Abstract:
A sealable vascular system includes an endovascular implant to be delivered in a compressed or folded state to an implantation site. The endovascular implant includes a tubular implant body and a sealable circumferential collar at said tubular implant body and including a variable sealing device and a control lead traversing from said variable sealing device to a user for controlling said variable sealing device by the user, said variable sealing device and said control lead being cooperatively operable to reversibly expand and contract said sealable circumferential collar such that said sealable circumferential collar is circumferentially adjustable during deployment thereof to achieve a repositionable fluid-tight seal between said sealable circumferential collar and the internal walls of the implantation site.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims is a divisional application of U.S. patent application Ser. No. 11/888,009 (Pub. No. 2009/0005760), now U.S. Pat. No. 8,252,036 filed Jul. 31, 2007 (which application claims priority of U.S. Provisional Patent Application Ser. No. 60/834,401, filed Jul. 31, 2006 and U.S. Provisional Patent Application Ser. No. 60/834,627, filed Aug. 1, 2006), the entire disclosures of which are hereby incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of vascular surgery and the treatment of aneurysms or other luminal vascular defects. Specifically, the present invention relates to a novel design for sealable endovascular implants and to methods of use for such implants in endovascular procedures for aneurysms of the thoracic or abdominal aorta or other vascular structural defects. 
     BACKGROUND OF THE INVENTION 
     Aneurysms of the thoracic and abdominal aorta represent a degenerative process of the aorta that is often attributed to atherosclerosis. Aneurysms are defined as a focal dilatation with at least a 50% increase over normal arterial diameter, usually associated with a degradation of the aortic media, or other structural defect in the aortic wall. 
     Medical research has suggested that these lesions are prone to occur in areas subjected to significant redirection of blood flow during diastole; however, the exact cause of such aneurysms is not known. A familial tendency to symptomatic aneurysms has been suggested. Degenerative aneurysms account for more than 90% of all infrarenal aneurysms of the abdominal aorta. Other potential causes include infection, cystic medial necrosis, arteritis, trauma, collagen vascular disorders, and anastomotic disruption. 
     Abdominal aortic aneurysms most commonly begin in the infrarenal aorta, and extend down to the iliac bifurcation. Aneurysms of the thoracic aorta are most commonly located in the descending thoracic aorta, beginning just distal to the origin of the left subclavian artery. 
     Aortic aneurysms generally affect elderly Caucasian men. Aortic aneurysms are less commonly reported among persona of African American, Asian, and Hispanic heritage. Abdominal aortic aneurysms are five times more common in men than in women. In men, the aneurysm process appears to begin at approximately age fifty years and reaches peak incidence at approximately age eighty years. Women appear to have a more delayed onset in which the aneurysm process appears to begin at approximately age 60 years. Smoking has been associated as a potential risk factor for the development of aortic aneurysms. Other risk factors include previous aneurysm repair or peripheral aneurysm (such as femoral or popliteal), coronary artery disease, and hypertension. 
     Although the reported findings from autopsy series vary widely, the incidence of aortic aneurysms probably exceeds 3-4% in individuals older than 65 years. Death from aneurysmal rupture remains one of the 15 leading causes of death in the United States. In addition, the overall prevalence of aortic aneurysms has increased significantly in the last 30 years. This is partly due to an increase in diagnosis based on the widespread use of imaging techniques. However, the prevalence of fatal and nonfatal rupture has also increased, suggesting a true increase in incidence. An aging population probably plays a significant role. 
     The surgical management of aortic aneurysms dates back to the early twentieth century, and has involved a variety of methods, including ligation, intraluminal wiring, cellophane wrapping, homografts, and grafts using nylon and polytetrafluoroethylene [PTFE] fabrics. 
     Prior to the development of endoaneurysmorrhaphy in 1962, postoperative surgical mortality rates were high (&gt;25%). Endovascular repair techniques have reduced the operative mortality to 1.8-5%. 
     Existing techniques for endovascular treatment of aneurysms involve placement of a tubular graft with seals to normal aortic walls above and below the aneurysm to create a tubular bridge to carry flow across the aneurysm without allowing flow to fill the aneurismal sac. Using these techniques, grafts may be placed using percutaneous access to the femoral arteries, and delivery/implantation using vascular catheters and fluoroscopic visualization. The deficiencies associated with existing endograft technology relate to leakage at the graft/aortic interface and/or post-implantation migration of the endograft. Small post-implantation leaks may be repaired with the placement of one or more extension cuffs above the endograft proximally, or below the implant distally to attempt to obtain a better seal with the vessel. The required use of such cuffs may add significantly to the overall cost and morbidity of the procedure. Major failures with endograft repair generally require emergent open surgery to avert catastrophic rupture of the aneurysm. Also, current endovascular systems require accurate size matching of endograft implants, leaving a very small margin for error. 
     In order for a patient to be a candidate for existing endograft methods and technologies, a proximal neck of at least 15 mm. of normal aorta must exist between the origin of the most inferior renal artery and the origin of the aneurysm in the case of abdominal aneurysms or the left subclavian artery for thoracic aortic aneurysms in order to permit an adequate seal. Similarly, at least 15 mm. of normal vessel must exist distal to the distal extent of the aneurysm for an adequate seal to be achieved. 
     Migration of existing endografts has also been a significant clinical problem, potentially causing leakage and re-vascularization of aneurysms and/or compromising necessary vascular supplies to arteries such as the carotid, subclavian, renal, or internal iliac vessels. This problem has been partially addressed by some existing endograft designs, in which barbs or hooks have been incorporated to help retain the endograft at its intended site. However, these existing endograft designs are not removable and repositionable once they are deployed. Thus, once such an endograft has been placed, open surgery is necessary if there is failure due to leakage or undesired occlusion of other vascular structures. 
     Because of the limitations imposed by existing vascular endograft devices and endovascular techniques, approximately eighty percent of abdominal and thoracic aneurysms repaired in the U.S. are still managed though open vascular surgery, instead of the lower morbidity of the endovascular approach. 
