Abstract:
A radially expandable stent graft  10  for placement in a lumen of a patient is disclosed. The stent graft  10  comprises: a prosthetic trunk  100  comprising a trunk lumen  110  there-through; a prosthetic branch  300  comprising a branch lumen  310  extending there-through, wherein the branch lumen  310  is in fluid communication with the trunk lumen  110  through a lateral opening  115  in the trunk lumen  110 ; a valve  150  comprising a fenestration  152  for providing temporary lateral access into the trunk lumen  110 , the valve  150  positioned opposite the lateral opening  115  in the trunk lumen  110 ; and a valve actuator. The valve actuator closes the fenestration  152  as the stent graft  10  expands.

Description:
FIELD OF INVENTION 
     This invention relates to medical devices and more particularly to devices which can be deployed by endovascular means into the vasculature of a patient. 
     INCORPORATION BY REFERENCE 
     The entire contents of each of the patent applications listed below are hereby incorporated by reference.
         U.S. patent application Ser. No. 10/962,763 entitled “Introducer for Iliac Side Branch Device”   PCT Patent Publication No WO 98/53761 entitled “A Prosthesis and a Method of Deploying a Prosthesis”   U.S. patent application Ser. No. 11/600,655 entitled “Stent Graft Introducer” (US Publication 2007/0123910)   U.S. patent application Ser. No. 11/788,285 entitled “Twin Bifurcated Stent Graft” (US Publication 2007/0250154)   Australian Patent Application No 2011202120, filed May 9, 2011 entitled “Paraplegia Prevention Valve For Stent Grafts”   U.S. patent application Ser. No. 11/231,621 (Published as US2006/0095118) entitled “Side Branch Stent Graft”.       

     BACKGROUND OF THE INVENTION 
     Some endovascular procedures require stent grafts to have temporary access ports or fenestrations. Various fenestrations have been developed that are openable or closeable and can therefore be described as valved fenestrations. Difficulties with existing valved fenestrations within stent grafts include the space they require and limitations on where they can be placed with respect to expandable stents and bifurcations for instance. Difficulties can arise in design of closing mechanisms for valved fenestrations as well. 
     Throughout this specification, when discussing the application of this invention to the aorta or other blood vessels, the term “distal” with respect to a prosthesis is intended to refer to a location that is, or a portion of the prosthesis that when implanted is, further downstream with respect to blood flow; the term “distally” means in the direction of blood flow or further downstream. The term “proximal” is intended to refer to a location that is, or a portion of the prosthesis that when implanted is, further upstream with respect to blood flow; the term “proximally” means in the direction opposite to the direction of blood flow or further upstream. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention there is provided a radially expandable stent graft for placement in a lumen of a patient, the stent graft comprising: 
     a prosthetic trunk comprising a trunk lumen therethrough; 
     at least one zig-zag stent extending around the prosthetic trunk, the stent comprising a plurality of struts and bends, the bends being between adjacent struts; 
     a valve comprising a fenestration openable into the trunk lumen; and 
     a tension member extending from the valve to an anchor point on the prosthetic trunk spaced from the valve, such that radial expansion of the stent graft pulls the tension member so as to close the fenestration. 
     In one form the valve comprises: 
     a short length of tubular valve material; and 
     a valve thread stitched around the valve material so as to close the fenestration when the valve thread is taut. 
     In one form the valve thread forms the tension member extending from the valve to an anchor point on the prosthetic trunk spaced from the valve. 
     In one form the stent graft comprises a releasable constraint arrangement constraining the zig-zag stent, 
     wherein the valve thread is tied to the zig-zag stent such that, release of the constraint arrangement pulls the thread which gathers the valve material so as to close the fenestration. 
     In one form the releasable constraint arrangement comprises: 
     a release wire; and 
     a loop of constraining thread, the constraining thread looped around the release wire and a strut of the zig-zag stent, the constraining thread drawn tight and tied to itself, 
     whereby the release wire is withdrawable from the loop of constraining thread so cease constraining the zig-zag stent and thereby close the fenestration. 
