Patent Publication Number: US-2012029611-A1

Title: Stent Graft System and Method of Use

Description:
TECHNICAL FIELD 
     The technical field of this disclosure is medical implantation devices, particularly, a stent graft system and method of use. 
     BACKGROUND 
     Stent grafts have been developed for the treatment of abdominal aortic aneurysms. An abdominal aortic aneurysm is a bulge that forms in the wall of the abdominal aorta, which is the main vessel of the arterial system of the body that extends through the abdomen. Abdominal aortic aneurysms can have various causes, such as high blood pressure, accident, or atherosclerosis, and can lose elasticity over time and rupture under normal blood pressure. A stent graft is typically a woven tube (graft) supported by one or more tubular metal or plastic stents. The stent graft is placed inside and spanning an aneurysm to exclude the abdominal aortic aneurysm from normal blood flow and reduces pressure on the aneurysmal vessel. 
     Presently, stent grafts include a number of pieces that are assembled within the patient to provide the finished stent graft assembly. The main larger piece includes a trunk with two descending limbs: an iliac limb and a contralateral limb. The contralateral limb can be shorter than or equal in length to the iliac limb, but both have a length extending from the trunk. A limb segment is deployed in the contralateral limb to extend between the contralateral limb and the iliac artery. Iliac extension stent grafts can be used to extend the iliac limb and/or the limb segment as required. Unfortunately, the number of parts required for the stent graft increases manufacturing and inventory costs. The stent graft pieces must be manufactured and stocked in a number of lengths and diameters at the supplier and at the hospital, so each separate part greatly increases the complexity of the therapy delivery. 
     The present stent grafts also present challenges during deployment. The typical contralateral limb has a small opening, making it difficult to locate and feed in a guidewire for guiding deployment of the limb segment in the contralateral limb. In addition, the thickness of the graft material when compressed creates bulk (volume) which limits the amount of graft material and thereby the diameter of the stent graft delivery configuration that can be compressed into a given size catheter, limiting flexibility and deployment location access. 
     It would be desirable to have a stent graft system and method of use that would overcome the above disadvantages. 
     SUMMARY 
     One aspect according to the present invention provides a stent graft system including a first stent graft component and a second stent graft component. The first stent graft component includes a first tubular graft having an integral first body and first leg, the first body having a first longitudinal axis, the first body defining a first crown opening and a first substantially elliptical opening, the first substantially elliptical opening being oriented at a first acute angle to the first longitudinal axis. The second stent graft component includes a second tubular graft having an integral second body and second leg, the second body having a second longitudinal axis, the second body defining a second crown opening and a second substantially elliptical opening, the second substantially elliptical opening being oriented at a second acute angle to the second longitudinal axis. The second body is disposed in the first body, and the second leg is disposed through the first substantially elliptical opening with the perimeter of the first elliptical opening in contact with the second body. 
     Another aspect according to the present invention provides a stent graft including a tubular graft having an integral body and leg, the body having a longitudinal axis, the body defining a crown opening and a substantially elliptical opening, the substantially elliptical opening being oriented at an acute angle to the longitudinal axis; an elliptical opening stent operably connected to the substantially elliptical opening; and a crown stent operably connected around the crown opening. 
     Another aspect according to the present invention provides a method of use of a stent graft system including positioning a first stent graft component in a first compressed configuration at a deployment site. The first stent graft component includes a first tubular graft having an integral first body and first leg, the first body having a first longitudinal axis, the first body defining a first crown opening and a first substantially elliptical opening, the first substantially elliptical opening being oriented at a first acute angle to the first longitudinal axis; and a first elliptical opening stent operably connected to the first substantially elliptical opening. The method further includes releasing the first stent graft component from the first compressed configuration to expand at the deployment site; and advancing a second stent graft component in a second compressed configuration through the first substantially elliptical opening to the deployment site. The second stent graft component includes a second tubular graft having an integral second body and second leg, the second body having a second longitudinal axis, the second body defining a second crown opening and a second substantially elliptical opening, the second substantially elliptical opening being oriented at a second acute angle to the second longitudinal axis; and a second elliptical opening stent operably connected to the substantially elliptical opening. The method further includes releasing the second stent graft component from the second compressed configuration to expand with the second body within the first body and the second leg disposed through the first substantially elliptical opening with the perimeter of the first substantially elliptical opening in contact with the second body. 
