Abstract:
A stent graft ( 40 ) has a tubular body with a first bifurcation ( 54 ) with first and second legs ( 50, 52 ) extending from the bifurcation. One of the legs ( 52 ) has a further bifurcation ( 62 ) to define a side arm. The stent graft can be deployed into the vasculature of a patient with the tubular body being in an aorta of the patient, a first leg extending down an iliac artery, a second leg being directed towards a contralateral iliac artery and the side arm directed to an internal artery of one of the iliac arteries. One of the legs can include a valved aperture to enable the placement of an indwelling catheter therethrough

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims priority from U.S. Provisional Patent Application Ser. No. 60/793,282 filed Apr. 19, 2006 entitled “TWIN BIFURCATED STENT GRAFT”. The entire content of this application is hereby incorporated by reference. 
     
    
     INCORPORATION BY REFERENCE  
       [0002]     The following co-pending patent applications are referred to in the following description: 
        U.S. patent application Ser. No. 10/962,763 entitled “Introducer for Iliac Side Branch Device”, filed Oct. 12, 2004, and published Aug. 15, 2005 as U.S. Patent Application Publication No. US-2005-0182476-A1;     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”, filed Nov. 16, 2006;     U.S. patent application Ser. No. 11/231,621 entitled “Side Branch Stent Graft”, filed Sep. 21, 2005, and published May 4, 2006 as U.S. Patent Application Publication No. US-2006-0095118-A1.        
 
         [0007]     The entire content of each of these applications is hereby incorporated by reference.  
       TECHNICAL FIELD  
       [0008]     This invention relates to a medical device and more particularly a device which can be deployed by endovascular means into the vasculature of a patient.  
       BACKGROUND OF THE INVENTION  
       [0009]     There have been proposed bifurcated endovascular devices which can be deployed into the vasculature, particularly in the region of the aortic bifurcation, so that an aneurysm in the aorta can be bridged by placement of the endovascular device with a proximal portion which seals into a non-aneurysed portion of the aorta adjacent to the renal arteries, a first leg which extends down one iliac artery to a non-aneurysed portion of the iliac artery and another short leg into which a leg extension may be placed to extend into a non-aneurysed portion of the contra-lateral iliac artery.  
         [0010]     There can be problems, however, if the aneurysm of the aorta extends down into one or other of the iliac arteries. Each of the common iliac arteries branches into the internal and external iliac arteries and it is necessary in such a situation that a blood flow path can be directed through an endovascular stent graft into each of these arteries.  
         [0011]     The object of this invention is to provide a single endovascularly deployed medical device which can solve this problem or at least provide a physician with a useful alternative.  
         [0012]     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.  
       SUMMARY OF THE INVENTION  
       [0013]     In one form therefore the invention is said to reside in a stent graft comprising a tubular body of a biocompatible graft material defining a main lumen therethrough, a bifurcation in the tubular body at one end thereof and a first leg and a second leg extending from the bifurcation, the first leg being a long leg and the second leg being a short leg, the first and second legs having respective first and second lumens therethrough and the first and second lumens being in fluid communication with the main lumen, characterised by the first long leg comprising a side arm with a side arm lumen therethrough and the side arm lumen being in fluid communication with the first leg lumen, whereby the stent graft can be deployed into the vasculature of a patient with the tubular body being in an aorta of the patient, the first leg extending down an iliac artery, the second leg being directed towards a contralateral iliac artery and the side arm on the first leg directed to an internal artery of the iliac artery.  
         [0014]     In one preferred embodiment the side arm comprises a tube of corrugated biocompatible graft material and the tube extends part helically around the first leg.  
         [0015]     In an alternative embodiment the side arm comprises a tube of biocompatible graft material and at least one self expanding stent on the tube of biocompatible graft material. Co-pending U.S. patent application Ser. No. 11/231,621 entitled “Side Branch Stent Graft” discloses side arm tubes suitable for the present invention.  
         [0016]     Preferably the first leg includes an aperture or fenestration proximally of the side arm and a valve arrangement to prevent fluid flow through the aperture from inside of the leg to outside of the leg.  