     SUMMARY OF THE INVENTION 
     The present invention is directed towards a novel design for endovascular implant grafts, and methods for their use for the treatment of aortic aneurysms and other structural vascular defects. A sealable, repositionable endograft system for placement in a blood vessel is disclosed, in which an endograft implant comprises a non-elastic tubular implant body with an elastic proximal end(s) and an elastic distal end(s). Both the elastic proximal and distal ends in an implant according to the present invention further comprise one or more circumferential sealable collars and one or more variable sealing device, capable of controllably varying the expanded diameter of said collar upon deployment to achieve the desired seal between the collar and the vessel&#39;s inner wall. An endovascular implant according to the present invention further comprises a central lumen and one or more control leads extending distally from releasable connections with each variable sealing device. Embodiments of endovascular implants according to the present invention may further be provided with retractable retention tines or other retention devices allowing an implant to be repositioned before final deployment. An endograft system according to the present invention further comprises a delivery catheter with an operable tubular sheath, capable of housing a folded or compressed endograft implant prior to deployment and capable of retracting or otherwise opening in at least its proximal end to allow implant deployment, said sheath sized and configured to allow its placement via a peripheral arteriotomy site, and of appropriate length to allow its advancement into the thoracic or abdominal aorta, as required for a specific application. 
     In use of an embodiment according to the present invention, an operator prepares an arteriotomy site in a patient in a suitable peripheral location, such as the femoral arteries. Upon incision into the artery, a guide wire is placed, and extended under radiographic visualization into the aorta. A catheter sheath is inserted, housing a collapsed endovascular graft. An injector cannula is inserted, with its proximal tip extending beyond the catheter sheath. Under radiographic visualization, radio-opaque or other contrast dye is injected into the injector cannula, and the contrast dye-enhanced view is used to position the proximal edge of the cannula above the beginning of the aneurysm sac. The catheter sheath is then partially retracted to expose the proximal portion of the endovascular implant. Through action initiated by the operator on the control leads, the variable sealing device for the proximal seal is activated, expanding the elastic circumferential sealable collar until firm contact is made with the vessel wall. At this point, additional radio-opaque or other contrast dye is injected, and the seal is assessed. If there are leaks, the variable sealing device is again activated to expand the diameter of the circumferential sealable collar for a firmer contact. The seal is reassessed and adjusted until there no contrast dye leaks are seen. If the radio-opaque or other contrast dye indicates that the device is placed too proximally and threatens or covers the renal or subclavian junctions, then it is loosened and moved distally. 
     Once the proximal circumferential sealable collar has been suitably sealed, the catheter sheath is then retracted beyond the distal extent of the aneurysm exposing the remainder of the graft. The variable sealing device for the distal seal is similarly activated, expanding the elastic circumferential sealable collar until firm contact is made with the vessel wall. At this point, additional radio-or other contrast dye is injected, and the distal seal is assessed. If there are leaks, the distal variable sealing device is again activated to expand the diameter of the distal circumferential sealable collar for a firmer contact. The seal is reassessed and adjusted until there no contrast dye leaks are seen. 
     For an implant for an abdominal aortic aneurysm according to the present invention, an endograft implant comprises a non-elastic tubular body with an elastic proximal and distal ends and a non-elastic contralateral cuff. An operator deploys and seals the proximal and distal ends of the implant as described above, with the distal end deployed and sealed in the iliac artery on the side of the initial arteriotomy. Then, a second arteriotomy is made on the opposite side. Radio-or other contrast dye injection is again used to allow visualization of the non-elastic contralateral cuff, and a second guide wire is placed from the second arteriotomy site through the non-elastic contralateral cuff. A contralateral delivery catheter is then introduced over the second guide wire. The contralateral delivery catheter comprises a slidable or removable sheath housing a folded or compressed endograft segmental implant which further comprises a non-elastic tubular body with an elastic proximal and distal ends. Both the elastic proximal and distal ends in an endograft segmental implant according to the present invention further comprise one or more circumferential sealable collars and one or more variable sealing device, capable of controllable varying the expanded diameter of said collar upon deployment to achieve the desired seal between the collar and the non elastic contralateral cuff proximally and between the collar and the vessel&#39;s inner wall distally. An endograft segmental implant according to the present invention further comprises a central lumen and one or more control leads extending distally from releasable connections with each variable sealing device. 
     Again, under radiographic control, radio-opaque or other contrast dye is injected into the injector cannula, and the contrast dye-enhanced view is used to position the proximal edge of the contralateral delivery catheter within the lumen of the non-elastic contralateral cuff. The contralateral delivery catheter sheath is then partially retracted to expose the proximal portion of the endograft segmental implant. Through action initiated by the operator on the control leads, the variable sealing device for the proximal seal is activated, expanding the elastic circumferential sealable collar until firm contact is made between the sealable collar and the non elastic cuff. At this point, additional radio-opaque or other contrast dye is injected, and the seal is assessed. If there are leaks, the variable sealing device is again activated to expand the diameter of the circumferential sealable collar for a firmer contact. The seal is reassessed and adjusted until there no contrast dye leaks are seen. 
     Finally, once the proximal circumferential sealable collar of the endograft segmental implant has been suitably sealed, the catheter sheath is then retracted beyond the distal extent of the aneurysm, exposing the remainder of the graft. The variable sealing device for the distal seal is similarly activated, expanding the elastic circumferential sealable collar until firm contact is made with the vessel wall. At this point, additional radio-opaque or other contrast dye is injected, and the distal seal is assessed. If there are leaks, the distal variable sealing device is again activated to expand the diameter of the distal circumferential sealable collar for a firmer contact. The seal is reassessed and adjusted until there no contrast dye leaks are seen. At this point, the operator may remove the injector cannula and detach the control leads from the variable sealing devices, and remove the control leads and guide wires from their arteriotomy sites and close the wounds. 
     The preceding description is presented only as an exemplary application of the devices and methods according to the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a side perspective view of the proximal tip of a delivery catheter containing a disclosed embodiment of the present invention of a compressed or folded bifurcated endovascular implant with a contralateral cuff housed within a sheath. 
         FIG. 1B  is a side perspective view of the proximal tip of a delivery catheter containing a disclosed embodiment of the present invention of a decompressed or unfolded endovascular implant removed from a sheath. 
         FIG. 2A  is a side perspective view of the proximal tip of a delivery catheter containing a disclosed embodiment of the present invention of a compressed or folded endograft segmental implant housed within a sheath of the present invention. 
         FIG. 2B  is a side perspective view of the proximal tip of a delivery catheter containing a disclosed embodiment of the present invention of a decompressed or unfolded endograft segmental implant removed from a sheath of the present invention. 
         FIG. 3  is a side perspective view of a disclosed embodiment of the present invention of an endograft segmental implant. 