     In one form the releasable constraint arrangement comprises: 
     a release wire; and 
     a loop of constraining thread, the constraining thread looped around the release wire and a strut of the zig-zag stent, the constraining thread drawn tight and tied to itself, 
     whereby the release wire is withdrawable from the loop of constraining thread so cease constraining the zig-zag stent and thereby close the fenestration. 
     In one form the stent graft comprises a pair of tension members, the tension members extending from opposite sides of the valve to respective anchor points. The pair may be symmetrically arranged. 
     In one form the stent graft comprises a single tension member tied at one end to a first strut of the zig-zag stent and tied at a second end to a second strut of the zig-zag stent, the second end opposite the first end. 
     In one form the zig-zag stent is super elastic. 
     According to a second aspect of the invention there is provided a radially expandable stent graft for placement in a lumen of a patient, the stent graft comprising: 
     a prosthetic trunk comprising a trunk lumen there-through; 
     a prosthetic branch comprising a branch lumen extending there-through, wherein the branch lumen is in fluid communication with the trunk lumen through a lateral opening in the trunk lumen; 
     a valve comprising a fenestration openable into the trunk lumen, the valve positioned opposite the lateral opening in the trunk lumen; and 
     a valve actuator, 
     wherein the valve actuator closes the fenestration as the stent graft expands. 
     In one form the stent graft comprises: 
     at least one zig-zag stent extending around the tubular body, the stent comprising a plurality of struts and bends, the bends being between adjacent struts; and 
     a releasable constraint arrangement constraining the zig-zag stent, 
     wherein release of the constraint arrangement actuates the valve actuator so as to close the fenestration as the stent graft expands. 
     In one form the stent graft the valve comprises: 
     a short length of tubular valve material; and 
     a tension member connected around the valve material so as to close the fenestration when the tension member is taut. 
     In one form the tension member is a valve thread. 
     In one form the valve actuator comprises the valve thread extending between the valve and an anchor point on the prosthetic trunk, the anchor point spaced from the valve. 
     In one form the valve thread is tied to the zig-zag stent such that release of the constraint arrangement pulls the thread which gathers the valve material so as to close the fenestration. 
     In one form the constraint arrangement comprises: 
     a release wire extending longitudinally along the prosthetic trunk; and 
     a loop of constraining thread engaged with the release wire and engaged around a portion of the prosthetic trunk circumferentially spaced a selected distance away from the release wire, and drawn tight and tied to itself constraining the zig-zag stent in a compressed condition. 
     In one form the stent graft comprises a pair of tension members, the tension members extending from opposite sides of the valve to respective anchor points. 
     In one form the stent graft comprises a single tension member tied at one end to a first strut of the zig-zag stent and tied at a second end to a second strut of the zig-zag stent, the second end opposite the first end. 
     In one form the zig-zag stent is super elastic. 
     According to a third aspect of the invention there is provided a radially expandable stent graft for placement in a lumen of a patient, the stent graft comprising: 
     a prosthetic trunk comprising a trunk lumen there-through; 
     a prosthetic branch comprising a branch lumen extending there-through, wherein the branch lumen is in fluid communication with the trunk lumen through a lateral opening in the trunk lumen; 
     a valve comprising a fenestration openable into the trunk lumen, the valve positioned opposite the lateral opening in the trunk lumen, the valve comprising a short length of tubular valve material and a tension member connected around the valve material so as to close the fenestration when the tension member is taut; 
     a valve actuator; 
     at least one zig-zag stent extending around the tubular body, the stent comprising a plurality of struts and bends, the bends being between adjacent struts; and 
     a releasable constraint arrangement constraining the zig-zag stent, 
     wherein release of the constraint arrangement actuates the valve actuator so as to close the fenestration as the stent graft expands. 
     In one form the tension member is a valve thread valve and the actuator comprises the valve thread extending between the valve and an anchor point on the prosthetic trunk, the anchor point spaced from the valve. 
     A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate by way of example the principles of the invention. While the invention is described in connection with such embodiments, it should be understood that the invention is not limited to any embodiment. On the contrary, the scope of the invention is limited only by the appended claims and the invention encompasses numerous alternatives, modifications and equivalents. For the purpose of example, numerous specific details are set forth in the following description in order to provide a thorough understanding of the present invention. 