         [0017]     Preferably the aperture includes a resilient reinforcement ring around the aperture.  
         [0018]     The valve arrangement can comprise a sleeve of a biocompatible graft material within the first leg and a self expanding stent within the sleeve, the sleeve being fastened at its proximal end to the first leg proximal of the aperture and the self expanding stent being fastened to the sleeve, whereby the self expanding stent forces the sleeve against the inner surface of the first leg around the aperture to prevent fluid flow through the aperture from inside of the leg to outside of the leg.  
         [0019]     In one preferred embodiment the sleeve of a biocompatible graft material comprises a cylindrical form. In an alternative embodiment the sleeve of a biocompatible graft material comprises a semi-cylindrical form.  
         [0020]     Alternatively the valve can be formed from a self expanding stent to which a part cylindrical portion of biocompatible graft material is stitched along spaced apart struts of the self expanding stent. These two components together can form a valve assembly which can be stitched into the longer leg of the stent graft.  
         [0021]     The valve assembly can further include a semi-circular resilient wire around the distal end of the part cylindrical portion of biocompatible graft material forming the valve member. This semi-circular resilient wire around the distal end of the part cylindrical portion of biocompatible graft material will assist with sealing off the fenestration by ensuring that the distal end of the valve member is held against the inside of the wall of the longer first leg of the stent graft.  
         [0022]     The biocompatible graft material can include polytetrafluoroethylene, Dacron, polyamide or any other suitable biocompatible graft material.  
         [0023]     While Dacron, expanded polytetrafluoroethylene (ePTFE), or other synthetic biocompatible materials can be used for the tubular graft material for the stent graft, a naturally occurring biomaterial, such as collagen, is highly desirable, particularly a specially derived collagen material known as an extracellular matrix (ECM), such as small intestinal submucosa (SIS). Besides SIS, examples of ECM&#39;s include pericardium, stomach submucosa, liver basement membrane, urinary bladder submucosa, tissue mucosa, and dura mater.  
         [0024]     SIS is particularly useful, and can be made in the fashion described in Badylak et al., U.S. Pat. No. 4,902,508; Intestinal Collagen Layer described in U.S. Pat. No. 5,733,337 to Carr and in 17 Nature Biotechnology 1083 (November 1999); Cook et al., WIPO Publication WO 98/22158, dated 28 May 1998, which is the published application of PCT/US97/14855, the teachings of which are incorporated herein by reference. Irrespective of the origin of the material (synthetic versus naturally occurring), the material can be made thicker by making multilaminate constructs, for example SIS constructs as described in U.S. Pat. Nos. 5,968,096; 5,955,110; 5,885,619; and 5,711,969. In addition to xenogenic biomaterials, such as SIS, autologous tissue can be harvested as well, for use in forming the tubular graft material. Additionally Elastin or Elastin-Like Polypetides (ELPs) and the like offer potential as a material to fabricate the tubular graft material to form a device with exceptional biocompatibility.  
         [0025]     SIS is available from Cook Biotech, West Lafayette, Ind., U.S.A.  
         [0026]     It will be seen that by this invention there is provided a stent graft which has a main bifurcation to allow access into each of the iliac arteries and in one of the legs extending from the bifurcation there is a further bifurcation or branch which will enable access into the internal iliac artery. There is some advantage in having a double or twin bifurcation stent graft.  
         [0027]     As discussed above there is preferably a valve arrangement proximal of the side arm or side branch of the iliac leg of the bifurcated stent graft. The valve allows an indwelling catheter to be provided through the sidearm in the iliac artery at the time of deployment to assist with deployment of leg extension into the internal iliac artery. U.S. patent application Ser. No. 10/962,763 entitled “Introducer for Iliac Side Branch Device” discloses an arrangement for using an indwelling catheter to access an internal iliac artery and the teaching of this specification is incorporated herewith in its entirety.  
         [0028]     In this case the indwelling catheter can be extended and its guide wire snared from the contra-lateral artery and the leg extension placed into the internal iliac artery before the leg extension is placed into the iliac artery.  
