Patent Publication Number: US-2023147309-A1

Title: Delivery system and method for self-centering a proximal end of a stent graft

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/869,278, filed May 7, 2022, which is a division of U.S. patent application Ser. No. 15/839,272, filed on Dec. 12, 2017, now U.S. Pat. No. 10,646,365, issued on May 12, 2020, which is a continuation of U.S. patent application Ser. No. 14/575,673, filed Dec. 18, 2014, now abandoned, which is a continuation of U.S. patent application Ser. No. 13/024,882, filed Feb. 10, 2011, now abandoned, which is a continuation of U.S. patent application Ser. No. 11/701,876, filed Feb. 1, 2007, now abandoned, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Nos. 60/851,282, filed Oct. 12, 2006, 60/833,533, filed Jul. 26, 2006, and 60/765,449, filed Feb. 3, 2006. U.S. application Ser. No. 11/701,876 is also a continuation-in-part of U.S. patent application Ser. No. 10/884,136, filed Jul. 2, 2004, now U.S. Pat. No. 7,763,063, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Applications Nos. 60/500,155, filed Sep. 4, 2003, and 60/499,652, filed Sep. 3, 2003; and is also a continuation-in-part of U.S. patent application Ser. No. 10/784,462, filed Feb. 23, 2004, now U.S. Pat. No. 8,292,943, which also claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Applications Nos. 60/500,155, filed Sep. 4, 2003, and 60/499,652, filed Sep. 3, 2003. The entire teachings of the above applications are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention lies in the field of endoluminal blood vessel repairs. The invention specifically relates to a delivery system and method for self-centering a proximal end of a stent graft, for example, for endoluminally repairing aneurysm and/or dissections of the thoracic transverse aortic arch, thoracic posterior aortic arch, and the descending thoracic portion of the aorta. The present invention lies in the field of prosthesis delivery systems, in particular, to a stent capture device for releasably holding a stent graft in an endovascular stent graft delivery system. 
     Description of the Related Art 
     A stent graft is an implantable device made of a tube-shaped surgical graft covering and an expanding or self-expanding frame. The stent graft is placed inside a blood vessel to bridge, for example, an aneurismal, dissected, or other diseased segment of the blood vessel, and, thereby, exclude the hemodynamic pressures of blood flow from the diseased segment of the blood vessel. 
     In selected patients, a stent graft advantageously eliminates the need to perform open thoracic or abdominal surgical procedures to treat diseases of the aorta and eliminates the need for total aortic reconstruction. Thus, the patient has less trauma and experiences a decrease in hospitalization and recovery times. The time needed to insert a stent graft is substantially less than the typical anesthesia time required for open aortic bypass surgical repair, for example. 
     Use of surgical and/or endovascular grafts have widespread use throughout the world in vascular surgery. There are many different kinds of vascular graft configurations. Some have supporting framework over their entirety, some have only two stents as a supporting framework, and others simply have the tube-shaped graft material with no additional supporting framework, an example that is not relevant to the present invention. 
     One of the most commonly known supporting stent graft frameworks is that disclosed in U.S. Pat. Nos. 5,282,824 and 5,507,771 to Gianturco (hereinafter collectively referred to as “Gianturco”). Gianturco describes a zig-zag-shaped, self-expanding stent commonly referred to as a z-stent. The stents are, preferably, made of nitinol, but also have been made from stainless steel and other biocompatible materials. 
     There are various features characterizing a stent graft. The first significant feature is the tube of graft material. This tube is commonly referred to as the graft and forms the tubular shape that will, ultimately, take the place the diseased portion of the blood vessel. The graft is, preferably, made of a woven sheet (tube) of polyester or PTFE. The circumference of the graft tube is, typically, at least as large as the diameter and/or circumference of the vessel into which the graft will be inserted so that there is no possibility of blood flowing around the graft (also referred to as endoleak) to either displace the graft or to reapply hemodynamic pressure against the diseased portion of the blood vessel. Accordingly, to so hold the graft, self-expanding frameworks are attached typically to the graft material, whether on the interior or exterior thereof. Because blood flow within the lumen of the graft could be impaired if the framework was disposed on the interior wall of the graft, the framework is connected typically to the exterior wall of the graft. The ridges formed by such an exterior framework help to provide a better fit in the vessel by providing a sufficiently uneven outer surface that naturally grips the vessel where it contacts the vessel wall and also provides areas around which the vessel wall can endothelialize to further secure the stent graft in place. 
     One of the significant dangers in endovascular graft technology is the possibility of the graft migrating from the desired position in which it is installed. Therefore, various devices have been created to assist in anchoring the graft to the vessel wall. 
     One type of prior art prosthetic device is a stent graft made of a self-expanding metallic framework. For delivery, the stent graft is, first, radially compressed and loaded into an introducer system that will deliver the device to the target area. When the introducer system holding the stent graft positioned in an appropriate location in the vessel and allowed to open, the radial force imparted by the self-expanding framework is helpful, but, sometimes, not entirely sufficient, in endoluminally securing the stent graft within the vessel. 
     U.S. Pat. No. 5,824,041 to Lenker et al. (hereinafter “Lenker”) discloses an example of a stent graft delivery system. Lenker discloses various embodiments in which a sheath is retractable proximally over a prosthesis to be released. With regard to FIGS. 7 and 8, Lenker names components 72 and 76, respectively, as “sheath” and “prosthesis-containment sheath.” However, the latter is merely the catheter in which the prosthesis 74 and the sheath 72 are held. With regard to FIGS. 9 and 10, the sheath 82 has inner and outer layers 91, 92 fluid-tightly connected to one another to form a ballooning structure around the prosthesis P. This ballooning structure inflates when liquid is inflated with a non-compressible fluid medium and flares radially outward when inflated. With regard to FIGS. 13 to 15, Lenker discloses the “sheath” 120, which is merely the delivery catheter, and an eversible membrane 126 that “folds back over itself (everts) as the sheath 120 is retracted so that there are always two layers of the membrane between the distal end of the sheath [120] and the prosthesis P.” Lenker at col. 9, lines 63 to 66. The eversion (peeling back) is caused by direct connection of the distal end 130 to the sheath 120. The Lenker delivery system shown in FIGS. 19A to 19D holds the prosthesis P at both ends 256, 258 while an outer catheter 254 is retracted over the prosthesis P and the inner sheath 260. The inner sheath 260 remains inside the outer catheter 254 before, during, and after retraction. Another structure for holding the prosthesis P at both ends is illustrated in FIGS. 23A and 23B. Therein, the proximal holder having resilient axial members 342 is connected to a proximal ring structure 346. FIGS. 24A to 24C also show an embodiment for holding the prosthesis at both ends inside thin-walled tube 362. 
     To augment radial forces of stents, some prior art devices have added proximal and/or distal stents that are not entirely covered by the graft material. By not covering with graft material a portion of the proximal/distal ends of the stent, these stents have the ability to expand further radially than those stents that are entirely covered by the graft material. By expanding further, the proximal/distal stent ends better secure to the interior wall of the vessel and, in doing so, press the extreme cross-sectional surface of the graft ends into the vessel wall to create a fixated blood-tight seal. 
     One example of such a prior art exposed stent can be found in United States Patent Publication US 2002/0198587 to Greenberg et al. The modular stent graft assembly therein has a three-part stent graft: a two-part graft having an aortic section 12 and an iliac section 14 (with four sizes for each) and a contralateral iliac occluder 80. FIGS. 1, 2, and 4 to 6 show the attachment stent 32. As illustrated in FIGS. 1, 2, and 4, the attachment stent 32, while rounded, is relatively sharp and, therefore, increases the probability of puncturing the vessel. 
     A second example of a prior art exposed stent can be found in U.S. Patent Publication 2003/0074049 to Hoganson et al. (hereinafter “Hoganson”), which discloses a covered stent  10  in which the elongated portions or sections 24 of the ends 20a and 20b extend beyond the marginal edges of the cover 22. See Hoganson at FIGS. 1, 3, 9, 11a, 11b, 12a, 12b, and 13. However, these extending exposed edges are triangular, with sharp apices pointing both upstream and downstream with regard to a graft placement location. Such a configuration of the exposed stent 20a, 20b increases the possibility of puncturing the vessel. In various embodiments shown in FIGS. 6a, 6b, 6c, 10, 14a, Hoganson teaches completely covering the extended stent and, therefore, the absence of a stent extending from the cover 22. It is noted that the Hoganson stent is implanted by inflation of a balloon catheter. 
     Another example of a prior art exposed stent can be found in U.S. Pat. No. 6,565,596 to White et al. (hereinafter “White I”), which uses a proximally extending stent to prevent twisting or kinking and to maintain graft against longitudinal movement. The extending stent is expanded by a balloon and has a sinusoidal amplitude greater than the next adjacent one or two sinusoidal wires. White I indicates that it is desirable to space wires adjacent upstream end of graft as close together as is possible. The stent wires of White I are actually woven into graft body by piercing the graft body at various locations. See White I at FIGS. 6 and 7. Thus, the rips in the graft body can lead to the possibility of the exposed stent moving with respect to the graft and of the graft body ripping further. Between the portions of the extending stent 17, the graft body has apertures. 
     The stent configuration of U.S. Pat. No. 5,716,393 to Lindenberg et al. is similar to White I in that the outermost portion of the one-piece stent—made from a sheet that is cut/punched and then rolled into cylinder—has a front end with a greater amplitude than the remaining body of the stent. 
     A further example of a prior art exposed stent can be found in U.S. Pat. No. 6,524,335 to Hartley et al. (hereinafter “Hartley”). FIGS. 1 and 2 of Hartley particularly disclose a proximal first stent 1 extending proximally from graft proximal end 4 with both the proximal and distal apices narrowing to pointed ends. 
     Yet another example of a prior art exposed stent can be found in U.S. Pat. No. 6,355,056 to Pinheiro (hereinafter “Pinheiro 1”). Like the Hartley exposed stent, Pinheiro discloses exposed stents having triangular, sharp proximal apices. 
     Still a further example of a prior art exposed stent can be found in U.S. Pat. No. 6,099,558 to White et al. (hereinafter “White II”). The White II exposed stent is similar to the exposed stent of White I and also uses a balloon to expand the stent. 
     An added example of a prior art exposed stent can be found in U.S. Pat. No. 5,871,536 to Lazarus, which discloses two support members 68 longitudinally extending from proximal end to a rounded point. Such points, however, create a very significant possibility of piercing the vessel. 
     An additional example of a prior art exposed stent can be found in U.S. Pat. No. 5,851,228 to Pinheiro (hereinafter “Pinheiro II”). The Pinheiro II exposed stents are similar to the exposed stents of Pinheiro I and, as such, have triangular, sharp, proximal apices. 
     Still another example of a prior art exposed stent can be found in Lenker (U.S. Pat. No. 5,824,041), which shows a squared-off end of the proximal and distal exposed band members 14. A portion of the exposed members 14 that is attached to the graft material 18, 20 is longitudinally larger than a portion of the exposed members 14 that is exposed and extends away from the graft material 18, 20. Lenker et al. does not describe the members 14 in any detail. 
     Yet a further example of a prior art exposed stent can be found in U.S. Pat. No. 5,824,036 to Lauterjung, which, of all of the prior art embodiments described herein, shows the most pointed of exposed stents. Specifically, the proximal ends of the exposed stent are apices pointed like a minaret. The minaret points are so shaped intentionally to allow forks 300 (see Lauterjung at  FIG.  5   ) external to the stent 154 to pull the stent 154 from the sheath 302, as opposed to being pushed. 
     A final example of a prior art exposed stent can be found in U.S. Pat. No. 5,755,778 to Kleshinski. The Kleshinski exposed stents each have two different shaped portions, a triangular base portion and a looped end portion. The totality of each exposed cycle resembles a castellation. Even though the end-most portion of the stent is curved, because it is relatively narrow, it still creates the possibility of piercing the vessel wall. 
     All of these prior art stents suffer from the disadvantageous characteristic that the relatively sharp proximal apices of the exposed stents have a shape that is likely to puncture the vessel wall. 
     Devices other than exposed stents have been used to inhibit graft migration. A second of such devices is the placement of a relatively stiff longitudinal support member longitudinally extending along the entirety of the graft. 
     The typical stent graft has a tubular body and a circumferential framework. This framework is not usually continuous. Rather, it typically takes the form of a series of rings along the tubular graft. Some stent grafts have only one or two of such rings at the proximal and/or distal ends and some have many stents tandemly placed along the entirety of the graft material. Thus, the overall stent graft has an “accordion” shape. During the systolic phase of each cardiac cycle, the hemodynamic pressure within the vessel is substantially parallel with the longitudinal plane of the stent graft. Therefore, a device having unsecured stents, could behave like an accordion, or concertina with each systolic pulsation, and may have a tendency to migrate downstream. (A downstream migration, to achieve forward motion, has a repetitive longitudinal compression and extension of its cylindrical body.) Such movement is entirely undesirable. Connecting the stents with support along the longitudinal extent of the device thereof can prevent such movement. To provide such support, a second anti-migration device can be embodied as a relatively stiff longitudinal bar connected to the framework. 
     A clear example of a longitudinal support bar can be found in Pinheiro I (U.S. Pat. No. 6,355,056) and Pinheiro II (U.S. Pat. No. 5,851,228). Each of these references discloses a plurality of longitudinally extending struts 40 extending between and directly interconnecting the proximal and distal exposed stents 20a, 20b. These struts 40 are designed to extend generally parallel with the inner lumen 15 of the graft 10, in other words, they are straight. 
     Another example of a longitudinal support bar can be found in U.S. Pat. No. 6,464,719 to Jayaraman. The Jayaraman stent is formed from a graft tube 21 and a supporting sheet 1 made of nitinol. This sheet is best shown in FIG. 3. The end pieces 11, 13 of the sheet are directly connected to one another by wavy longitudinal connecting pieces 15 formed by cutting the sheet 1. To form the stent graft, the sheet 1 is coiled with or around the cylindrical tube 21. See FIGS. 1 and 4. Alternatively, a plurality of connecting pieces 53 with holes at each end thereof can be attached to a cylindrical fabric tube 51 by stitching or sutures 57, as shown in FIG. 8. Jayaraman requires more than one of these serpentine shaped connecting pieces 53 to provide longitudinal support. 
     United States Patent Publication 2002/0016627 and U.S. Pat. No. 6,312,458 to Golds each disclose a variation of a coiled securing member 20. 
     A different kind of supporting member is disclosed in FIG. 8 of U.S. Pat. No. 6,053,943 to Edwin et al. 
     Like Jayararnan, U.S. Pat. No. 5,871,536 to Lazarus discloses a plurality of straight, longitudinal support structures 38 attached to the circumferential support structures 36, see FIGS. 1, 6, 7, 8, 10, 11, 12, 14. FIG. 8 of Lazarus illustrates the longitudinal support structures 38 attached to a distal structure 36 and extending almost all of the way to the proximal structure 36. The longitudinal structures 38, 84, 94 can be directly connected to the body 22, 80 and can be telescopic 38, 64. 
     United States Patent Publication 2003/0088305 to Van Schie et al. (hereinafter “Van Schie”) does not disclose a support bar. Rather, it discloses a curved stent graft using an elastic material 8 connected to stents at a proximal end 2 and at a distal end 3 (see  FIGS.  1 ,  2   ) thereof to create a curved stent graft. Because Van Schie needs to create a flexible curved graft, the elastic material 8 is made of silicone rubber or another similar material. Thus, the material 8 cannot provide support in the longitudinal extent of the stent graft. Accordingly, an alternative to the elastic support material 8 is a suture material 25 shown in FIGS. 3 to 6. 
     SUMMARY OF THE INVENTION 
     The invention provides a delivery system and method for self-centering a proximal end of a stent graft that overcome the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that provides a vessel repair device that implants/conforms more efficiently within the natural or diseased course of the aorta by aligning with the natural curve of the aorta, decreases the likelihood of vessel puncture, increases the blood-tight vascular connection, retains the intraluminal wall of the vessel position, is more resistant to migration, and delivers the stent graft into a curved vessel while minimizing intraluminal forces imparted during delivery and while minimizing the forces needed for a user to deliver the stent graft into a curved vessel. 
     With the foregoing and other objects in view, there is provided, in accordance with the invention, a method for implanting a prosthesis centrally within a curved lumen, including the steps of loading a prosthesis into a delivery sheath, the prosthesis having a proximal end and the sheath having a distal end, advancing the sheath in a patient towards the curved lumen to place at least the proximal end within the curved lumen, and centering the proximal end of the prosthesis and/or the distal end of the sheath within the curved lumen. 
     With the objects of the invention in view, there is also provided a method for centrally implanting a prosthesis, including the steps of placing at least a proximal end of a prosthesis in a curved lumen of a patient and centering the proximal end of the prosthesis within the curved lumen before implanting the prosthesis therein. 
     With the objects of the invention in view, there is also provided a method for implanting a prosthesis centrally within a curved lumen, including the steps of loading a prosthesis into a delivery sheath, the prosthesis having a proximal end and the sheath having a distal end, in a first advancing step, advancing the outer catheter containing the inner sheath together towards the curved lumen to a location proximal of the curved lumen, and, in a second advancing step, advancing the inner sheath containing the prosthesis into the curved lumen to place at least the proximal end within the curved lumen while the outer catheter substantially remains at the location, centering the proximal end of the prosthesis and/or the distal end of the sheath within the curved lumen, and, after carrying out the centering step, deploying the proximal end of the prosthesis centered within the curved lumen. 
     With the objects of the invention in view, there is also provided a method of implanting a prosthesis in a patient at a treatment site, including the steps of providing a prosthesis delivery system with a relatively flexible inner sheath and a relatively stiff outer sheath, loading a prosthesis inside the inner sheath, loading the inner sheath containing the prosthesis within the outer sheath, advancing the outer sheath in a patient towards the treatment site up to a given position at a distance from the treatment site. While the outer sheath is retained in the given position, the inner sheath is advanced out from the outer sheath to the treatment site to place at least a proximal end of inner sheath within the treatment site and the proximal end of the prosthesis and/or the distal end of the inner sheath is centered within the curved lumen. The inner sheath is retracted to at least partially implant the prosthesis at the treatment site, and, upon completion of prosthesis implantation, both of the inner and outer sheaths are retracted out from the patient. 
     In accordance with another mode of the invention, after carrying out the centering step, the prosthesis is deployed centered within the curved lumen. 
     In accordance with a further mode of the invention, the proximal end of the prosthesis has an orifice defining an inflow plane and a proximal end implantation site of the lumen defines an implant plane, and the centering step is carried out by substantially aligning the inflow plane with the implant plane. 
     In accordance with an added mode of the invention, after carrying out the centering step, the prosthesis is deployed with the inflow plane substantially aligned with the implant plane. 