     The present invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the present invention is not unnecessarily obscured. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To assist with understanding of the invention, reference will now be made to the accompanying drawings which show preferred embodiments of the invention. 
       In the drawings: 
         FIGS. 1   a  and  1   b  show a first embodiment of a portion of a stent graft according to the invention; 
         FIGS. 2   a  and  2   b  show the embodiment of  FIG. 1   a  but show the stents lying flat, rather than in their actual positions curving circumferentially around the trunk; 
         FIG. 2   c  is similar to  FIG. 2   a , but removes the valve material to show other elements of a valve actuator in more detail; 
         FIG. 2   d  is similar to  FIG. 2   c , but shows an second embodiment; 
         FIG. 3  shows a third embodiment of a stent graft according to the invention; 
         FIGS. 4   a  and  4   c  show a fourth embodiment of a stent graft according to the invention; 
         FIG. 4   b  shows the stent graft of  FIGS. 4   a  and  4   c  with an indwelling catheter extending through it; 
         FIG. 5   a  shows the vascular of a patient having longer common iliac arteries, the vascular having an aortoiliac aneurysm; 
         FIG. 5   b  is similar to  FIG. 5   a , but shows the vascular of a patient having shorter common iliac arteries; 
         FIG. 5   c  shows the stent graft of  FIGS. 4   a - 4   c  deployed within the vascular shown in  FIG. 5   b;    
         FIG. 6  shows a stent graft according to a fifth embodiment of the invention, that is similar to the stent graft of  FIGS. 4   a - 4   c , being loaded onto a delivery device; and 
         FIGS. 7   a  to  7   f  show the various stages of deployment of the stent graft of  FIG. 6 . 
     
    
    
     DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1   a  and  1   b , a portion of a radially expandable stent graft  10  for placement in a lumen of the patient is shown. The stent graft  10   a  comprises a prosthetic trunk  100  comprising a trunk lumen  110  therethrough and a plurality of zigzag stents extending around the prosthetic trunk  100 . For example, stent  120  has struts  122  and bends  126 , as is most clearly shown in  FIG. 1   b . A valve  150  comprising a fenestration  152  for providing temporary lateral access into the trunk lumen  110  is also provided. 
     Referring now to  FIGS. 2   a  and  2   b , the valve  150  can be seen more clearly. These figures correspond to  FIGS. 1   a  and  1   b , but show the stents lying flat, rather than in their actual positions curving circumferentially around the trunk  100 . In  FIG. 2   a , a tension member in the form of a valve thread  154  can be seen extending from the valve  150  to an anchor point  156  on the prosthetic trunk  100  at a position spaced from the valve  150 . The valve thread  154  may be a suture. The positioning is such that radial expansion of the stent graft  10  from the position shown in  FIG. 2   a  to the position shown in  FIG. 2   b  pulls the valve thread  154  so as to close the fenestration  152 . 
     The valve  150  comprises a short length of tubular valve material  158  and at least one valve thread  154  stitched around the valve material  158  so as to close the fenestration  152  when the valve thread or suture  154  is taut. 
     In  FIG. 2   a , a pair of loops of constraining thread  174  engaged with release wires  172  is shown. When the release wires  172  are removed, the loops of constraining thread  174  come free as is shown in  FIG. 2   b . This allows the stent  120 , to expand so as to pull the valve threads  154  so as to close the fenestration  152 . 
     The use of reducing ties to achieve a reduction in the circumference of the stent graft  10   a  is known and is explained in the specification of U.S. patent application Ser. No. 11/507,115 entitled “Assembly of Stent Grafts” which is hereby incorporated in its entirety into this specification. With the arrangement shown in  FIGS. 1   a ,  1   b ,  2   a  and  2   b  however, the potential energy of the compressed or constrained stents is used to actuate a valve upon extraction of release wires  172 . 