         [0029]     In a further form the invention is said to reside in a stent graft comprising a tubular body of a biocompatible graft material defining a main lumen therethrough an aperture defining a fenestration in the tubular body and a valve arrangement to prevent fluid flow through the aperture.  
         [0030]     Preferably the aperture includes a resilient reinforcement ring around the aperture.  
         [0031]     Preferably the valve arrangement comprises a sleeve of a biocompatible graft material within the tubular body and a self expanding stent within the sleeve, the sleeve being fastened at its proximal end to the first leg proximal of the aperture and the self expanding stent being fastened to the sleeve, whereby the self expanding stent forces the sleeve against the inner surface of the tubular body around the aperture to prevent fluid flow through the aperture.  
         [0032]     The sleeve of a biocompatible graft material can comprise a cylindrical form or alternatively a semi-cylindrical form.  
         [0033]     In one embodiment the valve arrangement comprises a valve assembly comprising a self expanding stent to which a part cylindrical portion of biocompatible graft material is stitched along spaced apart struts of the self expanding stent.  
         [0034]     The valve assembly can further comprise a semi-circular resilient wire around the distal end of the part cylindrical portion of biocompatible graft material forming the valve member.  
         [0035]     This then generally describes the invention but to assist with understanding reference will now be made to the accompanying drawings which show further embodiments of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0036]     In the drawings;  
         [0037]      FIG. 1  shows a first embodiment of stent graft according to the invention as it would be deployed into the vasculature before placement of an iliac side branch;  
         [0038]      FIG. 2  shows the embodiment of  FIG. 1  with the side branch installed into the internal iliac artery and the leg extension in the contralateral iliac artery;  
         [0039]      FIG. 3  shows a schematic view of part of the leg of the stent graft of the present invention in particular showing one embodiment of the valve arrangement;  
         [0040]      FIG. 4  shows a cross-section of embodiment shown in  FIG. 3 ;  
         [0041]      FIG. 5  shows a same view as  FIG. 4  except with the indwelling catheter extending through the corrugated side arm and valve;  
         [0042]      FIG. 6  shows an alternative embodiment of stent graft deployed into a schematic vasculature with an alternative arrangement of side arm;  
         [0043]      FIG. 7  shows embodiment of  FIG. 6  at the stage where the indwelling catheter has been snared and pulled down the contralateral artery and the indwelling catheter has been used to deploy an extension piece into internal iliac artery;  
         [0044]      FIG. 8  shows an alternative embodiment of valve arrangement suitable for the embodiment of stent graft shown in  FIGS. 6 and 7 ;  
         [0045]      FIG. 9  shown a cross-section thought the valve arrangement of  FIG. 8 ;  
         [0046]      FIG. 10  shows the valve arrangement of  FIGS. 8 and 9  with an indwelling catheter extending through it;  
         [0047]      FIG. 11  shows an alternative embodiment of valve arrangement suitable for the embodiment of stent graft shown in  FIGS. 6 and 7 ;  
         [0048]      FIG. 12  shown a detail of the valve arrangement of  FIG. 11  showing the self expanding stent with a valve member mounted onto it;  
         [0049]      FIG. 13  shown a cross-section thought valve arrangement of  FIG. 11 ;  
         [0050]      FIG. 14  shows the valve arrangement of  FIGS. 11 and 13  with an indwelling catheter extending through it:  
         [0051]      FIG. 15A  to  15 M show the various stages of deployment of a stent graft according to one embodiment of the present invention; and  
         [0052]      FIG. 16A  to  16 K show the various stages of deployment of a stent graft according to another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0053]     Looking more closely at the drawings and in particular  FIGS. 1 and 2  it will be seen that a schematic view of part of the vascular arrangement of a patient is illustrated incorporating a stent graft according to the present invention.  
         [0054]     The vasculature comprises an aorta  10  in the region between the renal arteries  12  and the aortic bifurcation  14 . Common iliac arteries  16  and  18  extend down from the aortic bifurcation  14 . The aorta  10  has an aneurysm  20  which extends down into the common iliac artery  18  as far as the bifurcation  22  between the internal iliac artery  24  and the external iliac artery  26 .  
