Abstract:
Disclosed is a method and apparatus for treating bifurcations of the vascular system, such as abdominal aneurysms at the bifurcation of the aorta and iliac arteries. A tubular implant having a proximal section, a distal section and a hinged connection therebetween is positioned across the bifurcation such that the proximal section extends into a first iliac and the distal section extends into the second iliac. The proximal and distal iliac sections are both advanced superiorly, causing the implant to fold at the hinge and advance across the aneurysm into the aorta. In one implementation, restraining sleeves are thereafter removed and the implant self expands to place aorta in fluid communication with the first and second iliacs, bypassing the bifurcation. Deployment catheters are also disclosed.

Description:
PRIORITY INFORMATION  
       [0001]     This application claims the priority benefit under 35 U.S.C. § 119(e) of Provisional Application 60/467,625 filed May 2, 2003 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to vascular grafts and vascular graft deployment systems.  
         [0004]     2. Description of the Related Art  
         [0005]     An abdominal aortic aneurysm is a sac caused by an abnormal dilation of the wall of the aorta, a major artery of the body, as it passes through the abdomen. The abdomen is that portion of the body which lies between the thorax and the pelvis. It contains a cavity, known as the abdominal cavity, separated by the diaphragm from the thoracic cavity and lined with a serous membrane, the peritoneum. The aorta is the main trunk, or artery, from which the systemic arterial system proceeds. It arises from the left ventricle of the heart, passes upward, bends over and passes down through the thorax and through the abdomen to about the level of the fourth lumbar vertebra, where it divides into the two common iliac arteries.  
         [0006]     The aneurysm usually arises in the infrarenal portion of the diseased aorta, for example, below the kidneys. When left untreated, the aneurysm may eventually cause rupture of the sac with ensuing fatal hemorrhaging in a very short time. High mortality associated with the rupture led initially to transabdominal surgical repair of abdominal aortic aneurysms. Surgery involving the abdominal wall, however, is a major undertaking with associated high risks. There is considerable mortality and morbidity associated with this magnitude of surgical intervention, which in essence involves replacing the diseased and aneurysmal segment of blood vessel with a prosthetic device which typically is a synthetic tube, or graft, usually fabricated of Polyester, Urethane, DACRON™, TEFLON.™, or other suitable material.  
         [0007]     To perform the surgical procedure requires exposure of the aorta through an abdominal incision which can extend from the rib cage to the pubis. The aorta must be closed both above and below the aneurysm, so that the aneurysm can then be opened and the thrombus, or blood clot, and arteriosclerotic debris removed. Small arterial branches from the back wall of the aorta are tied off. The DACRON™ tube, or graft, of approximately the same size of the normal aorta is sutured in place, thereby replacing the aneurysm. Blood flow is then reestablished through the graft. It is necessary to move the intestines in order to get to the back wall of the abdomen prior to clamping off the aorta.  
         [0008]     If the surgery is performed prior to rupturing of the abdominal aortic aneurysm, the survival rate of treated patients is markedly higher than if the surgery is performed after the aneurysm ruptures, although the mortality rate is still quite high. If the surgery is performed prior to the aneurysm rupturing, the mortality rate is typically slightly less than 10%. Conventional surgery performed after the rupture of the aneurysm is significantly higher, one study reporting a mortality rate of 66.5%. Although abdominal aortic aneurysms can be detected from routine examinations, the patient does not experience any pain from the condition. Thus, if the patient is not receiving routine examinations, it is possible that the aneurysm will progress to the rupture stage, wherein the mortality rates are significantly higher.  
         [0009]     Disadvantages associated with the conventional, prior art surgery, in addition to the high mortality rate include the extended recovery period associated with such surgery; difficulties in suturing the graft, or tube, to the aorta; the loss of the existing aorta wall and thrombosis to support and reinforce the graft; the unsuitability of the surgery for many patients having abdominal aortic aneurysms; and the problems associated with performing the surgery on an emergency basis after the aneurysm has ruptured. A patient can expect to spend from one to two weeks in the hospital after the surgery, a major portion of which is spent in the intensive care unit, and a convalescence period at home from two to three months, particularly if the patient has other illnesses such as heart, lung, liver, and/or kidney disease, in which case the hospital stay is also lengthened. Since the graft must be secured, or sutured, to the remaining portion of the aorta, it is many times difficult to perform the suturing step because the thrombosis present on the remaining portion of the aorta, and that remaining portion of the aorta wall may many times be friable, or easily crumbled.  
