Abstract:
A stent graft ( 10; 40; 80 ) has a tubular body ( 12; 42; 82 ) of a biocompatible material and at least two fenestrations ( 18, 20; 48, 50; 84, 86, 88 ). The at least two fenestrations ( 10, 20; 48, 50; 84, 86, 88 ) are adjacent each other and each has a tube ( 24, 26; 54, 55; 90, 92, 94 ) extending into the tubular body ( 12; 42; 82 ). The tubes ( 24, 26; 54, 55; 90, 92, 94 ) are joined inside the tubular body ( 12; 42; 82 ) into a single larger tube ( 30; 60; 96 ) to facilitate catheterization.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to a medical device and more particularly to a stent graft for endovascular deployment. In particular, the invention relates to the configuration of branched stent grafts. 
       BACKGROUND OF THE INVENTION 
       [0002]    Stent grafts have been devised for endovascular deployment to bypass a diseased portion of a vessel and such. stent grafts can be deployed into body vessels such as the aorta. Where there are branches from the bodily vessel such as the aorta it is desirable to have a branch in the stent graft so that flow into the branch vessel is possible. 
         [0003]    In the renal and suprarenal region of aorta, the use of a stent graft with branches extending from the stent graft is difficult and there have been proposed stent grafts with internal branches into which can be deployed a side arm extension to extend from the internal branch of the stent graft into a branch vessel. 
         [0004]    It can be difficult however to catheterize such internal legs. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention seeks to provide a stent graft with a construction that facilitates catheterization particularly where there are multiple branches to be connected. Preferred embodiments of the invention will be particularly discussed in relation to deployment of a stent graft into the renal and suprarenal regions of the aorta for deployment of a stent graft into the coeliac artery, the superior mesenteric artery and the renal arteries. However, the invention is not so limited and may be applied to other regions where there are branches from a main graft, such as in the thoracic arch. 
         [0006]    Throughout this specification the term distal with respect to a portion of the aorta, a deployment device or a prosthesis is the end of the aorta, deployment device or prosthesis further away in the direction of blood flow from the heart, and the term proximal means the portion of the aorta, deployment device or end of the prosthesis nearer to the heart. When applied to other vessels similar terms such as caudal and cranial should be understood. 
         [0007]    In one form, therefore, although this may not necessarily be the only or broadest form, an aspect of the invention provides a stent graft including a tubular body of a biocompatible material, at least two fenestrations in the tubular body, the at least two fenestrations being adjacent each other, a tube extending into the tubular body from each fenestration and the tubes being joined and opening into a single tube of larger diameter within the tubular body of the stent graft. 
         [0008]    It will be seen that by having at least two tubes extending from fenestrations opening into a larger single tube, it is easier to catheterise by presenting a larger tube into which a guide wire can be deployed for instance by brachial access to enter the larger tube and subsequently one or other of the smaller tubes. The single tube of larger diameter thus acts as a guide to a catheter and provides a funnelling function to the at least two tubes. 
         [0009]    In the case where the stent graft according to a preferred embodiment of the present invention is intended for use in the suprarenal region, the tubes extend toward the proximal end of the stent graft from the fenestration. 
         [0010]    In a preferred embodiment the tubular body has a tapered portion and the fenestrations are provided in the tapered portion. In the region of the coeliac and superior mesenteric arteries, the aorta tapers as these major branch vessels extend from the aorta and tapering of the stent graft assists with maintaining a good blood flow and pressure in the stent graft. 
         [0011]    The single tube of larger diameter is preferably joined to the wall of the tubular body so that it is held to one side of the lumen through the stent graft and can be relatively easily located using a guide wire. 
         [0012]    In one embodiment, the at least two tubes may extend to positions that are adjacent laterally around the tubular body or that are adjacent longitudinally along the tubular body. 
         [0013]    In an embodiment, there may be three fenestrations and three tubes extending to a single larger tube from the three fenestrations. 
         [0014]    At least one of, and preferably each of, the fenestrations may include at least one reinforcing ring of nitinol wire therearound. 