         [0055]     To traverse the aneurysm  20  a twin bifurcated aortic stent graft  40  according to one embodiment of the present invention has been deployed into the aorta  10 . In this drawing the introduction device which is used to deploy the stent graft into the vasculature has been omitted to assist clarity. 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 is suitable for use with the present invention. The proximal end  42  of the bifurcated stent graft  40  is engaged into non-aneurysed portion  28  of the aorta  10  just distal of the renal arteries  12 . In this embodiment stent graft  40  has a proximally extending supra-renal exposed stent  44  with barbs  46  engaging the wall of the aorta proximal of the renal arteries to provide a secure position to prevent migration of the stent graft. The stent graft  40  has a short leg  50  and a long leg  52  extending from the graft bifurcation  54 . The longer leg  52  has a sealing surface  56  at its distal end which engages into a non-aneurysed portion of the external iliac artery  26 .  
         [0056]     The longer leg  52  has a side arm  60  which in this embodiment is in the form of a corrugated tube extending in a part helical manner from its connection at a fenestration  62  into the longer leg  52 . The side arm  60  extends in a distal direction and helically partly around the longer leg  52  and has a distal end  61  remote from its connection with the longer leg  52  which opens adjacent to the internal iliac artery  24 .  
         [0057]     A fenestration  64  is placed into the longer leg  52  proximal of the connection of the side arm  60  into the longer leg  52 . The fenestration  64  has a valve arrangement within it to close it off as will be discussed with reference to FIGS.  3  to  5 .  
         [0058]     During deployment of the stent graft into the vasculature of a patient an in-dwelling catheter  66  extends through the side arm  60  and out through the valved fenestration  64 . The indwelling catheter includes a guide wire  68 .  
         [0059]      FIG. 2  shows the embodiment of  FIG. 1  but after deployment of a extension piece  70  into the corrugated side arm  60  and deployment of a leg extension  72  into the short leg  50  of the bifurcated stent graft  40  which seals into a non-aneurysed portion of the iliac artery  16 . U.S. patent application Ser. No. 10/962,763 entitled “Introducer for Iliac Side Branch Device” discloses an arrangement for using an indwelling catheter to access an internal iliac artery. At this stage the indwelling catheter has been withdrawn and the fenestration  64  is closed off by the valve arrangement.  
         [0060]     The extension piece  70  seals into a non-aneurysed portion of the internal iliac artery  24 .  
         [0061]     The process of deployment of a stent graft according to this embodiment of the invention will be discussed with reference to  FIGS. 15A  to  15 M.  
         [0062]      FIGS. 3, 4  and  5  show a first embodiment of valve arrangement suitable for the present invention.  
         [0063]     In this embodiment the longer leg  52  of the bifurcated stent graft  40  as shown in  FIG. 1  has a fenestration  64  defined by a peripheral resilient ring  80  which is stitched into the tube of the longer leg  52 . Inside the longer leg is a semi-circular portion of biocompatible graft material  82  and a resilient self-expanding zigzag stent  85  which engages with the semi-circular biocompatible graft material  82  and engages it against the inside wall of the longer leg  52  and in particular over the fenestration  64 . By this arrangement the fenestration  64  is held in a closed configuration. The semi-circular piece  82  is stitched by stitching  83  at its proximal end to the inner wall of the longer leg  52 .  
         [0064]     Substantially opposite to the fenestration  64  in the tubular longer leg  52  the side arm  60  extends from a fenestration  62  in the tubular longer leg  52 .  
         [0065]      FIG. 5  shows the embodiment as shown in  FIG. 4  except that an indwelling catheter  66  and guide wire  68  through the indwelling catheter extend through the side arm  60  and through the fenestration  64  and this lifts the valve  82  off the fenestration  64  against the restoring force of the resilient self expanding stent  85 .  
         [0066]      FIGS. 6 and 7  show an alternative embodiment of bifurcated stent graft according to the present invention in the vasculature of a patient. The vasculature and the bifurcated stent graft are similar to the earlier embodiment shown in  FIGS. 1 and 2  and the same reference numerals are used for corresponding items.  