     The foregoing and other features and advantages will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a stent graft component; 
         FIG. 2  is a side view of a stent graft system; 
         FIG. 3  is a side view of an assembled stent graft system; 
         FIG. 4  is a flow chart of a method of creating a stent graft system; 
         FIGS. 5A-5F  are cut-away side views of a method of creating a stent graft system; 
         FIG. 6  is a close-up view of an elliptical opening stent for a stent graft system; 
         FIGS. 7-9  are additional embodiments of a stent graft component; and 
         FIGS. 10A-10D  are various views of an exemplary stent graft system; 
         FIGS. 11A &amp; 11B  are side views of another exemplary stent graft system; and 
         FIG. 12  is a side view of another exemplary assembled stent graft system. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a side view of a stent graft component. The first stent graft component  100  includes a tubular graft  110 , an elliptical opening stent  130 , a crown stent  132 , body stents  134 , and leg stents  136 . The tubular graft  110  has an integral body  112  and leg  114 . In this example, the body  112  has a longitudinal axis  116  and a leg intersection point  118  near the longitudinal axis  116  where the leg  114  meets the body  112 . The body  112  defines a crown opening  122  and a substantially elliptical opening  124 . The substantially elliptical opening  124  is oriented at an acute angle α to the longitudinal axis  116 . The elliptical opening stent  130  is operably connected to the substantially elliptical opening  124 , the crown stent  132  is operably connected around the crown opening  122 , the body stents  134  are operably connected around the body  112 , and the leg stents  136  are operably connected around the leg  114 . In this example, the elliptical opening stent  130  is attached to several of the body stents  134 . In one embodiment, the acute angle α is between 20 degrees and 70 degrees. In another embodiment, the acute angle α is about 30 degrees. The longitudinal axis  116  is generally parallel to the sides of the body  112  and need not be located in the center of the body  112 . The body  112  can be symmetrical in cross section, or can have the larger portion aligned with the leg  114  or the substantially elliptical opening  124 . 
     Those skilled in the art will appreciate that the stent graft component can be adapted as desired for a particular application. Substantially elliptical as used herein in conjunction with the substantially elliptical opening is defined as having a generally elliptical shape, such as a regular or irregular ellipse, circle, oval, egg shape, eggplant shape, tear drop shape, or the like. The perimeter of the generally elliptical shape can include minor deviations from the generally elliptical shape as desired for a particular application, e.g., the perimeter can be peanut shaped. In one embodiment, the elliptical opening stent extends around the whole perimeter of the substantially elliptical opening. In another embodiment, the elliptical opening stent extends partially around the perimeter of the substantially elliptical opening. In yet another embodiment, the elliptical opening stent includes a number of separate stent segments extending partially or fully around the perimeter of the substantially elliptical opening. In yet another embodiment, the elliptical opening stent is one of the other stents, such as the body stent, with a portion of the body stent urging open the substantially elliptical opening without necessarily following the perimeter of the substantially elliptical opening. The elliptical opening stent as used herein is defined as any stent or portion of a stent that urges open the substantially elliptical opening when the stent graft component is in an expanded configuration. In yet another embodiment, no elliptical opening stent is provided around the substantially elliptical opening. 
     The stent graft component can be made of any suitable biocompatible materials. Exemplary materials for the elliptical opening stent  130 , crown stent  132 , body stent  134 , and leg stent  136  include stainless steels, such as 316L stainless steel; shape memory alloys, such as nitinol; and nickel-cobalt-chromium-molybdenum alloy, such as MP35N® alloy available from SPS Technologies, Inc., of Jenkintown, Pa.; titanium; tantalum; or the like. Those skilled in the art will appreciate that various stent configurations are possible. In one alternative, the stent is woven into the graft material. In another alternative, the stent is added when the stent graft component is at the deployment site, by injecting a hardenable material into recesses within the stent graft component. 