     With the embodiment shown in  FIGS. 2   a  and  2   b , there are a pair of tension members, the tension members extending from opposite sides of the valve to respective anchor points. This is illustrated more clearly in  FIG. 2   c  where paired tension members  154  are labeled  154   a  and  154   b , paired constraining treads  174  are labeled  174   a  and  174   b . There are also a pair of releasable constraint arrangements. Each arrangement is the same. The arrangement on the left hand side of  FIG. 2   c  comprises: a release wire  172   a ; and a loop of constraining thread  174   a , the constraining thread  174   a  looped around the release wire  172   a  and a strut  122  of the zig-zag stent. The constraining thread  174   a  is drawn tight and tied to itself. The release wire  172   a  is withdrawable from the loop of constraining thread  174   a  so cease constraining the zig-zag stent  120  and thereby close the fenestration  152 . The arrangement on the right hand side of  FIG. 2   c  is a mirror image of the arrangement on the left hand side described above. 
     An alternative embodiment is shown in  FIG. 2   d . With this embodiment, only a single tension member  154  in the form of a valve thread  154  is provided. It can be seen that a single release wire  172  holds a pair of constraining treads  174   a ,  174   b . When this release wire  172  is withdrawn, the spaced apart struts labeled  122   a  and  122   b  move apart and pull opposite ends  154   e   1  and  154   e   2  thereby closing the fenestration  152 . In still further embodiments (not shown) a pair of release wires such as is shown in  FIGS. 2   a  and  2   c  is be used with a single tension member  154  of the type shown in  FIG. 2   d . This allows greater control over the closing of the fenestration  152 . 
     With the embodiments illustrated, the expandable stent  120  is a nitinol (metal alloy of nickel and titanium) stent. 
     The portion of the radially expandable stent graft  10   a  shown in  FIGS. 1   a ,  1   b ,  2   a  and  2   b  will have numerous applications and, depending on those applications, may be incorporated into stent grafts of the type shown in  FIG. 3  (a third embodiment of the invention) or more complex stent grafts having multiple bifurcations for instance. For example  FIGS. 4   a  to  4   c  show a bi-branch stent graft  10   c  according to a fourth aspect of the invention for treating aortoiliac aneurysms. 
       FIGS. 5   a  and  5   b  show a portion of the vascular system having an aortoiliac aneurysm.  FIG. 5   a  shows the vascular of a patient having longer common iliac arteries  510 ,  520  and  FIG. 5   b  shows the vascular of a patient having shorter common iliac arteries  510 ,  520 . 
     There are currently known “bi-Branch” devices that are successful in treating aortoiliac aneurysms in patients with the longer common iliac arteries shown in  FIG. 5   a  (greater than 40 mm in length). Such a device is described U.S. patent application Ser. No. 11/788,285 entitled “Twin Bifurcated Stent Graft” (US Publication 2007/0250154). These devices can be deployed endovascularly using up-and-over sheath access from the contralateral femoral artery to the ipsilateral leg to the ipsilateral internal iliac artery as is described in the aforementioned U.S. patent application Ser. No. 11/788,285. 
     A limitation of such devices is their inability to adequately treat Asian populations, who commonly have shorter common iliac arteries (less than 40 mm in length) compared to western populations, as illustrated in  FIG. 5   b.    
     The access ports currently used on bi-Branch devices for up-and-over sheath access from the contralateral femoral artery to the ipsilateral leg to the ipsilateral internal iliac artery, do not allow for treatment of shorter common iliac arteries (&lt;40 mm in length) due to their positioning on the ipsilateral leg, and cannot readily be repositioned to be opposite the internal opening of the helical side branch. 
     The fourth embodiment of the invention, in the form of a stent graft  10   c  shown in  FIGS. 4   a  to  4   c , is able to be used to treat populations having shorter common iliac arteries (less than 40 mm in length).  FIG. 5   c  shows such a stent graft  10  deployed. 
     When the valve  150  is open as is shown in  FIG. 4   b , minimal resistance is experienced by the physician when tracking a sheath  400  through into the side arm  300 , as the valve opening forms a large, unobstructed fenestration  152 . Once the valve opening is no longer required, the release wire(s)  172  can be removed. This allows the stent  120  to expand, as is most clearly illustrated progressively from  FIG. 2   a  to  FIG. 2   b . Radial expansion of the stent  120  graft actuates the valve  150  closed by pulling the valve thread  154  so as to close the fenestration  152  as shown in  FIG. 4   c.    
     In the embodiment described above, the tension member  154  is a valve thread. In other embodiments, other tension members such as wire may be used. 