         [0067]     The vasculature comprises an aorta  10  in the region between the renal arteries  12  and the aortic bifurcation  14 . Common iliac arteries  16  and  18  extend down from the aortic bifurcation. The aorta  10  has an aneurysm  20  which extends down into the common iliac artery  18  so far as the bifurcation  22  between the internal iliac artery  24  and the external iliac artery  26 .  
         [0068]     To traverse the aneurysm a bifurcated aortic stent graft  40  has been deployed into the aorta  10 . The proximal end  42  of the bifurcated stent graft  40  is engaged into non-aneurysed portion  28  of the aorta  10  just distal of the renal arteries  12 . In this embodiment stent graft  40  has a proximally extending supra-renal exposed stent  44  with barbs  46  engaging the wall of the aorta proximal of the renal arteries to provide a secure position to prevent migration of the stent graft. The stent graft  40  has a short leg  50  and a long leg  52  extending from the graft bifurcation  54 . The longer leg  52  has a sealing surface  56  at its distal end which engages into a non-aneurysed portion of the external iliac artery  26 .  
         [0069]     The longer leg  52  has a side arm  90  which in this embodiment is in the form of a stented tube extending from a fenestration  92  in the longer leg  52 . The side arm  90  extends in a distal direction and has an end  94  remote from its connection with the longer leg  52  which opens adjacent to the internal iliac artery  24 .  
         [0070]     A fenestration  64  is placed into the longer leg  52  proximal of the connection of the side arm  90  into the longer leg  52 . The fenestration  64  has a valve arrangement within it to close it off as will be discussed with reference to FIGS.  8  to  10 .  
         [0071]     During deployment of the stent graft into the vasculature of a patient an in-dwelling catheter  66  extends through the side arm  90  and out through the valved fenestration  64 . The indwelling catheter includes a guide wire  68  therethrough.  
         [0072]      FIG. 7  shows the embodiment of  FIG. 6  but after deployment of a extension piece  70  into the side arm  90 . U.S. patent application Ser. No. 10/962,763 entitled “Introducer for Iliac Side Branch Device” discloses an arrangement for using an indwelling catheter to access an internal iliac artery. At this stage the indwelling catheter has been withdrawn and the fenestration  64  is closed off by the valve arrangement. The extension piece  70  seals into a non-aneurysed portion of the internal iliac artery  24 .  
         [0073]      FIGS. 8, 9  and  10  show an alternative embodiment of valve arrangement suitable for the present invention.  
         [0074]     In this embodiment of valve the longer leg  52  of the bifurcated stent graft  40  as shown in  FIG. 6  has a fenestration  64  defined by a peripheral resilient ring  80  which is stitched into the tubular wall of the longer leg  52 . Inside the longer leg is a cylindrical portion of biocompatible graft material  96  and a self-expanding zigzag stent  98  which engages with the cylindrical biocompatible graft material  96  and engages it against the inside wall of the longer leg  52  and in particular over the fenestration  64 . By this arrangement the fenestration  64  is held in a closed configuration. The cylindrical portion of biocompatible graft material  96  is stitched by stitching  99  at its proximal end to the inner wall of the longer leg  52 .  
         [0075]      FIG. 10  shows the embodiment as shown in  FIG. 9  except that an indwelling catheter  66  and guide wire  68  through the catheter extend through the side arm  60  and through the fenestration  64  and this lifts the valve  96  for the fenestration  64 .  
         [0076]     FIGS.  11  to  14  show a further embodiment of valve arrangement suitable for the present invention.  
         [0077]     In this embodiment the longer leg  200  of the bifurcated stent graft  40  ( FIG. 1 ) has a fenestration  202  defined by a peripheral resilient ring  204  which is stitched into the tube of the longer leg  200 . Inside the longer leg is a self expanding stent  206  which has a plurality of struts  208  and bends  210 . The self expanding stent  206  is shown in  FIG. 12 .  
         [0078]     The self expanding stent  206  has a valve member  212  formed from a piece of biocompatible graft material stitched onto spaced apart struts  208  to provide a part cylindrical surface on the self expanding stent  206  to form a valve assembly  214 .  