         FIG. 4  is a perspective anatomic view of a disclosed embodiment of the present invention in which the proximal tip of an implant delivery catheter placed in a first side through a femoral artery is positioned in an abdominal aorta in an infrarenal location, but above the origin of an abdominal aortic aneurysm. 
         FIG. 5  is a perspective anatomic view of the disclosed embodiment of the present invention of  FIG. 4  in which an injector cannula has been introduced through a lumen of the implant delivery catheter, and protrudes proximal to the tip of the implant delivery catheter to fully expose all injector ports for radio-opaque contrast dye injection therethrough. 
         FIG. 6  is a perspective anatomic view of the disclosed embodiment of the present invention of  FIG. 5  in which the sheath of the implant delivery catheter has been retracted or partially opened to allow the endograft implant therein to partially decompress or unfold, to expose the proximal elastic implant end and a length of the non-elastic tubular body. 
         FIG. 7  is a perspective anatomic view of the disclosed embodiment of the present invention of  FIG. 6  in which the implant delivery catheter has been slightly withdrawn under radiographic control to position the proximal tip of the implant distal to the origins of the renal arteries to preserve flow therein. 
         FIG. 8  is a perspective anatomic view of the disclosed embodiment of the present invention of  FIG. 7  in which operator action on one or more control leads connected to one or more variable sealing devices has caused the extended circumferential sealable collar of the implant&#39;s elastic proximal end to firmly and fully contact the inner wall of the aorta, effecting a vascular seal therein. 
         FIG. 9  is a perspective anatomic view of the disclosed embodiment of the present invention of  FIG. 8  in which operator action has fully retracted or opened and removed the sheath of the implant delivery catheter allowing the endograft implant therein to fully decompress or unfold, to expose a distal elastic implant end and a non-elastic contralateral cuff. 
         FIG. 10  is a perspective anatomic view of the disclosed embodiment of the present invention of  FIG. 9  in which operator action on one or more control leads connected to one or more variable sealing devices has caused the extended circumferential sealable collar of the implant&#39;s elastic distal end to firmly and fully contact the inner wall of the common iliac artery above the origin of the internal iliac artery, effecting a vascular seal therein and preserving flow through the internal iliac artery. 
         FIG. 11  is a perspective anatomic view of the disclosed embodiment of the present invention of  FIG. 10  in which operator action has placed a hooked second guide wire to grasp and stabilize the non-elastic contralateral cuff under radiographic visualization through an access via a second side through a femoral artery. 
         FIG. 12  is a perspective anatomic view of the disclosed embodiment of the present invention of  FIG. 11  in which operator action has placed a contralateral delivery catheter over the second guide wire. 
         FIG. 13  is a perspective anatomic view of the disclosed embodiment of the present invention of  FIG. 12  in which operator action has removed the sheath of the contralateral delivery catheter allowing the endograft segmental implant therein to fully decompress or unfold, to expose a proximal segmental elastic implant end, a distal segmental elastic implant end, and the full length of the non-elastic segmental tubular implant body connecting said ends. 
         FIG. 14  is a perspective anatomic view of the disclosed embodiment of the present invention of  FIG. 13  in which operator action on one or more control leads connected to one or more variable sealing devices has caused the extended circumferential sealable collar of the implant&#39;s proximal segmental elastic implant end to expand to firmly and fully contact the inner walls of the non-elastic contralateral cuff effecting a proximal seal, and then similarly caused the extended circumferential sealable collar of the implant&#39;s distal segmental elastic implant end to expand to firmly and fully contact the inner wall of the common iliac artery on the second side above the origin of the internal iliac artery, effecting a vascular seal therein and preserving flow through the internal iliac artery. 
         FIG. 15  shows an diagrammatic view of a patient in a dorsal supine position, with a disclosed embodiment of an endovascular implant according to the present invention in sealed position in the patient&#39;s abdominal aorta proximally and distally, and with arteriotomy incisions in both femoral arteries with an injector cannula and proximal and distal control leads in place in the patient&#39;s right arteriotomy site for radiographic contrast dye injection and a second guide wire in place in the patient&#39;s left arteriotomy site, corresponding to the procedural stage shown in  FIG. 11 . 
         FIG. 16  is a longitudinal anatomic view showing a disclosed embodiment of a thoracic endovascular implant according to the present invention in sealed position proximally and distally in a patient&#39;s descending thoracic aorta. 
         FIG. 17  is a longitudinal anatomic view showing an alternate disclosed embodiment of a thoracic endovascular implant in a patient&#39;s descending thoracic aorta according to the present invention in which a first thoracic endovascular implant with a non-elastic distal cuff has been sealed in position proximally and distally has been joined by a second thoracic endovascular implant with a non-elastic tubular body with an elastic proximal end and an elastic distal end, both containing circumferential sealable collars and variable sealing devices capable of achieving a desired seal between the collar and the vessel&#39;s inner wall. 
         FIG. 18A  is a side perspective view of the disclosed embodiment of an endovascular implant according to the present invention in which the proximal and distal circumferential sealable collars are provided with retractable retention tines and shown in a retracted, pre-deployment position. 
         FIG. 18B  is a cross-sectional view of a disclosed embodiment according to the present invention of a proximal or distal circumferential sealable implant collar with retention tines covered by a compressible foam sheathing in a retracted, pre-deployment position. 
         FIG. 19A  is a longitudinal anatomic view of a disclosed embodiment according to the present invention of an endovascular implant which is being deployed and sealed proximally in an abdominal aorta containing an infrarenal aneurysm, with incomplete distal circumferential sealable implant collar expansion and seal at this stage of the procedure. 
         FIG. 19B  is a cross-sectional view of the distal circumferential sealable implant collar in  FIG. 19A , showing the compressible foam sheathing covering the collar&#39;s retention tines within a vessel&#39;s lumen. 
         FIG. 20A  is a longitudinal anatomic view of a disclosed embodiment according to the present invention of an endovascular implant which is being deployed and sealed proximally in an abdominal aorta containing an infrarenal aneurysm, with complete proximal circumferential sealable implant collar expansion and seal at this stage of the procedure. 
         FIG. 20B  is a cross-sectional view of the proximal circumferential sealable implant collar in  FIG. 20A , showing compression of the compressible foam sheathing allowing the collar&#39;s retention tines to contact and engage the aortic wall circumferentially. 
         FIG. 21A  is a perspective view of an embodiment of a variable sealing device according to the present invention. 
         FIG. 21B  is a sectional view of an embodiment of a variable sealing device according to the present invention, in which the mechanism is in a released, locked state. 