         [0010]     Since many patients having abdominal aortic aneurysms have other chronic illnesses, such as heart, lung, liver, and/or kidney disease, coupled with the fact that many of these patients are older, the average age being approximately 67 years old, these patients are not ideal candidates for such major surgery.  
         [0011]     More recently, a significantly less invasive clinical approach to aneurysm repair, known as endovascular grafting, has been developed. Parodi, et al. provide one of the first clinical descriptions of this therapy. Parodi, J. C., et al., “Transfemoral Intraluminal Graft Implantation for Abdominal Aortic Aneurysms,” 5 Annals of Vascular Surgery 491 (1991). Endovascular grafting involves the transluminal placement of a prosthetic arterial graft within the lumen of the artery.  
         [0012]     In general, transluminally implantable prostheses adapted for use in the abdominal aorta comprise a tubular wire cage surrounded by a tubular PTFE or Dacron sleeve. Both balloon expandable and self expandable support structures have been proposed. Endovascular grafts adapted to treat both straight segment and bifurcation aneurysms have also been proposed. For bifurcated aneurysms, it has been suggested that the prosthesis be formed from two separate parts. In such systems, the first part may extend from the aorta into the first iliac branch. The second part is for the second iliac branch. The two parts are linked together during surgery. This complicates the surgical procedure and makes it more time consuming. In addition, the connection between the two parts may leak and cause blood to enter the aneurysm. Furthermore, because the first part of the prosthesis is designed for the aorta, it requires a relatively large delivery system (e.g., 18 to 24 millimeters) to delivery the compressed prosthesis. Such a large delivery system may require surgical cut-down to enter the vessel lumen.  
         [0013]     Notwithstanding the foregoing, there remains a need for a structurally simple, easily deployable transluminally implantable endovascular prosthesis.  
       SUMMARY OF THE INVENTION  
       [0014]     One aspect of the present invention provides a first tubular segment having a device distal end and a device proximal end, the distal end defining a distal opening and the proximal end defining a proximal opening. A second tubular segment has a device distal end and a device proximal end with the distal end defining a distal opening and the proximal end defining a proximal opening. A flexible connection such as a hinge or link connects the distal ends of the first and second tubular segments. The distal openings of the first and second tubular segments may be approximately D-shaped with one straight side each and the flexible connection is disposed between the straight sides of the first and second tubular segments.  
         [0015]     In accordance with another aspect of the present invention, there is provided a method of treating a bifurcation of a vessel into a first branch and a second branch. The method comprises the steps of providing a catheter having a proximal portion, a distal portion and a deployment zone therebetween. The catheter is positioned such that the proximal zone extends into the first branch, the distal zone extends into the second branch, and the deployment zone is aligned with the vessel. The deployment zone is advanced superiorly into the vessel, and the bifurcation graft is deployed from the catheter.  
         [0016]     The positioning step may comprise positioning the catheter such that the proximal portion extends from the patient through a first access site and the distal portion extends from the patient through a second access site. At least one of the first and second access sites is on the leg.  
         [0017]     The advancing step may comprise advancing the proximal and distal sections of the catheter in a superior direction, to cause the deployment zone to advance superiorly. The deploying step may comprise removing a restraint from the bifurcation graft.  
         [0018]     In accordance with a further aspect of the present invention, there is provided a self expandable bifurcation graft. The graft comprises a first tubular body, having a superior end and an inferior end. A second tubular body is provided, having a superior end and an inferior end. A flexible connection connects the superior end of the first tubular body and the superior end of the second tubular body. The first and second tubular bodies may be integrally formed, or formed separately and attached at the flexible connection.  
         [0019]     The superior ends of the first and second tubular bodies are configured such that when the tubular bodies are moved about the flexible connector into a side-by-side relationship, each of the superior ends define a semi-circular opening. The flexible connection may comprise a polymeric hinge, such as a fabric layer. In one implementation, the flexible connection comprises ePTFE, and may be continuous with an ePTFE sleeve that extends over at least a portion of the first and second tubular bodies. Alternatively, the flexible connection may comprise Dacron. The flexible connection may alternatively comprise a suture. Alternatively, the flexible connection may comprise a wire hook or loop.  