         [0079]     Around the lower circumference of the valve member  212  is a portion of resilient wire  213  retained by stitching  215  to assist with retaining the part circular shape of the valve member to endure good sealing against the inside surface of the tubular body of the longer leg  200 .  
         [0080]     This valve assembly is stitched into the tubular body of the longer leg  200  by stitching  216  at the bends  210  so that the valve member underlies the fenestration  202  and closes off the fenestration to flow therethrough from inside the longer leg to outside. A cross section of the valve at this stage is shown in  FIG. 13 .  
         [0081]     Substantially opposite to the fenestration  202  in the tubular longer leg  200  a side arm  218  extends from a fenestration  220  in the tubular longer leg  200 . The side arm  218  is in this embodiment formed from a corrugated graft material.  
         [0082]      FIG. 14  shows the embodiment as shown in  FIG. 13  except that an indwelling catheter  66  and guide wire  68  through the indwelling catheter extend through the side arm  218  and through the fenestration  202  and this lifts the valve member  212  off the fenestration  202  against the restoring force of the resilient self expanding stent  206 .  
         [0083]      FIGS. 15A  to  15 M show the various stages of deployment of a stent graft according to one embodiment of the present invention.  
         [0084]      FIG. 15A  shows a schematic version of one embodiment of a stent graft 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  100  has a nose cone dilator  102  at its proximal end and a stent graft assembly according to one embodiment of the present invention  104  is mounted onto the deployment device. This embodiment of stent graft  104  has an helical side arm  106  on the longer leg  108  of the stent graft  104 . An indwelling catheter  110  extends from the deployment device  100  through the helical side arm  106  exiting at valved aperture  112  and extending to a groove  114  in the nose cone dilator  102  outside of the stent graft  104 . The indwelling catheter  110  has a flexible curved proximal end  116 .  
         [0085]     Detail of the tubular side arm  106  and valve arrangement  112  are shown in  FIG. 15B . The tubular side arm  106  extends around the longer leg  108  from a fenestration  107  and the indwelling catheter  110  extends into the tubular side arm and out through the valved aperture  112 . The valved aperture  112  has a flap valve  113  on its inside to ensure that the aperture is closed when the indwelling catheter is removed. The flap valve is substantially the same as the as the construction shown in FIGS.  3  to  6 .  
         [0086]      FIG. 15C  shows a schematic vasculature of a patient including an aorta  10  renal arteries  12  and an aortic bifurcation  14 . Extending from the aortic bifurcation are iliac arteries  16  and  18 . The aorta has an aneurysm  20  which extends down the iliac artery to the position of the internal iliac artery  24 . The iliac bifurcation  22  defines the bifurcation between the internatal iliac artery  24  and the external iliac artery  26 .  
         [0087]     As shown in  FIG. 15C  the deployment device  100  has been deployed over a guide wire  120  so that its nose cone  102  extends up into the aneurysm  20  and the distal end of the nose cone  102  is substantially adjacent to the aortic bifurcation  14 . As shown in the detail in  FIG. 15C  the indwelling catheter and particularly its curved tip  116  has been compressed by the sheath  122  into the groove  114  in the nose cone dilator.  
         [0088]     As shown in  FIG. 15D  the sheath  122  of the deployment device has been withdrawn slightly to release the curved tip  116  of the indwelling catheter  110  and the indwelling guide wire  124  from the indwelling catheter  110  has been extended. Because of the curved end of the indwelling catheter the indwelling guide wire  124  has extended down the contra-lateral iliac artery  16 . A snare catheter  128  has been deployed into the contra-lateral common iliac artery and a snare  130  of the snare catheter  128  has been extended to grasp the guide wire  124 . The guide wire  124  is extracted via the snare catheter  128  so that it becomes a through-and-through guide wire. It is important at this stage to ensure there is slack maintained in the guide wire at the aortic bifurcation to prevent damage to the aortic bifurcation. This position is shown in  FIG. 15E .  
         [0089]     The use of and indwelling catheter with a curved tip to facilitate snaring from a contralateral iliac artery is taught in U.S. patent application Ser. No. 11/600,655 entitled ‘Stent Graft Introducer’ and the teaching therein is incorporated herein in its entirety.  