         [0015]    Preferably the single tube of larger diameter includes zig-zag self expanding stent and/or at least one of, and preferably each of, the tubes extending from the fenestrations also includes zig-zag self expanding stent. The zig-zag self-expanding stent may, in either case, be external. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0016]    Preferred embodiments of the present invention are now described, by way of example only, with reference to the accompanying drawings, in which: 
           [0017]      FIG. 1  shows a side view of a first embodiment of a stent graft; 
           [0018]      FIG. 2  shows a cross-sectional view of the stent graft of  FIG. 1  along the lines  2 - 2 ′ of  FIG. 1 ; . 
           [0019]      FIG. 3  shows a cross-sectional view of the stent graft of  FIG. 1  along the lines  3 - 3 ′ in  FIG. 2 ; 
           [0020]      FIGS. 4A to 4E  show a top view and cross-sectional views at various levels as shown in  FIG. 2 ; 
           [0021]      FIG. 5  shows another embodiment of a stent graft; 
           [0022]      FIG. 6  shows a cross-sectional view of the stent graft of  FIG. 5  along the lines  6 - 6 ′ of  FIG. 5 ; 
           [0023]      FIG. 7  shows a cross-sectional view of the stent graft of  FIG. 5  along the lines  7 - 7 ′ in  FIG. 6 ; 
           [0024]      FIGS. 8A to 8E  show a top view and cross-sectional views at various levels as shown in  FIG. 6 ; 
           [0025]      FIG. 9  shows another embodiment of a stent graft; and 
           [0026]      FIG. 10  shows a view of the stent graft of  FIG. 9  from the proximal end. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Looking more closely at the drawings and in particular  FIGS. 1 to 4  showing a first embodiment of a stent graft, it will be seen that stent graft  10  has a tubular body  12  of a biocompatible material, which includes a tapered central region  14 . The tubular body is supported by stents  16 . Preferably these stents are self expanding Gianturco zig-zag Z stents but other forms of stents may also be included or used. 
         [0028]    In the tapered region  14 , there are at least two fenestrations  18  and  20  defined by a resilient nitinol wire  22  around the periphery of the fenestration. 
         [0029]    As can be seen in  FIG. 2 , there are a pair of tubes  24  and  26  extending up from the fenestrations  18  and  20  towards the proximal end  28  of the stent graft  10  and these tubes  24  and  26  open into a single larger tube  30  which opens into the lumen  32  of the stent graft  10 . The larger tube  30  is  10  connected by stitching  34  to the tubular body  24  and a zig-zag self-expanding stent  36  is deployed around the outside of the larger body to enable or maintain patency once deployed and released within the human or animal body. 
         [0030]    Although  FIGS. 1 and 2  show a pair of tubes  24  and  26 , there may be provided more than two of such tubes. 
         [0031]      FIG. 4  shows various cross-sectional views of the stent graft shown in  FIGS. 1 to 3 . 
         [0032]    A top view of the stent graft is shown in  FIG. 4A . The stent graft tubular body  12  has the at least two tubes  24  and  26  opening into a single tube  30  and the single tube  30  is joined to the tubular wall  12  at  34  so that the tube  30  is held to one side of the tubular body. 
         [0033]      FIG. 4B  shows a cross-sectional view at the level B shown in  FIG. 2 . The larger tube  30  is shown in section and the smaller tubes  24  and  26  can be seen extending down from it within the lumen  32  of the stent graft tubular body  12 . 
         [0034]      FIG. 4C  shows a cross-sectional view at the level C shown in  FIG. 2 . The smaller tubes  24  and  26  can be seen in cross-section within the lumen  32  of the stent graft tubular body  12 . 
         [0035]      FIG. 4D  shows a cross-sectional view at the level D shown in  FIG. 2 . It can be seen that the tubular body  12  is of lesser diameter because the tubular body is in the tapered portion  14  and only the tube  24  can be seen in cross-section. 
         [0036]    Further distally, at the cross-section E as shown in  FIG. 4 , the tubular body is substantially circular but of lesser diameter than further up. 