     In accordance with an additional mode of the invention, the centering step is carried out by centering at least the distal end of the sheath within the curved lumen with a sheath centering device. 
     In accordance with an additional mode of the invention, the loading step is carried out by partially collapsing the prosthesis to a size smaller than an interior of the sheath and inserting the partially collapsed prosthesis into the sheath and the deployment step is carried out by releasing the prosthesis centered within the curved lumen. 
     In accordance with yet a further mode of the invention, the sheath is provided as a relatively flexible inner sheath and the inner sheath is slidably disposed inside a relatively stiff outer catheter. 
     In accordance with yet an added mode of the invention, the advancing step is carried out by first advancing the outer catheter containing the inner sheath together towards the curved lumen to a location proximal of the curved lumen and subsequently advancing the inner sheath containing the prosthesis into the curved lumen while the outer catheter substantially remains at the location. 
     In accordance with yet an additional mode of the invention, the centering step is carried out within a curved portion of an aorta. 
     In accordance with again another mode of the invention, the prosthesis is provided with a tubular graft body defining an inflow plane and an exit plane and all portions of the stents on the graft body are disposed between the inflow plane and the exit plane. 
     In accordance with again a further mode of the invention, a guidewire is placed through an implantation site within the curved lumen, the advancing step is carried out by guiding the delivery sheath containing the prosthesis along the guidewire, and the centering step is carried out by moving the proximal end of the prosthesis and/or the distal end of the sheath in a direction away from the guidewire at the implantation site. 
     In accordance with again an added mode of the invention, a tip is provided and the centering of the proximal end of the prosthesis is carried out with the tip. 
     In accordance with again an additional mode of the invention, the tip is slidably disposed within the delivery sheath. 
     In accordance with still a further mode of the invention, the tip is operatively connected to the delivery sheath to perform the centering step with the tip and the sheath. 
     In accordance with still an added mode of the invention, a tip is slidably disposed within the delivery sheath to place the tip at the distal end of the sheath, a sheath centering device is connected to the tip through the sheath, and the centering step is carried out with the sheath centering device. 
     In accordance with still an additional mode of the invention, a tip is provided with a sheath centering device, the tip is slidably disposed within the delivery sheath to place the tip at the distal end of the sheath, and the centering step is carried out by expanding the sheath centering device out from the tip. 
     In accordance with another mode of the invention, a sheath centering device is provided at the proximal end of the sheath and the centering step is carried out with the sheath centering device. 
     In accordance with still another mode of the invention, the centering step is carried out with a sheath centering device physically separate from the sheath. 
     In accordance with yet another mode of the invention, before carrying out the centering step, a central axis of the sheath centering device is placed approximately orthogonal to a longitudinal axis of the sheath. 
     In accordance with an additional mode of the invention, the centering step is carried out with a sheath centering device surrounding an exterior of the sheath. 
     In accordance with again another mode of the invention, the centering step is carried out with a sheath centering device disposed between an exterior surface of the sheath and a wall of a lumen in which the sheath is present. 
     In accordance with a concomitant mode of the invention, the centering step is carried out with a sheath centering device disposed within the sheath. 
     Other features that are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in a delivery system and method for self-centering a proximal end of a stent graft, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which: 
         FIG.  1    is a side elevational view of a stent graft according to the invention; 
         FIG.  2    is a side elevational view of a stent of the stent graft of  FIG.  1   ; 
         FIG.  3    is a cross-sectional view of the stent of  FIG.  2    with different embodiments of protrusions; 
         FIG.  4    is a perspective view of a prior art round mandrel for forming prior art stents; 
         FIG.  5    is a fragmentary, side elevational view of a prior art stent in a portion of a vessel; 
         FIG.  6    is a perspective view of a dodecahedral-shaped mandrel for forming stents in  FIGS.  1  to  3   ; 
         FIG.  7    is a fragmentary, side elevational view of the stent of  FIGS.  1  to  3    in a portion of a vessel; 
         FIG.  8    is a fragmentary, enlarged side elevational view of the proximal end of the stent graft of  FIG.  1    illustrating movement of a gimbaled end; 
         FIG.  9    is a side elevational view of a two-part stent graft according to the invention; 
         FIG.  10    is a fragmentary, side elevational view of a delivery system according to the invention with a locking ring in a neutral position; 
         FIG.  11    is a fragmentary, side elevational view of the delivery system of  FIG.  10    with the locking ring in an advancement position and, as indicated by dashed lines, a distal handle and sheath assembly in an advanced position; 
         FIG.  12    is a fragmentary, enlarged view of a sheath assembly of the delivery system of  FIG.  10   ; 
         FIG.  13    is a fragmentary, enlarged view of an apex capture device of the delivery system of  FIG.  10    in a captured position; 
         FIG.  14    is a fragmentary, enlarged view of the apex capture device of  FIG.  13    in a released position; 
         FIG.  15    is a fragmentary, enlarged view of an apex release assembly of the delivery system of  FIG.  10    in the captured position; 
         FIG.  16    is a fragmentary, enlarged view of the apex release assembly of  FIG.  15    in the captured position with an intermediate part removed; 
         FIG.  17    is a fragmentary, enlarged view of the apex release assembly of  FIG.  16    in the released position; 
         FIG.  18    is a fragmentary, side elevational view of the delivery system of  FIG.  11    showing how a user deploys the prosthesis; 
         FIG.  19    is a fragmentary cross-sectional view of human arteries including the aorta with the assembly of the present invention in a first step of a method for inserting the prosthesis according to the invention; 
         FIG.  20    is a fragmentary cross-sectional view of the arteries of  FIG.  19    with the assembly in a subsequent step of the method for inserting the prosthesis; 
         FIG.  21    is a fragmentary cross-sectional view of the arteries of  FIG.  20    with the assembly in a subsequent step of the method for inserting the prosthesis; 
         FIG.  22    is a fragmentary cross-sectional view of the arteries of  FIG.  21    with the assembly in a subsequent step of the method for inserting the prosthesis; 
         FIG.  23    is a fragmentary cross-sectional view of the arteries of  FIG.  22    with the assembly  15  in a subsequent step of the method for inserting the prosthesis; 
         FIG.  24    is a fragmentary cross-sectional view of the arteries of  FIG.  23    with the assembly in a subsequent step of the method for inserting the prosthesis; 
         FIG.  25    is a fragmentary, diagrammatic, perspective view of the coaxial relationship of delivery system lumen according to the invention; 
         FIG.  26    is a fragmentary, cross-sectional view of the apex release assembly according to the invention; 
         FIG.  27    is a fragmentary, side elevational view of the stent graft of  FIG.  1    with various orientations of radiopaque markers according to the invention; 
         FIG.  28    is a fragmentary perspective view of the stent graft of  FIG.  1    with various orientations of radiopaque markers according to the invention; 
         FIG.  29    is a perspective view of a distal apex head of the apex capture device of  FIG.  13   ; 
         FIG.  30    is a fragmentary side elevational view of the distal apex head of  FIG.  29    and a proximal apex body of the apex capture device of  FIG.  13    with portions of a bare stent in the captured position; 
         FIG.  31    is a fragmentary, side elevational view of the distal apex head and proximal apex body of  FIG.  30    with a portion of the proximal apex body cut away to illustrate the bare stent in the captured position; 
         FIG.  32    is a fragmentary side elevational view of the distal apex head and proximal apex body of  FIG.  30    in the released position; 
         FIG.  33    is a fragmentary, cross-sectional view of an embodiment of handle assemblies according to the invention; 
         FIG.  34    is a cross-sectional view of a pusher clasp rotator of the handle assembly of  FIG.  33   ; 
         FIG.  35    is a plan view of the pusher clasp rotator of  FIG.  34    viewed along line C-C; 
         FIG.  36    is a plan and partially hidden view of the pusher clasp rotator of  FIG.  34    with a helix groove for a first embodiment of the handle assembly of  FIGS.  10 ,  11 , and  18   ; 
         FIG.  37    is a cross-sectional view of the pusher clasp rotator of  FIG.  36    along section line A-A; 
         FIG.  38    is a plan and partially hidden view of the pusher clasp rotator of  FIG.  36   ; 
         FIG.  39    is a cross-sectional view of the pusher clasp rotator of  FIG.  38    along section line B-B; 
         FIG.  40    is a perspective view of a rotator body of the handle assembly of  FIG.  33   ; 
         FIG.  41    is an elevational and partially hidden side view of the rotator body of  FIG.  40   ; 
         FIG.  42    is a cross-sectional view of the rotator body of  FIG.  41    along section line A-A; 
         FIG.  43    is an elevational and partially hidden side view of the rotator body of  FIG.  40   ; 
         FIG.  44    is an elevational and partially hidden side view of a pusher clasp body of the handle assembly of  FIG.  33   ; 
         FIG.  45    is a cross-sectional view of the pusher clasp body of  FIG.  44    along section line A-A; 
         FIG.  46    is a cross-sectional view of the pusher clasp body of  FIG.  44    along section line B-B; 
         FIG.  47    is a fragmentary, side elevational view of a portion of the handle assembly of  FIG.  33    with a sheath assembly according to the invention; 
         FIG.  48    is an exploded side elevational view of a portion of the handle assembly of  FIG.  47   ; 
         FIG.  49    is a fragmentary elevational and partially hidden side view of a handle body of  15  the handle assembly of  FIG.  33   ; 
         FIG.  50    is a fragmentary, exploded side elevational view of a portion of a second embodiment of the handle assembly according to the invention; 
         FIG.  51    is a fragmentary, side elevational view of the portion of  FIG.  50    in a neutral position; 
         FIG.  52    is an exploded view of a first portion of the second embodiment of the handle assembly; 
         FIG.  53    is a fragmentary, exploded view of a larger portion of the second embodiment of the handle assembly as compared to  FIG.  52    with the first portion and the sheath assembly; 
         FIG.  54    is perspective view of a clasp body of the second embodiment of the handle assembly; 
         FIG.  55    is an elevational side view of the clasp body of  FIG.  54   ; 
         FIG.  56    is a cross-sectional view of the clasp body of  FIG.  55    along section line A-A; 
         FIG.  57    is a plan view of the clasp body of  FIG.  54   ; 
         FIG.  58    is a plan view of the clasp body of  FIG.  57    viewed from section line B-B; 
         FIG.  59    is a fragmentary and partially hidden side elevational view of a clasp sleeve of the second embodiment of the handle assembly; 
         FIG.  60    is a fragmentary, cross-sectional view of a portion the clasp sleeve of  FIG.  59    along section line A; 
         FIG.  61    is a fragmentary, cross-sectional view of the clasp sleeve of  FIG.  59    along section line C-C; 
         FIG.  62    is a fragmentary and partially hidden side elevational view of the clasp sleeve of  FIG.  59    rotated with respect to  FIG.  59   ; 
         FIG.  63    is a fragmentary, cross-sectional view of the nose cone and sheath assemblies of  FIG.  10   ; 
         FIG.  64    is a fragmentary, perspective view of a portion of self-alignment configuration according to the invention; 
         FIG.  65    is a diagrammatic, fragmentary, cross-sectional view of a distal portion of the delivery system with the self-alignment configuration according to the invention inside the descending thoracic aorta and with the self-alignment configuration in an orientation opposite a desired orientation; 
         FIG.  66    is a diagrammatic, fragmentary, cross-sectional view of the distal portion of the delivery system of  FIG.  65    with the self-alignment configuration partially inside the descending thoracic aorta and partially inside the aortic arch and with the self-alignment configuration in an orientation closer to the desired orientation; 
         FIG.  67    is a diagrammatic, fragmentary, cross-sectional view of the distal portion of the delivery system of  FIG.  65    with the self-alignment configuration primarily inside the aortic arch and with the self-alignment configuration substantially in the desired orientation; 
         FIG.  68    is a fragmentary, enlarged, partially exploded perspective view of an alternative embodiment of a distal end of the graft push lumen of  FIG.  25   ; 
         FIG.  69    is a photograph of a user bending a stent graft assembly around a curving device to impart a curve to a guidewire lumen therein; 
         FIG.  70    is a side elevational view of a stent graft according to the invention; 
         FIG.  71    is a side elevational view of an alternative embodiment of the stent graft with a clasping stent and a crown stent; 
         FIG.  72    is a photograph depicting a side view of the stent graft of  FIG.  71   ; 
         FIG.  73    is a photograph of a perspective view from a side of a proximal end of the stent graft of  FIGS.  1  and  70    with a bare stent protruding from the proximal end thereof; 
         FIG.  74    is a photograph of an enlarged, perspective view from the interior of the proximal end of the stent graft of  FIG.  71   ; 
         FIG.  75    is a photograph of a perspective view from a distal end of the stent graft of  FIG.  71    with an alternative embodiment of the crown stent where less of the stent is attached to the graft; 
         FIG.  76    is a photograph of a side view of the stent graft of  FIG.  71    partially withdrawn from a flexible sheath of the delivery system according to the invention with some of the capture stent apices releasably held within the apex capture device of the delivery system. 
         FIG.  77    is a photograph of a perspective view of the captured stent graft of  FIG.  76    from the proximal end thereof and with some of the capture stent apices releasably held within the apex capture device of the delivery system; 
         FIG.  78    is a photograph of a perspective view from the proximal end of the stent graft of  FIGS.  1  and  70    deployed in an exemplary vessel; 
         FIG.  79    is a photograph of a perspective view from the proximal end of the stent graft of  FIG.  71    deployed in an exemplary vessel; 
         FIG.  80    is a cross-sectional view of the apex capture assembly of  FIGS.  13 ,  14 ,  29  to  32 , and  63    along a plane orthogonal to the longitudinal axis of the delivery system according to the invention without the inner sheath; 
         FIG.  81    is a fragmentary, cross-sectional view of the apex capture assembly of  FIG.  80    along a plane orthogonal to the view plane of  FIG.  80    and through the longitudinal axis of the delivery system according to the invention without the inner sheath; 
         FIG.  82    is a fragmentary, side elevational view of a distal end of the delivery system according to the invention with the inner sheath in a curved orientation and having an alternative embodiment of a D-shaped marker thereon; 
         FIG.  83    is a fragmentary, plan view of the distal end of  FIG.  82    viewed from above; 
         FIG.  84    is a fragmentary, plan and partially hidden view of the distal end of  FIG.  82    viewed from below with the D-shaped marker on the opposite top side; 
         FIG.  85    is a fragmentary, elevational view of the distal end of  FIG.  82    viewed from the top of  FIG.  82    and parallel to the longitudinal axis of the catheter of the delivery system; 
         FIG.  86    is a side elevational view of the delivery system according to the invention with an alternative embodiment of a rotating distal handle; 
         FIG.  87    is a fragmentary, cross-sectional view of the rotating distal handle of  FIG.  86   ; 
         FIG.  88    is a is a fragmentary, cross-sectional view of an alternative embodiment of the rotating distal handle of  FIG.  86   ; 
         FIG.  89    is a fragmentary, perspective view of the distal end of the delivery system of  FIG.  86   ; 
         FIG.  90    is a perspective view from the distal side of another embodiment of the delivery system of the invention; 
         FIG.  91    is a fragmentary, enlarged, exploded, side elevational view of the apex release assembly of the delivery system of  FIG.  90   ; 
         FIG.  92    is a fragmentary, enlarged, partially exploded, side elevational view of the locking knob assembly of the delivery system of  FIG.  90   ; 
         FIG.  93    is a perspective view of a clasp sleeve of a handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  94    is an exploded, perspective view of a clasp body assembly of the handle assembly of  FIG.  90   ; 
         FIG.  95    is an exploded, perspective view of a rotator assembly of the handle assembly of  FIG.  90   ; 
         FIG.  96    is a perspective view of the rotator assembly of  FIG.  95    in an assembled state; 
         FIG.  97    is a fragmentary, exploded, side elevational view of a delivery sheath of the delivery system of  FIG.  90   ; 
         FIG.  98    is a fragmentary, exploded, side elevational view of the delivery sheath of  FIG.  97    rotated approximately 90 degrees; 
         FIG.  99    is an enlarged, side elevational view of a portion of the delivery sheath of  FIG.  98   ; 
         FIG.  100    is a fragmentary, enlarged, side elevational view of the distal end of the delivery system of  FIG.  90   ; 
         FIG.  101    is a fragmentary, partially hidden side elevational view and partially cross-sectional view of the proximal end of the handle assembly of  FIG.  90    with the sheath lumen removed; 
         FIG.  102    is a fragmentary, cross-sectional view of the proximal end of the handle assembly of  FIG.  101   ; 
         FIG.  103    is a fragmentary, enlarged, cross-sectional view of the actuation knob and clasp body assemblies of the handle assembly of  FIG.  102   ; 
         FIG.  104    is a fragmentary, enlarged, cross-sectional view of the rotator assembly of the handle assembly of  FIG.  102   ; 
         FIG.  105    is a fragmentary, further-enlarged, cross-sectional view of the rotator assembly of the handle assembly of  FIG.  104   ; 
         FIG.  106    is a fragmentary, transverse cross-sectional view of the handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  107    is a fragmentary, transverse cross-sectional view of the handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  108    is a fragmentary, transverse cross-sectional view of the handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  109    is a fragmentary, transverse cross-sectional view of the handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  110    is a fragmentary, transverse cross-sectional view of the handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  111    is a fragmentary, enlarged, transverse cross-sectional view of the handle assembly of  FIG.  110   ; 
         FIG.  112    is a fragmentary, transverse cross-sectional view of the handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  113    is a fragmentary, enlarged transverse cross-sectional view of the handle assembly of  FIG.  112   ; 
         FIG.  114    is a fragmentary, transverse cross-sectional view of the handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  115    is a fragmentary, transverse cross-sectional view of the handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  116    is a fragmentary, transverse cross-sectional view of the handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  117    is a fragmentary, transverse cross-sectional view of the handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  118    is a fragmentary, transverse cross-sectional view of the handle assembly of the delivery system of  FIG.  90   ; 
         FIG.  119    is a fragmentary, shaded, cross-sectional view of a distal portion of the handle assembly of  FIG.  90    without the proximal handle; 
         FIG.  120    is a fragmentary, diagrammatic cross-sectional view of the thoracic aorta with a prior art stent graft having an inflow plane at an angle to an implant plane; 
         FIG.  121    is a fragmentary, diagrammatic cross-sectional view of the thoracic aorta with a stent graft placed according to the invention with the inflow plane aligned with the implant plane; 
         FIG.  122    is a diagrammatic, side elevational view of a first exemplary embodiment of a stent graft centering device according to the invention; 
         FIG.  123    is a fragmentary, diagrammatic, cross-sectional view of the stent graft centering device of  FIG.  122    in an aorta; 
