  and the open second end  30 . This allows for the flow of oxygenated blood directly from the left ventricle  40  through the pathway  42  and into the vasculature  36 .  
         [0022]    Turning now to FIG. 4, the implant  10  is illustrated enlarged and in cross-section. The implant  10  is shown as it would appear before being operably inserted in the environment shown in FIG. 1. In reference now to FIG. 2, in preferred embodiments, the implant  10  includes a scaffold  50  to provide framework or support overall to the implant  10 . The scaffold  50  is generally made from a material that will provide strength and integrity to the overall implant  10  and with which will be able to withstand the muscular pressure exerted by systolic and diastolic contractions of the myocardium  32 . The scaffold  50  may either be impermeable or permeable. Suitable materials for the scaffold  50  include titanium or stainless steel. If the scaffold  50  is designed to be permeable, the scaffold  50  is formed into a matrix such as a permeable mesh.  
         [0023]    In the embodiment shown in FIG. 2, the scaffold  50  defines an interior volume  52 , a first end  54  and an opposite, second end  56 . The scaffold  50  also defines an exterior surface  58  and an opposite, interior surface  60 . As can be seen in FIG. 2, the interior surface  60  is immediately adjacent to and lines the interior volume  52 . In the particular embodiment shown in FIG. 2, the scaffold  50  is non-straight. In particular, the scaffold  50  defines an interior angle between a first portion  62  and a second portion  64 . In the embodiment shown, the angle between the first portion  62  and the second portion  64  is between 80°-100°, inclusive, preferably 90°. As such, the scaffold  50  is L-shaped.  
         [0024]    In reference now to FIG. 3, the scaffold  50  is shown with a tubing  70  in covering relation to the scaffold  50 . As can be seen in FIG. 3, the scaffold interior surface  60  is completely covered by the tubing  70  from the scaffold first end  54  all the way to the scaffold second end  56 . Together, the scaffold interior surface  60  and the tubing  70  define a lumen  72 . The lumen  72  corresponds to the interior  18  of the finished implant  10 . The lumen  72  also forms at least a part of the blood pathway  42  (FIG. 1).  
         [0025]    Still in reference to FIG. 3, the scaffold exterior surface  58  is also completely covered by the tubing  70  from the scaffold first end  54  to the scaffold second end  56 . In this context, by “completely covered”, it is meant that the tubing  70  is continuous and without apertures, openings, passages, slits, slots, or other voids such that it forms a complete blanket over the scaffold  50  protecting the scaffold  50  from any exposures. From a review of FIG. 3, it can be seen that the tubing  70  completely encases the scaffold  50  to provide protection, durability, strength, and vascular compatibility to the scaffold  50 . In preferred embodiments, the tubing  70  is made from expanded polytetrafluoroethylene (ePTFE).  
         [0026]    FIGS.  2 - 4  illustrate example steps that may be followed to construct the implant  10 . In FIG. 2, the tubing  70  is shown extended through the interior volume  52  of the scaffold  50 . One way of accomplishing this step is by providing the scaffold  50  and inserting the tubing  70  through the interior volume  52  of the scaffold  50 .  
         [0027]    In general, the tubing  70  includes a wall  74  having a circular cross-section, such that the tubing  70  is generally cylindrical in shape. The tubing  70  includes an open first end  76 , and an opposite, open second end  78 . As can be seen in FIG. 2, the tubing  70  can be divided into three sections: a first section  80 , a second section  82 , and a third section  84 . The first section  80  is a portion of the tubing that, during this step of the construction process in FIG. 2, extends from the first end  54  of the scaffold  50  exterior of the scaffold  50  in this step (but it is in subsequent steps, FIG. 3). That is, the first section  80  is not in contact with the scaffold  50 . The second section  82  extends between the first section  80  and the third section  84 . The second section  82  is the portion of the tubing  70  that is adjacent to and in contact with the scaffold  50  between the first end  54  and the second end  56 . In the construction step shown in FIG. 2, the second section  82  extends along the interior surface  60  of the scaffold  50 . The third section  84  projects from the second end  56  of the scaffold  50 . The third section  84  is not in contact with the scaffold  50 . The third section  84  defines the open second end  78 , while the first section  80  defines the first open end  76 .  
         [0028]    [0028]FIG. 3 shows another step for constructing the implant  10 . In FIG. 3, the tubing  70  can be seen to include at least a first fold  86  covering the scaffold first end  54 . This may be accomplished by folding the first section  80  of the tubing  70  back against itself around the first end  54  and to cover the exterior surface  58  of the scaffold  50 . In the particular embodiment shown, the first end  76  of the tubing  70  is adjacent to and against the scaffold second end  56 . As can be seen in FIG. 3, the third section  84  remains in the same form that it was in FIG. 2, that is, extending from the scaffold second end  56 , with the tubing second end  78  being remote from the scaffold  50 .  
         [0029]    Next, the tubing  70  and the scaffold  50  are bonded together to form a composite  90 . The bonding may be done in a variety of methods including mechanical bonding, chemical bonding, and thermal bonding. FIG. 4 illustrates the resulting implant  10  after the tubing  70  and the scaffold  50  have been bonded together. The resulting implant  10  in FIG. 4 is the same implant shown in FIG. 1.  
         [0030]    Reference is now made to FIGS.  5 - 9 . FIG. 5 illustrates another embodiment of an implant  100 . The implant  100  is shown within a blood vessel  102 . The blood vessel  102  can be a coronary vessel or any of the vessels in the lumen body. The implant  100  can be used to extend through the myocardium of a human heart, as described above in connection with the embodiment of FIG. 1. The implant  100  functions as a stent  103  to help insure the passage of blood through a pathway  104 . In the one shown in FIG. 5, the implant  100  is cylindrical in shape having a wall  106 , opposite first and second ends  108 ,  110 , and an interior volume  112 . The interior volume  112  forms a portion of the blood pathway  104 .  