         [0020]     In one implementation of the invention, the bifurcation graft comprises a self expandable wire frame. The flexible connection may comprise a wire loop pivotably connecting a first frame portion in the first tubular body to a second frame portion in the second tubular body. Alternatively, opposing apexes or other portions of the first frame portion and the second frame portion may be directly interlinked, to provide a flexible hinge without a distinct wire loop. The wire loop may be integral with the frame, or distinct from the frame.  
         [0021]     In accordance with another aspect of the present invention, there is provided a method of treating a bifurcation of a vessel into a first branch and a second branch. The method comprises the steps of providing a tubular implant having a proximal section, a distal section and a side opening therebetween. The implant is positioned such that the proximal section is in a first iliac and the distal section is in a second iliac. The portion of the implant having the side opening is advanced into the aorta, and deployed in the aorta to place the aorta in fluid communication with the proximal and distal sections.  
         [0022]     In accordance with another aspect of the present invention, there is provided a method of accessing a bifurcation of a vessel into a first branch and a second branch sections. The method comprises the steps of providing a catheter having a bifurcation graft therein, and a proximal portion separated from a distal portion by a flex point. The catheter is positioned across the bifurcation. The method additionally comprises the step of bending the catheter at the flex point, and advancing the flex point towards the vessel. The flex point may comprise a junction between a first tube and a second tube on the catheter.  
         [0023]     Further features and advantages of the present invention will become apparent to those of ordinary skill in the art in view of the detailed description of preferred embodiments which follow, when considered together with the attached drawings and claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]      FIG. 1  is a schematic representation of a vascular prosthesis, having certain features and advantages according to an embodiment of the invention, positioned within an abdominal aortic aneurysm.  
         [0025]      FIG. 2  is a side perspective view of the vascular prosthesis of  FIG. 1 .  
         [0026]      FIG. 3  is a top perspective view of the vascular prosthesis of  FIG. 1  in a straightened configuration.  
         [0027]      FIG. 4  is a top (anatomically proximal end) plan view of the vascular prosthesis of  FIG. 1 .  
         [0028]      FIG. 5  is a side view of a modified embodiment of the vascular prosthesis of  FIG. 1 .  
         [0029]      FIG. 6A  is a partial cross-sectional view of a deployment apparatus having certain features and advantages according to an embodiment of the invention.  
         [0030]      FIG. 6B  is a partial cross-sectional view of a modified embodiment of a deployment apparatus.  
         [0031]      FIG. 7  is a schematic representation of a guidewire positioned across the ipsilateral and contralateral iliacs.  
         [0032]      FIG. 8  is a schematic representation of a deployment apparatus of  FIG. 6  positioned across the ipsilateral and contralateral iliacs.  
         [0033]      FIG. 9  is a schematic representation of a deployment apparatus of  FIG. 6  partially withdrawn and two guidewires positioned across the aneurysm into the aorta.  
         [0034]      FIG. 10  is a schematic representation of a deployment apparatus of  FIG. 6  positioned across the aneurysm into the aorta.  
         [0035]      FIG. 11  is a schematic representation of a deployment apparatus of  FIG. 6  positioned across the aneurysm into the aorta and partially withdrawn to deploy the vascular prosthesis.  
         [0036]      FIG. 12 a  schematic representation of a vascular prosthesis, having certain features and advantages according to another embodiment of the invention, positioned within an abdominal aortic aneurysm.  
         [0037]      FIG. 13  is a side view of the vascular prosthesis of  FIG. 12 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0038]      FIG. 1  illustrates a schematic representation of the abdominal part of the aorta and its principal branches. In particular, the abdominal aorta  30  is characterized by a right renal artery  32  and left renal artery  34 . The large terminal branches of the aorta  30  are the right and left common iliac arteries  36  and  38 . Additional vessels (e.g., second lumbar, testicular, inferior mesenteric, middle sacral) have been omitted for simplification. An aneurysm  40  is illustrated in the infrarenal portion of the diseased aorta. An endoluminal vascular prosthesis  42 , in accordance with an embodiment of the present invention, is illustrated spanning the aneurysm  40 .  