     Exemplary materials for the tubular graft  110  include biocompatible, blood-impermeable graft membranes, such as polyester, polyethylene, expanded polytetrafluoroethylene (ePTFE), polyurethane, propylene, nylon, and the like. In one embodiment, the material for the tubular graft  110  can be thinner than conventional graft material because the two bodies of the stent graft components overlap in the assembled stent graft system. 
       FIG. 2 , in which like elements share like reference numbers with  FIG. 1 , is a side view of a stent graft system. The stent graft system  101  includes first stent graft component  100  and second stent graft component  200 . In this example, the first stent graft component  100  is identical to the second stent graft component  200 , although in other embodiments the stent graft components can be different in size and/or shape. 
     The second stent graft component  200  includes a tubular graft  210 , an elliptical opening stent  230 , a crown stent  232 , body stents  234 , and leg stents  236 . The tubular graft  210  has an integral body  212  and leg  214 . The body  212  has a longitudinal axis  216  and a leg intersection point  218  on the longitudinal axis  216  where the leg  214  meets the body  212 . The body  212  defines a crown opening  222  and a substantially elliptical opening  224 . The elliptical opening stent  230  is operably connected to the substantially elliptical opening  224 , the crown stent  232  is operably connected around the crown opening  222 , the body stents  234  are operably connected around the body  212 , and the leg stents  236  are operably connected around the leg  214 . In this example, the elliptical opening stent  230  is attached to several of the body stents  234 . Also in this example, the crown stent  132  and the crown stent  232  each includes an odd number of peaks beyond the graft material of the body  112  and body  212 , respectively, so that when the components are combined the peaks are complementary and follow the whole perimeter of the crown opening to form a continuous row of peaks when the stent graft system is assembled. Those skilled in the art will appreciate that the number and configuration of the crown stent peaks can be selected as desired for a particular application. In another embodiment, the number of peaks can be even. In one embodiment, the peaks are aligned so the peaks of one stent graft component overlap the peaks of the other stent graft component, providing an overlapping double row of peaks when the stent graft system is assembled. 
       FIG. 3 , in which like elements share like reference numbers with  FIG. 2 , is a side view of an assembled stent graft system. The assembled stent graft system  300  has body  212  of the second stent graft component  200  disposed in the body  112  of the first stent graft component  100 . In this example, the crown opening  222  of the second stent graft component  200  substantially aligned with the crown opening  122  of the first stent graft component  100 . In one embodiment, the body  212  is held in place relative to the body  112  by friction of the interference fit between the body  212  and the body  112 . In one embodiment, the body  212  is held in place relative to the body  112  by operably connecting the body  212  to the body  112  with fasteners, such as sutures, staples, hooks, anchors, adhesives, rivets, screws, or the like. The second leg  214  of the second stent graft component  200  is disposed through the substantially elliptical opening  124  of the first stent graft component  100  with the perimeter of the first elliptical opening  124  in contact with the body  212  of the second stent graft component  200 . The longitudinal axis  116  of the first stent graft component  100  is substantially aligned with the longitudinal axis  216  of the second stent graft component  200 . In this example, the peaks of the crown stent  132  and the crown stent  232  alternate around the perimeter of the crown opening. Substantially aligned as used herein in conjunction with the crown opening  222  and crown opening  122  is defined as being generally coplanar, with allowance for minor angular and/or axial (dimensional) offsets that do not affect function. In another embodiment, the body of one of the stent graft components is longer than the body of the other stent graft component, so that the crown openings are not aligned. This allows the crown stent of one stent graft component to contact the aorta at a position longitudinally offset from the position where the crown stent of the other stent graft component contacts the aorta. In yet another embodiment, the crown openings are not aligned due to the particular placement of the individual stent graft components even though the body of the two stent graft components are the same length. 
     Those skilled in the art will appreciate that additional stent graft components can be added to the stent graft system as desired for a particular application. In one example, a seal graft, such as a tubular graft with or without supporting stents, can be placed within the body of the second stent graft component and the leg of the first stent graft component to seal the joint where the second stent graft component meets the first stent graft component. The seal graft extends across the substantially elliptical opening of the second stent graft component to provide the seal for blood flow from the body of the second stent graft component into the leg of the first stent graft component and out to the vessel. 