         FIG.  124    is a fragmentary, diagrammatic, perspective view of a second exemplary embodiment of a stent graft centering device according to the invention; 
         FIG.  125    is a fragmentary, diagrammatic, cross-sectional view of the stent graft centering device of  FIG.  124    with one balloon inflated in an aorta; 
         FIG.  126    is a diagrammatic, plan view of the stent graft centering device of  FIG.  124    with three balloons inflated; 
         FIG.  127    is a diagrammatic, hidden, perspective view of a fourth exemplary embodiment of a stent graft centering device according to the invention in a first position; 
         FIG.  128    is a diagrammatic, hidden, perspective view of the stent graft centering device of  FIG.  127    in a second position; 
         FIG.  129    is a fragmentary, diagrammatic, cross-sectional view of a fifth exemplary embodiment of a stent graft centering device according to the invention; 
         FIG.  130    is a fragmentary, diagrammatic, cross-sectional illustration forces acting upon the stent graft centering device of  FIG.  129   ; 
         FIG.  131    is a fragmentary, diagrammatic, cross-sectional view of a sixth exemplary embodiment of a stent graft centering device according to the invention in a first position; 
         FIG.  132    is a fragmentary, diagrammatic, cross-sectional view of the stent graft centering device of  FIG.  131    in a second position; 
         FIG.  133    is a fragmentary, diagrammatic, perspective view of a seventh exemplary embodiment of a stent graft centering device according to the invention in a closed position; 
         FIG.  134    is a fragmentary, diagrammatic, perspective view of the stent graft centering device of  FIG.  133    in an open position; 
         FIG.  135    is a fragmentary, diagrammatic, perspective view of the stent graft centering device of  FIG.  133    in captured state; 
         FIG.  136    is a fragmentary, diagrammatic, side elevational view of an eighth exemplary embodiment of a stent graft centering device according to the invention; 
         FIG.  137    is a fragmentary, diagrammatic, side elevational view of the stent graft centering device of  FIG.  136    in an extended state; 
         FIGS.  138  and  140    is a fragmentary, diagrammatic, exploded view the stent graft centering device of  FIG.  136   ; 
         FIG.  139    is a fragmentary, diagrammatic, side elevational view the stent graft centering device of  FIG.  136    in a retracted state with a stent captured; 
         FIG.  141    is a fragmentary, diagrammatic, side elevational view the stent graft centering device of  FIG.  136    in an extended centering state with a stent captured; 
         FIG.  142    is a fragmentary, diagrammatic, side elevational view the stent graft centering device of  FIG.  136    in an extended centering state with a stent released; 
         FIG.  143    is a fragmentary, diagrammatic, cross-sectional view of an ninth exemplary embodiment of a stent graft centering device according to the invention in an aorta; 
         FIG.  144    is a fragmentary, diagrammatic, side elevational view of a tenth exemplary embodiment of a stent graft centering device according to the invention in a straight orientation; 
         FIG.  145    is a fragmentary, diagrammatic, side elevational view of the stent graft centering device of  FIG.  144    in a crooked orientation; 
         FIG.  146    is a fragmentary, diagrammatic, side elevational view of the stent graft centering device of  FIG.  144    in a bent orientation; 
         FIG.  147    is a fragmentary, diagrammatic, cross-sectional view of an eleventh exemplary embodiment of a stent graft centering device according to the invention in a centered orientation; 
         FIG.  148    is a fragmentary, diagrammatic, cross-sectional view of the stent graft centering device of  FIG.  147    with a delivery system therein and a stent graft closed; 
         FIG.  149    is a fragmentary, diagrammatic, cross-sectional view of the stent graft centering device of  FIG.  147    with a delivery system therein and a stent graft open; 
         FIGS.  150  and  150 A  are fragmentary, diagrammatic, perspective views of the stent graft centering device of  FIG.  147    with balloons inflated. 
         FIG.  151    is a fragmentary, diagrammatic, perspective view of the stent graft centering device of  FIG.  147    with balloons deflated; 
         FIG.  152    is a fragmentary, diagrammatic, cross-sectional view of a twelfth exemplary embodiment of a stent graft centering device according to the invention in an aorta; 
         FIG.  153    is a fragmentary, diagrammatic, cross-sectional view of the stent graft centering device of  FIG.  152    centering a stent graft delivery device with the stent graft closed; 
         FIG.  154    is a fragmentary, diagrammatic, cross-sectional view of the stent graft centering device of  FIG.  152    centering a stent graft delivery device with the stent graft open; 
         FIG.  155    is a fragmentary, diagrammatic, cross-sectional view of the stent graft centering device of  FIG.  152   ; 
         FIG.  156    is a fragmentary, diagrammatic, side elevational view of a thirteenth exemplary embodiment of a stent graft centering device according to the invention; 
         FIG.  157    is a fragmentary, diagrammatic, side elevational view of a prior art stent graft in an aorta having the inflow plane at an angle to the implant plane; 
         FIG.  158    is a fragmentary, diagrammatic, side elevational view of the stent graft centering device of  FIG.  156    in an aorta having the inflow plane aligned with the implant plane; 
         FIG.  159    is a fragmentary, diagrammatic, perspective view of a fourteenth exemplary embodiment of a stent graft centering device according to the invention; 
         FIG.  160    is a fragmentary, diagrammatic, perspective view of a fifteenth exemplary embodiment of a stent graft centering device according to the invention; 
         FIG.  161    is a fragmentary, diagrammatic, perspective view of a control assembly of the stent graft centering device of  FIG.  160   ; 
         FIG.  162    is a fragmentary, diagrammatic, perspective view of a sixteenth exemplary embodiment of a stent graft centering device according to the invention in a first configuration; 
         FIG.  163    is a fragmentary, diagrammatic, perspective view of the stent graft centering device of  FIG.  162    in a second configuration; 
         FIG.  164    is a fragmentary, diagrammatic, side elevational view of a seventeenth exemplary embodiment of a stent graft centering device according to the invention in an expanded orientation; 
         FIG.  165    is a fragmentary, diagrammatic, side elevational view of the stent graft centering device of  FIG.  164    in a further expanded orientation; 
         FIG.  166    is a fragmentary, diagrammatic, side elevational view of the stent graft centering device of  FIG.  164    in a contracted orientation; 
         FIG.  167    is a fragmentary, diagrammatic, side elevational view of the stent graft centering device of  FIG.  164    in an open position; 
         FIG.  167 A  is a fragmentary, diagrammatic, enlarged side elevational view of a portion of the stent graft centering device of  FIG.  167    in the open position; 
         FIG.  168    is a fragmentary, diagrammatic, enlarged, side elevational view of a portion of the stent graft centering device of  FIG.  164    in a captured position; 
         FIG.  169    is a fragmentary, diagrammatic, side elevational view of the stent graft centering device of  FIG.  167    in a captured position of a stent; 
         FIG.  170    is a fragmentary, diagrammatic, perspective view of an eighteenth exemplary embodiment of a stent graft centering device according to the invention in a closed orientation; 
         FIG.  171    is a fragmentary, diagrammatic, perspective view of the stent graft centering device of  FIG.  110    through a stent graft; 
         FIG.  172    is a fragmentary, diagrammatic, perspective view of the stent graft centering device of  FIG.  171    in an open orientation without the stent graft; 
         FIG.  173    is a fragmentary, diagrammatic, side elevational view of a nineteenth exemplary embodiment of a stent graft centering device according to the invention in a closed orientation; 
         FIG.  174    is a fragmentary, diagrammatic, side elevational view of the stent graft centering device of  FIG.  173    in an open orientation; 
         FIG.  175    is a fragmentary, diagrammatic, side elevational view of the stent graft centering device of  FIG.  174    through a stent graft; and 
         FIG.  176    is a fragmentary, diagrammatic, side elevational view of a twentieth exemplary embodiment of a stent graft centering device according to the invention. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward. 
     The present invention provides a stent graft, delivery system, and method for implanting a prosthesis with a two-part expanding delivery system that treats, in particular, thoracic aortic defects from the brachiocephalic level of the aortic arch distally to a level just superior to the celiac axis and provides an endovascular foundation for an anastomosis with the thoracic aorta, while providing an alternative method for partial/total thoracic aortic repair by excluding the vessel defect and making surgical repair of the aorta unnecessary. The stent graft of the present invention, however, is not limited to use in the aorta. It can be endoluminally inserted in any accessible artery that could accommodate the stent graft&#39;s dimensions. 
     Stent Graft 
     The stent graft according to the present invention provides various features that, heretofore, have not been applied in the art and, thereby, provide a vessel repair device that implants/conforms more efficiently within the natural or diseased course of the aorta, decreases the likelihood of vessel puncture, and increases the blood-tight vascular connection, and decreases the probability of graft mobility. 
     The stent graft is implanted endovascularly before or during or in place of an open repair of the vessel (i.e., an arch, in particular, the ascending and/or descending portion of the aorta) through a delivery system described in detail below. The typical defects treated by the stent graft are aortic aneurysms, aortic dissections, and other diseases such as penetrating aortic ulcer, coarctation, and patent ductus arteriosus, related to the aorta. When endovascularly placed in the aorta, the stent graft forms a seal in the vessel and automatically affixes itself to the vessel with resultant effacement of the pathological lesion. 
     Referring now to the figures of the drawings in detail and first, particularly to  FIG.  1    thereof, there is shown an improved stent graft  1  having a graft sleeve  10  and a number of stents  20 . These stents  20  are, preferably, made of nitinol, an alloy having particularly special properties allowing it to rebound to a set configuration after compression, the rebounding property being based upon the temperature at which the alloy exists. For a detailed explanation of nitinol and its application with regard to stents, see, e.g., U.S. Pat. Nos. 4,665,906, 5,067,957, and 5,597,378 to Jervis and to Gianturco. 
     The graft sleeve  10  is cylindrical in shape and is made of a woven graft material along its entire length. The graft material is, preferably, polyester, in particular, polyester referred to under the name DACRON® or other material types like Expanded Polytetrafluoroethylene (“EPTFE”), or other polymeric based coverings. The tubular graft sleeve  10  has a framework of individual lumen-supporting wires each referred to in the art as a stent  20 . Connection of each stent  20  is, preferably, performed by sewing a polymeric (nylon, polyester) thread around an entirety of the stent  20  and through the graft sleeve  10 . The stitch spacings are sufficiently close to prevent any edge of the stent  20  from extending substantially further from the outer circumference of the graft sleeve  10  than the diameter of the wire itself. Preferably, the stitches have a 0.5 mm to 5 mm spacing. 
     The stents  20  are sewn either to the exterior or interior surfaces of the graft sleeve  10 .  FIG.  1    illustrates all stents  20 ,  30  on the exterior surface  16  of the graft sleeve  10 . In an exemplary non-illustrated embodiment, the most proximal  23  and distal stents and a bare stent  30  are connected to the interior surface of the graft sleeve  10  and the remainder of the stents  20  are connected to the exterior surface  16 . Another possible non-illustrated embodiment alternates connection of the stents  20 ,  30  to the graft sleeve  10  from the graft exterior surface to the graft interior surface, the alternation having any periodic sequence. 
     A stent  20 , when connected to the graft sleeve  10 , radially forces the graft sleeve  10  open to a predetermined diameter D. The released radial force creates a seal with the vessel wall and affixes the graft to the vessel wall when the graft is implanted in the vessel and is allowed to expand. 
     Typically, the stents  20  are sized to fully expand to the diameter D of the fully expanded graft sleeve  10 . However, a characteristic of the present invention is that each of the stents  20  and  30  has a diameter larger than the diameter D of the fully expanded graft sleeve  10 . Thus, when the stent graft  1  is fully expanded and resting on the internal surface of the vessel where it has been placed, each stent  20  is imparting independently a radially directed force to the graft sleeve  10 . Such pre-compression, as it is referred to herein, is applied (1) to ensure that the graft covering is fully extended, (2) to ensure sufficient stent radial force to make sure sealing occurs, (3) to affix the stent graft and prevent it from kinking, and (4) to affix the stent graft and prevent migration. 
     Preferably, each of the stents  20  is formed with a single nitinol wire. Of course other biocompatible materials can be used, for example, stainless steel, biopolymers, cobalt chrome, and titanium alloys. 
     An exemplary shape of each stent  20  corresponds to what is referred in the art as a Z-stent, see, e.g., Gianturco (although the shape of the stents  20  can be in any form that satisfies the functions of a self-expanding stent). Thus, the wire forming the stent  20  is a ring having a wavy or sinusoidal shape. In particular, an elevational view orthogonal to the center axis  21  of the stent  20  reveals a shape somewhere between a triangular wave and a sinusoidal wave as shown in  FIG.  2   . In other words, the view of  FIG.  2    shows that the stents  20  each have alternating proximal  22  and distal  24  apices. Preferably, the apices have a radius r that does not present too great of a point towards a vessel wall to prevent any possibility of puncturing the vessel, regardless of the complete circumferential connection to the graft sleeve  10 . In particular, the radius r of curvature of the proximal  22  and distal  24  apices of the stent  20  are, preferably, equal. The radius of curvature r is between approximately 0.1 mm and approximately 3.0 mm, in particular, approximately 0.5 rom. 
     Another advantageous feature of a stent lies in extending the longitudinal profile along which the stent contacts the inner wall of a vessel. This longitudinal profile can be explained with reference to  FIGS.  3  to  7   . 
     Prior art stents and stents according to the present invention are formed on mandrels  29 ,  29 ′ by winding the wire around the mandrel  29 ,  29 ′ and forming the apexes  22 ,  24 ,  32 ,  34  by wrapping the wire over non-illustrated pins that protrude perpendicular from the axis of the mandrel. Such pins, if illustrated, would be located in the holes illustrated in the mandrels  29 ,  29 ′ of  FIGS.  4  and  6   . Prior art stents are formed on a round mandrel  29  (also referred to as a bar). A stent  20 ′ formed on a round mandrel  29  has a profile that is rounded (see  FIG.  5   ). Because of the rounded profile, the stent  20 ′ does not conform evenly against the inner wall of the vessel  2  in which it is inserted. This disadvantage is critical in the area of stent graft  1  seal zones—areas where the ends of the graft  10  need to be laid against the inner wall of the vessel  2 . Clinical experience reveals that stents  20 ′ formed with the round mandrel  29  do not lie against the vessel  2 ; instead, only a mid-section of the stent  20 ′ rests against the vessel  2 , as shown in  FIG.  5   . Accordingly, when such a stent  20 ′ is present at either of the proximal  12  or distal  14  ends of the stent graft  1 , the graft material flares away from the wall of the vessel  2  into the lumen—a condition that is to be avoided. An example of this flaring can be seen by comparing the upper and lower portions of the curved longitudinal profile of the stent  20 ′ in  FIG.  5    with the linear longitudinal profile of the vessel  2 . 
     To remedy this problem and ensure co-columnar apposition of the stent and vessel, stents  20  of the present invention are formed on a multiple-sided mandrel. In particular, the stents  20  are formed on a polygonal-shaped mandrel  29 ′. The mandrel  29 ′ does not have sharp edges. Instead, it has flat sections and rounded edge portions between the respective flat sections. Thus, a stent formed on the mandrel  29 ′ will have a cross-section that is somewhat round but polygonal, as shown in  FIG.  3   . The cross-sectional view orthogonal to the center axis  21  of such a stent  20  will have beveled or rounded edges  31  (corresponding to the rounded edge portions of the mandrel  29 ′) disposed between flat sides or struts  33  (corresponding to the flat sections of the mandrel  29 ′). 
     To manufacture the stent  20 , apexes of the stents  20  are formed by winding the wire over non-illustrated pins located on the rounded portions of the mandrel  29 ′. Thus, the struts  33  lying between the apexes  22 ,  24 ,  32 ,  34  of the stents  20  lie flat against the flat sides of the mandrel  29 ′. When so formed on the inventive mandrel  29 ′, the longitudinal profile is substantially less rounded than the profile of stent  20 ′ and, in practice, is substantially linear. 
     For stents  20  having six proximal  22  and six distal  24  apices, the stents  20  are formed on a dodecahedron-shaped mandrel  29 ′ (a mandrel having twelve sides), which mandrel  29 ′ is shown in  FIG.  6   . A stent  20  formed on such a mandrel  29 ′ will have the cross-section illustrated in  FIG.  3   . 
     The fourteen-apex stent  20  shown in  FIG.  7    illustrates a stent  20  that has been formed on a fourteen-sided mandrel. The stent  20  in  FIG.  7    is polygonal in cross-section (having fourteen sides) and, as shown in  FIG.  7   , has a substantially linear longitudinal profile. Clinically, the linear longitudinal profile improves the stent&#39;s  20  ability to conform to the vessel  2  and press the graft sleeve  10  outward in the sealing zones at the extremities of the individual stent  20 . 
     Another way to improve the performance of the stent graft  1  is to provide the distal-most stent  25  on the graft  10  (i.e., downstream) with additional apices and to give it a longer longitudinal length (i.e., greater amplitude) and/or a longer circumferential length. When a stent  25  having a longer circumferential length is sewn to a graft, the stent graft  1  will perform better clinically. The improvement, in part, is due to a need for the distal portion of the graft material  10  to be pressed firmly against the wall of the vessel. The additional apices result in additional points of contact between the stent graft  1  and vessel wall, thus ensuring better apposition to the wall of the vessel and better sealing of the graft material  10  to the vessel. The increased apposition and sealing substantially improves the axial alignment of the distal end  14  of the stent graft  1  to the vessel. As set forth above, each of the stents  20  and  30  has a diameter larger than the diameter D of the fully expanded graft sleeve  10 . Thus, if the distal stent  25  also has a diameter larger than the diameter D, it will impart a greater radial bias on all 360 degrees of the corresponding section of the graft than stents not having such an oversized configuration. 
     A typical implanted stent graft  1  typically does not experience a lifting off at straight portions of a vessel because the radial bias of the stents acting upon the graft sleeve give adequate pressure to align the stent and graft sleeve with the vessel wall. However, when a typical stent graft is implanted in a curved vessel (such as the aorta), the distal end of the stent graft  1  does experience a lift off from the vessel wall. The increased apposition and sealing of the stent graft  1  according to the present invention substantially decreases the probability of lift off because the added height and additional apices enhance the alignment of the stent graft perpendicular to the vessel wall as compared to prior art stent grafts (no lift off occurs). 
     The number of total apices of a stent is dependent upon the diameter of the vessel in which the stent graft  1  is to be implanted. Vessels having a smaller diameter have a smaller total number of apices than a stent to be implanted in a vessel having a larger diameter. Table 1 below indicates exemplary stent embodiments for vessels having different diameters. For example, if a vessel has a 26 or 27 mm diameter, then an exemplary diameter of the graft sleeve  10  is 30 mm. For a 30 mm diameter graft sleeve, the intermediate stents  20  will have 5 apices on each side (proximal and distal) for a total of 10 apices. In other words, the stent defines 5 periodic “waves.” The distal-most stent  25 , in comparison, defines 6 periodic “waves” and, therefore, has 12 total apices. It is noted that the distal-most stent  25  in  FIG.  1    does not have the additional apex. While Table 1 indicates exemplary embodiments, these configurations can be adjusted or changed as needed. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Vessel Diameter 
                 Graft Diameter 
                 Stent Apices/Side 
               
