Abstract:
A stent graft ( 2 ) for treatment of an emergency rupture of, for instance, the aorta adjacent the aortic bifurcation. The stent graft comprising a tubular body ( 8 ) with a bifurcation ( 10 ) in the tubular body defining a first long leg ( 12 ) and a second short leg ( 14 ). The second leg has a valve arrangement ( 18 ) to prevent fluid flow through the second leg from the stent graft. The valve can be opened from external of the stent graft for the placement of a leg extension stent graft ( 90 ) therethrough.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of provisional application Ser. No. 60/857,228, filed Nov. 7, 2006. 
    
    
     TECHNICAL FIELD 
     This invention relates to a medical device and more particularly to a medical device suitable treatment of emergency rupture in vessels of the human or animal body. 
     BACKGROUND OF THE INVENTION 
     In cases where an artery of the human or animal body has ruptured due to some trauma such as an accident or due to damage of the vessel wall due to stenosis or disease, it is desirable to, as soon as possible, deploy a stent graft across the rupture to isolate the artery wall, in that region, from blood flow in the artery. Where the artery includes a bifurcation such as the aortic bifurcation it is possible to place an aorto-uni-iliac stent graft extending from a portion of the aorta above the rupture into one of the iliac arteries, however, such a procedure does not completely isolate the rupture region because of cross flow of blood in small arteries between the iliac and femoral arteries. 
     It may be possible to deploy a stent graft with a bifurcation through one of the iliac arteries and then deploy a leg extension stent graft into the other of the other iliac arteries to connect with the bifurcated stent graft, however, this can be a relatively long and more complex procedure and blood loss through the rupture during the procedure can be serious. 
     It is the object of this invention to provide a stent graft arrangement which will assist in over coming excessive blood loss in the case of an emergency rupture in the case of a vessel incorporating a bifurcation and to provide an option for further treatment or at least providing a useful alternative to a surgeon. 
     Throughout this specification the term “distal” with respect to a portion of the aorta, a deployment device or a prosthesis means the end of the aorta, deployment device or prosthesis further away in the direction of blood flow away 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. 
     In our earlier patent application, PCT Patent Publication No. WO 98/53761 entitled “A Prosthesis and a Method Deploying a Prosthesis” there is disclosed an introducer for a stent graft which can be used to deploy the stent graft according to the present invention. This feature and other features disclosed in WO 98/53761 are incorporated herewith in their entirety into this specification. 
     SUMMARY OF THE INVENTION 
     In one form thereof, the invention is said to reside in a stent graft for treatment of an emergency rupture of a vessel of the human or animal body which incorporates a vessel bifurcation, the stent graft comprising a main tubular body of a biocompatible graft material defining a main lumen therethrough, a graft bifurcation in the tubular body defining a first long leg extending from the graft bifurcation and either a second short leg extending from the graft bifurcation or an aperture or fenestration, each of the first long leg and second short leg having respective leg lumens therethrough, each leg lumen or aperture being in fluid communication with the main lumen, the second short leg or aperture comprising a valve arrangement to prevent fluid flow through the second short leg or aperture from the main lumen and the valve arrangement being able to be opened from outside of the stent graft for the placement of a leg extension stent graft therethrough. 
     Preferably, from the graft bifurcation a second short leg is defined and the stent graft can be introduced into the vessel with the longer leg extending into one of the vessels extending from the vessel bifurcation and the shorter leg directed towards the other vessels extending from the vessel bifurcation. 
     Preferably, the second short leg is fastened to the tubular body within the tubular body at an end remote from the graft bifurcation, and can comprise a reinforcing ring of a shape memory metal at a distal end thereof. 
     Alternatively, the second short leg can be invaginated within the main tubular body. 
     Preferably, the valve arrangement comprised in the second short leg with the inner end thereof held in a substantially U-shape by a reinforcement ring being formed from a shape memory material and in a twin U-shape and being able to be opened to a circular shape so that a leg extension stent graft can be deployed through it. The substantially U-shape formed by the reinforcement ring can be stitched to the tubular body of the stent graft. 
     Alternatively, the leg extension stent graft can be an intraluminal plug. 
     In an alternative form, the invention comprises a stent graft for treatment of an emergency rupture of an aorta of the human or animal body at or near an aortic bifurcation and the aperture or fenestration is defined. The stent graft comprising a main tubular body of a biocompatible graft material defining a main lumen therethrough, a distal end of the tubular body being of a diameter to be received into and seal in an iliac artery and a proximal end being of a diameter to be received into and seal in the aorta, being the aperture in the tubular body intermediate the ends and directed in use towards the contralateral-iliac artery, the aperture including a valve arrangement to prevent fluid flow out of the aperture from the main lumen and the valve arrangement being able to be opened from outside of the stent graft for the placement of a leg extension stent graft therethrough whereby the stent graft can be introduced into the aorta with the distal end extending into the iliac artery, the proximal end being received in the aorta proximally of the rupture and the aperture directed towards the contralateral-iliac artery. 