         FIG. 21C  is a sectional view of an embodiment of a variable sealing device according to the present invention, in which the mechanism is in an engaged, unlocked state. 
         FIG. 21D  is a perspective view of an embodiment of a sealable collar containing a variable sealing device according to the present invention. 
         FIG. 22A  is a longitudinal anatomic view of a disclosed embodiment according to the present invention of an endovascular implant incorporating an endograft monitoring device attached to the aneurysmal sac wall and the outer wall of the endograft in which the endograft has been effectively sealed in position proximally and distally to an aneurysm, thus devascularizing the aneurysmal sac to allow the walls of the aneurysm to collapse against the endograft, and hold the endograft monitoring device in a collapsed position. 
         FIG. 22B  is a longitudinal anatomic view of a disclosed embodiment according to the present invention of an endovascular implant incorporating an endograft monitoring device of  FIG. 22A  in which the aneurysmal sac has become revascularized, allowing the endograft monitoring device to spring open such that it may be visualized on x-ray or other diagnostic visualization means. 
         FIG. 22C  shows an alternate embodiment of an endovascular implant incorporating an endograft monitoring device according to the present invention, in which said endograft monitoring device comprises more than one spring-like attachment to both the outer wall of the endograft and to the inner wall of the aneurysmal sac, and in which the aneurysmal sac has been sealed and devascularized, allowing the walls of the aneurysm to collapse against the endograft, and hold the endograft monitoring device in a collapsed position. 
         FIG. 22D  shows the alternate embodiment of an endovascular implant incorporating an endograft monitoring device according to the present invention of  FIG. 22C , in which said endograft monitoring device comprises more than one spring-like attachment to both the outer wall of the endograft and to the inner wall of the aneurysmal sac, and in which the aneurysmal sac has become revascularized, allowing the endograft monitoring device to spring open such that it may be visualized on x-ray or other diagnostic visualization means. 
         FIG. 22E  shows yet another an alternate embodiment of an endovascular implant incorporating an endograft monitoring device according to the present invention, in which said endograft monitoring device comprises a plurality of spring-like attachment to both the outer wall of the endograft and to the inner wall of the aneurysmal sac, and in which the aneurysmal sac has been sealed and devascularized, allowing the walls of the aneurysm to collapse against the endograft, and hold the endograft monitoring device in a collapsed position. 
         FIG. 22F  shows the embodiment of an endovascular implant incorporating an endograft monitoring device according to the present invention of  FIG. 22E , in which said endograft monitoring device comprises more than one spring-like attachment to both the outer wall of the endograft and to the inner wall of the aneurysmal sac, and in which the aneurysmal sac has become revascularized, allowing the endograft monitoring device to spring open such that it may be visualized on x-ray or other diagnostic visualization means. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The present invention may be understood more readily by reference to the following detailed description of the preferred embodiments of the invention and the examples included herein. However, before the preferred embodiments of the devices and methods according to the present invention are disclosed and described, it is to be understood that this invention is not limited to the exemplary embodiments described within this disclosure, and the numerous modifications and variations therein that will be apparent to those skilled in the art remain within the scope of the invention disclosed herein. It is also to be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting. 
     Unless otherwise noted, the terms used herein are to be understood according to conventional usage by those of ordinary skill in the relevant art. In addition to the definitions of terms provided below, it is to be understood that as used in the specification and in the claims, “a” or “an” can mean one or more, depending upon the context in which it is used. 
     The present invention is directed towards novel designs for sealable and repositionable endovascular implant grafts, and methods for their use for the treatment of aortic aneurysms and other structural vascular defects. 
     In an exemplary embodiment according to the present invention, a sealable vascular endograft system for placement in a vascular defect is provided, comprising an elongated main implant delivery catheter with an external end and an internal end for placement in a blood vessel with internal walls. In such an exemplary embodiment, the main implant delivery catheter further comprises a main implant delivery catheter sheath which may be openable or removable at said internal end and a main implant delivery catheter lumen containing within a compressed or folded endovascular implant. Further in such an exemplary embodiment, an endovascular implant comprises a non-elastic tubular implant body with an elastic proximal end terminating in a proximal sealable circumferential collar controlled by a proximal variable sealing device which is operated by a proximal control lead that traverses said main implant delivery catheter and exits at said external end for interface by an operator, such that said proximal sealable circumferential collar may be expanded or contracted by said operator to achieve a fluid-tight seal between said proximal sealable circumferential collar and the internal walls of said blood vessel proximal to said vascular defect. Moreover, in such an exemplary embodiment, an endovascular implant further comprises a non-elastic tubular implant body with an elastic distal end terminating in a distal sealable circumferential collar controlled by a distal variable sealing device which is operated by a distal control lead that exits said main implant delivery catheter at said external end for interface by an operator, such that said distal sealable circumferential collar may be expanded or contracted by said operator to achieve a fluid-tight seal between said distal sealable circumferential collar and the internal walls of said blood vessel distal to the vascular defect. 
     Referring now in more detail to the drawings, in which like numerals indicate like elements throughout the several views,  FIG. 1A  shows a side perspective view of the proximal tip of a main implant delivery catheter  100  with a main implant delivery catheter lumen  102  containing a disclosed embodiment of compressed or folded endovascular implant  200  housed within a main implant delivery catheter sheath  104 . The endovascular implant  200  in the embodiment shown in  FIG. 1A  includes a non-elastic tubular implant body  106  with an elastic proximal end  108  and an elastic distal end  110 . The elastic proximal end  108  terminates in a proximal sealable circumferential collar  112 , controlled by a proximal variable sealing device  116  which is operated by a proximal control lead  120  that traverses the main implant delivery catheter  100  and exits distally for interface with an operator (not shown in  FIG. 1A ). The elastic distal end  110  terminates in a distal sealable circumferential collar  114 , controlled by a distal variable sealing device  118  which is operated by a distal control lead  122  that exits the main implant delivery catheter  100  distally for interface with an operator (not shown in  FIG. 1A ). 
     The embodiment of an endovascular implant  200  of  FIG. 1A  is further shown in  FIG. 1B  removed from the main implant delivery catheter  100  and in a semi- or partially expanded or non-folded state. In addition to the elements described in  FIG. 1A , the endovascular implant  200  in the embodiment shown in  FIG. 1B  may also include a contralateral non-elastic cuff  126 . 