               
                 (mm) 
                 (mm) 
                 (Distal-most Stent #) 
               
               
                   
               
             
            
               
                 19 
                 22 
                 5(5) 
               
               
                 20-21 
                 24 
                 5(5) 
               
               
                 22-23 
                 26 
                 5(5) 
               
               
                 24-25 
                 28 
                 5(6) 
               
               
                 26-27 
                 30 
                 5(6) 
               
               
                 28-29 
                 32 
                 6(7) 
               
               
                 30-31 
                 34 
                 6(7) 
               
               
                 32-33 
                 36 
                 6(7) 
               
               
                 34 
                 38 
                 6(7) 
               
               
                 35-36 
                 40 
                 7(8) 
               
               
                 37-38 
                 42 
                 7(8) 
               
               
                 39-40 
                 44 
                 7(8) 
               
               
                 41-42 
                 46 
                 7(8) 
               
               
                   
               
            
           
         
       
     
     To increase the security of the stent graft  1  in a vessel, an exposed or bare stent  30  is provided on the stent graft  1 , preferably, only at the proximal end  12  of the graft sleeve  10 —proximal meaning that it is attached to the portion of the graft sleeve  10  from which the blood flows into the sleeve, i.e., blood flows from the bare stent  30  and through the sleeve  10  to the left of  FIG.  1   . The bare stent  30  is not limited to being attached at the proximal end  12 . Another non-illustrated bare stent can be attached similarly to the distal end  14  of the graft sleeve  10 . 
     Significantly, the bare stent  30  is only partially attached to the graft sleeve  10 . Specifically, the bare stent  30  is fixed to the graft sleeve  10  only at the distal apices  34  of the bare stent  30 . Thus, the bare stent  30  is partially free to extend the proximal apices  32  away from the proximal end of the graft sleeve  10 . 
     The bare stent  30  has various properties, the primary one being to improve the apposition of the graft material to the contour of the vessel wall and to align the proximal portion of the graft covering in the lumen of the arch and provide a blood-tight closure of the proximal end  12  of the graft sleeve  10  so that blood does not pass between the vascular inside wall and outer surface  16  of the sleeve  10  (endoleak). 
     An exemplary configuration for the radius of curvature α of the distal apices  34  is substantially equal to the radius r of the proximal  22  and distal  24  apices of the stent  20 , in particular, it is equal at least to the radius of curvature r of the proximal apices of the stent  20  directly adjacent the bare stent  30 . Thus, as shown in  FIG.  8   , a distance between the proximal apices  22  of the most proximal stent  23  and crossing points of the exposed portions of the bare stent  30  are substantially at a same distance from one another all the way around the circumference of the proximal end  12  of the graft sleeve  10 . Preferably, this distance varies based upon the graft diameter. Accordingly, the sinusoidal portion of the distal apices  34  connected to the graft sleeve  10  traverse substantially the same path as that of the stent  23  closest to the bare stent  30 . Thus, the distance d between the stent  22  and all portions of the bare stent  30  connected to the graft sleeve  10  remain constant. Such a configuration is advantageous because it maintains the symmetry of radial force of the device about the circumference of the vessel and also aids in the synchronous, simultaneous expansion of the device, thus increasing apposition of the graft material to the vessel wall to induce a proximal seal—and substantially improve the proximal seal—due to increasing outward force members in contact with the vessel wall. 
     Inter-positioning the stents  23 ,  30  in phase with one another, creates an overlap, i.e., the apices  34  of the bare stent  30  are positioned within the troughs of the stent  23 . A further advantage of such a configuration is that the overlap provides twice as many points of contact between the proximal opening of the graft  10  and the vessel in which the stent graft  1  is implanted. The additional apposition points keep the proximal opening of the graft sleeve  10  open against the vessel wall, which substantially reduces the potential for endoleaks. In addition, the overlap of the stents  23 ,  30  increases the radial load or resistance to compression, which functionally increases fixation and reduces the potential for device migration. 
     In contrast to the distal apices  34  of the bare stent  30 , the radius of curvature β of the proximal apices  32  (those apices that are not sewn into the graft sleeve  10 ) is significantly larger than the radius of curvature α of the distal apices  34 . An exemplary configuration for the bare stent apices has a radius approximately equal to 1.5 mm for the proximal apices  32  and approximately equal to 0.5 mm for the distal apices  34 . Such a configuration substantially prevents perforation of the blood vessel by the proximal apices  32 , or, at a minimum, makes is much less likely for the bare stent  30  to perforate the vessel because of the less-sharp curvature of the proximal apices  32 . 
     The bare stent  30  also has an amplitude greater than the other stents  20 . Preferably, the peak-to-peak amplitude of the stents  20  is approximately 1.3 cm to 1.5 cm, whereas the peak-to-peak amplitude of the bare stent  30  is approximately 2.5 cm to 4.0 cm. Accordingly, the force exerted by the bare stent  30  on the inner wall of the aorta (due to the bare stent  30  expanding to its native position) is spread over a larger surface area. Thus, the bare stent  30  of the present invention presents a less traumatic radial stress to the interior of the vessel wall—a characteristic that, while less per square mm than an individual one of the stents  20  would be, is sufficient, nonetheless, to retain the proximal end  12  in position. Simultaneously, the taller configuration of the bare stent  30  guides the proximal opening of the stent graft in a more “squared-off” manner. Thus, the proximal opening of the stent graft is more aligned with the natural curvature of the vessel in the area of the proximal opening. 
     As set forth above, because the vessel moves constantly, and due to the constantly changing pressure imparted by blood flow, any stent graft placed in the vessel has the natural tendency to migrate downstream. This is especially true when the stent graft  1  has graft sleeve segments  18  with lengths defined by the separation of the stents on either end of the segment  18 , giving the stent graft  1  an accordion, concertina, or caterpillar-like shape. When such a shape is pulsating with the vessel and while hemodynamic pressure is imparted in a pulsating manner along the stent graft from the proximal end  12  to the downstream distal end  14 , the stent graft  1  has a tendency to migrate downstream in the vessel. It is desired to have such motion be entirely prohibited. 
     Support along a longitudinal extent of the graft sleeve  10  assists in preventing such movement. Accordingly, as set forth above, prior art stent grafts have provided longitudinal  15  rods extending in a straight line from one stent to another. 
     The present invention, however, provides a longitudinal, spiraling/helical support member  40  that, while extending relatively parallel to the longitudinal axis  11  of the graft sleeve  10 , is not aligned substantially parallel to a longitudinal extent of the entirety of the stent graft  1  as done in the prior art. “Relatively parallel” is referred to herein as an extent that is more along the longitudinal axis  11  of the stent graft  1  than along an axis perpendicular thereto. 
     Specifically, the longitudinal support member  40  has a somewhat S-turn shape, in that, a proximal portion  42  is relatively parallel to the axis  11  of the graft sleeve  10  at a first degree  41  (being defined as a degree of the 360 degrees of the circumference of the graft sleeve  10 ), and a distal portion  44  is, also, relatively parallel to the axis  11  of the tube graft, but at a different second degree  43  on the circumference of the graft sleeve  10 . The difference between the first and second degrees  41 ,  43  is dependent upon the length L of the graft sleeve  10 . For an approximately 20 cm (approx. 8″) graft sleeve, for example, the second degree  43  is between 80 and 110 degrees away from the first degree  41 , in particular, approximately 90 degrees away. In comparison, for an approximately 9 cm (approx. 3.5″) graft sleeve, the second degree  43  is between 30 and 60 degrees away from the first degree  41 , in particular, approximately 45 degrees away. As set forth below, the distance between the first and second degrees  41 ,  43  is also dependent upon the curvature and the kind of curvature that the stent graft  1  will be exposed to when in vivo. 
     The longitudinal support member  40  has a curved intermediate portion  46  between the proximal and distal portions  42 ,  44 . By using the word “portion” it is not intended to mean that the rod is in three separate parts (of course, in a particular configuration, a multi-part embodiment is possible). An exemplary embodiment of the longitudinal support member  40  is a single, one-piece rod made of stainless steel, cobalt chrome, nitinol, or polymeric material that is shaped as a fully curved helix  42 ,  44 ,  46  without any straight portion. In an alternative stent graft embodiment, the proximal and distal portions  42 ,  44  can be substantially parallel to the axis  11  of the stent graft  1  and the central portion  46  can be helically curved. 
     One way to describe an exemplary curvature embodiment of the longitudinal support member  40  can be using an analogy of asymptotes. If there are two asymptotes extending parallel to the longitudinal axis  11  of the graft sleeve  10  at the first and second degrees  41 ,  43  on the graft sleeve  10 , then the proximal portion  42  can be on the first degree  41  or extend approximately asymptotically to the first degree  41  and the distal portion  44  can be on the second degree  43  or extend approximately asymptotically to the second degree  43 . Because the longitudinal support member  40  is one piece in an exemplary embodiment, the curved portion  46  follows the natural curve formed by placing the proximal and distal portions  42 ,  44  as set forth herein. 
     In such a position, the curved longitudinal support member  40  has a centerline  45  (parallel to the longitudinal axis  11  of the graft sleeve  10  halfway between the first and second degrees  41 ,  43  on the graft sleeve  10 ). In this embodiment, therefore, the curved portion intersects the centerline  45  at approximately 20 to 40 degrees in magnitude, preferably at approximately 30 to 35 degrees. 
     Another way to describe the curvature of the longitudinal support member can be with respect to the centerline  45 . The portion of the longitudinal support member  40  between the first degree  41  and the centerline  45  is approximately a mirror image of the portion of the longitudinal support member  40  between the second degree  43  and the centerline  45 , but rotated one-hundred eighty degrees (180°) around an axis orthogonal to the centerline  45 . Such symmetry can be referred to herein as “reverse-mirror symmetrical.” 
     The longitudinal support member  40  is, preferably, sewn to the graft sleeve  10  in the same way as the stents  20 . However, the longitudinal support member  40  is not sewn directly to any of the stents  20  in the proximal portions of the graft. In other words, the longitudinal support member  40  is independent of the proximal skeleton formed by the stents  20 . Such a configuration is advantageous because an independent proximal end creates a gimbal that endows the stent graft with additional flexibility. Specifically, the gimbaled proximal end allows the proximal end to align better to the proximal point of apposition, thus reducing the chance for endoleak. The additional independence from the longitudinal support member allows the proximal fixation point to be independent from the distal section that is undergoing related motion due to the physiological motion of pulsutile flow of blood. Also in an exemplary embodiment, the longitudinal support member  40  is pre-formed in the desired spiral/helical shape (counter-clockwise from proximal to distal), before being attached to the graft sleeve  10 . 
     Because vessels receiving the stent graft  1  are not typically straight (especially the aortic arch), the final implanted position of the stent graft  1  will, most likely, be curved in some way. In prior art stent grafts (which only provide longitudinally parallel support rods), there exist, inherently, a force that urges the rod, and, thereby, the entire stent graft, to the straightened, natural shape of the rod. This force is disadvantageous for stent grafts that are to be installed in an at least partly curved manner. 
     The curved shape of the longitudinal support member  40  according to the present invention eliminates at least a majority, or substantially all, of this disadvantage because the longitudinal support member&#39;s  40  natural shape is curved. Therefore, the support member  40  imparts less of a force, or none at all, to straighten the longitudinal support member  40 , and, thereby, move the implanted stent graft in an undesirable way. At the same time, the curved longitudinal support member  40  negates the effect of the latent kinetic force residing in the aortic wall that is generated by the propagation of the pulse wave and systolic blood pressure in the cardiac cycle, which is, then, released during diastole. As set forth in more detail below, the delivery system of the present invention automatically aligns the stent graft  1  to the most optimal position while traversing the curved vessel in which it is to be implanted, specifically, the longitudinal support member  40  is placed substantially at the superior longitudinal surface line of the curved aorta (with respect to anatomical position). 
     In an exemplary embodiment, the longitudinal support member  40  can be curved in a patient-customized way to accommodate the anticipated curve of the actual vessel in which the graft will be implanted. Thus, the distance between the first and second degrees  41 ,  43  will be dependent upon the curvature and the kind of curvature that the stent graft  1  will be exposed to when in vivo. As such, when implanted, the curved longitudinal support member  40  will, actually, exhibit an opposite force against any environment that would alter its conformance to the shape of its resident vessel&#39;s existing course(es). 
     Preferably, the support member  40  is sewn, in a similar manner as the stents  20 , on the  5  outside surface  16  of the graft sleeve  10 . 
     In prior art support rods, the ends thereof are merely a terminating end of a steel or nitinol rod and are, therefore, sharp. Even though these ends are sewn to the tube graft in the prior art, the possibility of tearing the vessel wall still exists. It is, therefore, desirable to not provide the support rod with sharp ends that could puncture the vessel in which the stent graft is placed. 
     The two ends of the longitudinal support member  40  of the present invention do not end abruptly. Instead, each end of the longitudinal support member loops  47  back upon itself such that the end of the longitudinal support member along the axis of the stent graft is not sharp and, instead, presents an exterior of a circular or oval shape when viewed from the ends  12 ,  14  of the graft sleeve  10 . Such a configuration substantially prevents the possibility of tearing the vessel wall and also provides additional longitudinal support at the oval shape by having two longitudinally extending sides of the oval  47 . 
     In addition, in another embodiment, the end of the longitudinal support member may be connected to the second proximal stent  28  and to the most distal stent. This configuration would allow the longitudinal support member to be affixed to stent  28  (see  FIG.  1   ) and the most distal stent for support while still allowing for the gimbaled feature of the proximal end of the stent graft to be maintained. 
     A significant feature of the longitudinal support member  40  is that the ends of the longitudinal support member  40  may not extend all the way to the two ends  12 ,  14  of the graft sleeve  10 . Instead, the longitudinal support member  40  terminates at or prior to the second-to-last stent  28  at the proximal end  12 , and, if desired, prior to the second-to-last stent  28 ′ at the distal end  14  of the graft sleeve  10 . Such an ending configuration (whether proximal only or both proximal and distal) is chosen for a particular reason—when the longitudinal support member  40  ends before either of the planes defined by cross-sectional lines  52 ,  52 ′, the sleeve  10  and the stents  20  connected thereto respectively form gimbaled portions  50 ,  50 ′. In other words, when a grasping force acting upon the gimbaled ends  50 ,  50 ′ moves or pivots the cross-sectional plane defining each end opening of the graft sleeve  10  about the longitudinal axis  11  starting from the planes defined by the cross-sectional lines  52 ,  52 ′, then the moving portions  50 ,  50 ′ can be oriented at any angle γ about the center of the circular opening in all directions (360 degrees), as shown in  FIG.  8   . The natural gimbal, thus, allows the ends  50 ,  50 ′ to be inclined in any radial direction away from the longitudinal axis  11 . 
     Among other things, the gimbaled ends  50 ,  50 ′ allow each end opening to dynamically align naturally to the curve of the vessel in which it is implanted. A significant advantage of the gimbaled ends  50 ,  50 ′ is that they limit propagation of the forces acting upon the separate parts. Specifically, a force that, previously, would act upon the entirety of the stent graft  1 , in other words, both the end portions  50 ,  50 ′ and the middle portion of the stent graft  1  (i.e., between planes  52 ,  52 ′), now principally acts upon the portion in which the force occurs. For example, a force that acts only upon one of the end portions  50 ,  50 ′ substantially does not propagate into the middle portion of the stent graft  1  (i.e., between planes  52 ,  52 ′). More significantly, however, when a force acts upon the middle portion of the stent graft  1  (whether moving longitudinally, axially (dilation), or in a torqued manner), the ends  50 ,  50 ′, because they are gimbaled, remain relatively completely aligned with the natural contours of the vessel surrounding the respective end  50 ,′ 50 ′ and have virtually none of the force transferred thereto, which force could potentially cause the ends to grate, rub, or shift from their desired fixed position in the vessel. Accordingly, the stent graft ends  50 , 50 ′ remain fixed in the implanted position and extend the seating life of the stent graft  1 . 
     Another advantage of the longitudinal support member  40  is that it increases the columnar strength of the graft stent  1 . Specifically, the material of the graft sleeve can be compressed easily along the longitudinal axis  11 , a property that remains true even with the presence of the stents  20  so long as the stents  20  are attached to the graft sleeve  10  with a spacing between the distal apices  24  of one stent  20  and the proximal apices  22  of the next adjacent stent  20 . This is especially true for the amount of force imparted by the flow of blood along the extent of the longitudinal axis  11 . However, with the longitudinal support member  40  attached according to the present invention, longitudinal strength of the stent graft  1  increases to overcome the longitudinal forces imparted by blood flow. 
     Another benefit imparted by having such increased longitudinal strength is that the stent graft  1  is further prevented from migrating in the vessel because the tube graft is not compressing and expanding in an accordion-like manner—movement that would, inherently, cause graft migration. 
     A further measure for preventing migration of the stent graft  1  is to equip at least one of any of the individual stents  20 ,  30  or the longitudinal support member  40  with protuberances  60 , such as barbs or hooks ( FIG.  3   ). See, e.g., United States Patent Publication 2002/0052660 to Greenhalgh. In an exemplary embodiment of the present invention, the stents  20 ,  30  are secured to the outer circumferential surface  16  of the graft sleeve  10 . Accordingly, if the stents  20  (or connected portions of stent  30 ) have protuberances  60  protruding outwardly, then such features would catch the interior wall of the vessel and add to the prevention of stent graft  1  migration. Such an embodiment can be preferred for aneurysms but is not preferred for the fragile characteristics of dissections because such protuberances  60  can excoriate the inner layer(s) of the vessel and cause leaks between layers, for example. 
     As shown in  FIG.  9   , the stent graft  1  is not limited to a single graft sleeve  10 . Instead, the entire stent graft can be a first stent graft  100  having all of the features of the stent graft  1  described above and a second stent graft  200  that, instead of having a circular extreme proximal end  12 , as set forth above, has a proximal end  212  with a shape following the contour of the most proximal stent  220  and is slightly larger in circumference than the distal circumference of the first stent graft  100 . Therefore, an insertion of the proximal end  212  of the second stent graft  200  into the distal end  114  of the first stent graft  100  results, in total, in a two-part stent graft. Because blood flows from the proximal end  112  of the first stent graft  100  to the distal end  214  of the second stent graft  200 , it is preferable to have the first stent graft  100  fit inside the second stent graft  200  to prevent blood from leaking out therebetween. This configuration can be achieved by implanting the devices in reverse order (first implant graft  200  and, then, implant graft  100 . Each of the stent grafts  100 ,  200  can have its own longitudinal support member  40  as needed. 
     It is not significant if the stent apices of the distal-most stent of the first stent graft  100  are not aligned with the stent apices of the proximal-most stent  220  of the second stent graft  200 . What is important is the amount of junctional overlap between the two grafts  100 ,  200 . 
     Delivery System 
     As set forth above, the prior art includes many different systems for endoluminally delivering a prosthesis, in particular, a stent graft, to a vessel. Many of the delivery systems have similar parts and most are guided along a guidewire that is inserted, typically, through an insertion into the femoral artery near a patient&#39;s groin prior to use of the delivery system. To prevent puncture of the arteries leading to and including the aorta, the delivery system is coaxially connected to the guidewire and tracks the course of the guidewire up to the aorta. The parts of the delivery system that will track over the wire are, therefore, sized to have an outside diameter smaller than the inside diameter of the femoral artery of the patient. The delivery system components that track over the guidewire include the stent graft and are made of a series of coaxial lumens referred to as catheters and sheaths. The stent graft is constrained, typically, by an outer catheter, requiring the stent graft to be compressed to fit inside the outer catheter. Doing so makes the portion of the delivery system that constrains the stent graft very stiff, which, therefore, reduces that portion&#39;s flexibility and makes it difficult for the delivery system to track over the guidewire, especially along curved vessels such as the aortic arch. In addition, because the stent graft exerts very high radial forces on the constraining catheter due to the amount that it must be compressed to fit inside the catheter, the process of deploying the stent graft by sliding the constraining catheter off of the stent graft requires a very high amount of force, typically referred to as a deployment force. Also, the catheter has to be strong enough to constrain the graft, requiring it to be made of a rigid material. If the rigid material is bent, such as when tracking into the aortic arch, the rigid material tends to kink, making it difficult if not impossible to deploy the stent graft. 
     Common features of vascular prosthesis delivery systems include a tapered nose cone fixedly connected to a guidewire lumen, which has an inner diameter substantially corresponding to an outer diameter of the guidewire such that the guidewire lumen slides easily over and along the guidewire. A removable, hollow catheter covers and holds a compressed prosthesis in its hollow and the catheter is fixedly connected to the guidewire lumen. Thus, when the prosthesis is in a correct position for implantation, the physician withdraws the hollow catheter to gradually expose the self-expanding prosthesis from its proximal end towards its distal end. When the catheter has withdrawn a sufficient distance from each portion of the expanding framework of the prosthesis, the framework can expand to its native position, preferably, a position that has a diameter at least as great as the inner diameter of the vessel wall to, thereby, tightly affix the prosthesis in the vessel When the catheter is entirely withdrawn from the prosthesis and, thereby, allows the prosthesis to expand to the diameter of the vessel, the prosthesis is fully expanded and connected endoluminally to the vessel along the entire extent of the prosthesis, e.g., to treat a dissection. When treating an aneurysm, for example, the prosthesis is in contact with the vessel&#39;s proximal and distal landing zones when completely released from the catheter. At such a point in the delivery, the delivery system can be withdrawn from the patient. The prosthesis, however, cannot be reloaded in the catheter if implantation is not optimal. 
     The aorta usually has a relatively straight portion in the abdominal region and in a lower part of the thoracic region. However, in the upper part of the thoracic region, the aorta is curved substantially, traversing an upside-down U-shape from the back of the heart over to the front of the heart. As explained above, prior art delivery systems are relatively hard and inflexible (the guidewire/catheter portion of the prior art delivery systems). Therefore, if the guidewire/catheter must traverse the curved portion of the aorta, it will kink as it is curved or it will press against the top portion of the aortic curve, possibly puncturing the aorta if the diseased portion is located where the guidewire/catheter is exerting its force. Such a situation must be avoided at all costs because the likelihood of patient mortality is high. The prior art does not provide any way for substantially reducing the stress on the curved portion of the aorta or for making the guidewire/catheter sufficiently flexible to traverse the curved portion without causing damage to the vessel. 