     Preferably, the aperture comprises a reinforcing ring of a shape memory metal. 
     Preferably, the valve arrangement comprises a tube of biocompatible graft material fastened around the aperture and extending into the tubular body with the inner end thereof held in a substantially U-shape by a reinforcement ring being formed from a shape memory material and in a twin U-shape and being able to be opened to a circular shape to deploy a leg extension stent graft therein. The substantially U-shape reinforcement ring can be stitched to the tubular body of the stent graft. 
     Alternatively, the leg extension stent graft can be an intraluminal plug. 
     In an alternative form, the invention is said to reside in a stent graft for treatment of an emergency rupture of the aorta adjacent the aortic bifurcation and a second short leg, emerging from the graft bifurcation is defined. The stent graft comprising a main tubular body of a biocompatible graft material defining a main lumen therethrough, a bifurcation in the tubular body defining a first long leg and the second short leg, each of the first and second legs having respective lumens therethrough and each in fluid communication with the main lumen, the second short leg comprising a valve arrangement to prevent fluid flow through the second short leg from the main lumen and the valve arrangement being able to be opened from outside of the stent graft for the placement of a leg extension stent graft therethrough. The second short leg having a distal opening and the valve arrangement comprising a tube of biocompatible material fastened around the distal opening and extending back into the second short leg. 
     Preferably, the tube of biocompatible material is fastened to the tubular body at an end remote from its attachment to the second short leg. 
     Preferably, the valve arrangement comprises a reinforcement ring on the tube at an end remote from its attachment to the second short leg, the reinforcement ring being formed from a shape memory material and in a twin U-shape and being able to be opened to a circular shape so that a leg extension stent graft can be deployed through it. 
     Preferably, the second short leg comprises a reinforcing ring of a shape memory metal at a distal end thereof. 
     Alternatively, the second short leg can be invaginated within the main tubular body. 
     Preferably, the valve arrangement comprised in the second short leg with the inner end thereof held in a substantially U-shape by a reinforcement ring being formed from a shape memory material and in a twin U-shape and being able to be opened to a circular shape. The substantially U-shape by a reinforcement ring can be stitched to the tubular body of the stent graft. 
     Preferably, the valve arrangement comprises a tube of biocompatible material fastened to the second short leg and extending back into the second short leg with a closure arrangement associated with the tube of biocompatible material and the closure arrangement resiliently closing off the tube of biocompatible material. 
     Alternative, the valve arrangement can comprise an aperture or a fenestration adjacent the junction between the main body instead of the second short leg. 
     It will be seen that by this invention there is provided an arrangement which initially is essentially an aorto-uni-iliac stent graft, that is, it has a main body portion to be deployed into the aorta, for instance, proximal of the aortic bifurcation and a single leg which can be placed into one of the iliac arteries but that it also has an aperture with a valve arrangement and the valve arrangement being able to be opened from outside of the stent graft for the placement of a leg extension stent graft therethrough. Such a device can be deployed by known endovascular techniques via a femoral and iliac artery. Such deployment will assist in stabilising a patient until a surgeon can decide whether to deploy a leg extension stent graft through the contralateral iliac artery into the valve arrangement or to deploy a plug into the contra-iliac artery and perform a femoro-femoral crossover graft operation. 
     The valve arrangement according to this invention is kept closed by the twin U shape and sealed by the walls of the tube engaging against each other by aortic blood pressure until such time as the valve arrangement is opened from outside of the stent graft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       This then generally describes the invention but to assist with understanding reference will now be made to the accompanying drawings that show preferred embodiments of the invention. 