     An alternate embodiment of a sealable endovascular implant according to the present invention is shown in  FIG. 2A . The proximal tip of a main implant delivery catheter  100  with a main implant delivery catheter lumen  102  containing a disclosed embodiment of compressed or folded straight endovascular implant  202  housed within a main implant delivery catheter sheath  104 . The endovascular implant  202  in the embodiment shown in  FIG. 2A  includes a non-elastic tubular implant body  106  with an elastic proximal end  108  and an elastic distal end  110 . The elastic proximal end  108  terminates in a proximal sealable circumferential collar  112 , controlled by a proximal variable sealing device  116  which is operated by a proximal control lead  120  that traverses the main implant delivery catheter  100  and exits distally for interface with an operator (not shown in  FIG. 2A ). The elastic distal end  110  terminates in a distal sealable circumferential collar  114 , controlled by a distal variable sealing device  118  which is operated by a distal control lead  122  that exits the main implant delivery catheter  100  distally for interface with an operator (not shown in  FIG. 2A ). 
     The embodiment of an endovascular implant  202  of  FIG. 2A  is further shown in  FIG. 2B  removed from the main implant delivery catheter  100  and in an semi- or partially expanded or non-folded state. A straight endovascular implant  202  according to the embodiment shown in  FIGS. 2A and 2B  provides a non-branching conduit between the proximal sealable circumferential collar  112  and the distal sealable circumferential collar  114 . 
     An embodiment of an endograft segmental implant according to the present invention is shown in  FIG. 3 . An endograft segmental implant  306  sealably interfaces to provide a conduit between a non-elastic vascular graft and a distal blood vessel. As shown in  FIG. 3 , an endograft segmental implant  306  includes a non-elastic tubular segmental implant body  308  with an elastic proximal segmental end  310  and an elastic distal segmental end  312 . The elastic proximal segmental end  310  terminates in a proximal segmental sealable circumferential collar  314 , controlled by a proximal segmental variable sealing device  318  which is operated by a proximal segmental control lead  322  that traverses a segmental implant delivery catheter (not shown in  FIG. 3 ) and exits distally for interface with an operator (not shown in  FIG. 3 ). The elastic distal segmental end  312  terminates in a distal sealable segmental circumferential collar  316 , controlled by a distal segmental variable sealing device  320  which is operated by a distal segmental control lead  324  that exits a segmental implant delivery catheter distally for interface with an operator (not shown in  FIG. 3 ). 
     In various embodiments according to the present invention, endovascular implants  200  may be constructed of solid, woven, non-woven, or mesh materials such as, but not limited to, natural or synthetic rubbers, nylon, Goretex, elastomers, polyisoprenes, polyphosphazenes, polyurethanes, vinyl plastisols, acrylic polyesters, polyvinylpyrrolidone-polyurethane interpolymers, butadiene rubbers, styrene-butadiene rubbers, rubber lattices, Dacron, PTFE, malleable metals, other biologically compatible materials or a combination of such biologically compatible materials in a molded, woven, or non-woven configuration, coated, non-coated, and other polymers or materials with suitable resilience and pliability qualities. In certain preferred embodiments according to the present invention, it is desirable for the non-elastic tubular implant body  106  and corresponding structures to be pliable to allow for folding or compressibility without allowing elasticity. In certain preferred embodiments according to the present invention, it is desirable for the elastic proximal end  108  and the elastic distal end  110  and corresponding structures to be both elastic and compressible or foldable. In any given preferred embodiment, the non-elastic tubular implant body  106 , the elastic proximal end  108 , the elastic distal end  110  and corresponding structures may be constructed of the same material of varying elasticity, or these structures may be constructed of different, but compatible materials. 
       FIGS. 4-9  illustrate an exemplary embodiment of sealable endovascular implants and an illustrative method of their use according to the present invention for the treatment of an infrarenal abdominal aortic aneurysm with vascular access through bilateral femoral arteriotomy sites. 
     In  FIG. 4  a main implant delivery catheter  100  has been placed in a first side through a femoral artery (not shown in  FIG. 4 ) and positioned in an abdominal aorta  402  in a location distal to the renal arteries  408 , but above the origin of an abdominal aortic aneurysm  410 . 
       FIG. 5  is a continuation of the disclosed embodiment of the present invention of  FIG. 4  in which an injector cannula  404  with one or more injection ports  406  has been introduced through a main implant delivery lumen  102  of the main implant delivery catheter  100 , and protrudes proximal to the tip of the implant delivery catheter  100  to fully expose the injector ports  406  for real-time visualization contrast dye injection therethrough. Such contrast dye injection may be performed using radio-opaque or other contrast dyes for fluoroscopy, computerized tomography, or other radiographic techniques. In alternate embodiments according to the present invention, other real-time visualization techniques may be used, including but not limited to, ultrasound or nuclear magnetic resonance techniques using appropriate contrast dye materials for injection. Such contrast dye injection allows an operator to assess the distance between the origins of the renal arteries  408 , and the origin of the aortic aneurysmal sac  410  for proper implant placement. 
       FIG. 6  is a continuation of the disclosed embodiment of the present invention of  FIG. 5  in which the main implant delivery catheter sheath  104  of the main implant delivery catheter  100  has been retracted or partially opened to allow the endovascular implant  200  therein to partially open or unfold from its initially compressed or folded position. Additional contrast dye injection through the injector cannula  404  may be performed by the operator at this point to verify the level of the proximal circumferential sealable collar  112  with respect to the level of the renal arteries  408 .  FIG. 7  is a continuation of the disclosed embodiment of the present invention of  FIG. 6  in which the level of the proximal circumferential sealable collar  112  has been adjusted by the operator with respect to the level of the renal arteries  408  for optimal deployment. 
       FIG. 8  is a continuation of the disclosed embodiment of the present invention of  FIG. 7  in which operator action on one or more proximal control leads  120  connected to one or more proximal variable sealing devices  116  has caused the proximal circumferential sealable collar  112  of the elastic proximal end  108  of the endovascular implant  200  to firmly and fully contact the aortic inner wall  124 , effecting a vascular seal therein. 
       FIG. 9  is a continuation of the disclosed embodiment of the present invention of  FIG. 8  in which operator action has fully retracted or opened and removed the main implant delivery sheath  104  of the main implant delivery catheter  100  allowing the endovascular implant  200  therein to fully decompress or unfold, thus exposing a distal elastic implant end  110  and a non-elastic contralateral cuff  126 . At this point in a deployment procedure, additional contrast dye injection would likely again be performed to ascertain that there is a complete seal at the level of the proximal circumferential sealable collar  112 . If leakage is still visualized, additional operator action on the proximal control lead (s)  120  may be used to further expand the proximal circumferential sealable collar  112  to secure an acceptable seal. Alternately, operator action may reduce the expanded proximal circumferential sealable collar  112  to allow its reposition and redeployment, again under real-time radiographic or other visualized control. 