         [0031]    FIGS.  6 - 8  show steps in constructing the implant  100 . As with the embodiment of FIGS.  1 - 4 , the implant  100  includes a scaffold  114  and tubing  116 . The scaffold  114 , in this embodiment, is straight and unbent. The scaffold  114  defines first and second opposite ends  118 ,  120 , an exterior surface  122 , and an opposite interior surface  124 .  
         [0032]    Still in reference to FIG. 6, the tubing  116  has an open first end  126  and an opposite second end  128 . The tubing  116  can be divided into first, second, and third sections  131 ,  132 , and  133 , respectively. The first section  131  extends from the first end  118  of the scaffold  114  and is not in immediate contact with the scaffold  114  in FIG. 6. The second section  132  is the portion of the tubing  116  that is in contact with the scaffold  114 . The second section  132  extends between the first and second ends  118 ,  120  and lines the interior surface  124  of the scaffold  114 . The third section  133  extends from the scaffold  114  from the second end  120  and does not immediately contact the scaffold  114  in the FIG. 6 illustration.  
         [0033]    [0033]FIG. 7 illustrates a second step in forming the implant  100 . In FIG. 7, the implant  100  is shown after the first section  131  has been folded around the first end  118  of the scaffold  114  to form a first fold  136  in the tubing  116 . Also shown in FIG. 7, the third section  133  has been folded around the second end  120  of the scaffold  114  to form a second fold  138  in the tubing  116 . As can be appreciated by reviewing FIG. 7, the tubing  116  is folded back around each of the ends  118 ,  120  such that the tubing  116  completely encases the scaffold  114 . That is, the first section  131  is folded around the first end  118  to cover the exterior surface  122 , as the third section  133  is folded around the second end  120  to also cover the exterior surface  122 . The first end  126  of the tubing  116  meets up with the second end  128  of the tubing  116  in a manner in which the ends  126 ,  128  either abut each other or overlap to form a seam or joint  140 . The joint  140  can be along any portion of the scaffold  114 . In the particular embodiment shown in FIG. 7, the joint  140  is at about the mid point between the first and second ends  118 ,  120  of the scaffold  114 .  
         [0034]    [0034]FIG. 8 illustrates the implant  100  after the tubing  116  and scaffold  114  are bonded to form bonded structure  142 . As with the implant  10 , the implant  100  may be formed by one or combinations of mechanical bonding, chemical bonding, and thermal bonding.  
         [0035]    The implant  100  can include an optional sleeve or cuff  144  around the joint  140  containing a tissue integration material, such as tissue growth inducing substances. This is described in commonly assigned U.S. Pat. No. 5,984,956, which is incorporated by reference herein.  
         [0036]    Attention is next directed to the embodiment of FIGS.  10 - 12 . An implant  150  is shown in FIG. 12, with steps in constructing the implant  150  shown in FIGS. 10 and 11. The implant  150  is analogous to the implant  10  of FIGS.  1 - 4  with the exception that the implant  150  is straight and unbent. The implant  150  is not L-shaped as the implant  10 .  
         [0037]    Other than the lack of an angle, the implant  150  is the same as the implant  10 . As such, the implant  150  includes a scaffold  152  and tubing  154 . The tubing  154  is bent around a first end  156  of the scaffold  152  to form a fold  158  adjacent to and against the first end  156 . The tubing  154  is folded over the scaffold  152  such that the first end  160  of the tubing  154  is adjacent to and against the second end  162  of the scaffold  152 . In this manner, the tubing  154  completely encases the scaffold  152  by completely lining the interior surface  164  of the scaffold  152  and covering the exterior surface  166  of the scaffold  152 . A second section  168  of the tubing  154  remains extending from the second end  162  and is out of immediate and adjacent contact with the scaffold  152 . FIG. 12 shows the implant  150  after the scaffold  152  and tubing  154  are bonded to form a bonded implant structure  170 . Again, the bonding can be done by one of, or combinations of, mechanical, chemical, and thermal bonding.  
         [0038]    From a review of each of the embodiments in FIGS.  1 - 12 , it should be appreciated that the implants formed have scaffolds that are completely encased and covered by tubing. In preferred embodiments, there is no portion of the scaffold wall (including interior surface, exterior surface, and end rims) that is left exposed—all of these portions are covered by the tubing.  
         [0039]    The implants  10 ,  100 , and  150  can be used to treat human patients. In one application, the implant can be used in a method for performing a coronary vessel bypass procedure. This method includes forming a blood flow path, such as pathway  42  from heart chamber  38  directly to the coronary vessel  36  at a site in the vessel positioned between an obstruction in the vessel and tissue of the heart to be supplied with blood by the vessel. This step includes placing the implant  10 ,  100 ,  150  in the heart wall  32  between the chamber  38  and the vessel  36  with one end of the implant  10 ,  100 ,  150  protruding into the chamber  38  beyond an interior surface of the heart wall  32 . The method includes the implant having tubing completely lining an interior surface and completely lining an exterior surface between opposite ends of the implant.  
         [0040]    Methods for treating human patients also may include forming a blood path in a blood vessel by positioning an implant in the vessel. The implant would include implants of the type described herein.  
         [0041]    The above description represents a complete description of example embodiments incorporating principles of the inventions. Many embodiments can be made.