         [0039]     With reference to  FIGS. 1-4 , the prosthesis  42  comprises a first tubular member or tube  44 A and a second tubular member or tube  44 B. The first tubular member  44 A has a device distal end  46 A, which defines a device distal opening  48 A, and a device proximal end  50 A, which defines a proximal opening  52 A. In a similar manner, the second tubular member  44 B has a device proximal end  46 B, which defines a proximal opening  48 B, and a device distal end  50 B, which defines a distal opening  52 B. As best seen in  FIG. 1 , each tubular member  44 A,  44 B is adapted such that it can extend across the aneurysm  40 .  
         [0040]     As will be understood in view of the disclosure herein, the device distal end  46 A of first or proximal tubular section  44 A along with the device proximal end  46 B of the second or distal section  44 B are both implanted in the anatomically proximal or superior orientation. The device proximal end  50 A and device distal end  50 B of iliac branches  44 A and  44 B, as implanted, are in the anatomically distal or inferior position.  
         [0041]     The distal end  46 A and proximal end  46 B of the tubes  44 A,  44 B are connected together by a flexible connection or hinge  54  such as a flexible material or link, which will be described in detail below. As best seen in  FIG. 4 , the opposing ends  46 A,  46 B of the tubes  44 A,  44 B have a generally D-shaped or other complementary cross-section such that the tubes  44 A,  44 B define a periphery  56  when the tubes  44 A and  44 B are folded into a side by side orientation, which preferably closely conforms to the cross-sectional shape of the aorta  58  at the superior end of the aneurysm  40 . This arrangement advantageously seals off or isolates the aneurysm  40  from blood flow while directing the blood into the openings  48 A,  48 B of the first and second tubes  44 A,  44 B.  
         [0042]     The flexible connection  54  defines a preferably sealed interface between the openings  48 A,  48 B of the tubes  44 A,  44 B. In the illustrated embodiment, this interface defines a generally flat side in contrast to the generally rounded shape of the periphery  56 . However, in modified embodiments, the interface can be of a different shape (e.g., rounded, jagged etc.).  
         [0043]     As best seen in  FIG. 1 , the opposing ends  46 A,  46 B of the prosthesis are preferably positioned as close as possible to the lowest renal artery so as to maximize the overlap between graft material and the healthy infrarenal aortic wall  58  and thereby promoting a good seal within the artery. In modified embodiments, the prosthesis may be extended over or beyond the renal arteries. In such embodiments (see e.g.  FIGS. 12 and 13  discussed below), the portion of the prosthesis extending over and/or beyond the renal arteries is advantageously not covered with a graft material.  
         [0044]     As best seen in  FIG. 1 , the proximal and distal openings  52 A,  52 B of the tubes  44 A,  44 B are preferably configured to closely conform to the cross-sectional shape of the right and left common iliac arteries  36 ,  38 . The openings  52 A,  52 B therefore have a substantially round or O-shaped cross-section as compared to the superior openings  48 A,  48 B. As such, each tube  44 A,  44 B transitions from the generally D-shaped openings  48 A,  48 B at the superior end to the generally O-shaped openings  52 A,  52 B at the inferior end.  
         [0045]     The vascular prosthesis  42  can be formed using a variety of known techniques. For example, in one embodiment, each tube  44 A,  44 B comprises an expandable tubular support or skeleton and a polymeric or fabric sleeve that is situated concentrically outside and/or inside of the tubular support. In another embodiment, the tubular support may be embedded within a polymeric matrix which makes up the sleeve. Regardless of whether the sleeve is inside or outside the support, the sleeve may be attached to the tubular support by any of a variety of techniques, including laser bonding, adhesives, clips, sutures, dipping or spraying or others, depending upon the composition of the sleeve and overall prosthesis design.  
         [0046]     The sleeve may be formed from any of a variety of synthetic polymeric materials, or combinations thereof, including ePTFE, PE, PET, Urethane, Dacron, nylon, polyester or woven textiles. In one embodiment, the material of sleeve is sufficiently porous to permit ingrowth of endothelial cells, thereby providing more secure anchorage of the prosthesis and potentially reducing flow resistance, sheer forces, and leakage of blood around the prosthesis. Alternatively, materials that inhibit endothelial growth may also be used. Porosity in polymeric sleeve materials may be estimated by measuring water permeability as a function of hydrostatic pressure, which will preferably range from about 3 to 6 psi.  