       In the drawings: 
         FIG. 1  shows a first embodiment of stent graft according to the present invention; 
         FIG. 2  shows a cross sectional view of the stent graft shown in  FIG. 1 ; 
         FIG. 3  shows an alternative embodiment of stent graft according to the present invention; 
         FIG. 4  shows a cross-sectional view of the embodiment of stent graft shown in  FIG. 3 ; 
         FIG. 5  shows a schematic aorta of a patient with the embodiment of the stent graft as shown in  FIG. 1  deployed therein; 
         FIG. 6  shows a further stage of the process depicted in  FIG. 5  with a leg extension stent graft deployed through the valve arrangement; 
         FIG. 7  shows an alternative subsequent step to that shown in  FIG. 5 ; 
         FIG. 8  shows detail of the valve arrangement for the embodiment shown in  FIG. 3 ; 
         FIG. 9  shows the embodiment of  FIG. 8  with a leg extension stent graft deployed through the valve arrangement; 
         FIG. 10  shows a transverse cross section of the embodiment shown in  FIG. 3  particularly showing the configuration of the valve arrangement; and 
         FIG. 11  shows the embodiment in  FIG. 10  after a leg extension stent graft has been deployed into the valve arrangement. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  and  FIG. 2  show a first embodiment of stent graft according to the present invention.  FIG. 1  shows a perspective view and  FIG. 2  shows a longitudinal cross sectional view of the stent graft of  FIG. 1 . In this embodiment the stent graft  2  comprises a tubular wall  4  of a biocompatible material supported by stents  6 . The actual number and placement of stents may vary depending upon the size of the stent graft and its intended configuration within the human or animal body. The stent graft has a main tubular body  8  and a bifurcation  10  from which extends a long tubular leg  12  and a short tubular leg  14 . 
     The stent graft  2  may have an exposed stent (not shown) extending proximally from the proximal end  3  to assist with fixation or can have barbs extending from the proximal-most stent  5 . 
     The main tubular body can have an expanded diameter of from 25 to 45 mm and a length of from 100 to 250 mm and each of the first and second legs can have a diameter of from 10 to 20 mm. The first leg can have a length of from 50 to 150 mm and the second leg can have a length of from 20 to 50 mm. 
     The short leg  14  terminates in a ring reinforcement  16  and a valve arrangement  18  extending back into the short leg from the ring reinforcement  16 . 
     The valve arrangement  18  comprises a tube of biocompatible graft material  20  which extends back into the short leg  14  and at its proximal end  22  there is a twin U-shaped reinforcing ring  24 . The twin U-shaped reinforcing ring  24  is essentially a continuous ring of shape memory metal such as Nitinol which, when folded back into itself, forms the twin U-shape with one U shape being inside the other. The reinforcing ring  24  is stitched to the proximal end of the tube  20  by stitching  23 . The twin U-shape of the reinforcing ring causes the tube  20  to fold in halves and in effect the combination of the twin U-shape and the folded tube acts as a valve to prevent fluid flow through the short leg  14 . The fluid flow is prevented by the flap  26  of the tube  20  bearing against the part  27  of the tube  20  and the inner wall of the short leg  14 . The length of the tube  20  can be 20 to 40 mm and it can have a diameter of from 10 to 20 mm. 
     Radiopaque markers  28  are provided around the distal end of the short leg  14  to assist catheterisation of the short leg once the stent graft has been deployed. 
       FIGS. 3 and 4  show an alternative embodiment of stent graft according to the present invention.  FIG. 3  shows a perspective view and  FIG. 4  shows a longitudinal cross sectional view of the stent graft of  FIG. 3 . In this embodiment the stent graft  30  includes a main tubular body  32  defined by a tubular wall  34  extending to a bifurcation or branch  36 . From the bifurcation or branch  36  a long tubular leg  38  extends and also there is an aperture or fenestration  40  which is defined by a reinforcing ring  42  substantially at the junction between the main tubular body and the long leg. 
     Extending back into the main tubular body  32  is a tube  44  of biocompatible material which is stitched to the main tube around the periphery of the aperture  40  by stitching  45 . At its proximal end  46  the tube  44  has a reinforcing ring  48  of a shape memory metal such as Nitinol retained by stitching  47 . The reinforcing ring  48  is a continuous length of the shape memory metal formed into a pair of U-shapes with one U shape being inside the other and thereby normally holding one side wall of the tube  44  against the other. This in effect closes off the tube  44  by means of a flap  50  which is one of the walls of the tube engaging against the side  51  of the tube  44  to form a valve to prevent fluid flow from the tubular body  32  out through the aperture  40 . The aperture  40  is surrounded by radiopaque markers  52  to assist a surgeon in locating the aperture for catheterisation. 
     The main tubular body can have an expanded diameter of from 25 to 45 mm and a length of from 100 to 250 mm and the first leg can have a diameter of from 10 to 20 mm. The first leg can have a length of from 50 to 150 mm. The length of the tube  44  can be 20 to 40 mm and it can have a diameter when opened out of from 10 to 20 mm. 