       FIG. 4  is a flow chart of the steps of a method of creating a stent graft system. The method  400  includes positioning a first stent graft component in a first compressed configuration at a deployment site  402 ; releasing the first stent graft component from the first compressed configuration to expand at the deployment site  404 ; advancing a second stent graft component in a second compressed configuration through the first substantially elliptical opening to the deployment site  406 ; and releasing the second stent graft component from the second compressed configuration to expand with the second body within the first body  408  and the second leg disposed through the first substantially elliptical opening with the perimeter of the first elliptical opening in contact with the second body. 
     The first stent graft component includes a first tubular graft having an integral first body and first leg, the first body having a first longitudinal axis, the first body defining a first crown opening and a first substantially elliptical opening, the first substantially elliptical opening being oriented at a first acute angle to the first longitudinal axis; and a first elliptical opening stent operably connected to the first substantially elliptical opening. 
     The second stent graft component includes a second tubular graft having an integral second body and second leg, the second body having a second longitudinal axis, the second body defining a second crown opening and a second substantially elliptical opening, the second substantially elliptical opening being oriented at a second acute angle to the second longitudinal axis; and a second elliptical opening stent operably connected to the second substantially elliptical opening. 
     In one embodiment, the method  400  can optionally include attaching the first stent graft component to the second stent graft component with a fastener, such as sutures, staples, hooks, anchors, adhesives, rivets, screws, or the like. In one embodiment, positioning a first stent graft component  402  includes positioning the first stent graft component through the vasculature, such as positioning the first stent graft component in a first compressed configuration at a deployment site through a first common iliac artery, and advancing a second stent graft component  408  includes advancing the second stent graft component from a second common iliac artery through the first substantially elliptical opening. 
       FIGS. 5A-5F , in which like elements share like reference numbers, are cut-away side views of the steps of a method of creating a stent graft system. In this example, the stent graft system is being deployed in an aortic aneurysm. 
     Referring to  FIG. 5A , a guidewire  510  is advanced through the common iliac artery  502  and into the aortic aneurysm  500 . A stent graft delivery system  512  holding a first stent graft component in a compressed configuration is advanced over the guidewire  510  to position the first stent graft component at the deployment site in the aortic aneurysm  500 . 
     Referring to  FIG. 5B , the stent graft delivery system releases the first stent graft component  520  from the compressed configuration to expand at the deployment site. In one embodiment, the stent graft delivery system releases the first stent graft component  520  by retracting a sheath holding the first stent graft component  520  in the compressed configuration. The guidewire can be retracted from the aortic aneurysm  500  after the first stent graft component  520  expands. The body  522  of the first stent graft component  520  is located at the neck  506  of the aortic aneurysm  500  and the leg  524  of the first stent graft component  520  is located in the common iliac artery  502 . The first stent graft component  520  includes a substantially elliptical opening  526  and a crown opening  528 . 
     Referring to  FIG. 5C , a guidewire  540  is advanced through the common iliac artery  504 , the substantially elliptical opening  526 , and the crown opening  528 . 
     Referring to  FIG. 5D , a stent graft delivery system  542  holding a second stent graft component in a compressed configuration is advanced over the guidewire  540  to position the second stent graft component at the deployment site in the aortic aneurysm  500 . 
     Referring to  FIG. 5E , the stent graft delivery system releases the second stent graft component  550  from the compressed configuration to expand at the deployment site. In one embodiment, the stent graft delivery system releases the second stent graft component  550  by retracting a sheath holding the second stent graft component  550  in the compressed configuration. The guidewire can be retracted from the aortic aneurysm  500  after the second stent graft component  550  expands. The body (not shown) of the second stent graft component  550  is located at the neck  506  of the aortic aneurysm  500  and the leg  554  of the second stent graft component  550  is located in the common iliac artery  504 . The second stent graft component  550  includes a substantially elliptical opening  556  (illustrated by dashed lines within the body  522  of the first stent graft component  520 ) and a crown opening  558 . 