         [0047]     The porosity characteristics of the polymeric sleeve may be either homogeneous throughout the axial length of the prosthesis  42 , or may vary according to the axial position along the prosthesis  42 . For example, with reference to  FIG. 1 , different physical properties may be called upon at different axial positions along the prosthesis  42  in use. For example, in the illustrated embodiment, the distal ends  46 A,  50 B, and the proximal ends  50 A,  46 B of the prosthesis  42  will seat against the native vessel wall, on either side of the aneurysm  40 . In these end portions, the prosthesis may be configured to encourage endothelial growth, or, to permit endothelial growth to infiltrate portions of the prosthesis in order to enhance anchoring and minimize leakage. The central portion of the prosthesis spans the aneurysm, and therefore anchoring is less of an issue. Instead, maximizing lumen diameter and minimizing blood flow through the prosthesis wall become primary objectives. Thus, the central portions of the prosthesis  42 , the polymeric sleeve may either be nonporous, or provided with pores of relatively lower porosity.  
         [0048]     In another embodiment, the ends  46 A,  46 B,  50 A,  50 B of prosthesis  42  may be provided with any of a variety of tissue anchoring structures, such as, for example, barbs, hooks, and/or exposed portions of the tubular support. Such anchoring structures over time, may become embedded in cell growth on the interior surface of the vessel wall. These configurations advantageously resist migration of the prosthesis within the vessel and reduce leakage around the ends of the prosthesis. The specific number, arrangement and/or structure of such anchoring structures can be optimized through routine experimentation.  
         [0049]     Numerous types of tubular supports may be utilized with the illustrated embodiment. These supports may be self expandable or expandable via, for example, an internal expanding device such as a balloon. See e.g., U.S. Pat. No. 6,123,722, which is hereby incorporated by reference herein. In one embodiment, a self expandable support may be formed of a shape memory alloy that can be deformed from an original, heat-stable configuration to a second heat-unstable configuration. See e.g., U.S. Pat. No. 6,051,020, which is hereby incorporated by reference herein. Such supports may also be formed from a wire or a piece of metal tubing that is laser cut. In another embodiment, the support is formed from any of a variety of self-expandable tubular wire supports, such as the tubular wire supports disclosed in U.S. Pat. Nos. 5,683,448, 5,716,365, 6,051,020, 6,187,036, which are hereby incorporated by reference herein, and other self-expandable configurations known to those of skill in the art. In general the support may comprise a series of end to end segments, each segment comprising a zig-zag wire frame having a plurality of apexes at its axial ends, and wire struts extending therebetween. Opposing apexes of adjacent segments may be connected in some or all opposing apex pairs, depending upon the desired performance.  
         [0050]     It should be appreciated that in modified embodiments the tubular support or skeleton may be positioned on only certain portions of the axial length of the prosthesis  42 . For example, in one embodiment, only the distal and proximal ends  46 A,  46 B,  50 A,  50 B of the prosthesis are provided with a tubular skeleton or support. In other embodiments, the prosthesis  42  is fully supported by a tubular support. (i.e., the tubular support extends through the entire length of the prosthesis). In still other embodiments, the prosthesis  42  may be formed with out a tubular support. In such embodiments, distal and proximal ends  46 A,  46 B,  50 A,  50 B of the prosthesis preferably include tissue anchoring structures as described above.  
         [0051]      FIG. 5  illustrates one manner for forming the flexible connection  54  between the first and second tubes  44 A,  44 B of the prosthesis  42 . As shown in  FIG. 5 , the prosthesis comprises a single outer tubular sheath  60  in which wire supports  62 A,  62 B are positioned. A slot or wedge shaped section  64  of the sheath  60  is removed from a portion of the sheath  60  that lies in a space between the two wire support sections  62 A,  62 B. This leaves a hinge strip  54  of the sheath  60  between the adjacent tubular supports  62 A,  62 B. The prosthesis  42  may be flexed about the flexible connection  54  by bending the ends of the prosthesis  42  in the directions of the arrows labeled A in  FIG. 5  to configure the prosthesis as illustrated in  FIG. 2 . In this manner, the connecting hinge strip of the sheath  60  forms the flexible connection  54  between the legs of the prosthesis  42 .  
