Abstract:
A prosthesis having a tubular body of a biocompatible graft material having a proximal end, a distal end, a lumen therethrough, and a sidewall. The prosthesis includes at least one perfusion branch extending from the sidewall of the tubular body and having a proximal end, a distal end, and a lumen therethrough, where the lumen of the perfusion branch is in temporary fluid communication with the lumen of the tubular body. The perfusion branch comprises a self-sealing component, that after predetermined period of time precludes fluid flow out of the distal end of the perfusion branch.

Description:
TECHNICAL FIELD 
     This invention relates to a medical device for use in relation to endovascular surgery. 
     BACKGROUND 
     Stent grafts, including fenestrated, branched and bifurcated stent grafts, for the treatment of aortic and thoracoabdominal aneurysms and other related vascular diseases are well known. One of the major complications associated with surgical treatment of thoracic and thoracoabdominal aortic aneurysms using a stent graft is paraplegia. During surgical repair, the intercostal and/or lumbar arteries may be acutely occluded resulting in a loss of blood circulation to the spinal arteries and ultimately leading to paraplegia. 
     Some current stent grafts include a perfusion branch that is similar to branches used to connect bridging stents to the renal arteries. The perfusion branch perfuses the aneurysm sac and allows blood circulation to the spinal arteries during surgery. These perfusion branches require a separate procedure after implantation to seal the perfusion branch from the aneurysm with a vascular occluder and prevent blood flow to the aneurysm. To overcome this limitation, it would be advantageous to provide a self-closing perfusion branch that does not require a separate surgery to seal the perfusion branch from the aneurysm. 
     BRIEF SUMMARY 
     A prosthesis having a tubular body of a biocompatible graft material having a proximal end, a distal end, a lumen therethrough, and a sidewall. The prosthesis includes at least one perfusion branch extending from the sidewall of the tubular body and having a proximal end, a distal end, and a lumen therethrough, where the lumen of the perfusion branch is in temporary fluid communication with the lumen of the tubular body. The perfusion branch comprises a self-sealing component, that after predetermined period of time precludes fluid flow out of the distal end of the perfusion branch. 
     In one embodiment, the self-sealing component comprises a flap element and a biodegradable attachment. The biodegradable attachment may comprise one or more dissolvable sutures, staples, clips, adhesive or the like. 
     The self-sealing component may include a biasing element. The biasing element may comprise bi-stable properties. 
     Other systems, methods, features and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be within the scope of the invention, and be encompassed by the following claims. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of an example of a branch stent-graft. 
         FIG. 2  is a side sectional view of  FIG. 1 . 
         FIG. 3  is a perspective of a first embodiment of a perfusion branch of a stent graft in an open state. 
         FIG. 4  is a perspective view of  FIG. 3  in a closed state. 
         FIG. 5  is a partial perspective view of a second embodiment of a perfusion branch in an open state. 
         FIG. 6  is a partial perspective view of  FIG. 5  in a closed state. 
         FIG. 7  is a perspective of a third embodiment of a perfusion branch of a stent graft in an open state. 
         FIG. 8  is a perspective view of  FIG. 7  in a closed state. 
         FIG. 9  is a perspective of a fourth embodiment of a perfusion branch of a stent graft in an open state. 
         FIG. 10  is a perspective view of  FIG. 9  in a closed state. 
     
    
    