         [0090]     As shown in  FIG. 15F  the deployment device  100  in then advanced so that the nose cone dilator  102  is proximal of the renal arteries  12 . This draws the indwelling guide wire  124  also up into the aorta  10 .  
         [0091]     The sheath  122  of the deployment device  110  is then withdrawn to release the shorter leg  109  of the stent graft  104 . This stage is shown in  FIG. 15G .  
         [0092]     As shown in  FIG. 15H  the indwelling catheter is withdrawn down into the contra-lateral iliac artery  16  and the sheath  122  is withdrawn so that it is distal of the distal end of the side arm  106  while still retaining the distal end of the longer leg  108 .  
         [0093]     As shown in  FIG. 15I  a dilator and sheath introducer  130  is advanced over the guide wire  124  in the contra-lateral iliac artery  16  and the indwelling catheter  110  and extension arm deployment device are tracked over the guide wire  124  so that the nose cone  132  of the sheath introducer enters the valved aperture  112  and tracks over the guide wire  124  into the side arm  106  until it exits the distal end of the side arm  134  as shown in  FIG. 15J . The sheath introducer nose cone  132  is then withdrawn leaving the sheath  130  in place. At this stage the indwelling guide wire  124  is still in a through-and-through position. As shown in  FIG. 15K , another guide wire  136  is introduced through the sheath  130  and extended from the sheath  130  to enter into the internal iliac artery  24 .  
         [0094]     As shown in  FIG. 15L  a side arm deployment device is deployed over the guide wire  136  into the internal iliac artery  24  so that balloon expandable covered stent  140  extends into the internal iliac artery  24  from the side arm  106 . As shown in  FIG. 15M , the indwelling guide wire  124  is then removed and the position of the distal end of the longer leg  108  is set into the external iliac artery  26  and the balloon expandable covered stent  140  is expanded. The sheath  130  is then withdrawn and the valve  112  automatically closes. A leg extension  144  is then placed into the short leg  107  of the graft  104 . The proximal end  146  of the stent graft is also released from the deployment device  100  such that a portion of the graft seals into a non-aneurysed portion of the aorta  10  distal of the renal arteries  12  while an uncovered suprarenal stent  148  extends over the renal arteries to provide secure fixation.  
         [0095]      FIGS. 16A  to  16 K show an alternative embodiment of stent graft according to the present invention and the process of deploying such a stent graft in the vasculature of a patient.  
         [0096]     The stent graft in this embodiment comprises a two piece body with a proximal portion  150  and a distal portion  152  which when joined together into the vasculature of the patient provide a composite stent graft. The proximal portion  150  has the proximally extending suprarenal stents  154  and the distal portion  152  is bifurcated with a shorter leg  156  and longer leg  158 . The longer leg  158  has the helical side arm  160  and the valved aperture  162  through which the indwelling catheter  164  extends.  
         [0097]     The process of deployment of the stent graft of this embodiment is substantially similar to that shown in  FIGS. 15 C  to  15 M except that, as shown in  FIG. 16C , as a first stage the proximal portion  150  is deployed and released into the aorta. Subsequently a separate device  170  with an indwelling catheter  164  is introduced which carries the distal portion  152  and the process of snaring the indwelling guide wire, release of the main stent graft and deployment of a side arm extension into the internal iliac artery as shown in  FIGS. 16D  to  16 J is substantially the same as shown in  FIGS. 15C  to  15 L. The final stage as shown in  FIG. 16K  of the deployment of the two piece stent graft includes release of the distal portion  152  inside the proximal portion  150  and the deployment of a leg extension  172  into the short leg  156  and release of the distal end of the longer leg  158 .  
         [0098]     It will be realised that an alternative embodiment access for deployment into the internal iliac artery maybe by a brachial approach and in such case the indwelling catheter in the side arm may extend through the main lumen of the stent graft and the valved aperture may not be necessary in such an embodiment.  
         [0099]     Throughout this specification various indications have been given as to the scope of invention but invention 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 limitations.