       FIG. 5  shows a schematic aorta  60  of a human body. The aorta has renal arteries  62  and lower down an aortic bifurcation  64 . Extending from the aortic bifurcation are iliac arteries  68  and  70 . 
     A rupture  66  has occurred in the aorta and it is the intention of a physician to isolate the rupture by placement of a stent graft into the aorta to span the rupture. 
     A stent graft  72  of the type shown in  FIGS. 1 and 2  has been deployed so that its proximal end is adjacent to the renal artery  62  with an infra-renal exposed stent  74  assisting and supporting the proximal end of the stent graft. The long leg  76  extends down the iliac artery  68  and seals therein. The valve arrangement  78  in the short leg  80  of the stent graft  72  prevents blood flow from the aorta into the aorta in the region of the aortic bifurcation and the contralateral iliac artery  70 . 
     To deploy the stent graft  72  of the present invention the Seldinger technique is used via a femoral artery and iliac artery into the aorta and the stent graft is carried on a deployment device. 
     There is a certain amount of blood flow possible between the iliac arteries through smaller vessels between them downstream of the aortic bifurcation and hence the arrangement shown in  FIG. 5  does not completely isolate the rupture  66 . 
     The placement of the stent graft as shown in  FIG. 5  does, however, give the physician time to decide what method can be used to isolate the rupture. 
     In  FIG. 6  one such method is depicted. In this embodiment a leg extension stent graft  90  has been placed through the contra lateral iliac artery  70  into the short leg  80  to open the valve arrangement  78 . The proximal end  92  of the leg extension stent graft  90  passes up into the main body of the stent graft  72  and the distal end of the leg extension stent graft  90  seals into and undamaged portion of the contra lateral iliac artery  70 . 
     By this arrangement the rupture  66  is isolated. To deploy the leg extension stent graft again the Seldinger technique can be used via the contralateral iliac artery. 
     An alternative arrangement is shown in  FIG. 7 . 
     In this embodiment for some reason perhaps because of an advanced stenosis or the like it is not possible to deploy a full leg extension stent graft through the contra iliac artery  70 . 
     Instead the physician has deployed an intraluminal plug  94  and performed a femoro-femoral cross-over grafting operation using a piece of corrugated graft material  96 . Once again by this arrangement the area of the rupture  66  has been isolated. To deploy the intraluminal plug again the Seldinger technique can be used via the contralateral iliac artery but because it is a much smaller component it may be deployed through the stenosed arteries. 
       FIGS. 8 to 11  show detail of a stent graft incorporating a valve side arm according to the stent graft illustrated in  FIGS. 3 and 4 . The same reference numerals will be used in  FIGS. 8 to 11  for corresponding items. 
     The valve arrangement includes an aperture or fenestration  40  in the distal end of the tubular body  34  with a tube of a biocompatible graft material  44  extending into the stent graft. The aperture  40  has a reinforcing ring  42  of a shape memory metal such as Nitinol or similar wire stitched around the aperture by means of stitching  41 . At the proximal end of the tube  44  is a twin U-shaped reinforcing ring  48  which is stitched to the tube  44  by stitching  49 . The twin U-shape is formed from a continuous length of shape memory metal with one U-shape within the other. The bends  48   b  between the outer U-shape  49  and the inner U-shape  48   a  are such that the outer U-shape is slightly less length than half of the full circumference of the reinforcement ring. The reinforcing ring  48  is formed into its twin U-shape and it being a shape memory metal is retained in that shape. The twin U-shape causes a flap  50  of the tube  44  to engage against the other wall  45  of the tube  44  as well as both engaging against the inside of the wall  34  of the stent graft thereby closing off blood flow from inside the stent graft out through the aperture  40 . 
     It will be noted that the apex  49   a  of the outer of the U-shaped reinforcement  49  is stitched to the wall  34  of the stent graft by stitching  47  to hold it in its desired position. Also the inner portion  48   a  of the twin U-shaped ring reinforcement  48  at its apex is slightly lower than the apex  49   a  of outer portion  49  of the twin U-shaped ring reinforcement  48 . This assists in ensuring that the flap  50  engages with the inside of the wall  54 . 
     If, however, the aperture  40  is catheterised from externally via the contralateral iliac artery the flap  50  can be lifted and the twin U-shape can be opened out to the form shown in  FIGS. 9 and 11 . A leg extension stent graft  90  can then be deployed through the aperture. Self expanding or balloon expandable stents  92  on the leg extension stent graft  90  will open and hold open the twin U shape into a circular shape. 
     Throughout this specification various forms of the invention are discussed but the invention is not limited to any one of these but may reside in two or more combined together. The examples are given for illustration and not for limitation.