       FIG. 10  is a continuation of the disclosed embodiment of the present invention of  FIG. 9  once a suitable proximal seal has been achieved. Operator action on one or more distal control leads  122  connected to one or more distal variable sealing devices  118  has caused the extended distal circumferential sealable collar  114  of the endovascular implant&#39;s  200  elastic distal end  110  to firmly and fully contact the inner wall of the common iliac artery  412  above the origin of the internal iliac artery  414 , effecting a vascular seal therein and preserving flow through the internal iliac artery  414 . Additional contrast dye injection through the injector cannula  404  would be used by the operator to confirm adequate seals both proximally and distally at this point. 
       FIG. 11  is a continuation of the disclosed embodiment of the present invention of  FIG. 10  in which operator action has placed a second guide wire  302  provided with an engagement tip  328  to grasp and stabilize the non-elastic contralateral cuff  126  under radiographic or other imaging control through an access via a second side through a femoral arteriotomy (not shown in  FIG. 11 ). 
       FIG. 12  is a continuation of the disclosed embodiment of the present invention of  FIG. 11  in which operator action has placed a contralateral delivery catheter  300  over the second guide wire  302 . The contralateral delivery catheter  300  includes a contralateral delivery catheter lumen  304  and a contralateral delivery catheter sheath  340  which may be operably opened or retracted by operator action. 
       FIG. 13  is a continuation of the disclosed embodiment of the present invention of  FIG. 12  in which operator action has removed the contralateral delivery catheter sheath  340  of the contralateral delivery catheter  300  allowing the endograft segmental implant  344  therein to fully decompress or unfold to expose a proximal segmental elastic implant end  348 , a distal segmental elastic implant end  356 , and the full length of a non-elastic segmental tubular implant body  346  connecting said ends  348  and  356 . 
       FIG. 14  is a continuation of the disclosed embodiment of the present invention of  FIG. 13  in which operator action on one or more proximal segmental control leads  354  connected to one or more proximal segmental variable sealing devices  352  has caused the expansion of proximal segmental circumferential sealable collar  350  of the endograft segmental implant&#39;s  344  elastic proximal segmental implant end  348  to firmly and fully contact the inner walls of the non-elastic contralateral cuff  126  effecting a proximal seal, and then similarly caused the distal segmental circumferential sealable collar  358  of the endograft segmental implant&#39;s  344  elastic distal segmental implant end  356  to expand to firmly and fully contact the inner wall of the common iliac artery  416  on the second side above the origin of the internal iliac artery  418 , effecting a vascular seal therein and preserving flow through the internal iliac artery  418 . Once sealed, the aortic aneurysmal sac  410  is devascularized and collapses. 
       FIG. 15  shows a diagrammatic view of a patient  500  in a dorsal supine position, with a disclosed embodiment of an endovascular implant  200  according to the present invention in sealed position in the patient&#39;s abdominal aorta  402  proximally and distally, and with arteriotomy incisions  332 ,  336  in both femoral arteries with an injector cannula  404  for radiographic contrast dye injection and proximal  120  and distal  122  control leads for operator manipulation in place in the patient&#39;s right arteriotomy site  332  and a second guide wire  302  in place in the patient&#39;s left arteriotomy site  336 , corresponding to the procedural stage shown in  FIG. 11 . 
       FIG. 16  shows an anatomic view of a disclosed embodiment of a thoracic endovascular implant  600  according to the present invention in sealed position proximally and distally in a patient&#39;s descending thoracic aorta  612 , traversing a devascularized thoracic aortic aneurysm  614 . In a patient, the ascending aorta  604  arises from the heart  602  and gives rise to the innominate artery  606 , the left common carotid artery  608 , and the left subclavian artery  610  before continuing as the descending thoracic aorta  612 . The thoracic endovascular implant  600  includes a non-elastic tubular thoracic implant body  616  with an elastic proximal thoracic end  618  and an elastic distal thoracic end  626 . The elastic proximal thoracic end  618  terminates in a proximal thoracic sealable circumferential collar  620 , controlled by a proximal thoracic variable sealing device  622  which is operated by a proximal thoracic control lead  624  that traverses a thoracic implant delivery catheter (not shown in  FIG. 16 ) and exits distally for interface with an operator (not shown in  FIG. 16 ). The elastic distal thoracic end  626  terminates in a distal sealable thoracic circumferential collar  628 , controlled by a distal thoracic variable sealing device  630  which is operated by a distal thoracic control lead  632  that exits a thoracic implant delivery catheter distally for interface with an operator (not shown in  FIG. 6 ). 
       FIG. 17  provides an anatomic view showing an alternate disclosed embodiment of a thoracic endovascular implant  700  in a patient&#39;s descending thoracic aorta  612  according to the present invention in which a first thoracic endovascular implant  718  includes a non-elastic distal cuff  730 , a proximal first thoracic circumferential sealable collar  724 , a proximal first thoracic variable sealing device  726 , and a proximal first thoracic control lead  728 . As shown in  FIG. 17 , the first thoracic endovascular implant  718  has been sealed in position proximally by operator action on the proximal first thoracic variable sealing device  726  using the proximal first thoracic control lead  728 , expanding the proximal first thoracic circumferential sealable collar  724  to achieve a proximal seal within the descending thoracic aorta  612 , and effectively devascularizing a thoracic aneurysm  614  therein. 
     As further shown in  FIG. 17 , the first thoracic endovascular implant  718  has been joined distally by a second thoracic endovascular implant  732 , which includes an elastic proximal second thoracic implant end  736 , a non-elastic tubular second thoracic implant body  734 , and an elastic distal second thoracic implant end  746 . The elastic proximal second thoracic implant end  736  includes a proximal second thoracic circumferential sealable collar  738 , a proximal second thoracic variable sealing device  740 , and a proximal second thoracic control lead  742 , and the elastic distal second thoracic implant end  746  includes a distal second thoracic circumferential sealable collar  748 , a distal second thoracic variable sealing device  750 , and a distal second thoracic control lead  752 . 