     The present invention, however, provides significant features not found in the prior art that assist in placing a stent graft in a curved portion of the aorta in a way that substantially reduces the stress on the curved portion of the aorta and substantially reduces the insertion forces needed to have the compressed graft traverse the curved portion of the aorta. As set forth above, the longitudinal support member  40  is pre-formed in a desired spiral/helical shape before being attached to the graft sleeve  10  and, in an exemplary embodiment, is curved in a patient-customized way to accommodate the anticipated curve of the actual vessel in which the graft will be implanted. As such, optimal positioning of the stent graft  1  occurs when the longitudinal support member  40  is placed substantially at the superior longitudinal surface line of the curved aorta (with respect to anatomical position). Such placement can be effected in two ways. First, the stent graft  1 , the support member  40 , or any portion of the delivery system that is near the target site can be provided with radiopaque markers that are monitored by the physician and used to manually align the support member  40  in what is perceived as an optimal position. The success of this alignment technique, however, is dependent upon the skill of the physician. Second, the delivery system can be made to automatically align the support member  40  at the optimal position. No such system existed in the prior art. However, the delivery system of the present invention provides such an alignment device, thereby, eliminating the need for physician guesswork as to the three-dimensional rotational position of the implanted stent graft  1 . This alignment device is explained in further detail below with respect to  FIGS.  64  to  67   . 
     The delivery system of the present invention also has a very simple to use handle assembly. The handle assembly takes advantage of the fact that the inside diameter of the aorta is substantially larger that the inside diameter of the femoral arteries. The present invention, accordingly, uses a two-stage approach in which, after the device is inserted in through the femoral artery and tracks up into the abdominal area of the aorta (having a larger diameter (see  FIG.  19   ) than the femoral artery), a second stage is deployed (see  FIG.  20   ) allowing a small amount of expansion of the stent graft while still constrained in a sheath; but this sheath, made of fabric/woven polymer or similar flexible material, is very flexible. Such a configuration gives the delivery system greater flexibility for tracking, reduces deployment forces because of the larger sheath diameter, and easily overcome kinks because the sheath is made of fabric. 
     To describe the delivery system of the present invention, the method for operating the delivery assembly  600  will be described first in association with  FIGS.  10 ,  11 , and  12   . Thereafter, the individual components will be described to allow a better understanding of how each step in the process is effected for delivering the stent graft  1  to any portion of the aorta  700  (see  FIGS.  19  to  24   ), in particular, the curved portion  710  of the aorta. 
     Initially, the distal end  14  of the stent graft  1  is compressed and placed into a hollow, cup-shaped, or tubular-shaped graft holding device, in particular, the distal sleeve  644  (see, e.g.,  FIG.  25   ). At this point, it is noted that the convention for indicating direction with respect to delivery systems is opposite that of the convention for indicating direction with respect to stent grafts. Therefore, the proximal direction of the delivery system is that portion closest to the user/physician employing the system and the distal direction corresponds to the portion farthest away from the user/physician, i.e., towards the distal-most nose cone  632 . 
     The distal sleeve  644  is fixedly connected to the distal end of the graft push lumen  642 , which lumen  642  provides an end face for the distal end  14  of the stent graft  1 . Alternatively, the distal sleeve  644  can be removed entirely. In such a configuration, as shown in  FIG.  12   , for example, the proximal taper of the inner sheath  652  can provide the measures for longitudinally holding the compressed distal end of the graft  1 . If the sleeve  644  is removed, it is important to prevent the distal end  14  of the stent graft  1  from entering the space between the interior surface of the hollow sheath lumen  654  and the exterior surface of the graft push lumen  642  slidably disposed in the sheath lumen  654 . Selecting a radial thickness of the space to be less than the diameter of the wire making up the stent  20 ,  30  (in particular, no greater than half a diameter thereof) insures reliable movement of the distal end  14  of the stent graft  1 . In another alternative configuration shown in  FIG.  68   , the distal sleeve  644  can be a disk-shaped buttress  644  present at the distal end of the graft push lumen  642 . An example configuration can provide the buttress  644  with a hollow proximal insertion peg  6442 , a hollow distal stiffening tube  6444 , and an intermediate buttress wall  6446 . The buttress  644  is concentric to the center axis of the delivery system  600  and allows the co-axial guidewire lumen  620  and apex release lumen  640  to pass therethrough. The peg  6442  allows for easy connection to the graft push lumen  643 . The stiffening tube  64  creates a transition in stiffness from the graft push lumen  642  to the apex release lumen  620  and guidewire lumen  640  and provides support to the lumen  620 ,  640  located therein. Such a transition in stiffness reduces any possibility of kinking at the distal end of the graft push lumen  642  and aids in transferring force from the graft push lumen  642  to the lumen therein  620 ,  640  when all are in a curved orientation. The buttress wall  6446  provides a flat surface that will contact the distal-end-facing side of the stent graft  1  and can be used to push the stent graft distally when the graft push lumen  642  is moved distally. The alternative configuration of the buttress  644  insures that the stent graft  1  does not become impinged within the graft push lumen  642  and the lumen therein  620 ,  640  when these components are moved relative to each other. 
     As set forth in more detail below, each apex  32  of the bare stent  30  is, then, loaded into the apex capture device  634  so that the stent graft  1  is held at both its proximal and distal ends. The loaded distal end  14 , along with the distal sleeve  644  and the graft push lumen  642 , are, in turn, loaded into the inner sheath  652 , thus, further compressing the entirety of the stent graft  1 . The captured bare stent  30 , along with the nose cone assembly  630  (including the apex capture device  634 ), is loaded until the proximal end of the nose cone  632  rests on the distal end of the inner sheath  652 . The entire nose cone assembly  630  and sheath assembly  650  is, then, loaded proximally into the rigid outer catheter  660 , further compressing the stent graft  1  (resting inside the inner sheath  652 ) to its fully compressed position for later insertion into a patient. See  FIG.  63   . 
     The stent graft  1  is, therefore, held both at its proximal and distal ends and, thereby, is both pushed and pulled when moving from a first position (shown in  FIG.  19    and described below) to a second position (shown in  FIG.  21    and described below). Specifically, pushing is accomplished by the non-illustrated interior end face of the hollow distal sleeve  644  (or the taper  653  of the inner sheath  652 ) and pulling is accomplished by the hold that the apex capture device  634  has on the apices  32  of the bare stent  30 . 
     The assembly  600  according to the present invention tracks along a guidewire  610  already inserted in the patient and extending through the aorta and up to, but not into, the left ventricle of the heart  720 . Therefore, a guidewire  610  is inserted through the guidewire lumen  620  starting from the nose cone assembly  630 , through the sheath assembly  650 , through the handle assembly  670 , and through the apex release assembly  690 . The guidewire  610  extends out the proximal-most end of the assembly  600 . The guidewire lumen  620  is coaxial with the nose cone assembly  630 , the sheath assembly  650 , the handle assembly  670 , and the apex release assembly  690  and is the innermost lumen of the assembly  600  immediately surrounding the guidewire  610 . 
     Before using the delivery system assembly  600 , all air must be purged from inside the assembly  600 . Therefore, a liquid, such as sterile U.S.P. saline, is injected through a non-illustrated tapered luer fitting to flush the guidewire lumen at a non-illustrated purge port located near a proximal end of the guidewire lumen. Second, saline is also injected through the luer fitting  612  of the lateral purge-port (see  FIG.  11   ), which liquid fills the entire internal co-axial space of the delivery system assembly  600 . It may be necessary to manipulate the system to facilitate movement of the air to be purged to the highest point of the system. 
     After purging all air, the system can be threaded onto the guidewire and inserted into the patient. Because the outer catheter  660  has a predetermined length, the fixed front handle  672  can be disposed relatively close to the entry port of the femoral artery. It is noted, however, that the length of the outer catheter  660  is sized such that it will not have the fixed proximal handle  672  directly contact the entry port of the femoral artery in a patient who has the longest distance between the entry port and the thoracic/abdominal junction  742 ,  732  of the aorta expected in a patient (this distance is predetermined). Thus, the delivery assembly  600  of the present invention can be used with typical anatomy of the patient. Of course, the assembly  600  can be sized to any usable length. 
     The nose cone assembly  630  is inserted into a patient&#39;s femoral artery and follows the guidewire  610  until the nose cone  632  reaches the first position at least to a level of the celiac axis and possibly further but not into the intended stent graft deployment site, which would prevent deployment of at least the downstream end of the stent graft. The first position is shown in  FIG.  19   . The nose cone assembly  630  is radiopaque, whether wholly or partially, to enable the physician to determine fluoroscopically, for example, that the nose cone assembly  630  is in the first position. For example, the nose cone  632  can have a radiopaque marker  631  anywhere thereon or the nose cone  632  can be entirely radiopaque. 
       FIGS.  19  to  24    illustrate the catheter  660  extending approximately up to the renal arteries. However, the catheter  660  of the present invention is configured to travel up to at least the celiac axis (not shown in  FIGS.  19  to  24   ). As used herein, the celiac axis is to be defined according to common medical terms. In a simplistic definition, the celiac axis is a plane that intersects and is parallel to a central axis of a patient&#39;s celiac at the intersection of the celiac and the aorta and, therefore, this plane is approximately orthogonal to the longitudinal axis of the abdominal/thoracic aorta at the point where the celiac intersects the aorta. Therefore, with respect to extension of the catheter  660  into the aorta, it is extended into the aorta up to but not past the intended downstream end of the implant. After arriving at this distal-most position, the distal end of the catheter  660  remains substantially steady along the longitudinal axis of the aorta until after the stent graft  1  is implanted (see  FIG.  24   ) and the entire delivery system is to be removed from the patient. While the delivery system of the present invention can be retracted in the orientation shown in  FIG.  24    except for one difference (the bare stent  32  is open and the apex release device  634  is released from compressing the bare stent  32 ), the preferred embodiment for removal of the catheter  660  from the aorta after implantation of the stent graft  1  occurs with reference to the condition shown ln  FIG.  19   —where all of the interior lumens  620 ,  640 ,  642 ,  654  are retracted inside the catheter  660  and the nose cone  631  is in contact with the distal end of the catheter  660 . 
     After the nose cone assembly  630  is in the first position shown in  FIG.  19   , the locking knob or ring  676  is placed from its neutral position into its advancement position. As will be described below, placing the locking knob  676  into its advancement position A allows both the nose cone assembly  630  and the internal sheath assembly  650  to move as one when the proximal handle  678  is moved in either the proximal or distal directions because the locking knob  676  radially locks the graft push lumen  642  to the lumens of the apex release assembly  690  (including the guidewire lumen  620  and an apex release lumen  640 ). The locking knob  676  is fixedly connected to a sheath lumen  654 . 
     Before describing how various embodiments of the handle assembly  670  function, a summary of the multi-lumen connectivity relationships, throughout the neutral, advancement, and deployment positions, is described. 
     When the locking ring is in the neutral position, the pusher clasp spring  298  shown in  FIG.  48    and the distal clasp body spring  606  shown in  FIG.  52    are both disengaged. This allows free movement of the graft push lumen  642  with the guidewire lumen  620  and the apex release lumen  640  within the handle body  674 . 
     When the locking knob  676  is moved into the advancement position, the pusher clasp spring  298  shown in  FIG.  48    is engaged and the distal clasp body spring  606  shown in  FIG.  52    is disengaged. The sheath lumen  654  (fixedly attached to the inner sheath  652 ) is, thereby, locked to the graft push lumen  642  (fixedly attached to the distal sleeve  644 ) so that, when the proximal handle  678  is moved toward the distal handle  672 , both the sheath lumen  654  and the graft push lumen  642  move as one. At this point, the graft push lumen  642  is also locked to both the guidewire lumen  620  and the apex release lumen  640  (which are locked to one another through the apex release assembly  690  as set forth in more detail below). Accordingly, as the proximal handle  678  is moved to the second position, shown with dashed lines in  FIG.  11   , the sheath assembly  650  and the nose cone assembly  630  progress distally out of the outer catheter  660  as shown in  FIGS.  20  and  21    and with dashed lines in  FIG.  11   . 
     At this point, the sheath lumen  654  needs to be withdrawn from the stent graft  1  to, thereby, expose the stent graft  1  from its proximal end  12  to its distal end  14  and, ultimately, entirely off of its distal end  14 . Therefore, movement of the locking knob  676  into the deployment position D will engage the distal clasp body spring  606  shown in  FIG.  52    and disengage the pusher clasp spring  298  shown in  FIG.  48   . Accordingly, the graft push lumen  642  along with the guidewire lumen  620  and the apex release lumen  640  are locked to the handle body  674  so as not to move with respect to the handle body  674 . The sheath lumen  654  is unlocked from the graft push lumen  642 . Movement of the distal handle  678  back to the third position (proximally), therefore, pulls the sheath lumen  654  proximally, thus, proximally withdrawing the inner sheath  652  from the stent graft  1 . 
     At this point, the delivery assembly  600  only holds the bare stent  30  of the stent graft  1 . Therefore, final release of the stent graft  1  occurs by releasing the bare stent  30  from the nose cone assembly  630 , which is accomplished using the apex release assembly  690  as set forth below. 
     In order to explain how the locking and releasing of the lumen occur as set forth above, reference is made to  FIGS.  33  to  62   . 
       FIG.  33    is a cross-sectional view of the proximal handle  678  and the locking knob  676 . A pusher clasp rotator  292  is disposed between a clasp sleeve  614  and the graft push lumen  642 . A specific embodiment of the pusher clasp rotator  292  is illustrated in  FIGS.  34  through  39   . Also disposed between the clasp rotator  292  and the graft push lumen  642  is a rotator body  294 , which is directly adjacent the graft push lumen  642 . A specific embodiment of the rotator body  294  is illustrated in  FIGS.  40  through  43   . Disposed between the rotator body  294  and the sheath lumen  654  is a pusher clasp body  296 , which is fixedly connected to the rotator body  294  and to the locking knob  676 . A specific embodiment of the pusher clasp body  296  is illustrated in  FIGS.  44  through  46   . A pusher clasp spring  298  operatively connects the pusher clasp rotator  292  to the rotator body  294  (and, thereby, the pusher clasp body  296 ). 
     An exploded view of these components is presented in  FIG.  48   , where an O-ring  293  is disposed between the rotator body  294  and the pusher clasp body  296 . As shown in the plan view of  FIG.  47   , a crimp ring  295  connects the sheath lumen  654  to the distal projection  297  of the pusher clasp body  296 . A hollow handle body  674  (see  FIGS.  10 ,  11 , and  33   ), on which the proximal handle  678  and the locking knob  676  are slidably mounted, holds the pusher clasp rotator  292 , the rotator body  294 , the pusher clasp body  296 , and the pusher clasp spring  298  therein. This entire assembly is rotationally mounted to the distal handle  672  for rotating the stent graft  1  into position (see  FIGS.  23  and  24    and the explanations thereof below). A specific embodiment of the handle body  674  is illustrated in  FIG.  49   . 
     A setscrew  679  extends from the proximal handle  678  to contact a longitudinally helixed groove in the pusher clasp rotator  292  (shown in  FIGS.  36  and  38   ). Thus, when moving the proximal handle  678  proximally or distally, the pusher clasp rotator  292  rotates clockwise or counter-clockwise. 
     An alternative embodiment of the locking knob  676  is shown in  FIG.  50    et seq. in which, instead of applying a longitudinal movement to rotate the pusher clasp spring  298  through the cam/follower feature of the proximal handle  678  and pusher clasp rotator  292 , a rotating locking knob  582  is located at the proximal end of the handle body  674 . The knob  582  has three positions that are clearly shown in  FIG.  51   : a neutral position N, an advancement position A, and a deployment position D. The functions of these positions N, A, D correspond to the positions N, A, D of the locking knob  676  and the proximal handle  678  as set forth above. 
     In the alternative embodiment, a setscrew or pin  584  is threaded into the clasp sleeve  614  through a slot  675  in the handle body  674  and through a slot  583  in the knob  582  to engage the locking knob  582 . The depth of the pin  584  in the clasp sleeve  614  is small because of the relatively small thickness of the clasp sleeve  614 . To provide additional support to the pin  584  and prevent it from coming out of the clasp sleeve  614 , an outer ring  6144  is disposed on the exterior surface of the proximal end of the clasp sleeve  614 . Because of the x-axis orientation of the slot  583  in the knob  582  and the y-axis orientation of the slot  675  in the handle body  674 , when the knob  582  is slid over the end of the handle body  674  and the setscrew  584  is screwed into the clasp sleeve  614 , the knob  582  is connected fixedly to the handle body  674 . When the locking knob  582  is, thereafter, rotated between the neutral N, advancement A, and deployment D positions, the clasp sleeve  614  rotates to actuate the spring lock (see  FIGS.  48  and  52   ). 
     A setscrew  586 , shown in  FIG.  53   , engages a groove  605  in the proximal clasp assembly  604  to connect the proximal clasp assembly  604  to the clasp sleeve  614  but allows the clasp sleeve  614  to rotate around the clasp body  602 . The clasp sleeve  614  is shown in  FIGS.  50  and  53    and, in particular, in  FIGS.  59  to  62   . The proximal clasp assembly  604  of  FIG.  53    is more clearly shown in the exploded view of  FIG.  52   . The proximal clasp assembly  604  is made of the components including a distal clasp body spring  606 , a locking washer  608 , a fastener  603  (in particular, a screw fitting into internal threads of the proximal clasp body  602 ), and a proximal clasp body  602 . The proximal clasp body  602  is shown, in particular, in  FIGS.  54  through  58   . The proximal clasp assembly  604  is connected fixedly to the handle body  674 , preferably, with a screw  585  shown in  FIG.  50    and hidden from view in  FIG.  51    under knob  582 . 
     The handle body  674  has a position pin  592  for engaging in position openings at the distal end of the locking knob  582 . The position pin  592  can be a setscrew that only engages the handle body  674 . When the locking knob  582  is pulled slightly proximally, therefore, the knob can be rotated clockwise or counter-clockwise to place the pin  592  into the position openings corresponding to the advancement A, neutral N, and deployment D positions. 
     As shown in  FIG.  18   , to begin deployment of the stent graft  1 , the user/physician grasps both the distal handle  672  and the proximal handle  678  and slides the proximal handle  678  towards the distal handle  672  in the direction indicated by arrow A. This movement, as shown in  FIGS.  19  to  21   , causes the flexible inner sheath  652 , holding the compressed stent graft  1  therein, to emerge progressively from inside the outer catheter  660 . Such a process allows the stent graft  1 , while constrained by the inner sheath  652 , to expand to a larger diameter shown in  FIG.  12   , this diameter being substantially larger than the inner diameter of the outer catheter  660  but smaller than the inner diameter of the vessel in which it is to be inserted. Preferably, the outer catheter  660  is made of a polymer (co-extrusions or teflons) and the inner sheath  652  is made of a material, such as a fabric/woven polymer or other similar material. Therefore, the inner sheath  652  is substantially more flexible than the outer catheter  660 . 
     It is noted, at this point, that the inner sheath  652  contains a taper  653  at its proximal end, distal to the sheath&#39;s  652  connection to the sheath lumen  654  (at which connection the inner sheath  652  has a similar diameter to the distal sleeve  644  and works in conjunction with the distal sleeve  644  to capture the distal end  14  of the stent graft  1 . The taper  653  provides a transition that substantially prevents any kinking of the outer catheter  660  when the stent graft  1  is loaded into the delivery assembly  600  (as in the position illustrated in  FIGS.  10  and  11   ) and, also, when the outer catheter  660  is navigating through the femoral and iliac vessels. One specific embodiment of the sheath lumen  654  has a length between approximately 30 and approximately 40 inches, in particular, 36 inches, an outer diameter of between approximately 0.20 and approximately 0.25 inches, in particular 0.238 inches, and an inner diameter between approximately 0.18 and approximately 0.22 inches, in particular, 0.206 inches. 
     When the proximal handle  678  is moved towards its distal position, shown by the dashed lines in  FIG.  11   , the nose cone assembly  630  and the sheath assembly  650  move towards a second position where the sheath assembly  650  is entirely out of the outer catheter  660  as shown in  FIGS.  20  and  21   . As can be seen most particularly in  FIGS.  20  and  21   , as the nose cone assembly  630  and the sheath assembly  650  are emerging out of the outer catheter  660 , they are traversing the curved portion  710  of the descending aorta. The tracking is accomplished visually by viewing radiopaque markers on various portions of the delivery system and/or the stent graft  1  with fluoroscopic measures. Such markers will be described in further detail below. The delivery system can be made visible, for example, by the nose cone  630  being radiopaque or containing radiopaque materials. 
     It is noted that if the harder outer catheter  660  was to have been moved through the curved portion  710  of the aorta  700 , there is a great risk of puncturing the aorta  700 , and, particularly, a diseased portion  744  of the proximal descending aorta  710  because the outer catheter  660  is not as flexible as the inner sheath  652 . But, because the inner sheath  652  is so flexible, the nose cone assembly  630  and the sheath assembly  650  can be extended easily into the curved portion  710  of the aorta  700  with much less force on the handle than previously needed with prior art systems while, at the same time, imparting harmless forces to the intraluminal surface of the curved aorta  710  due to the flexibility of the inner sheath  652 . 
     At the second position shown in  FIG.  21   , the user/physician, using fluoroscopic tracking of radiopaque markers (e.g., marker  631 ) on any portion of the nose cone or on the stent graft  1  and/or sheath assemblies  630 ,  650 , for example, makes sure that the proximal end  112  of the stent graft  1  is in the correct longitudinal position proximal to the diseased portion  744  of the aorta  700 . Because the entire inserted assembly  630 ,  650  in the aorta  700  is still rotationally connected to the portion of the handle assembly  670  except for the distal handle  672  (distal handle  672  is connected with the outer sheath  660  and rotates independently of the remainder of the handle assembly  670 ), the physician can rotate the entire inserted assembly  630 ,  650  clockwise or counterclockwise (indicated in  FIG.  20    by arrow B) merely by rotating the proximal handle  678  in the desired direction. Such a feature is extremely advantageous because the non-rotation of the outer catheter  660  while the inner sheath  652  is rotating eliminates stress on the femoral and iliac arteries when the rotation of the inner sheath  652  is needed and performed. 
     Accordingly, the stent graft  1  can be pre-aligned by the physician to place the stent graft  1  in the optimal circumferential position.  FIG.  23    illustrates the longitudinal support member  40  not in the correct superior position and  FIG.  24    illustrates the longitudinal support member  40  in the correct superior position. The optimal superior surface position is, preferably, near the longest superior longitudinal line along the circumference of the curved portion of the aorta as shown in  FIGS.  23  and  24   . As set forth above, when the longitudinal support member  40  extends along the superior longitudinal line of the curved aorta, the longitudinal support member  40  substantially eliminates any possibility of forming a kink in the inferior radial curve of the stent graft  1  during use and also allows transmission of longitudinal forces exerted along the inside lumen of the stent graft  1  to the entire longitudinal extent of the stent graft  1 , thereby allowing the entire outer surface of the stent graft  1  to resist longitudinal migration. Because of the predefined curvature of the support member  40 , the support member  40  cannot align exactly and entirely along the superior longitudinal line of the curved aorta. Accordingly, an optimal superior surface position of the support member  40  places as much of the central portion of the support member  40  (between the two ends  47  thereof) as possible close to the superior longitudinal line of the curved aorta. A particularly desirable implantation position has the superior longitudinal line of the curved aorta intersecting the proximal half of the support member  40 —the proximal half being defined as that portion of the support member  40  located between the centerline  45  and the proximal support member loop  47 . However, for adequate implantation purposes, the centerline  45  of the support member  40  can be as much as seventy circumferential degrees away from either side of the superior longitudinal line of the curved aorta. Adequate implantation can mean that the stent graft  1  is at least approximately aligned. When implantation occurs with the stent graft  1  being less than seventy degrees, for example, less than forty degrees, away from either side of the superior longitudinal line of the curved aorta, then it is substantially aligned. 