     The first stent graft component  520  and second stent graft component  550  fit together to provide a flow path past the aortic aneurysm  500  to the common iliac arteries  502 ,  504 . The body (not shown) of the second stent graft component  550  is located within the body  522  of the first stent graft component  520 . In this example, the crown opening  558  of the second stent graft component  550  is substantially aligned with and inside of the crown opening  528  of the first stent graft component  520 . The leg  554  of the second stent graft component  550  is disposed through the first substantially elliptical opening  526  of the first stent graft component  520  with the perimeter of the first substantially elliptical opening in contact with the body (not shown) of the second stent graft component  550 . The substantially elliptical opening  556  of the second stent graft component  550  is positioned to align with the lumen of the leg  524  of the first stent graft component  520 . In one embodiment, the first stent graft component  520  can be fastened to the second stent graft component  550  as desired to preclude leakage, with fasteners, such as sutures, staples, hooks, anchors, adhesives, rivets, screws, or the like. In another embodiment, a stent graft sleeve can be installed within the first stent graft component  520  and/or the second stent graft component  550  to provide an added seal. 
     Referring to  FIG. 5F , the deployed stent graft system  560  includes the first stent graft component  520  and the second stent graft component  550 . In one embodiment, the material of the tubular graft can be thinner than the material of conventional stent grafts because the bodies of the stent graft components  520 ,  550  overlap at the neck  506  of the aortic aneurysm  500  as illustrated by the hashed portion  562 . Those skilled in the art will appreciate that different deployment approaches are possible as desired for a particular application. For example, in another embodiment, the stent graft system can be deployed without the use of guidewires. In yet another embodiment, the stent graft system can be deployed through the common iliac artery or arteries. 
       FIG. 6  is a close-up view of an elliptical opening stent for a stent graft system. The elliptical opening stent holds the substantially elliptical opening in the stent graft component open to receive the guidewire and stent graft delivery system during deployment and to seal with the other stent graft component after deployment. The elliptical opening stent has a small crossing profile when the stent graft component is in the compressed configuration. In this embodiment, the elliptical opening stent  600  includes a body portion  602  and a spring portion  604 . The body portion  602  has an even profile that allows the body stents to be crimped or wired to the body portion  602 . The spring portion  604  urges the substantially elliptical opening to an open configuration. The elliptical opening stent  600  can be attached to the tubular graft by suture, adhesive, lamination, or the like. The elliptical opening stent  600  need not be affixed directly to the graft material of the tubular graft. 
       FIGS. 7-9  are additional embodiments of a stent graft component.  FIG. 7  is a side view of a stent graft component with a graft flap. The graft flap  700  is a flap of graft material integrally joined to the tubular graft  702 . The graft flap  700  extends outward near the leg intersection point  704  and beyond and around the support stent and springs of substantially elliptical opening  706 . The graft flap  700  can assist in sealing around the substantially elliptical opening between the two stent graft components of the deployed stent graft system. In one embodiment, the graft flap of one stent graft component is operably connected to the other stent graft component with fasteners, such as staples, sutures, adhesives, rivets, screws, or the like. In one embodiment, the graft flap extends partially around the substantially elliptical opening. 
       FIG. 8  is a side view of a stent graft component with an elliptical opening stent having longitudinally oriented peaks and a body elliptical stent. The elliptical opening stent  800  of the stent graft component  802  includes a number of peaks  804 . The axes  806  of the peaks  804  are longitudinally oriented, which is defined as used herein as substantially oriented parallel to the longitudinal axis  808  of the stent graft component  802 . In this embodiment, the stent graft component  802  also includes a body elliptical stent  810  operably connected around the body  812  opposite the substantially elliptical opening  814  and intersecting the leg intersection point  816 . The body elliptical stent  810  in this example also has longitudinally oriented peaks and is symmetrical to the elliptical opening stent  800  across the axial mid-plane of the stent graft component  802 . The body elliptical stent  810  in one stent graft component assists sealing about the other stent graft component in the deployed stent graft system. 
       FIG. 9  is a side view of a stent graft component with an elliptical opening stent having peaks oriented orthogonally to the substantially elliptical opening. The elliptical opening stent  900  of the stent graft component  902  includes a number of peaks  904 . The axes  906  of the peaks  904  are oriented orthogonally to the substantially elliptical opening  908 . 