     DETAILED DESCRIPTION 
     As used here, the term “distal” furthest from the heart during a procedure and “proximal” means closest to the heart during a procedure. These terms will be understood with reference to the figures. 
       FIG. 1  shows a stent-graft  10  having a proximal end  12  and a distal end  14  with one or more stents  16  attached to the graft  24 . Stent-graft  10  has one or more branches  18 ,  20  at least partially extending from the external surface of the stent-graft  10 . As shown in  FIG. 2 , the branches  18 ,  20  may have a portion  26  that extends from the outer surface of the stent-graft  10 , and a portion  28  that extends into the lumen of the stent-graft  10 . In other embodiments, the branch may extend entirely from the outer surface or entirely from the inner surface into the lumen. Branches may have one or more stents supporting them as shown in  FIGS. 1 and 2 . The stents may be external as shown at numeral  22  or internal as shown in  FIG. 2  at numeral  28 . One or more of the branches may be used to connect up with a branch vessel branching from the main body vessel into which stent-graft  10  has been placed. Further branch extensions may be inserted into the branches. Although the presently described embodiment shows only two branches, a device having three or more branches is also contemplated. 
     At least one of the branches may be provided as a perfusion branch. A perfusion branch is a branch that is temporarily left open to perfuse the sac of an aneurysm. Perfusion of the sac for a short time may encourage collateral blood vessels to form and reduce the chance of paraplegia. Perfusion branches have been used, but require a secondary procedure upon completion of the initial procedure to occlude them with a vascular occlude. 
       FIGS. 3-10  illustrate devices that are self-closing perfusion systems that do not require any additional procedure or component to close when it is desirable to close the perfusion branch. 
       FIGS. 3 and 4  show a first embodiment of such a perfusion system.  FIG. 3  shows a perfusion branch in an open position and  FIG. 4  shows the branch in a closed position. As shown in  FIG. 3 , perfusion branch  30  includes tubular component  32  having proximal  34  and distal ends  36 , and lumen  38  extending therebetween. Disposed in lumen  38  is perfusion element  40 . Perfusion element  40  may take the form of a valve. Perfusion element  40  has a proximal end  42 , a distal end  44 , and in this example, a perfusion flap  46 . Flap  46  has a sealing member  48  that holds the flap  46  against an inner wall of the tubular component  32  to keep the branch  30  open to fluid flow. Sealing member  48  may be held in place with a biodegradable element  50 , such as dissolvable sutures, threads, staples, clips, adhesive and the like, as are known in the art. 
     In operation, the perfusion branch remains open to allow fluid flow entirely through the perfusion branch to perfuse the aneurysm or branch vessels. After a predetermined period of time, determined by the type of biodegradable element  50  used, the biodegradable element will biodegrade and/or dissolve. At this time, the sealing member  48  is released and is self-biased towards the opposite wall of the branch as shown in  FIG. 4 , causing the flap  46  to close the lumen  38 , thus self-sealing the perfusion branch. In one embodiment the sealing member comprises bi-stable characteristics. 
       FIGS. 5 and 6  show a second embodiment of such a perfusion system.  FIG. 5  shows a perfusion branch in an open position and  FIG. 6  shows the branch in a closed position.  FIGS. 5 and 6  show a partial perspective view of a distal end of a perfusion branch  30 . In this second embodiment, the sealing member  48  is an internal tube. Like the flap  46  of the first embodiment, the tube is held open at at least one end with a sealing member  48 , such as a biasing ring. Sealing member  48  is held in its open configuration by one or more biodegradable elements  50  at one portion  52  to maintain its ring shape and hence hold the lumen open as shown in  FIG. 5 . As shown in  FIG. 5 , another portion  54  of the sealing member  48  is sutured to the tubular component  32  in a permanent manner with non-biodegradable elements such as sutures, staples, clips, adhesive and the like. After a predetermined period of time, determined by the type of biodegradable element  50  used, the biodegradable element will biodegrade and/or dissolve. At this time, the sealing member  48  is released and is self-biased towards the opposite wall of the branch as shown in  FIG. 6 , causing the sealing member (the internal tube) to close at at least one end, here shown as the distal end, thus self-sealing the perfusion branch. Alternatively, the sealing element can be at the proximal end of the sealing tube or a sealing element can be at both ends of the tube in this embodiment. 
       FIGS. 7 and 8  show a third embodiment of such a perfusion system.  FIG. 7  shows a perfusion branch in an open position and  FIG. 8  shows the branch in a closed position. FIGS. and  8  are similar to the first embodiment shown in  FIGS. 3 and 4 , with a distal stent or spring  56  cooperating to bias the flap  46  against the opposite wall of the perfusion branch  30 . As shown in  FIG. 7 , stent  56  is held compressed by the flap  46  which is held against the wall to keep the lumen open by one or more biodegradable elements  50 , such as sutures, clips, staples, dissolvable adhesive and the like. In this embodiment, element  58 , may not on its own have biasing force. Stent  56  is a self-expanding stent as is known in the art. After a predetermined period of time, determined by the type of biodegradable element  50  used, the biodegradable elements  50  will biodegrade and/or dissolve and the stent  56  will spring open under its self-expanding forces and bias the flap against the opposite wall of the lumen as shown in  FIG. 8 , thereby sealing the lumen. 
       FIGS. 9 and 10  show a fourth embodiment of such a perfusion system.  FIG. 9  shows a perfusion branch in an open position and  FIG. 10  shows the branch in a closed position. In  FIG. 9 , the distal end  36  of the perfusion branch has a double ring structure. The first ring  60  is permanently attached, such as sewing, gluing, enclosing, and the like, to the distal end of the perfusion branch  30  and has a biasing force. The second ring  62  is attached to the first ring  60  by one or more biodegradable elements  50  and maintains ring  60  in a circular shape to keep the lumen open. At least one permanent element, such as a hinge  64  maintains a portion of ring  62  in contact with a portion of ring  60 . In this embodiment, the rings are attached to each other. After a predetermined period of time, determined by the type of biodegradable element  50  used, the biodegradable elements  50  will biodegrade and/or dissolve and the second ring  62  will spring away from the distal end. Ring  60 , upon being released from the second ring will bias shut. In other words, ring  60  has a relaxed shape that is biased towards the closed position. Rings  60  and  62  may be made of the same material or different materials. For example, ring  60  may be made of shape memory material and ring  62  may be made of another alloy, such as stainless steel. In another embodiment the rings are of the same material but treated such that the ring  60  has its self-closing characteristics. 
     Those of skill in the art will appreciate that embodiments not expressly illustrated herein may be practiced within the scope of the present invention, including that features described herein for different embodiments may be combined with each other and/or with currently-known or future-developed technologies while remaining within the scope of the claims presented here. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting. And, it should be understood that the following claims, including all equivalents, are intended to define the spirit and scope of this invention. Furthermore, the advantages described above are not necessarily the only advantages of the invention, and it is not necessarily expected that all of the described advantages will be achieved with every embodiment of the invention.