     In prior art stent grafts and stent graft delivery systems, the stent graft is, typically, provided with symmetrically-shaped radiopaque markers along one longitudinal line and at least one other symmetrically-shaped radiopaque marker disposed along another longitudinal line on the opposite side (one-hundred eighty degrees (180°)) of the stent graft. Thus, using two-dimensional fluoroscopic techniques, the only way to determine if the stent graft is in the correct rotational position is by having the user/physician rotate the stent graft in both directions until it is determined that the first longitudinal line is superior and the other longitudinal line is anterior. Such a procedure requires more work by the physician and is, therefore, undesirable. 
     According to an exemplary embodiment of the invention illustrated in  FIGS.  27  and  28   , unique radiopaque markers  232 ,  234  are positioned on the stent graft  1  to assist the user/physician in correctly positioning the longitudinal support member  40  in the correct aortic superior surface position with only one directional rotation, which corresponds to the minimal rotation needed to place the stent graft  1  in the rotationally correct position. 
     Specifically, the stent graft  1  is provided with a pair of symmetrically shaped but diametrically opposed markers  232 ,  234  indicating to the user/physician which direction the stent graft  1  needs to be rotated to align the longitudinal support member  40  to the superior longitudinal line of the curved aorta (with respect to anatomical position). Preferably, the markers  232 ,  234  are placed at the proximate end  12  of the graft sleeve  10  on opposite sides (one-hundred eighty degrees (180°)) of the graft sleeve  10 . 
     The angular position of the markers  232 ,  234  on the graft sleeve  10  is determined by the position of the longitudinal support member  40 . In an exemplary embodiment, the support member  40  is between the two markers  232 ,  234 . To explain such a position, if the marker  232  is at a 0 degree position on the graft sleeve  10  and the marker  234  is at a one-hundred eighty degree (180°) position, then the centerline  45  of the support member  40  is at a ninety degree position. However, an alternative position of the markers can place the marker  234  ninety degrees away from the first degree  41  (see  FIG.  1   ). Such a positioning is dependent somewhat upon the way in which the implantation is to be viewed by the user/physician and can be varied based on other factors. Thus, the position can be rotated in any beneficial way. 
     Exemplary ancillary equipment in endovascular placement of the stent graft  1  is a fluoroscope with a high-resolution image intensifier mounted on a freely angled C-arm. The C-arm can be portable, ceiling, or pedestal mounted. It is important that the C-arm have a complete range of motion to achieve AP to lateral projections without moving the patient or contaminating the sterile field. Capabilities of the C-arm should include: Digital Subtraction Angiography, High-resolution Angiography, and Roadmapping. 
     For introduction of the delivery system into the groin access arteries, the patient is, first, placed in a sterile field in a supine position. To determine the exact target area for placement of the stent graft  1 , the C-arm is rotated to project the patient image into a left anterior oblique projection, which opens the radial curve of the thoracic aortic arch for optimal visualization without superimposition of structures. The degree of patient rotation will vary, but is usually 40 to 50 degrees. At this point, the C-arm is placed over the patient with the central ray of the fluoroscopic beam exactly perpendicular to the target area. Such placement allows for the markers  232 ,  234  to be positioned for correct placement of the stent graft  1 . Failure to have the central ray of the fluoroscopic beam perpendicular to the target area can result in parallax, leading to visual distortion to the patient anatomy due to the divergence of the fluoroscopic x-ray beam, with a resultant misplacement of the stent graft  1 . An angiogram is performed and the proposed stent graft landing zones are marked on the visual monitor. Once marked, neither the patient, the patient table, nor the fluoroscopic C-arm can be moved, otherwise, the reference markers become invalid. The stent graft  1  is, then, placed at the marked landing zones. 
     In an exemplary embodiment, the markers  232 ,  234  are hemispherical, in other words, they have the approximate shape of a “D”. This shape is chosen because it provides special, easy-to-read indicators that instantly direct the user/physician to the correct placement position for the longitudinal support member  40 .  FIG.  27   , for example, illustrates a plan view of the markers  232 ,  234  when they are placed in the upper-most superior longitudinal line of the curved aorta. The correct position is indicated clearly because the two hemispheres have the flat diameters aligned on top of or immediately adjacent to one another such that a substantially complete circle is formed by the two hemispherically rounded portions of the markers  232 ,  234 . This position is also indicated in the perspective view of  FIG.  28   . 
     Each of  FIGS.  27  and  28    have been provided with examples where the markers  232 ,  234  are not aligned and, therefore, the stent graft  1  is not in the correct insertion position. For example, in  FIG.  27   , two markers  232 ′,  234 ′ indicate a misaligned counter-clockwise-rotated stent graft  1  when viewed from the plane  236  at the right end of the stent graft  1  of  FIG.  23    looking toward the left end thereof and down the axis  11 . Thus, to align the markers  232 ′,  234 ′ in the most efficient way possible (the shortest rotation), the user/physician sees that the distance between the two flat diameters is closer than the distance between the highest points of the hemispherical curves. Therefore, it is known that the two flat diameters must be joined together by rotating the stent graft  1  clockwise. 
       FIG.  28    has also been provided with two markers  232 ″,  234 ″ indicating a misaligned clockwise-rotated stent graft  1  when viewed from the plane  236  at the right end of the stent graft  1  of  FIG.  27    looking toward the left end thereof and down the axis  11 . Thus, to align the markers  232 ″,  234 ″ in the most efficient way possible (the shortest rotation), the user/physician sees that the distance between the highest points of the hemispherical curves is smaller than the distance between the two flat diameters. Therefore, it is known that the two flat diameters must be joined together by rotating the stent graft  1  in the direction that the highest points of the hemispherical curves point; in other words, the stent graft  1  must be rotated counter-clockwise. 
     A significant advantage provided by the diametrically opposed symmetric markers  232 ,  234  is that they can be used for migration diagnosis throughout the remaining life of a patient after the stent graft  1  has been placed inside the patient&#39;s body. If fluoroscopic or radiographic techniques are used any time after the stent graft  1  is inserted in the patient&#39;s body, and if the stent graft  1  is viewed from the same angle as it was viewed when placed therein, then the markers&#39;  232 ,  234  relative positions observed should give the examining individual a very clear and instantaneous determination as to whether or not the stent graft  1  has migrated in a rotational manner. 
     The hemispherical shape of the markers  232 ,  234  are only provided as an example shape. The markers  232 ,  234  can be any shape that allows a user/physician to distinguish alignment and direction of rotation for alignment. For example, the markers  232 ,  234  can be triangular, in particular, an isosceles triangle having the single side be visibly longer or shorter than the two equal sides. 
     As set forth above, alignment to the optimal implantation position is dependent upon the skill of the physician(s) performing the implantation. The present invention improves upon the embodiments having longitudinal and rotational radiopaque markers  232 ,  234  and substantially eliminates the need for rotational markers. Specifically, it is noted that the guidewire  610  travels through a curve through the aortic arch towards the heart  720 . It is, therefore, desirable to pre-shape the delivery system to match the aorta of the patient. 
     The guidewire lumen  620  is formed from a metal, preferably, stainless steel. Thus, the guidewire lumen  620  can be deformed plastically into any given shape. In contrast, the apex release lumen  640  is formed from a polymer, which tends to retain its original shape and cannot plastically deform without an external force, e.g., the use of heat. Therefore, to effect the pre-shaping of the delivery assembly  600 , the guidewire lumen  620 , as shown in  FIG.  64   , is pre-shaped with a curve at a distal-most area  622  of the lumen  620 . The pre-shape can be determined, for example, using the fluoroscopic pre-operative techniques described above, in which the guidewire lumen  620  can be customized to the individual patient&#39;s aortic shape. Alternatively, the guidewire lumen  620  can be pre-shaped in a standard manner that is intended to fit an average patient. Another alternative is to provide a kit that can be used to pre-shape the guidewire lumen  620  in a way that is somewhat tailored to the patient, for example, by providing a set of delivery systems  600  or a set of different guidewire lumens  620  that have different radii of curvature. 
     With the pre-curved guidewire lumen  620 , when the nose cone  632  and inner sheath  652  exit the outer catheter  660  and begin to travel along the curved guidewire  610 , the natural tendency of the pre-curved guidewire lumen  620  will be to move in a way that will best align the two curves to one another (see  FIGS.  20  and  21   ). The primary factor preventing the guidewire lumen  620  from rotating itself to cause such an alignment is the torque generated by rotating the guidewire lumen  620  around the guidewire  610 . The friction between the aorta and the device also resists rotational motion. The delivery system  600 , however, is configured naturally to minimize such torque. As set forth above with respect to  FIGS.  15  to  17   , the guidewire lumen  620  freely rotates within the apex release lumen  640  and is only connected to the apex release lumen  640  at the proximal-most area of both lumen  620 ,  640 . While the inner sheath  652  advances through the aortic arch, the two lumen  620 ,  640  are rotationally connected only at the 
     apex release assembly  690 . This means that rotation of the guidewire lumen  620  about the guidewire  610  and within the apex release lumen  640  occurs along the entire length of the guidewire lumen  620 . Because the metallic guidewire lumen  620  is relatively rotationally elastic along its length, rotation of the distal-most portion (near the nose cone assembly  630 ) with respect to the proximal-most portion (near the apex release assembly  690 ) requires very little force. In other words, the torque resisting rotation of the distal-most portion to conform to the curve of the guidewire  610  is negligible. Specifically, the torque is so low that the force resisting the alignment of the guidewire lumen  620  to the guidewire  610  causes little, negligible, or no damage to the inside of the aorta, especially to a dissecting inner wall of a diseased aorta. 
     Due to the configuration of the delivery system  600  of the present invention, when the guidewire lumen  620  is extended from the outer catheter  660  (along with the apex release lumen  640 , the stent graft  1 , the inner sheath  652  as shown in  FIGS.  20  and  21   , for example), the pre-shape of the guidewire lumen  620  causes automatic and natural rotation of the entire distal assembly—including the stent graft  1 —along its longitudinal axis. This means that the length and connectivity of the guidewire lumen  620 , and the material from of which the guidewire lumen  620  is made, allow the entire distal assembly ( 1 ,  620 ,  630 ,  640 ,  650 ) to naturally rotate and align the pre-curved guidewire lumen  620  with the curve of the guidewire  610 —this is true even if the guidewire lumen  620  is inserted into the aorta entirely opposite the curve of the aorta (one-hundred eighty degrees (180°)). In all circumstances, the curved guidewire lumen  620  will cause rotation of the stent graft  1  into an optimal implantation position, that is, aligning the desired portion of the support member  40  within ±70 degrees of the superior longitudinal line of the curved aorta. Further, the torque forces acting against rotation of the guidewire lumen  620  will not be too high to cause damage to the aorta while carrying out the rotation. 
     The self-aligning feature of the invention begins with a strategic loading of the stent graft  1  in the inner sleeve  652 . To describe the placement of the supporting member  40  of the stent graft  1  relative to the curve  622  of the guidewire lumen  620 , an X-Y coordinate curve plane is defined and shown in  FIG.  64   . In particular, the guidewire lumen  620  is curved and that curve  622  defines the curve plane  624 . 
     To insure optimal implantation, when loading the stent graft  1  into the inner sheath  652 , a desired point on the supporting member  40  between the centerline  45  of the stent graft  1  and the proximal support member loop  47  is aligned to intersect the curve plane  624 . An exemplary, but not required, location of the desired point on the supporting member  40  is located forty-five (45) degrees around the circumference of the stent graft  1  shown in  FIG.  1    beginning from the first degree  41  in line with the proximal support member loop  47 . When the stent graft  1  is loaded in an exemplary orientation, it is ready for insertion into the inner sleeve  652 . During the loading process, the stent graft  1  and the guidewire lumen  620  are held constant rotationally. After such loading, the inner sleeve  652  is retracted into the outer catheter  660  and the delivery system  600  is ready for purging with saline and use with a patient. 
       FIGS.  65  to  67    illustrate self-alignment of the distal assembly  620 ,  630 ,  640 ,  650  after it is pushed out from the distal end of the outer catheter  660  (see  FIGS.  20  and  21   ).  FIG.  65    shows an aorta  700  and the distal assembly after it has traversed the iliac arteries  802  and enters the descending thoracic portion  804  of the aorta. The nose cone assembly  630  is positioned just before the aortic arch  806  and the stent graft  1  is contained within the inner sheath  652 . A reference line  820  is placed on the stent graft  1  at a longitudinal line of the stent graft  1  that is intended to align with the superior longitudinal line  808  (indicated with dashes) of the aortic arch  806 . In  FIG.  65   , the reference line  820  also lies on the curved plane  624  defined by the pre-curved guidewire lumen  620 . As can be clearly seen from  FIG.  65   , the reference line  820  is positioned almost on or on the inferior longitudinal line of the curved aorta—thus, the stent graft  1  is one-hundred eighty degrees (180°) out of alignment.  FIG.  66    shows the nose cone assembly  630  fully in the aortic arch  806  and the inner sleeve  652  at the entrance of the aortic arch  806 . With the self-aligning configuration of the pre-curved guidewire lumen  620 , movement of the distal assembly from the position shown in  FIG.  65    to the position shown in  FIG.  66    causes a rotation of the reference line  820  almost ninety degrees (90°) clockwise (with respect to a view looking upward within the descending aorta) towards the superior longitudinal line  808 . In  FIG.  67   , the nose cone assembly  630  has reached, approximately, the left subclavian artery  810 . Rotational movement of the distal assembly is, now, complete, with the reference line  820  almost aligned with the superior longitudinal line  808  of the aortic arch  806 . From the views of  FIGS.  65  to  67   , also shown is the fact that the pre-curved guidewire lumen  620  has not caused any portion of the inner sleeve  652  to push against the inner surface of the aortic arch  806  with force—force that might exacerbate an aortic dissection. 
     It is noted that the guidewire lumen  620  need not be rotationally fixedly connected to the apex release lumen  640  when the apex release assembly  690  is in the locked position shown in  FIGS.  15  and  16   . Instead, a non-illustrated, freely rotatable coupling can be interposed anywhere along the guidewire lumen  620  (but, preferably, closer to the apex release assembly  690 ). This coupling would have a proximal portion rotationally fixedly connected to the to the apex release lumen  640  when the apex release assembly  690  is in the locked position shown in  FIGS.  15  and  16    and a freely-rotatable distal portion that is fixedly connected to all of the guidewire lumen  620  disposed distal thereto. Thus, the guidewire lumen  620  near the sheath assembly  650  will always be freely rotatable and, thereby, allow easy and torque-free rotation of the guidewire lumen  620  about the guidewire  610 . 
     It is also noted that the pre-curved section  622  of the guidewire lumen need not be made at the manufacturer. As shown in  FIG.  69   , a curving device can be provided with the delivery system  600  to allow the physician performing the implantation procedure to tailor-fit the curve  622  to the actual curve of the vessel in which the stent graft  1  is to be implanted. Because different patients can have different aortic arch curves, a plurality of these curving devices can be provided with the delivery system  600 , each of the curving devices having a different curved shape. Each device can also have two sides with each side having a different curved shape, thus, reducing the number of devices if a large number of curves are required. Further, the curving devices can all be rotationally connected on a common axle or spindle for each of transport, storage, and use. 
     For tailoring the curve to the patient&#39;s curved vessel, the physician can, for example, fluoroscopically view the vessel (e.g., aortic arch) and determine therefrom the needed curve by, for example, holding up the curving device to the display. Any kind of curving device can be used to impart a bend to the guidewire lumen  620  when the guidewire lumen  620  is bent around the circumference. 
     Because of the predefined curvature of the support member  40 , the support member  40  cannot align exactly and entirely along the superior longitudinal line of the curved aorta. Accordingly, an optimal superior surface position of the support member  40  places as much of the central portion of the support member  40  (between the two ends  47  thereof) as possible close to the superior longitudinal line  808  of the curved aorta. A particularly desirable implantation position has the superior longitudinal line  808  of the curved aorta intersecting the proximal half of the support member  40 —the proximal half being defined as that portion of the support member  40  located between the centerline  45  and the proximal support member loop  47 . However, for adequate implantation purposes, the centerline  45  of the support member  40  can be as much as seventy circumferential degrees away from either side of the superior longitudinal line of the curved aorta. 
     When the stent graft  1  is in place both longitudinally and circumferentially ( FIG.  21   ), the stent graft  1  is ready to be removed from the inner sheath  652  and implanted in the vessel  700 . Because relative movement of the stent graft  1  with respect to the vessel is no longer desired, the inner sheath  652  needs to be retracted while the stent graft  1  remains in place, i.e., no longitudinal or circumferential movement. Such immovability of the stent graft  1  is insured by, first, the apex capture device  634  of the nose cone assembly  630  holding the front of the stent graft  1  by its bare stent  30  (see  FIGS.  13 ,  22 , and  23   ) and, second, by unlocking the locking knob  676 /placing the locking ring/knob in the D position—which allows the sheath lumen  654  to move independently from the guidewire lumen  620 , apex release lumen  640 , and graft push lumen  642 . The apex capture device  634 , as shown in  FIGS.  13 ,  14 ,  30  and  311    (and as will be described in more detail below), is holding each individual distal apex  32  of the bare stent  30  in a secure manner—both rotationally and longitudinally. 
     The nose cone assembly  630 , along with the apex capture device  634 , is securely attached to the guidewire lumen  620  (and the apex release lumen  640  at least until apex release occurs). The inner sheath  652  is securely attached to a sheath lumen  654 , which is coaxially disposed around the guidewire lumen  620  and fixedly attached to the proximal handle  678 . The stent graft  1  is also supported at its distal end by the graft push lumen  642  and the distal sleeve  644  or, the taper  653  of the inner sheath  652 . (The entire coaxial relationship of the various lumens  610 ,  620 ,  640 ,  642 ,  654 , and  660  is illustrated for exemplary purposes only in  FIG.  25   , and a portion of which can also be seen in the exploded view of the handle assembly in  FIG.  50   ) Therefore, when the proximal handle  678  is moved proximally with the locking knob  676  in the deployment position D, the sheath lumen  654  moves proximally as shown in  FIGS.  13 ,  22 , and  23   , taking the sheath  652  proximally along with it while the guidewire lumen  620 , the apex release lumen  640 , the graft push lumen  642 , and the distal sleeve  644  remain substantially motionless and, therefore, the stent graft  1  remains both rotationally and longitudinally steady. 
     The stent graft  1  is, now, ready to be finally affixed to the aorta  700 . To perform the implantation, the bare stent  30  must be released from the apex capture device  634 . As will be described in more detail below, the apex capture device  634  shown in  FIGS.  13 ,  14 , and  29  to  32   , holds the proximal apices  32  of the bare stent  30  between the distal apex head  636  and the proximal apex body  638 . The distal apex head  636  is fixedly connected to the guidewire lumen  620 . The proximal apex body  638 , however, is fixedly connected to the apex release lumen  640 , which is coaxial with both the guidewire lumen  620  and the sheath lumen  654  and disposed therebetween, as illustrated diagrammatically in  FIG.  25   . (As will be described in more detail below, the graft push lumen  642  is also fixedly connected to the apex release lumen  640 .) Therefore, relative movement of the apex release lumen  640  and the guidewire lumen  620  separates the distal apex head  636  and a proximal apex body  638  from one another. 
     To cause such relative movement, the apex release assembly  690  has, in an exemplary embodiment, three parts, a distal release part  692 , a proximal release part  694 , and an intermediate part  696  (which is shown in the form of a clip in  FIGS.  16  and  26   ). To insure that the distal apex head  636  and the proximal apex body  638  always remain fixed with respect to one another until the bare stent  30  is ready to be released, the proximal release part  694  is formed with a distal surface  695 , the distal release part  692  is formed with a proximal surface  693 , and the intermediate part  696  has proximal and distal surfaces corresponding to the surfaces  695 ,  693  such that, when the intermediate part  696  is inserted removably between the distal surface  695  and the proximal surface  693 , the intermediate part  696  fastens the distal release part  692  and the proximal release part  694  with respect to one another in a form-locking connection. A form-locking connection is one that connects two elements together due to the shape of the elements themselves, as opposed to a force-locking connection, which locks the elements together by force external to the elements. Specifically, as shown in  FIG.  26   , the clip  696  surrounds a distal plunger  699  of the proximal release part  694  that is inserted slidably within a hollow  698  of the distal release part  692 . The plunger  699  of the proximal release part  694  can slide within the hollow  698 , but a stop  697  inside the hollow  698  prevents the distal plunger  699  from withdrawing from the hollow  698  more than the longitudinal span of the clip  696 . 
     To allow relative movement between the distal apex head  636  and the proximal apex body  638 , the intermediate part  696  is removed easily with one hand and, as shown from the position in  FIG.  16    to the position in  FIG.  17   , the distal release part  692  and the proximal release part  694  are moved axially towards one another (preferably, the former is moved towards the latter). Such movement separates the distal apex head  636  and the proximal apex body  638  as shown in  FIG.  14   . Accordingly, the distal apices  32  of the bare stent  30  are free to expand to their natural position in which the bare stent  30  is released against the vessel  700 . 
     Of course, the apex release assembly  690  can be formed with any kind of connector that moves the apex release lumen  640  and the guidewire lumen  620  relative to one another. In an exemplary alternative embodiment, for example, the intermediate part  696  can be a selectable lever that is fixedly connected to either one of the distal release part  692  or the proximal release part  694  and has a length equal to the width of the clip  696  shown in  FIG.  26   . Thus, when engaged by pivoting the lever between the distal release part  692  and the proximal release part  694 , for example, the parts  692 ,  694  cannot move with respect to one another and, when disengaged by pivoting the lever out from between the parts  692 ,  694 , the distal release part  692  and the proximal release part  694  are free to move towards one another. 
     The apex capture device  634  is unique to the present invention in that it incorporates features that allow the longitudinal forces subjected on the stent graft  1  to be fully supported, through the bare stent  30 , by both the guidewire lumen  620  and apex release lumen  640 . Support occurs by providing the distal apex head  636  with a distal surface  639 —which surface  639  supports the proximal apices  32  of the bare stent  30  (shown in the enlarged perspective view of the distal apex head  636  in  FIG.  29   ). When captured, each proximal apex  32  of the bare stent  30  separately rests on a distal surface  639 , as more clearly shown in  FIGS.  30  and  31   . The proximal spokes of the distal apex head  636  slide within the fingers of the proximal apex body  638  as these parts moves towards one another. A slight space, therefore, exists between the fingers and the outer circumferential surfaces of the spokes. To insure that the bare stent  30  does not enter this space (which would prevent a proper release of the bare stent  30  from the apex capture device  634 , a radial thickness of the space must be less than the diameter of the wire making up the bare stent  30 . Preferably, the space is no greater than half a diameter of the wire. 