       FIGS. 10A-10D , in which like elements share like reference numbers, are various views of an exemplary stent graft system. The figures illustrate an exemplary model of a stent graft system. 
       FIG. 10A  is a side view of a stent graft component. The first stent graft component  1000  includes a tubular graft  1010 , a crown stent  1032 , body stents  1034 , and leg stents  1036 . The tubular graft  1010  has an integral body  1012  and leg  1014 . The body  1012  has a longitudinal axis  1016  and a leg intersection point  1018  on or near the longitudinal axis  1016  where the leg  1014  meets the body  1012 . The body  1012  defines a crown opening  1022  and a substantially elliptical opening  1024 . The crown stent  1032  is operably connected around the crown opening  1022 , the body stent  1034  is operably connected around the body  1012 , and the leg stent  1036  is operably connected around the leg  1014 . In this example, some of the body stents  1034  are attached to the perimeter  1030  of the substantially elliptical opening  1024 , so the body stents acts as the elliptical opening stent. 
       FIG. 10B  is a top view of a stent graft component. In this example, the crown stent  1032  includes an odd number of peaks around the perimeter  1021  of the crown opening  1022  and outside the body  1012 . The peaks of one stent graft component are complementary with the peaks of the other stent graft component in the stent graft system, so the peaks follow the whole perimeter of the crown opening to form a continuous row of peaks when the stent graft system is assembled. 
       FIG. 10C  is a side view of a stent graft system. The stent graft system  1001  includes first stent graft component  1000  and second stent graft component  2000 . In this example, the first stent graft component  1000  is identical to the second stent graft component  2000 . The second stent graft component  2000  includes a tubular graft  2010 , an elliptical opening stent  2030 , a crown stent  2032 , a body stent  2034 , and a leg stent  2036 . The tubular graft  2010  has an integral body  2012  and leg  2014 . The body  2012  has a longitudinal axis  2016  and a leg intersection point  2018  on the longitudinal axis  2016  where the leg  2014  meets the body  2012 . The body  2012  defines a crown opening  2022  and a substantially elliptical opening  2024 . The crown stent  2032  is operably connected around the crown opening  2022 , the body stent  2034  is operably connected around the body  2012 , and the leg stent  2036  is operably connected around the leg  2014 . In this example, some of the body stents  2034  are attached to the perimeter  2030  of the substantially elliptical opening  2024 , so the body stents acts as the elliptical opening stent. 
       FIG. 10D  is a side view of an assembled stent graft system. The assembled stent graft system  2001  has body  2012  of the second stent graft component  2000  disposed in the body  1012  of the first stent graft component  1000  with the crown opening  2022  of the second stent graft component  2000  substantially aligned with the crown opening  1022  of the first stent graft component  1000 . The second leg  2014  of the second stent graft component  2000  is disposed through the substantially elliptical opening  1024  of the first stent graft component  1000  with the perimeter of the first elliptical opening  1024  in contact with the body  2012  of the second stent graft component  2000 . The longitudinal axis  1016  of the first stent graft component  1000  is substantially aligned with the longitudinal axis  2016  of the second stent graft component  2000 . In this example, the peaks of the crown stent  1032  and the crown stent  2032  alternate around the perimeter of the crown opening. 
       FIGS. 11A &amp; 11B , in which like elements share like reference numbers, are side views of another exemplary stent graft system. In this example, the body of the stent graft component blends into the leg. The stent graft component in this example does not include a graft flap. Because of the blending, the longitudinal axis is defined as lying along the circumference of the leg and passing through the body. The acute angle between the substantially elliptical opening and the longitudinal axis is defined by the angle between the longitudinal axis and a line in the plane of and bisecting the substantially elliptical opening, although the substantially elliptical opening and the longitudinal axis may not intersect. In this example, no elliptical opening stent is placed around the substantially elliptical opening. 
       FIG. 11A  is a side view of a stent graft system. The stent graft system  3001  includes first stent graft component  3000  and second stent graft component  4000 . In this example, the first stent graft component  3000  is identical to the second stent graft component  4000 . 