       FIGS. 6 and 7   a  to  7   d  show the various stages of deployment of a stent graft according to the embodiment of the present invention shown in  FIGS. 4   a  to  4   c.    
       FIG. 6  shows a schematic version of an embodiment of a stent graft  10   d  according to the present invention loaded onto a delivery device. For convenience the sheath of the delivery device has been withdrawn to show the assembly inside it. The delivery device  600  has a nose cone dilator  414  at its proximal end and a stent graft assembly  10   d  according to a fifth embodiment of the invention is mounted onto the delivery device  600 . This embodiment of stent graft  10   d  has a helical side arm  300  on the longer leg  100  of the stent graft  10   d  (similar to stent graft  10   c  shown in  FIGS. 4   a  to  4   c ). An indwelling catheter  400  extends from the delivery device  600  through the helical side arm  300  exiting at valved fenestration  152  and extending to a groove  414  in the nose cone dilator  402  outside of the stent graft  10 . The indwelling catheter  400  has a flexible curved proximal end  416 . 
     The tubular side arm  300  extends around the longer leg  100  and the indwelling catheter  400  extends into the tubular side arm  300  and out through the valved fenestration  152 . The valved fenestration  152  is the same as the as the construction shown in  FIGS. 4   a  to  4   c.    
       FIG. 7   a  shows a schematic vasculature of a patient including an aorta  500  renal arteries  504  and an aortic bifurcation  508 . Extending from the aortic bifurcation  508  are iliac arteries  510  and  520 . The aorta has an aneurysm which extends down the common iliac artery to the position of the internal iliac artery  540 . The iliac bifurcation defines the bifurcation between the internal iliac artery  540  and the external iliac artery  560 . 
       FIG. 7   a  also shows the delivery device  600  with the nose cone dilator  402  proximal of the renal arteries  504  with the indwelling guide wire  490  drawn up into the aorta  500 . The process of getting the delivery device  600  into this position, using the indwelling catheter with a curved tip shown in  FIG. 6  to facilitate snaring from a contralateral iliac artery, is taught in U.S. patent application Ser. No. 11/788,285 entitled “Twin Bifurcated Stent Graft” (US Publication 2007/0250154). 
     The sheath  622  of the delivery device  600  is then withdrawn to release the shorter leg of the stent graft  200 . 
     The indwelling catheter is then withdrawn down into the contra-lateral iliac artery  510  and the sheath  622  is withdrawn so that it is distal of the distal end of the side arm  300  while still retaining the distal end of the longer leg  100 . This is shown in detail in  FIG. 7   b.    
     As shown in  FIG. 7   b  a dilator and sheath introducer  450  is advanced over the guide wire  490  in the contra-lateral iliac artery  510  and the indwelling catheter  400  and extension arm deployment device are tracked over the guide wire  490  so that the nose cone  460  of the sheath introducer enters the valved fenestration  152  and tracks over the guide wire  490  into the side arm  300  until it exits the distal end of the side arm as shown in  FIG. 7   c . The sheath introducer nose cone  460  is then withdrawn leaving the sheath  450  in place. At this stage the indwelling guide wire  490  is still in a through-and-through position. As shown in  FIG. 7   d , another guide wire  496  is introduced through the sheath  450  and extended from the sheath  450  to enter into the internal iliac artery  540 . 
     As shown in  FIG. 7   e  a side arm deployment device is deployed over the guide wire  496  into the internal iliac artery  540  so that balloon expandable covered stent  700  extends into the internal iliac artery  540  from the side arm  300 . The indwelling guide wire  490  is then removed and the position of the distal end of the longer leg  100  is set into the external iliac artery  260  and the balloon expandable covered stent  700  is expanded 
     The final positions are shown in  FIGS. 7   f  and  5   c . To achieve these position, the sheath  450  is withdrawn and the valve  152  is closed by removing the release wires  172  as is shown in  FIG. 7   f . The proximal end of the stent graft is also released from the delivery device  600  such that a portion of the graft seals into a non-aneurysed portion of the aorta  500  distal of the renal arteries  504  while an uncovered suprarenal stent  90  extends over the renal arteries to provide secure fixation. A leg extension  290  may then be placed into the short leg  200  of the graft  10  as is shown if  FIG. 5   c.    
     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. 
     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.