         [0052]     The wire supports  62 A,  62 B may also extend across or be connected across the flexible connection  54 . In modified embodiments, other methods and devices may be used to link the first and second tubes  44 A,  44 B together. For example, the flexible connection  54  may be formed by interlocking wire structures which form a series of pivotable links. Adjacent apexes  51 ,  53  ( FIG. 4 ) may be pivotably linked to each other by a separate loop of metal or suture to provide a hinge. Alternatively, the opposing apexes  51 ,  53  may be directly interlinked with each other, without a distinct loop. In other embodiments, the flexible connection  54  may be formed from a fabric hinge with or without mechanical interlinking, or other structures as will be apparent to those of skill in the art in view of the disclosure herein. In another embodiment, the wire supports  62 A,  62 B may extend integrally across the flexible connection  54 .  
         [0053]      FIG. 6A  is a partial cross-sectional side view of one embodiment of a deployment apparatus  70 , which can be used to deploy the prosthesis  42  described above. The deployment apparatus  70  comprises an elongate flexible multicomponent tubular body  72  comprising a first (proximal) sheath  74 A and second (distal) sheath  74 B. Although not illustrated, an outer sheath may be positioned over the first and second sheaths  74 A,  74 B to span the junction  78  to enhance trackability during positioning as will be explained in more detail below.  
         [0054]     The tubular body  72  and other components of this system can be manufactured in accordance with any of a variety of techniques well known in the catheter manufacturing field. Extrusion of tubular catheter body parts from material such as Polyethylene, PEBAX, PEEK, nylon and others is well understood. Suitable materials and dimensions can be readily selected taking into account the natural anatomical dimensions in the iliacs and aorta, together with the dimensions of the desired implant and percutaneous or other access site.  
         [0055]     A pair of opposing stops or pushers  76 A,  76 B are axially movably positioned with respect to the sheaths  74 A,  74 B. The prosthesis  42  is positioned in a compressed or reduced diameter state within the sheaths  74 A,  74 B between opposing stops  76 A,  76 B. Preferably, the prosthesis  42  is mounted such that the link  54  is positioned generally at a junction  78  between the opposing ends of the sheaths  74 A,  74 B. As will be explained in detail below, proximal (inferior direction) retraction of the sheaths  74 A,  74 B through the respective iliac arteries and with respect to the proximal stops or pushers  76 A,  76 B, will deploy the prosthesis  42 .  
         [0056]      FIG. 6B  is a partial cross-sectional side view a modified deployment apparatus  70 ′, which can be used to deploy the prosthesis  42  described above. In this embodiment, the first and second sheaths  74 A′,  74 B′ partially overlap each other. As such, the first sheath  74 A′ has an outer diameter that is slightly smaller than the inner diameter of the second sheath  74 B′. This arrangement advantageously eliminates the junction  78  between the first and second sheaths during translumenal navigation thereby eliminating or reducing the need for an outer sheath (not illustrated). The prosthesis  42  may be positioned with the flexible connection  54  within about 1 cm or 2 cm of the distal end of the first sheath  74 A. Opposing stops (not illustrated) may be provided as described above.  
         [0057]     A technique for deploying the prosthesis  42  using the deployment apparatus  70  described in  FIG. 6A  will now be described with reference to  FIGS. 7-11 . With initial reference to  FIG. 7 , there is disclosed a schematic representation of the abdominal part of the aorta  30  and its principal branches as described above. A standard 0.035″ diameter guidewire  80  is in position across the ipsilateral and contralateral iliac arteries  36  and  38 . The guidewire  80  may be introduced, for example, from the contralateral side through a percutaneous puncture, and advanced superiorly towards the aorta  30 . A retrieval catheter (not shown) is introduced superiorly through a vascular access site and into the ipsilateral iliac, and used to grasp the guidewire  80  and retract it inferiorly and out through the ipsilateral vascular access site in accordance with known techniques.  
         [0058]     As shown in  FIG. 8 , the deployment apparatus  70  is advanced over the guidewire  80  from, for example, the ipsalateral access site along the guidewire  80  and out the contralateral access site. The guidewire  80  can thereafter be removed. The opposing device proximal end  81  and device distal end  82  of the deployment apparatus  70  extend outside the patient on the ipsalateral iliac side and the contralateral iliac side. The junction  78  between the opposing ends of the sheaths  74 A,  74 B is preferably positioned between the right and left common iliac arteries  36 ,  38 . The catheter is rotationally oriented such that the flexible connection  54  is on the inferior side. To aid positioning, one or both of the opposing ends of the outer sheaths  74 A,  74 B may be provided with radio opaque markers in the vicinity of the junction  78  to enable visualization during placement. Any of a variety of techniques may be used to provide radio opaque markers, such as, for example, providing the outer sheaths with bands or staples made of radio opaque material or dispersing radio opaque material into the material that forms the sheaths.  