     In an exemplary application according to the present invention as shown in  FIG. 17 , an operator would first secure a seal in the proximal descending thoracic aorta using the first thoracic endovascular implant  718 , and then seal the proximal and distal aspects, respectively, of the second thoracic endovascular implant  732 , using real-time radiographic or other visualization techniques with injected contrast dye as previously described in this disclosure. 
       FIGS. 18A and 18B  show an embodiment of an endovascular implant according to the present invention similar to the disclosure of  FIG. 1B , with the additional inclusion of one of more retention tines  136  attached to the proximal circumferential sealable collar  112  and distal circumferential sealable collar  114 . 
     In a preferred embodiment according to the present invention, a plurality of retention tines  136  is used. In a preferred embodiment according to the present invention, the retention tines  136  are oriented to extend radially outward from the proximal circumferential sealable collar  112  and distal circumferential sealable collar  114 . In various preferred embodiment according to the present invention, the retention tines  136  may be oriented to extend perpendicularly or at any other desired angle outward from the proximal circumferential sealable collar  112  and distal circumferential sealable collar  114 . 
     In various preferred embodiment according to the present invention, the retention tines  136  may be constructed of any biocompatible material including, but not limited to, metals, plastics, or ceramics. 
     As further shown in  FIG. 18B  the retention tines  136  of the proximal circumferential sealable collar  112  and distal circumferential sealable collar  114  covered by a compressible foam sheathing  134  in a pre-deployment position. In various preferred embodiment according to the present invention, the compressible foam sheathing  134  may be constructed of any biocompatible material of suitable compressibility to allow the foam to be substantially compressed by the pressure of the proximal circumferential sealable collar  112  and distal circumferential sealable collar  114  against the inner wall of a target artery, upon operator deployment. The compressible foam sheathing  134  may also be constructed of material of suitable memory characteristics to allow the foam to substantially decompress to its pre-deployment position, covering the retention tines  136 , if pressure against the arterial wall is removed, thus allowing repositioning or removal of an endovascular implant according to the present invention at the operator&#39;s discretion. 
     Compressible foam sheathing  134  may be any biocompatible foam material of either an open or closed cell structure with sufficient compressibility and resilience to allow rapid recovery in a non-compressed state. In various preferred embodiments according to the present invention, such foam materials may be viscoelastic foam with a compressible cellular material that has both elastic (spring-like) and viscous (time-dependent) properties. Viscoelastic foam differs from regular foam by having time-dependent behaviors such as creep, stress relaxation, and hysteresis. 
       FIGS. 19A and 19B  show the exemplary endovascular implant of  FIGS. 18A and 18B  in the anatomic context of an endovascular implant  200  being deployed and sealed proximally in an abdominal aorta  402  containing an aneurysm  410 , with complete expansion and seal at the level of the proximal circumferential sealable implant collar  112  against the aortic inner wall  124 , but incomplete expansion and no seal against the arterial inner wall  144  at the level of the distal circumferential sealable implant collar  114  at this stage of the procedure. As shown in the cross-sectional view of  FIG. 19B , the retention tines  136  of the proximal circumferential sealable collar  112  and distal circumferential sealable collar  114  are covered by a compressible foam sheathing  134  in a pre-deployment position. 
       FIGS. 20A and 20B  further show the exemplary endovascular implant of  FIGS. 18A and 18B  in the anatomic context of an endovascular implant  200  being deployed and sealed proximally in an abdominal aorta  402  containing an aneurysm  410 , now with complete expansion of the distal circumferential sealable implant collar  114  and complete seal against the arterial inner wall  144  at this stage of the procedure. As shown in the cross-sectional view of  FIG. 20B , compressible foam sheathing  134  is compressed between the distal circumferential sealable collar  114  and the arterial inner wall  144 , allowing the retention tines  136  to engage the arterial inner wall  144  in their deployed position, thereby serving to retain the deployed position of the endovascular implant  200 . 
     In given various preferred embodiments according to the present invention, retention tines  136  and the compressible foam sheathing  134  as described above may be used in conjunction with any or all circumferentially sealable elements in this disclosure, including but not limited to, proximal circumferential sealable collars  112 , distal circumferential sealable collars  114 , proximal segmental circumferential sealable collars  314 , distal segmental circumferential sealable collars  316 , proximal thoracic circumferential sealable collars  620 , distal thoracic circumferential sealable collars  628 , proximal first thoracic circumferential sealable collars  724 , proximal second thoracic circumferential sealable collars  738 , and distal second thoracic circumferential sealable collars  748 . 
       FIGS. 21A-D  illustrate details of an embodiment of a variable sealing device according to the present invention. A variable sealing mechanism assembly  2100  comprises a sealing device housing  2102  attached to a sealer belt  2104  with a sealer belt fixed end  2108  attached to said housing  2102  and with a sealer belt moveable end  2110  operably passing through said housing and collecting in a concentric belt receiver channel  2130  as said sealer belt moveable end  2110  exits said housing  2102 . The sealer belt moveable end  2110  contains a plurality of uniformly distributed belt engagement slots  2106 . The belt engagement slots  2106  may be round, oval, square, rectangular, triangular, or any other shape, but are sized, spaced, and configured on said sealer belt moveable end  2110  to engage with sealer gear teeth  2116  of a sealer gear  2114  rotatably located within a housing gear recess  2112  contained within said housing  2102 . The sealer gear teeth  2116  are oriented to present on the outer circumference of said sealer gear  2114 . On the inner circumference of said sealer gear  2114 , a plurality of uniformly distributed sealer gear retainment slots  2118  are configured to receive a locking member  2120 . The locking member  2120 , in various embodiments according to the present invention may be a simple strip or bar as shown in  FIGS. 21A-D , or it may be triangular, cross-shaped, stellate or other geometric shapes that would allow the sealer gear retainment slots  2118  to receive the ends of said locking member  2120 . The locking member  2120  is fabricated of a metal or plastic with resilient spring-like properties, such that, when depressed or pulled in a perpendicular vector with respect to the sealer gear  2114 , the ends of said locking member  2120  are withdrawn from the sealer gear retainment slots  2118 , thus allowing the sealer gear  2114  to rotate within said housing gear recess  2112 , as shown in  FIGS. 21B  and C. The locking member  2120  is further provided with one or more sealer gear drive pins  2126 , which are received in gear drive pin slots  2128  of said sealer gear  2114  when the locking member  2120  is depressed, as shown in  FIG. 21C . In various preferred embodiments according to the present invention, the gear drive pins  2126  and the gear drive pin slots  2128  may be tapered, straight, or otherwise shaped to facilitate their secure engagement and release. The locking member  2120  is depressed by action of a control lead shaft  2124 , which is removably attached to the locking member  2120  at a control lead attachment  2122 . In an exemplary embodiment of the present invention, as shown in  FIG. 21C , while the locking member  2120  is released from the gear drive pin slots  2128  by a depressing action of the control lead shaft  2124 , rotation of the control lead shaft  2124  will permit the sealer gear drive pins  2126  to transmit a rotational force to the sealer gear  2114 , engaging the belt engagement slots  2106  in the movable end of the sealer belt  2110 , and causing the movable end of the sealer belt  2110  to move in or out of the concentric belt receiver channel  2130 . This motion has the effect of increasing or decreasing the surface area of the sealer belt  2104 . 