     Having the distal surface  639  be the load-bearing surface of the proximal apices  32  ensures expansion of each and every one of the distal apices  32  from the apex release assembly  690 . The proximal surface  641  of the distal apex head  636  (see  FIG.  30   ) meets with the interior surfaces of the proximal apex body  638  to help carry the apex load because the apices of the bare stent  30  are captured therebetween when the apex capture device  634  is closed. Complete capture of the bare stent  30 , therefore, fully transmits any longitudinal forces acting on the bare stent  30  to both the guidewire lumen  620  and apex release lumen  640 , making the assembly much stronger. Such capture can be clearly seen in the cut-away view of the proximal apex body  638  in  FIG.  31   . For release of the apices  32  of the bare stent  30 , the proximal apex body  638  moves leftward with respect to  FIGS.  30  to  33    (compare  FIGS.  30  and  31    with  FIG.  32   ). Because friction exists between the apices  32  and the “teeth” of the proximal apex body  638  when the apices  32  are captured, the apices  32  will also try to move to the left along with the proximal apex body  638  and, if allowed to do so, possibly would never clear the “teeth” to allow each apex  32  to expand. However, as the proximal apex body  638  disengages (moves in the direction of arrow C in  FIG.  31   ), direct contact with the distal surface  639  entirely prevents the apices  32  from sliding in the direction of arrow C along with the proximal apex body  638  to ensure automatic release of every captured apex  32  of the bare stent  30 . Because the proximal apex body  638  continues to move in the direction of arrow C, eventually the “teeth” will clear their respective capture of the apices  32  and the bare stent  30  will expand entirely. The release position of the distal apex head  636  and the proximal apex body  638  is shown in  FIGS.  14  and  32   , and corresponds to the position of the apex release assembly  690  in  FIG.  17   . As can be seen, tapers on the distal outer surfaces of the proximal apex body  638  further assist in the prevention of catching the proximal apices  32  of the bare stent  30  on any part of the apex capture device  634 . In this configuration, the distal surfaces  639  bear all the load upon the bare stent  30  and the fingers of the proximal apex body  638 . 
     Simply put, the apex capture device  634  provides support for load placed on the stent graft  1  during advancement A of the inner sheath  652  and during withdrawal of the inner sheath  652  (i.e., during deployment D). Such a configuration benefits the apposition of the bare stent  30  by releasing the bare stent  30  after the entire graft sleeve  10  has been deployed, thus reducing the potential for vessel perforation at the point of initial deployment. 
     When the stent graft  1  is entirely free from the inner sheath  652  as shown in  FIG.  24   , the proximal handle  678  is, then, substantially at or near the third position (deployment position) shown in  FIG.  10   . 
     The stent graft  1  is, now, securely placed within the vessel  700  and the entire portion  630 ,  650 ,  660  of the assembly  600  may be removed from the patient. 
       FIGS.  70  and  71    illustrate alternative configurations of the stent graft  1  of  FIG.  1   . The stent graft  1000  of  FIG.  70    is similar to the stent graft  1  of  FIG.  1   . The stent graft  1000  has a graft  1010  and a number of stents  1020 . The stents  1020  are attached either to the exterior or interior surfaces of the graft sleeve  1010 . Preferably, the stents  1020  are sewn to the graft  1010 . The stent graft  1000  shown in  FIG.  70    has been discussed above with respect to  FIG.  1   , for example, and, therefore, the discussion relevant to features already discussed will not be repeated for the sake of brevity. 
       FIG.  70    shows an exemplary embodiment of the curved ends  1047  of the connecting rod  1040 . In particular, the rod  1040  forms a loop (whether, polygonal, ovular, or circular) and has an end portion  1048  that continues back parallel and next to the rod  1040  for a short distance. This end portion  1048 , along with the adjacent portion of the rod  1040  allows, for example, connective stitching to cover two lengths of the rod  1040  and better secures the end portion  1048  to the graft sleeve  1010 . In such configuration, there is limited or even no chance of a sharp end of the rod  1040  to be exposed to harm the graft sleeve  1010  or the vessel wall in which the stent graft  1000  is placed. 
     An alternative embodiment of the stent graft  1000  is shown as stent graft  1100  in  FIG.  71   . This stent graft  1100  contains a graft sleeve  1110  that completely covers the bare stent  30  shown in  FIGS.  1  and  70    and is hereinafter referred to with respect to  FIGS.  71  to  78    as a clasping stent  1130 . As shown particularly well in  FIGS.  72  and  74   , the clasping stent  1130  is entirely covered by the graft  1110  but is not attached to the material of the graft  1110  along its entirety. 
     At least some of the proximal apices  1132 , preferably, at least three or four, are left unconnected to permit a releasable connection with the fingers of the proximal apex body  638  when the fingers are extended through the apex openings  1134 . Of course, in certain applications, it may be beneficial to only leave one apex  1132  unconnected. The unconnected portion of each the apices  1132  has a minimal longitudinal length of about 10 percent of the longitudinal length of the stent and a maximum longitudinal length of up to approximately 90 percent of the length of the stent. Preferably, the longitudinal length of the unconnected portion is between approximately 30 to 40 percent as shown in  FIGS.  72  and  74   , which show the clasping stent  1130  sewn to the interior of the graft  1110 . For ease of comparison,  FIG.  73    illustrating the proximal end of the stent graft of  FIGS.  1  and  70    is included next to  FIG.  74   . The unconnected portions of apices  1132  need not have the same longitudinal lengths. Depending on the application, one or some of the unconnected portions of apices  1132  can have a longitudinal length different from other ones of the unconnected portions of apices  1132 .  FIG.  75   , for example, illustrates an embodiment near the maximum longitudinal length of the unconnected portion of the clasping stent  1130 . 
       FIGS.  76  and  77    illustrate a proximal end of the stent graft  1100  of  FIG.  71    partially deployed from the flexible inner sheath  652 . As can be seen in  FIG.  76   , the entire capturing assemblies of the apex capture device  634  reside inside the stent graft  1100  when the apices are captured. Only the distal-most portion of the distal apex head  636  extends out from the interior of the stent graft  1100 . With regard to the view of  FIG.  77   , it can be seen that only a few of the apices  1132  of the clasping stent  1130  are actually held by the apex capture device  634 . 
     It is noted at this point that implantation of the stent graft  1 ,  1000 ,  1100  of the present invention occurs while blood is flowing from the heart of the patient. Accordingly, the stent graft  1100  cannot occlude the vessel in which it is to be implanted and, in order to do so, there must exist a lumen for passing blood throughout the time after the stent graft  1100  has partially or fully expanded within the vessel. If all of the apices  1132  of the clasping stent  1130  were held within the apex capture device  634 , then there is a possibility of occluding the vessel if the unattached portion of the apices  1132  are too short to provide such a lumen. To avoid this condition, if only some apices  1132  of the clasping stent  1130  are captured, as illustrated in  FIG.  77   , then a sufficiently large lumen exists to allow blood flow through the vessel in which the stent graft is to be implanted. Alternatively, if a large percentage of the apices  1132  are left unconnected, as shown, for example, in  FIG.  75   , then all of the apices  1132  can be releasably held by the apex capture device  634  while the graft sleeve  1110  remains entirely open to allow blood flow through the stent graft  1100  during the stent graft  1100  implantation process. 
     There exists a drawback to placing the clasping stent  1130  as the proximal stent of the stent graft  1100  because material of the graft  1110  is proximal of the clasping stent  1130 . If unsupported, this material could move disadvantageously toward the interior of the stent graft  1100  after implantation and decrease or occlude blood flow. To prevent such movement, the stent graft  1100  also includes a crown stent  1140 . Like the clasping stent  1130 , the crown stent  1140  is shown in  FIGS.  71 ,  72 ,  74  to  76 , and  78    as being attached to the inside of the graft  1120  and, in this exemplary embodiment, is sewn to the material of the graft using the same polyester suture as the other stents. Of course, the crown stent  1140  can be attached to the exterior of the graft  1010 . In such a configuration, the crown stent  1140  augments the rigidity of the material of the graft  1120  to reduce enfolding thereof at the proximal end of the stent graft  1100 . 
     Alternatively and/or additionally, a non-illustrated distal crown stent can be attached to the inside or outside of the graft  1120  at the opposite distal end of the stent graft  1100 . In such a configuration, this distal crown stent  1140  augments the rigidity of the material at the distal end of the graft  1120  to reduce enfolding thereof. 
     The material of the graft  1120  can extend and bridge the entire distance between two proximal crown apices  1122 . It is noted, however, that, alternatively or additionally, the material of the graft  1120  may be partially cut out between crown apices  1122  of the crown stent  1140  to define a plurality of a radially distensible flange portions  1124  at the proximal end of the stent graft  1100 , as shown in  FIG.  74   . 
     There are various advantages provided by the stent graft  1100  over the prior art. First, the clasping and crown stents  1130 ,  1140  improve the apposition of the material of the graft to the intima of the vessel in which the stent graft  1100  is placed, in particular, in the aorta. Second, by better aligning the proximal portion of the stent graft  1110  in the lumen of the arch, the clasping and crown stents  1130 ,  1140  provide an improved blood-tight closure of the proximal end of the stent graft  1110  so that blood does not pass between the intima of the vasculature and the outer surface of the stent graft  1110 . 
     As set forth above, if the apex capture device  634  captures less than all of the apices of the clasping stent  1130 . The resulting openings allow blood flow during implantation. It is illustrated particularly well in  FIGS.  1 ,  13 ,  14 , and  70    that the material of the graft  10  of stent graft  1 ,  1000  begins only distal of the center of the bare stent  32 . In comparison, as shown in  FIGS.  71  and  73   , the material of the graft  1120  begins well proximal of the proximal-most apices of the clasping stent  1130 . Thus, this embodiment allows the material of the graft  1120  to extend much further into a vessel (i.e., further into the curved arch of the aorta). Therefore, a physician can repair a vessel further upstream in the aorta than the embodiment of the stent graft  1 ,  1000  of  FIGS.  1  and  70   . 
     In the prosthesis embodiment of  FIGS.  1  and  70   , there is direct contact between the metal of the bare stent  32  and the intima of the blood vessel. In contrast thereto, the configuration of the stent graft  1100  with the clasping stent  1130  places material of the graft  1120  between the metal of the clasping stent  1130  and the intima. Such a configuration provides a more atraumatic connection between the vessel and the proximal end of the stent graft  1100  than the configuration of  FIGS.  1  and  70   . This advantage is especially important for treating dissections—where the intima is in a weakened condition. 
       FIG.  63    illustrates interaction between the catheter  660 , the inner sheath  652 , and the nose cone assembly  630  (including the nose cone  632 , the distal apex head  636 , and the proximal apex body  638 ). In this illustration, first, the catheter  660  is in a proximal position that does not cover the inner sheath  652  in any way. For example, this position of the catheter  660  occurs when the inner sheath  652  has extended out of the catheter  660  as shown in  FIGS.  20  and  21   . 
     Next, the inner sheath  652  is clearly shown in its expanded state (caused by the non-illustrated prosthesis disposed therein and expanding outward). The distal-most end of the inner sheath  652  is disposed between the distal apex head  636  and the nose cone  632 . In such an orientation, the inner sheath  652  is in the position that occurs during extension out of the catheter  660  as shown for example, in  FIGS.  20  and  21   . Because the nose cone  632  screws onto the distal end of the distal apex head  636 , the distal-most end of the inner sheath  652  is releasably captured between the two parts  632 ,  636  until it is removed. Retraction of the sheath lumen  654  proximally pulls the distal-most captured end of the inner sheath  652  out from the capturing interface. 
     Finally, the proximal apex body  638  is in a retracted position proximal of the distal apex head  636 . This orientation is for illustrative purposes only to show the interaction of the distal apex head  636  and the proximal apex body  638  because the separation would not occur in use until, as set forth above, the inner sheath  652  is fully retracted from over the stent graft  1  and the proximal apices  32  of the stent  30  have been released as shown in  FIG.  14   . 
       FIG.  80    is a cross-section through the catheter  660 , the fingers of the proximal apex body  638 , the distal apex body  636 , the apex release lumen  640 , and the guidewire  620 .  FIG.  81    is a cross-section of the distal end of the delivery system along the longitudinal axis of the delivery system. These two figures illustrate the space  662  that exists between the catheter  660  and both of the proximal apex body  638  and the distal apex body  636  to make room for the inner sheath  652  to surround the parts  636 ,  638  and pass between the nose cone  632  and the distal apex head  636  and enter the pass  664  that allows the inner sheath  652  to be releasably held there as shown in  FIG.  63    until it is desired to remove the inner sheath  652  therefrom. 
       FIG.  82    shows a distal end of the delivery system according to the invention in the orientation of  FIGS.  20  and  21   , for example. The inner sheath  652  is curved and has an alternative embodiment of a D-shaped marker  234  thereon. In contrast to the configuration of two markers  234  on the stent graft  1  as shown in  FIGS.  27  and  28   , there is only one marker  234  on the inner sheath  652 . As illustrated in the orientations of  FIGS.  83 ,  84 , and  85   , the marker  234  allows the user to see how the inner sheath  652  should be oriented prior to implantation. 
       FIGS.  86 ,  87 ,  88 , and  89    illustrate an alternative embodiment of the front handle  672  that is rotatably attached to the handle  674  and rotatably fixed to the catheter  660 . 
       FIGS.  90  to  119    depict another exemplary embodiment of various features of the delivery assembly  600 . 
       FIG.  90    shows the entire delivery assembly  600  with a portion of nose cone assembly  630  removed to reveal the distal apex head  636 . 
     On the proximal end of the delivery assembly  600 , the enlarged view of  FIG.  91    depicts an alternative embodiment of the apex release assembly  690 . In  FIG.  91   , a proximal pusher support tube  645  surrounds two coaxial lumens, the guidewire lumen  620  and the apex release lumen  640 . The proximal pusher support tube  645  is longitudinally fixed to the proximal end of the graft push lumen  642  and has substantially the same diameter as the graft push lumen  642 . Because the proximal pusher support tube  645  is used for pushing/pulling the combination lumen  642 ,  645 , and due to the fact that the proximal pusher support tube  645  only resides within the handle body or proximal thereof, the proximal pusher support tube  645  can be made of a relatively stiff material, such as stainless steel, for example. In contrast, the graft push lumen  642  needs to flex and bend when extending out of the outer catheter  660  and into vasculature. Thus, the graft push lumen  642  is made from a relatively flexible material, such as a plastic. In  FIG.  91   , the proximal portion of the proximal pusher support tube  645  is cut away to reveal the features therein, including the guidewire lumen  620  and the apex release lumen  640 . 
     The apex release lumen  640  is axially fixed to the proximal apex body  638 . The guidewire lumen  620 , on the other hand, is axially fixed to the distal apex head  636 . Thus, distal movement of the apex release lumen  640  with respect to the guidewire lumen  620  separates the tines of the proximal apex body  638  extending over the spokes of the distal apex head  636 . To effect this relative movement, proximal and distal crimping devices  621  and  641  are respectively attached to the guidewire  620  and the apex release lumen  640 . The distal release part  692  is connected, through a non-illustrated set screw, to the distal crimping device  641 . The proximal release part  694  is connected, also through a non-illustrated set screw, to the proximal crimping device  621 . Finally, a proximal luer connector  800  is connected to the proximal-most end of the proximal pusher support tube  645  so that all of the lumen  620 ,  640 ,  645  can be filled and/or drained with a liquid, such as saline. 
       FIG.  92    is an enlarged view of the alternative embodiment of the locking knob  582  first shown in  FIGS.  50  and  51   . To better explain the features of  FIG.  92   , reference is made to the separated clasp sleeve  614  of  FIG.  93   , which was first depicted in  FIGS.  50 ,  53 , and  59  to  62   . This clasp sleeve  614  is longitudinally fixedly and rotationally freely connected to the handle body  674  through the setscrew  584  that protrudes into the slot  675  of the handle body  674 . The setscrew  584  is screwed into but not through the proximal end of the clasp sleeve as shown in  FIG.  93   , for example. This setscrew  584  protrudes into the slot  675  in the handle body  674 . When so connected, the clasp sleeve  614  cannot move longitudinally with respect to the handle body  674  but can rotationally move along the arc defined by the length of the slot  675 . The setscrew  584  protrudes from the outer circumference of the handle body  674  because it enters into the longitudinal slot  583  in the locking knob  582 . Thus, the setscrew  584  also controls the longitudinal movement distance of the locking knob  582 . When the knob  582  is at rest, the setscrew  584  resides in the distal end of the slot  583  because of the bias caused by spring  607  (see  FIG.  94   ). 
     The second setscrew  592  (also referred to as a position pin) starts from the handle body  674  but does not extend inside the handle body  674 . The setscrew  592  does, however, protrude out from the handle body  674  and into the three-position slot  587  of the locking knob  582 . Thus, the setscrew  592  controls the rotation of the knob  582  within the three positions. 
     The third setscrew  585  is screwed through a threaded hole in the handle body  674  and into a co-axial threaded hole  6021  of the clasp body  602  until the setscrew  585  is even with the exterior surface of the handle body  674 . Thus, the setscrew  585  does not protrude from the outer circumference of the handle body  674 . 
     The proximal clasp assembly  604  was first illustrated in  FIG.  52   . In  FIG.  94   , the proximal clasp assembly  604  is illustrated with different detail. The clasp body  602  has a distal interior cavity  6023  shaped to receive therein the distal clasp body spring  606 , which is a torsion spring in this exemplary embodiment. The locking washer  608  is connected to the distal end of the clasp body  602  by a non-illustrated setscrew that, for example, runs through the bore illustrated at the 12 o&#39;clock position on the locking washer  608  in  FIG.  94   . To keep the clasp body assembly pressed into the clasp sleeve  614 , as shown in  FIGS.  101  and  102    for example, a distal spring washer  605  and a proximal compression spring  607  are inserted into a proximal interior cavity  6024 . Placement of the locking knob  676  onto the handle body  674 , as shown in  FIG.  92    for example, compresses the compression spring  607  between the locking knob  676  and the proximal surface of the spring washer  605  residing inside the proximal interior cavity  6023  of the clasp body  602 . This compression forces the knob  676  proximally to keep the spring  592  inside the three-position slot  675 . The spring washer  605  is present to prevent the spring  607  from binding when the locking knob  676  is rotated between the three rotational positions. The smooth surface of the washer  605  does not catch the distal end of the compression spring  607  when the spring  607  rotates. 
     The rotator assembly includes the pusher clasp rotator  292 , the pusher clasp spring  298 , and the rotator body  294 . These parts are first depicted in  FIGS.  34  to  43  and  47  to  48    and are next depicted in  FIGS.  95  and  96   . In  FIG.  95   , the rotator assembly is illustrated in an exploded, unassembled state and  FIG.  96    shows the assembly in an assembled state. When assembled, the two protruding ends of the pusher clasp spring  298  are respectively inserted into the longitudinal slots  2942  and  2922  of each of the rotator body  294  and the pusher clasp rotator  292 . Because the distal end of the rotator body  294  is smaller in diameter than the cavity of the pusher clasp rotator  292 , the end of the spring that fits inside the slot  2922  must be longer than the end of the spring  298  that fits inside the slot  2942  of the rotator body  294 . 
     The rotator body  294  is secured inside the pusher clasp rotator  292  by two dowels  2926  that are press fit through a first orifice in the clasp rotator  292  after the rotator body  294  is inside the clasp rotator  292 . These dowels  2926 , then, pass through a circumferential groove  2944  substantially without touching the walls of the groove  2944  and, then, through a second orifice in the clasp rotator  292  directly opposite the first orifice. In such a configuration, the rotator body  294  is longitudinally fixed but rotationally free inside the clasp rotator  292 . The first and second orifices and the groove  2944  are clearly shown in  FIG.  113    (with the dowels  2926  removed for clarity). 
       FIGS.  44  to  48    illustrated the pusher clasp body  296  and its relationship with the sheath lumen  654 .  FIGS.  97  and  98    further illustrate two views of the pusher clasp body  296  and its distal projection  297 . The proximal end of the sheath lumen  654  passes through the crimp ring  295  and over the distal projection  297 . Then, to secure the sheath lumen  654  to the pusher clasp body  296 , the crimp ring  295  is compressed/crimped. Such a connection both longitudinally and rotationally stabilizes the sheath lumen  654  with respect to the pusher clasp body  296 . Two pins  2962  hold the pusher clasp body  296  to the proximal handle  678  so that longitudinal movement of the proximal handle  678  translates into a corresponding longitudinal movement of the pusher clasp body  296  within the handle body  674 . These pins  2962  pass through a plug  2964 , shown in  FIG.  114   , and then into the pusher clasp body  296 . The length of the pins that exist through the plug  2964  and also through the pusher clasp body  296  gives enough support to prevent movement of the handle  678  from breaking the pins  2962 , which might occur if the plug  2964  were not present. 
     It is noted that the conical expansion of the proximal end of the inner sheath  652  is different in  FIGS.  97  and  98   . This is because the embodiment shown in  FIGS.  97  and  98    illustrates an expansion portion of the inner sheath  652  that is sutured on only one side thereof. Accordingly, when viewed along the suture line (as in  FIG.  98   ), the cone has one flat side. In contrast, when viewed in an elevation 90 degrees turned from that suture line (as in  FIG.  97   ), the expansion portion has a conical elevational view. 
     Also shown in  FIG.  98    on the inner sheath  652  is a D-shaped radiopaque marker  232 . This marker  232  is enlarged in  FIG.  99    and can be, for example, secured to the inner sheath  652  by three sutures, diagrammatically indicated with an “X.” 
       FIG.  100    is an enlarged view of the distal end of the handle assembly  670  shown in  FIG.  90   . This embodiment of the distal apex head  636  shows an alternative embodiment of the proximal portion that was first shown in  FIG.  29   . As can be seen in the drawing, the proximal side of the distal apex head  636  is tapered. This tapered shape allows the distal apex head  636  to enter further into the interior cavity between the prongs of the proximal apex body  638  than the distal apex head  636  shown in  FIG.  29   . It is noted that the portion of the delivery system at the distal end is to be flexible so that this portion can traverse curved vessels. Thus, it is desirable for the length of the distal apex head  636  and the proximal apex body  638  (semi-rigid parts) to be as short as possible. By allowing the distal apex head  636  to travel further into the proximal apex body  638 , the longitudinal length of the two parts  636  can be shorter. 
     Now that the various parts of the handle assembly  670  have been shown and described separately, the interactions and orientations when assembled can now be further understood with reference to the following description and to  FIGS.  101  to  105   . 
       FIGS.  101  to  102    show the proximal half of the handle assembly  670  from just proximal of the locking knob  676  to just distal of the distal end of the proximal handle  678  (when the handle  678  is in a proximal position). The hidden lines shown in  FIG.  101    aid in the understanding of this portion. It is noted that the sheath lumen  654  is not illustrated in  FIG.  101    for clarity. 
       FIG.  102    clearly shows the components that are involved in the proximal half of the handle assembly  670 . The handle body  674  is surrounded by the distal handle  678  and a portion of the locking knob  676 . Inside the proximal end of the handle body  674  is the clasp body  602 , which is surrounded by the proximal end of the clasp sleeve  614 . The locking washer  608  is positioned inside the clasp sleeve  614  at the distal end of the clasp body  602 . Separated at a distance from the distal end of the locking washer  608  is the rotator assembly, which, as set forth above, is longitudinally fixed to the proximal handle  678 . The rotator assembly includes the pusher clasp rotator  292  surrounding the pusher clasp spring  298  and the rotator body  294 . The pusher clasp body  296  is disposed on the distal end of the rotator body  294  and the crimp ring  295  secures the sheath lumen  654  on the distal projection  297  of the pusher clasp body  296 . 
       FIG.  103    is an enlarged view of the proximal portion of  FIG.  102    by the locking knob  676 . These figures show the alignment of the bores in the clasp body  602  and the locking washer  608  so that the non-illustrated setscrew can fasten the two parts to one another. Also shown in  FIG.  103    is the alignment between the groove  605  for receiving therein the setscrew  586  (see  FIGS.  53  and  93   ) and connecting the proximal clasp assembly  604  to the clasp sleeve  614  so that the clasp sleeve  614  can still rotate around the clasp body  602 . Also visible in the enlarged view of  FIG.  103    is the three coaxial lumen  620 ,  640 ,  645  that pass through the clasp body  602 . 
     Like  FIG.  103   ,  FIG.  104    is an enlarged view of the distal portion of the handle assembly  670  around the pusher clasp rotator  292 . This view not only shows the orientations of the rotator body  294  and the pusher clasp body  296  with respect to the pusher clasp rotator  292 , but the three coaxial lumen passing therethrough are also evident. The groove  2944  for receiving the non-illustrated dowels  2926  therein is also visible in this view. As can be seen, the guidewire lumen  620  and the apex release lumen  640  each pass entirely through the pusher clasp body  296  but the proximal pusher support tube  645  ends just after the distal end of the rotator body  294  for homeostasis purposes. It is at this end point that the proximal pusher support tube  645  is connected to the graft push lumen  642 . This two-part structure of the proximal pusher support tube  645  and the graft push lumen  642  is, in an exemplary embodiment, a bonding of a proximal stainless steel lumen  645  and a plastic lumen  642 , for example, a polyurethane-based extrusion. As set forth above, a rigid lumen  645  in the handle portion keeps rigidity there and a flexible lumen  642  distal of the distal handle  672  allows the lumen to flex as needed. The distal end of the rotator body  294  is also fluidically sealed off from the interior of the distal interior of the delivery system with a hemostasis o-ring  293 .  FIG.  105    is still a further enlarged view around the pusher clasp spring  298 . 