     The first stent graft component  3000  includes a tubular graft  3010 , a crown stent  3032 , body stents  3034 , and leg stents  3036 . The tubular graft  3010  has an integral body  3012  and leg  3014 . The body  3012  has a longitudinal axis  3016  lying along the circumference of the leg  3014  and passing through the body  3012 . The body  3012  defines a crown opening  3022  and a substantially elliptical opening  3024 , the perimeter of which is illustrated by dashed lines. The crown stent  3032  is operably connected around the crown opening  3022 , the body stent  3034  is operably connected around the body  3012 , and the leg stent  3036  is operably connected around the leg  3014 . 
     The second stent graft component  4000  includes a tubular graft  4010 , an elliptical opening stent  4030 , a crown stent  4032 , a body stent  4034 , and a leg stent  4036 . The tubular graft  4010  has an integral body  4012  and leg  4014 . The body  4012  has a longitudinal axis  4016  lying along the circumference of the leg  4014  and passing through the body  4012 . The body  4012  defines a crown opening  4022  and a substantially elliptical opening  4024 , the perimeter of which is illustrated by dashed lines. The longitudinal axis  4016  and the substantially elliptical opening  4024  are divided by an acute angle a. The crown stent  4032  is operably connected around the crown opening  4022 , the body stent  4034  is operably connected around the body  4012 , and the leg stent  4036  is operably connected around the leg  4014 . 
       FIG. 11B  is a side view of an assembled stent graft system. The assembled stent graft system  4001  has the body of the second stent graft component  4000  disposed in the body  3012  of the first stent graft component  3000  with the crown opening  4022  of the second stent graft component  4000  substantially aligned with the crown opening  3022  of the first stent graft component  3000 . The second leg  4014  of the second stent graft component  4000  is disposed through the substantially elliptical opening  3024  of the first stent graft component  3000  with the perimeter of the first elliptical opening  3024  in contact with the body of the second stent graft component  4000 . The longitudinal axis  3016  of the first stent graft component  3000  is substantially aligned with the longitudinal axis  4016  of the second stent graft component  4000 . In this example, the peaks of the crown stent  3032  and the crown stent  4032  alternate around the perimeter of the crown opening. 
       FIG. 12  is a side view of another exemplary assembled stent graft system. In this example, the body of one stent graft component is longer than the body of the other stent graft component, so the crown openings of the two stent graft components are not substantially aligned. 
     The first stent graft component  5000  includes a tubular graft  5010 , a crown stent  5032 , body stents  5034 , and leg stents  5036 . The tubular graft  5010  has an integral body  5012  and leg  5014 . The body  5012  has a longitudinal axis  5016  lying along the circumference of the leg  5014  and passing through the body  5012 . The body  5012  defines a crown opening  5022  and a substantially elliptical opening  5024 , the perimeter of which is illustrated by dashed lines. The crown stent  5032  is operably connected around the crown opening  5022 , the body stent  5034  is operably connected around the body  5012 , and the leg stent  5036  is operably connected around the leg  5014 . 
     The second stent graft component  6000  includes a tubular graft  6010 , a crown stent  6032 , body stents (not shown), and leg stents  6036 . The tubular graft  6010  has an integral body  6012  and leg  6014 . The body  6012  has a longitudinal axis  6016  lying along the circumference of the leg  6014  and passing through the body  6012 . The body  6012  defines a crown opening  6022  and a substantially elliptical opening (not shown). The crown stent  6032  is operably connected around the crown opening  6022 , the body stent (not shown) is operably connected around the body  6012 , and the leg stent  6036  is operably connected around the leg  6014 . 
     The assembled stent graft system  6001  has the body  6012  of the second stent graft component  6000  disposed in the body  5012  of the first stent graft component  5000  with the crown opening  6022  of the second stent graft component  6000  aligned longitudinally above the crown opening  5022  of the first stent graft component  5000 . The second leg  6014  of the second stent graft component  6000  is disposed through the substantially elliptical opening  5024  of the first stent graft component  5000  with the perimeter of the first elliptical opening  5024  in contact with the body  6012  of the second stent graft component  6000 . The longitudinal axis  5016  of the first stent graft component  5000  is substantially aligned with the longitudinal axis  6016  of the second stent graft component  6000 . 
     While specific embodiments are disclosed herein, various changes and modifications can be made without departing from the spirit and scope of the invention.