       FIG. 21D  shows an exemplary embodiment according to the present invention, in which a sealable collar  2140  contains a variable sealing mechanism assembly  2100  comprising a sealing device housing  2102  attached to a sealer belt  2104  with a sealer belt fixed end  2108  attached to said housing  2102  and with a sealer belt moveable end  2110  operably passing through said housing and collecting in a concentric belt receiver channel  2130  as said sealer belt moveable end  2110  exits said housing  2102 . The sealable collar  2140  is constructed of a tubular elastic body in a closed loop defining a central collar lumen  2142 . The sealer belt  2104  may pass circumferentially through substantially all of the sealable collar  2140 , as shown in  FIG. 21D , but in alternate embodiments may pass through only some of the circumference of the sealable collar  2140 . As the variable sealing mechanism assembly  2100  is operated, the length of the sealer belt  2104  may enlarge or constrict, with similar action on the sealable collar  2140 , thus allowing a variable seal to be achieved between the sealable collar  2140  and the inner lumen of a vessel wall (not shown in  FIG. 21D ) containing the sealable collar  2140 . 
     Within certain embodiments of the present invention, an endograft may also incorporate radio-opaque, echogenic materials and magnetic resonance imaging (MRI) responsive materials (i.e., MRI contrast agents) to aid in visualization of the device under x-ray, ultrasound, fluoroscopy MRI or other imaging modalities. In addition, various embodiments according to the present invention may incorporate markers comprising various radio-opaque, echogenic materials and magnetic resonance imaging (MRI) responsive materials that may be placed on the walls of an aneurysm sac or on other anatomic sites for improved postoperative visualization to monitor for aneurysmal revascularization. 
     As shown in  FIGS. 22A-22F , various embodiments according to the present invention may also be provided with one or more endograft monitoring devices to facilitate diagnosis of postoperative graft failure and aneurysm revascularization. In some embodiments according to the present invention, endograft monitoring devices may be pressure sensors positioned to demonstrate positive pressure within the former aneurysmal sac in some manner that may be identifiable by electronic, radiographic, or other visual or electronic communications.  FIGS. 22A-F  illustrate yet other embodiments of endograft monitoring devices according to the present invention. 
       FIGS. 22A-22B  show an embodiment of a sealable vascular endograft system  2200  which incorporates an endograft monitoring device comprising an radio-opaque graft attachment member  2205  joined at a monitoring pivot  2210  to a radio-opaque aneurysmal attachment  2220  which is affixed by an operator at the time of endograft placement to the inner wall of the aneurysmal sac  2215 , which is shown in a collapsed, nonvascularized state in  FIG. 22A , but in an expanded, revascularized state in  FIG. 22B . As further shown in  FIG. 22B , the expansion of the aneurysmal sac  2215 , has the further effect of increasing the angle between the radio-opaque graft attachment member  2205  and the radio-opaque aneurysmal attachment  2220 . In such an embodiment, plain radiographs or other visualization means could be employed to evaluate the angle between the attachment members of an endograft monitoring device to detect endograft failure and revascularization of the aneurysm without requiring more invasive and expensive diagnostic studies. 
       FIGS. 22C and 22D  illustrate yet another embodiment of an embodiment of a sealable vascular endograft system  2200  which incorporates an endograft monitoring device comprising an radio-opaque graft attachment  2202  pivotably joined by two or more radio-opaque graft frame members  2212  which are in turn joined frame pivots  2204  to radio-opaque aneurysmal frame members  2214  which are joined at an aneurysmal attachment  2216  which is affixed by an operator at the time of endograft placement to the inner wall of the aneurysmal sac  2215 , which is shown in a collapsed, nonvascularized state in  FIG. 22C , but in an expanded, revascularized state in  FIG. 22D . As further shown in  FIG. 22D , the expansion of the aneurysmal sac  2215 , has the further effect of increasing the angles between the radio-opaque graft frame member  2212  and the radio-opaque aneurysmal frame members  2214  to create a square or polygonal shape visible on radiographs. In such an embodiment, plain radiographs or other visualization means could again be employed to evaluate the angles between the attachment members of an endograft monitoring device to detect endograft failure and revascularization of the aneurysm without requiring more invasive and expensive diagnostic studies. 
       FIGS. 22E and 22F  illustrate still another embodiment of an embodiment of a sealable vascular endograft system  2200  which incorporates an endograft monitoring device comprising two or more radio-opaque graft attachment  2202  pivotably joined by two or more radio-opaque graft frame members  2212  which are in turn joined frame pivots  2204  to radio-opaque aneurysmal frame members  2214  which are joined at two or more aneurysmal attachments  2216  which are affixed by an operator at the time of endograft placement to the inner wall of the aneurysmal sac  2215 , which is shown in a collapsed, nonvascularized state in  FIG. 22E , but in an expanded, revascularized state in  FIG. 22F . As further shown in  FIG. 22F , the expansion of the aneurysmal sac  2215 , has the further effect of increasing the angles between the radio-opaque graft frame member  2212  and the radio-opaque aneurysmal frame members  2214  to create a square or polygonal shape visible on radiographs. In such an embodiment, three-dimensional, cage-like structures could be formed by the various frame members described, further enhancing the clinical visibility of an indication of aneurysmal revascularization. 
     Although the foregoing embodiments of the present invention have been described in some detail by way of illustration and example for purposes of clarity and understanding, it will be apparent to those skilled in the art that certain changes and modifications may be practiced within the spirit and scope of the present invention. Therefore, the description and examples presented herein should not be construed to limit the scope of the present invention, the essential features of which are set forth in the appended claims.