         [0059]     Although not illustrated, the deployment apparatus  70  may be advanced over the guidewire with the outer sheath (not illustrated) positioned over the first and second sheaths  74 A,  74 B and spanning the junction  78 . Once the junction is properly positioned approximately mid-bifurcation, the outer sheath may be removed to expose the junction  78 .  
         [0060]     As shown in  FIG. 9 , the outer sheaths  74 A,  74 B may then be partially inferiorly retracted to expose the opposing ends  46 A,  46 B of the prosthesis  42 . First and second guide wires  84 A,  84 B can be advanced through the tubes  44 A,  44 B of the prosthesis  42 , one from the contralateral side and one from the ipsilateral side, until the distal ends of the guidewires  84 A,  84 B exit the deployment apparatus  70  through the junction  78  between opposing ends of the outer sheaths  74 A,  74 B. The guidewires (or single guidewire, if desired) may then be navigated across the aneurysm  40  into the aorta  30 . With the deployment apparatus  72 ′ of  FIG. 6A , the second sheath  74 B′ may be partially withdrawn inferiorly with respect to the first sheath  74 A′ so as to provide a gap  78  between the first and second sheaths  74 A′,  74 B′ through which the guidewires may be advanced as described above.  
         [0061]     The opposing superior ends  46 A,  46 B of the prosthesis  42  are then positioned at the aortic neck  58  by pushing the proximal end  81  and the distal end  82  of the deployment apparatus  70  extending out of the patient from the ipsilateral and contralateral access sites in the superior direction as illustrated by the arrows labeled B in  FIG. 10 . In response, the two tubes  44 A,  44 B of the prosthesis  72  pivot about the flexible connector  54  and the deployment apparatus  70  can be used to push the opposing ends  46 A and  46 B of the prosthesis  42  over the guidewires  84 A,  84 B and into position as shown in  FIG. 10 . The opposing ends of the first and second sheaths  74 A,  74 B, in the vicinity of the junction  78 , may contact and push against the flexible connection  54  during advancement of the prosthesis  42  across the aneurysm. To aid visualization during positioning, the superior ends  46 A,  46 B of the prosthesis  42  and/or sheaths  74 A,  74 B may be provided with radio opaque markers to enable visualization during placement. Any of a variety of techniques may be used to provide such radio opaque markers, such as, for example, providing the sheaths with bands or staples made of radio opaque material or dispersing radio opaque material into or onto the sheath material or onto the tubular support, or crimping, welding or otherwise attaching markers to the wire support.  
         [0062]     As shown in  FIG. 11 , the first and second sheaths  74 A,  74 B can then be inferiorly withdrawn in the direction of the arrows marked “C” while the stops  76 A,  76 B are held axially stationary to deploy the ends  46 A,  46 B of the prosthesis  42  as shown in  FIG. 11 . This allows the superior end of the implant to self expand within the aorta. Continued proximal retraction of the first and second sheaths  74 A,  74 B deploys the inferior ends  50 A,  50 B of the prosthesis  72  in the right and left common iliac arteries  36 ,  38  as shown in  FIG. 1 . The deployment catheter  70  may thereafter be proximally withdrawn from the patient by way of the first and second percutaneous access sites.  
         [0063]     As mentioned above, it is sometimes desirable to extend the prosthesis over or beyond the renal arteries so as to maximize the overlap between graft material and the healthy infrarenal aortic wall  58  and thereby promote a good seal within the artery. Such an arrangement is particularly advantageous if the aneurysm is positioned near the renal arteries.  
         [0064]      FIGS. 12-14  illustrate an exemplary embodiment of a prosthesis  100  particularly configured such that it may be extended over and/or beyond the renal arteries  32 ,  34 . This exemplary embodiment is generally configured similar to the prosthesis  42  described above. Accordingly, reference numbers used above will be used to describe similar components.  