         [0037]    The smaller tubes  24  and  26  could be provided with one or more self-expanding stents therein to maintain patency of the tubes once the stent graft has been deployed. 
         [0038]    Now looking at  FIGS. 5 to 8 , showing an alternative embodiment of a stent graft according to the present invention, it will be seen that stent graft  40  has a tubular body  12  which includes a tapered central region  44 . The tubular body is supported by stents  46 . Preferably these stents are self-expanding Gianturco zig-zag Z stents but other forms of stents may also be included or used. 
         [0039]    In the tapered region  14 , there are at least two fenestrations  48  and  50  defined by a resilient nitinol wire  52  around the periphery of the fenestration. 
         [0040]    As can be seen in  FIGS. 6 and 7 , there are a pair of tubes  54  and  55  extending up from the fenestrations  48  and  50  towards the proximal end  58  of the stent graft  40  and these tubes  54  and  55  open into a single larger tube  60  which opens into the lumen  62  of the stent graft  40 . The larger tube  60  is connected by stitching  64  to the tubular body  44 . 
         [0041]    As with the first disclosed embodiment, this embodiment could also have more than two tubes  48 ,  50 . 
         [0042]    As can be particularly seen in  FIG. 7  the larger tube  60  has a zig-zag self-expanding stent  66  deployed around the outside of the larger tube to enable or maintain patency once deployed and released within the human or animal body. The smaller tubes  54  and  55  extending from the fenestrations  48  and  50  also have zig-zag self expanding stents  57  deployed around their outsides to maintain patency of these tubes once the stent graft has been deployed and released within the human or animal body. 
         [0043]      FIG. 8  shows various cross-sectional views of the stent graft shown in  FIGS. 5 to 7 . 
         [0044]    A top view of the stent graft is shown in  FIG. 8A . The stent graft tubular body  42  has the at least two tubes  54  and  55  opening into a single tube  60  and the single tube  60  is joined to the tubular wall  42  at  64  so that the tube  60  is held to one side of the tubular body. 
         [0045]      FIG. 8B  shows a cross-sectional view at the level B shown in  FIG. 6 . The larger tube  60  is shown in section and the smaller tubes  54  and  55  can be seen extending down from it within the lumen  62  of the stent graft tubular body  42 . 
         [0046]      FIG. 8C  shows a cross-sectional view at the level C shown in  FIG. 6 . The smaller tubes  54  and  65  can be seen in cross-section within the lumen  62  of the stent graft tubular body  42 . 
         [0047]      FIG. 8D  shows a cross-sectional view at the level D shown in  FIG. 6 . It can be seen that the tubular body  42  is of lesser diameter because the tubular body is in the tapered portion  44  and part of the tubes  54  and  55  can be seen in cross-section. 
         [0048]    Further distally at the cross-section E as shown in  FIG. 8  the tubular body is substantially circular but of lesser diameter than further proximally. 
         [0049]      FIG. 9  shows another embodiment of the stent graft according to the present invention. In this embodiment the stent graft has a tubular body  80  supported by stents  82 . In this embodiment there are at least three fenestrations  84 ,  86  and  88  and three tubes  90 ,  92 ,  94 , extending from the fenestrations  84 ,  86  and  88  respectively. In this embodiment the fenestrations  84 ,  86  and  88  are arranged in a substantially triangular pattern. 
         [0050]    As can be seen in  FIG. 10 , the three tubes  90 ,  92  and  94  open into a single larger tube  96  within the lumen  98  of the tubular body  80 . 
         [0051]    Throughout this specification various indications have been given as to the scope of this invention but the invention is not limited to any one of these but may reside in two or more of these combined together. The examples are given for illustration only and not for limitation. 
         [0052]    Throughout this specification and the claims that follow unless the context requires otherwise, the words ‘comprise’ and ‘include’ and variations such as ‘comprising’ and ‘including’ will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. 
         [0053]    The disclosures of U.S. Pat. No. 60/838,776 and in the Abstract accompanying this application are incorporated herein by reference.