         [0065]     As with the previous embodiment, the prosthesis  100  comprises a first tubular member or tube  44 A and a second tubular member or tube  44 B. The first tubular member  44 A has a device distal end  46 A, which defines a device distal opening (not shown), and a device proximal end  50 A, which defines a proximal opening (not shown). In a similar manner, the second tubular member  44 B has a device proximal end  46 B, which defines a proximal opening (not shown), and a device distal end  50 B, which defines a distal opening (not shown). The distal end  46 A and proximal end  46 B of the tubes  44 A,  44 B are connected together by a flexible connection or hinge  54  as described above. The tubes  44 A,  44 B may be formed in a variety of manners including a combination of tubular support or skeleton and a sleeve. In the illustrated embodiment, the tubes  44 A,  44 B are formed from a wire support  62 A,  62 B and a tubular sheath  60 , which in the illustrated embodiment is generally positioned over the wire support  62 A,  62 B.  
         [0066]     As shown in  FIG. 12 , the prosthesis  54  may be positioned such that the hinge  54  is positioned at or above the renal arteries  32 ,  34 . Accordingly, the distal end  46 A of the first tubular member  44 A and the proximal end  46 B of the second tubular member  44 B extend over and/or beyond the renal arteries  32 ,  34 . To permit blood flow from the renal arties  32 ,  34 , the portions of the distal end  46 A of the first tubular member  44 A and the proximal end  46 B of the second tubular member  44 B that extend over the renal arteries  32 ,  34  are not covered with the tubular sheath  60 . In this manner, blood from the renal arties  32 ,  34  may flow through the exposed wire supports  62 A,  62 B while the wire supports  62 A,  62 B contact the arterial wall to provide support for the prosthesis  100 . In other embodiments, the wire supports  62 A,  62 B may be provided any of variety of tissue anchoring structures as described above.  
         [0067]     In the illustrated arrangements, the wire supports  62 A,  62 B are exposed by cutting or forming an edge  102 A,  102 B (see  FIG. 13 ) which extends from the to the outer sides of the prosthesis  100  distally to the hinge  54  or inner side of the tubular members  44 A. The illustrated edge  102 A,  102 B is straight, however, in modified embodiments, the edge  102 A,  102 B may be curved, segmented etc. Other arrangements for allowing blood from the renal arties  32 ,  34  to pass through the prosthesis  100  may also be used. For example, the porosity of the sleeve  60  in the proximal region may be increased and/or various holes or openings may be formed in the sleeve  60 .  
         [0068]     With continued reference to  FIGS. 12 and 13 , in this embodiment, the tubes  44 A,  44 B of the prosthesis  100  terminate within the aneurysm  40 . Accordingly, leg extensions  104 A,  104 B may be attached to the prosthesis such that the assembled prosthesis  100  extends across the aneurysm. The extensions  104 A,  104 B may be formed in a variety of manners and may include a skeleton and sleeve as described above. Various attachment devices (e.g., barbs, hooks, etc.) may be provided to facilitate attachment of the extensions  104 A,  104 B to the tubes  44 A,  44 B. For example, in the illustrated embodiment, a portion  106 A,  106 B, of the tubular support wire support  62 A,  62 B is folded over the sleeve  60  such that it lies on the outside of the sleeve  60 .  
         [0069]     The extensions  104 A,  104 B may be attached in situ (see e.g., U.S. Pat. No. 6,685,736, the disclosure of which is hereby incorporated by reference in its entirety herein) or before deployment. In certain embodiments, the extensions  104 A,  104 B may comprise self expandable grafts which are inserted into and expanded within the tubes  44 A,  44 B. See e.g., (U.S. Pat. No. 6,685,736, the disclosure of which is hereby incorporated by reference in its entirety herein). Of course, the tubes  44 A,  44 B may also be configured to extend across the aneurysm. In such an embodiment, the portions  106 A,  106 B may over time become embedded in cell growth on the interior surface of the vessel thereby advantageously resisting migration and reducing leakage around the ends of the prosthesis  100 .  
         [0070]     While a number of preferred embodiments of the invention and variations thereof have been described in detail, other modifications and methods of using and medical applications for the same will be apparent to those of skill in the art. Accordingly, it should be understood that various applications, modifications, combinations, sub-combinations and substitutions may be made of equivalents without departing from the spirit of the invention or the scope of the claims.