     A transverse cross-sectional view through the handle assembly  670  is illustrative of the interaction between and relationship of various components of this assembly  670 . The cross-sections shown in  FIGS.  106  to  118    progress from proximal to distal. 
     A first transverse cross-section through the longitudinal slot  583  of the locking knob  676  is illustrated in  FIG.  106   . In this cross-sectional plane, the clasp body  602  is shown as filling up most of the interior of the clasp sleeve  614 . The anchoring bore in the clasp sleeve  614  for the setscrew  585  is shown aligned with the slot  583 . 
     A second transverse cross-section through the three-position slot  587  of the locking knob  676  is illustrated in  FIG.  107   . In this cross-sectional plane, the clasp body  602  still is shown as filling up most of the interior of the clasp sleeve  614 . The slot  6022  of the clasp body  602  for receiving one end of the torsion spring  606  is also depicted in  FIG.  107   . 
     A third transverse cross-section through the clasp body  602  before the locking washer  608  is illustrated in  FIG.  108   . In this cross-sectional plane, the slot  6022  of the clasp body  602  is aligned with a slot  6143  inside the proximal end of the clasp sleeve  614  that is not visible in  FIG.  93    but is visible through the cutout in  FIGS.  59  and  60   . This alignment is merely shown in  FIG.  108    for understanding the different depths of these slots  6022 ,  6143 . Like the pusher clasp spring  298 , the distal clasp body spring  606  has ends with different lengths. The first, shorter, end is inserted into the inner slot  6022  of the clasp body  602  and the second, longer end is inserted into the slot  6143  of the clasp sleeve  614 . 
     The fourth transverse cross-section between the proximal clasp assembly  604  and the rotator assembly shows, in  FIG.  109   , the spatial separation of these two assemblies that is depicted, for example, in  FIGS.  101  to  102   . Visible in these figures is the longitudinal slot  6141  that, as shown in  11  in the cross-sections of  FIGS.  110  to  111   , guides the movement of the pusher clasp rotator  292  by delimiting a space that corresponds to the width of the boss  2924  that extends out from the outer circumferences of the pusher clasp rotator  292 . This slot  6141  allows the pusher clasp rotator  292  to move longitudinally freely with respect to the clasp sleeve  614 ; simultaneously, this connection prevents any rotation of the pusher clasp rotator  292  that is independent from rotation of the clasp sleeve  614 . Accordingly, as the clasp sleeve  614  rotates about its longitudinal axis, the pusher clasp rotator  292  will rotate as well. The further enlarged view of the center of the configuration illustrated in  FIG.  110    is depicted in  FIG.  111   . Here, the rotator assembly portions are clearly shown with the pusher clasp spring  298  therebetween. 
     The sixth cross-section of  FIG.  112   , and the enlarged view of the sixth cross-section in  FIG.  113   , illustrate the longitudinally fixed but rotationally free connection between the pusher clasp rotator  292  and the rotator body  294 . The two bores in the pusher clasp rotator  292  for receiving the dowels  2926  (not illustrated here) are clearly shown to intersect the open space in the groove  2944  of the rotator body  294 . 
     A seventh cross-section in  FIG.  114    shows the connection of the pusher clasp body  296  and the proximal handle  678  through the plug  2964 . This view also depicts the fluid communication between the interior of the handle assembly  670  and the luer fitting  612 . When the luer  612  is connected to a fluid supply, the flushing liquid enters the interior cavity distal of the rotator body  294  and sealed off by the o-ring  293  and purges all air therein at the distal end of the delivery system.  FIG.  114    also shows the graft push lumen  642  extending through the handle body  674  beginning after the distal side of the o-ring  293 . 
     The eighth cross-section of  FIG.  115    illustrates the distal projection  297  at which the crimp ring  295  holds the sheath lumen  654  onto the pusher clasp body  296 . This figure also illustrates the open radial space between the clasp sleeve  614  and the graft push lumen  642 . To keep the relatively long extent of the flexible inner lumen  620 ,  640 ,  642  passing through the open interior of the handle body  674  from moving out of a centered orientation (i.e., from bending out from the longitudinal axis of the handle body  674 , sliding spacers  6142  are periodically provided along the clasp sleeve  614  as shown in  FIGS.  93  and  116  to  118   . These spacers  6142  are only needed while the proximal handle  678  is moving the rotator assembly and the pusher clasp body  296  in a distal direction to prevent bending of the interior flexible lumen  620 ,  640 ,  642 . Accordingly, the spacers  6142  can slide within the groove  6141  of the clasp sleeve  614  up to and over the distal end of the clasp sleeve  614  (the right side of the sleeve  614  as viewed in  FIG.  93   ; see also  FIG.  117   ). Each of these spacers  6142  is self secured in a slidable manner to the clasp sleeve  614 . 
       FIG.  117    depicts a ninth cross-section through a distal end of the clasp sleeve  614  within the distal handle  672 . The distal handle  672  freely rotates about the handle body  674  in an exemplary embodiment. In such an embodiment, the outer catheter  660  will also freely rotate about all of the lumen  620 ,  640 ,  642  therein because of the fixation between the outer catheter  660  and the distal handle  672 . See  FIG.  118   . 
     The shaded parts in  FIG.  119    are provided to show portions of the features around the clasp body  602 . In this view, the rotator assembly is removed. 
     The following text describes the four movements for implanting a prosthesis with the delivery system and the relative connections between relevant lumens when in the three different settings of the locking knob  676 . 
     The first movement will be referred to as the advancement stage and utilizes position  1  of the locking knob  676 . When in position  1 , the distal spring  298  is engaged around and holds the pusher support tube  645  (and, therefore, graft push lumen  642 ) to the rotator assembly  292 ,  294 . This assembly  292 ,  294  is fixed at the distal end of the rotator body  294  inside the pusher clasp body  296  (through a non-illustrated setscrew passing through the threaded bore  2966  shown in  FIG.  98   ). As set forth above, the pusher clasp body  296  is fixed to the proximal handle  678  and, therefore, the pusher support tube  245  moves with the proximal handle  678  in position  1 . 
     In this first movement, the entire distal assembly is advanced up to the implantation site using the proximal handle  678 . Thus, when the handle  678  moves distally, all of the lumen, including the guidewire lumen  620 , the apex release lumen  640 , the graft push lumen  642 /proximal pusher support tube  645 , and the sheath lumen  654 , are locked together and move distally with a corresponding movement of the proximal handle  678 . As the outer catheter  660  is longitudinally fixed to the distal handle  672 , it remains longitudinally fixed during the first movement. The lumen displacement in the advancement stage is depicted in  FIGS.  19  to  21   . 
     The second movement will be referred to as the primary deployment stage and utilizes position  2  of the locking knob  676 . When in position  2 , the distal spring  298  is disengaged from the pusher support tube  645  and the proximal spring  606  becomes engaged around the pusher support tube  645  to anchor only the push rod  642  (without lumen  620 ,  640 ) to the proximal handle  678  and allow retraction of sheath lumen  654  (and, thereby, the inner sheath  652 ) while all other lumens are disengaged and remain stationary. 
     In this second movement, the inner sheath  654  needs to be moved in the proximal direction, as shown in  FIGS.  22  to  24   . Accordingly, when the handle  678  moves distally, only the sheath lumen  654  moves with the handle  678 . Thus, in position  2  of the locking knob  676 , the sheath lumen  654  is locked to the proximal handle  678  and moves proximally with a corresponding movement of the proximal handle  678 ; all of the other lumen, including the guidewire lumen  620 , the apex release lumen  640 , and the graft push lumen  642 /proximal pusher support tube  645 , are unlocked and remain in the distally deployed position. See  FIGS.  22  to  24   . 
     The third movement will be referred to as the final deployment stage because, in this movement, the apex capture device  634  completely releases the distal end of the prosthesis as shown in  FIG.  14   . Here, the apex release lumen  640  is unlocked (using the release mechanism of  FIG.  91   ) with respect to the guidewire lumen  620  and the graft push lumen  642 / 645 . 
     The fourth movement will be referred to as the extraction stage and utilizes position  4  of the locking knob (the third of the three positions in the slot  587  of the locking knob  676 ). When in position  4 , both the distal spring  298  and the proximal spring  606  are disengaged from the pusher support tube  645  to allow the user to pull the proximal end of the pusher support tube  645  and withdraw it from the implantation site. The entire inner lumen assembly  620  and  640  travels with the proximal movement of the pusher support tube  645  because the release mechanism (see  FIG.  91   ) is pulled with the support tube  645  as it moves proximally. 
     Self-Centering Tip 
     As set forth above, the bare stent  30  provides an outward, expanding force at the proximal end  12 . The bare stent  30  and the proximal stent  23  are in a compressed state when attached to the graft sleeve  10  and also provide an outward, expanding force to the graft sleeve  10 . Therefore, when implanted, these forces center the proximal end of the stent graft  1  in the vessel and press the graft sleeve  10  against the vessel wall to prevent leaks that might occur between the graft sleeve  10  and the vessel wall. Such leaks at the proximal end  12  are to be avoided in stent graft implantation. 
     Because some physicians are concerned that the bare stent could damage the aortic wall, especially in the case of aortic dissection, they prefer to use a stent graft without a bare stent, such as the stent graft  1100  shown in  FIGS.  72  and  74  to  77   . In this configuration, the proximal end  12  can travel further upstream in the aorta and, in doing so, place the graft sleeve  10  closer to the heart. Such an implantation has various advantages, such as the removal of the possibility of bare stent puncture or damage to the vessel and the ability to treat diseased portions of the aorta closer to the heart. 
     However, if the bare stent  30  is removed, the ability to center the proximal end  12  is affected. One deficiency of thoracic grafts not having a bare stent is a misalignment of the proximal end of the prosthesis with the aortic curvature, which leads to improper apposition of the proximal end of the graft with the aortic arch inner curvature. Proper apposition is a desirable characteristic. 
     Stent grafts, by their nature of replacing the through-conduit of a damaged tubular vessel, have a proximal opening  12  for receiving therein the incoming fluid previously carried by the damaged vessel. See, e.g.,  FIG.  1   . It is desirable to directly contact the entire perimeter of this opening to the inside surface of the vessel in which the stent graft is to be placed because an opening between the proximal end of the stent graft and the vessel wall would allow a secondary flow outside and around the stent graft. This bypassing secondary flow is to be avoided when implanting stent grafts in a vessel and is particularly undesirable when implanting a stent graft in the aorta. The present invention provides a device, system and method for reducing and/or eliminating the possibility of such a bypassing flow by placing the proximal end  12  in a desired position within the vessel. 
     For the purposes of discussion, a few terms will be defined. The plane intersecting the proximal end opening of a stent graft is referred to herein as the inflow plane. The ring of tissue inside the vessel at which the proximal end opening is to be implanted is referred to herein as an upstream implant ring. The plane in which the upstream implant ring resides in the vessel is referred to herein as the implant plane. A longitudinal tangent is referred to herein as a line that is orthogonal to the implant plane at a point on the upstream implant ring. 
     A most-desirable implantation of the stent graft occurs when the inflow plane and the implant plane are co-planar. In this orientation, the longitudinal tangent of each point along the upstream implant plane is orthogonal to the inflow plane. This means that the outward force imparted by the proximal end of the stent graft is along a line that is co-planar with the implant plane, thereby insuring that the fluid-sealing force of the proximal end is maximized at the upstream implant ring. 
     When a stent graft is implanted in a longitudinally straight vessel, the inflow plane and the implant plane are virtually co-planar. In this orientation, a maximum outward sealing force is established at each point on the upstream implant ring, thereby maximizing the possibility of creating a permanent fluid-tight seal along the entire perimeter of the upstream implant ring. 
     When a stent graft is to be placed in a longitudinally curved vessel, as shown in  FIGS.  19  to  24  and  65  to  67   , for example, co-planar alignment of the implant plane and the inflow plane does not occur naturally. In fact, prior art stent grafts and delivery systems could not establish this co-planar alignment of the implant plane and the inflow plane when the stent graft was placed in a curved vessel. As such, when the stent graft was implanted in the curved vessel, the inflow plane was left at an angle to the implant plane, which, in turn, created a gap at the inferior side of the curved vessel. In some instances, this gap allowed fluid to flow impermissibly around the implanted stent graft. 
     One of the primary reasons for this misalignment is due to the behavior of the guidewire within the curved portion of the vessel. The guidewire  610  does not remain centered within the vessel throughout the curved portion of the vessel—as illustrated diagrammatically in  FIGS.  19  to  24  and  65  to  67   . Instead, in practice, the guidewire  610  tracks toward the superior (outside) curve from approximately the center axis of the vessel until it actually contacts the interior of the superior curve at least at one point within the curved vessel. The curved guidewire, therefore, not only guides the stent graft towards the superior curve, it does so while imparting an outwardly directed force to the stent graft—a force that naturally moves the stent graft off center in the curved vessel. 
     This non-axial tracking of the guidewire  610  is diagrammatically shown in  FIG.  120   . Here, the inflow plane  300  and the implant plane  400  are at an angle α to one another. Because the diameter of the upstream implant ring  12  has a maximum length that is defined by the opening of the graft material, an inferior gap β appears between the inferior curved vessel wall and the upstream implant ring  12 . The present invention provides devices and methods for automatically centering the stent graft  1100  within the vessel and, thereby, substantially align the implant plane  400  with the inflow plane  300  as shown in  FIG.  121   . As used herein, substantial alignment of the implant plane  400  and the inflow plane  300  is an angular difference of less than 15 degrees between the two planes. 
     A first exemplary embodiment of the device that improves proximal end apposition when it is placed in the aortic lumen prior to deployment in curved anatomy is illustrated in  FIGS.  122  and  123   . The previously described tip  632  is altered as shown in  FIG.  122   . The new tip  632 ′ has an overall length that is greater as compared to the tip  632 . The distal section  6322 ′ is tapered similarly to tip  632 . The proximal section  6324 ′ is straight and, hence, not bendable while tracking over the guidewire  610 . This stiff proximal section  6324 ′, along with the stiff distal and proximal clasps, produces an elongated stiff region in the nose cone assembly  630  of the delivery system  600 . This stiff region does not accommodate the superior curvature of the aorta and pushes the distal end of the delivery system down towards the inferior curvature when tracking in curved anatomies. 
       FIG.  123    illustrates how a modified tip pushes the proximal end of the stent graft down (as viewed in  FIG.  123   ) towards the inferior curve of the curved aortic lumen. If the proximal end  12  of the stent graft  1100  is deployed while centered as shown, the proximal end  12  will have proper apposition with the aortic wall at the inferior curvature. 
     A second exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  124  to  126   . In this embodiment, the tip  632 ″ contains therein a set of balloons  6322 ″ that, when inflated independently, exit and extend from a respective slit  6324 ″. The number of balloons can be 1, 2, 3, 4, or more. In the exemplary embodiments shown, there are three balloons spaced 120 degrees apart from one another. Which balloon(s) that are inflated after the tip  632 ″ is positioned in the curved vessel will depend upon the position of the slits  6324 ″. As shown in  FIG.  125   , one balloon  6322 ″ can be inflated to center the tip  632 ″ or, as shown in  FIG.  126   , all three balloons  6322 ″ can be inflated. 
     A third exemplary embodiment of the proximal end apposition improvement device takes its genesis from the bare stent  30 . In all of the embodiments for improving apposition, the bare stent  30  is removed. Because some physicians are concerned that a bare stent can damage an aortic wall, especially in the case of aortic dissection, the invention proposes creating a bio-absorbable bare stent. Such a bare stent  30  dissolves over time but ensures proper alignment of the proximal end of the graft during deployment. Because the bare stent is absorbed, any potential for damaging the aortic wall is eliminated. 
     A fourth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  127  and  128   . A dual-cone  410  device centers the nose cone assembly  630  of the delivery system  600  within the lumen. Centering the nose cone assembly within the aortic lumen, in turn, will ensure that the proximal end of the stent graft  1100  is properly aligned with the aorta. The dual-cone device can be made of silicone. The bases of the two opposing conical parts are adjacent one another. When the ends of the conical parts are pressed towards one another, the diameter of the conical base increases. As the base increases in diameter, its circular expansion comes in contact with the superior curve of the aortic wall to force the nose cone assembly  630  towards the center of the aortic lumen. When fully expanded, the proximal end  13  of the stent graft  1100  is in a desired centered position and is, therefore, ready for deployment. It is noted that the shape of the conical components can be modified to allow greater expansion of the conical base at specific locations. 
     A fifth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  129  and  130   . This centering system uses a pull-wire  420  that can center the tip end of the delivery system within the aortic lumen. The pull-wire  420  resides inside the delivery system between the stent graft  1100  and inner sheath  652 . One end of the pull-wire  420  can be attached to the nose cone assembly  630 , for example, the proximal apex body  638  and the other end of the continuous wire is attached to a mechanism at the proximal portion of the delivery system  600 , whether at the proximal end of the handle assembly  670  or at the apex release assembly  690 . This mechanism, when operated, pulls the wire proximally to produce a force P having two resultant forces P′ and P″ shown in  FIG.  130   . even though P′ is the smaller of the two resultant forces, if force P is large enough, P′ will pull the tip towards the inferior curve of the aorta.  FIG.  129    illustrates the distal end of the delivery system being centered by pulling on the wire  520  to create centered apposition of the proximal end  12  of the stent graft  1100 . 
     A sixth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  131  and  132   . The apex clasp device  636 ,  638  is formed in two halves or three thirds. In this configuration, the split clasp mechanism allows angular adjustment of the proximal end of the graft within the aortic lumen to insure optimum apposition with the aortic wall as shown in the comparison of  FIGS.  131  and  132   . The split clasp allows the user to move forward and backward some specific apices along the proximal circumference of the stent graft  1100  which, in turn, changes the angle of the inflow plane  300  with respect to the implant plane  400 . By using this process and system, the physician can adjust the orientation of the proximal end  12  to ensure proper apposition against the aortic arch inner curvature. 
     A seventh exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  133  to  135   . As set forth above, the apex clasp device  636 ,  638  uses a set of distally projecting fork tines and an internal castellated portion to create openings in which the proximal apices  32  of the bare stent  30  or the proximal apices  1132  of the clasping stent  1130  are held releasably. Instead of the apex clasp device  636 ,  638 , each of the apices  32 ,  1132  are individually held with an apex capture mechanism that is shown in  FIGS.  133  to  135   . Pushing the wire in one of the apex capture mechanisms causes the proximal end  12  of the stent graft  1100  to move. A combination of such pushing forces on one or more of these apex capture mechanisms will cause the proximal end  12  to move into a desired apposition of the inflow plane  300  and the implant plane  400 . When the wires are pulled, they move proximally and release the capture of the respective stent apex  32 ,  1132 . 
     An eighth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  136  to  142   . Here, the tip  632  has slots through which extend loops of wires that, when extended as shown in  FIGS.  137 ,  141 , and  142   , center the tip  632  within the vessel in which it is placed. The mechanism is composed of wires that are contained inside the slots in a straight configuration. Compressing the wires causes them to protrude from the slots and form loops that can press against the vessel wall, thereby centering the tip  632  within the vessel. Extension of the loops can be actuated through a single pull mechanism, for example, with a telescoping slide. Centering of the tip is actuated by pulling on a knob (for example) located at the proximal end of the delivery system. The knob is connected to the wire loops by a catheter that extends from the knob to the distal end of the loops. The loops, in turn, are fixed at their distal end. Pulling on the knob would cause the catheter to slide in a proximal direction causing a compression of the wire loops, making them protrude from the tip  632  as shown in  FIGS.  137 ,  141 , and  142   . In addition, the catheter can contain a component that engages the clasp as it is moved proximally. Thus, as the catheter is moved, at approximately three-fourths of the actuation stroke, the component on the catheter engages the clasp and with the remainder of knob retraction the clasp would be released. 
     A ninth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIG.  143   . In this approach, an accessory device  430  is introduced into one or more of the contra lateral limbs of the patient or radially through the arm. Before, during or after, the delivery system is used to extend the aortic stent graft into the aortic arch for implantation. The accessory device  430  is, then, extended into the aortic arch and pressed against a portion of the delivery system. For example, as shown in  FIG.  3   , the accessory device  430  can be introduced through the left sub-clavian artery and used to bias the delivery catheter away from the greater curve of the arch. The accessory device  430  can have many forms. It could be a balloon, a mechanical mechanism, and a pusher from the trans-femoral approach, a balloon or a mechanical mechanism is practical. Each of these concepts can be applied in a direct approach from the left sub-clavian artery or the Brachiocephalic Trunk. 
     A tenth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  144  to  146   . In this embodiment, the properties of temperature sensitive nickel-titanium are combined with the technology of localized heating to present a controlled shape manipulation. Shape memory bends are imparted to portions of the delivery system  600  prior to incorporation in the delivery system  600 . Then, the portions are placed into the desired configuration, e.g., linear, and incorporated into the delivery system  600 . Heater bands  440  are distributed along the delivery system  600  adjacent the memory bends. As shown in  FIGS.  144  to  146   , application of heat at the memory bends will cause the adjacent portion of the delivery system  600  to bend. If the bends are coordinated, they can be made to bend the in-vivo delivery system  600  in any desired way, in particular, to center the tip in the vessel and, thereby, implant the proximal end  12  of the stent graft  1100  with a proper apposition. Alternatively, ultrasonic sensitive crystals can be used as the heater bands. Thus, when energy is applied, the crystal heat up and cause the nickel-titanium memory portion to bend into their pre-programmed memory shape. 
     An eleventh exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  147  to  151   . In this embodiment, a hollow balloon delivery catheter  450  having a balloon configuration  452  is provided. The balloon delivery catheter  450  has an interior bore  454  through which the outer catheter  660 , the nose cone assembly  630 , and the inner sheath  652  travel.  FIGS.  149  to  151    illustrate an exemplary method for using the balloon delivery catheter  450  of the present invention. First, the balloon delivery catheter  450  is inserted into at least part of the aortic arch and the balloon configuration  452  is inflated to center and hold the balloon delivery catheter  450  in position within the aorta. See  FIG.  147   . Then, the distal end of the delivery assembly  600  is passed through the balloon delivery catheter  450  as shown in  FIG.  148   . The proximal end  12  of the stent graft  1100  is deployed in the aortic arch and, after satisfactory apposition of the inflow plane  300  and the implant plane  400  is verified, the balloon configuration  452  is deflated and the balloon delivery catheter  450  can be removed. Finally, the stent graft  1100  is fully implanted as set forth above. 
     In the exemplary balloon configuration  652  shown in  FIGS.  150  and  151   , there are three balloons  452  with spaces therebetween so that blood can flow past the balloons  452  when inflated. This tri-balloon device is shown in  FIGS.  150  and  151   . 
     Alternative to the balloon delivery catheter  450 , a balloon configuration  452  can be added at the distal end of the outer catheter  660 . When the outer catheter  660  is at its distal-most position in the aorta, the balloon configuration  450  inflates and centers the nose cone assembly  630  within the aorta. Thus, when the inner sheath  652  containing the stent graft  1100  is extended from the outer catheter  660 , the nose cone assembly  630  is centered within the aorta and the inner sheath  652  and nose cone assembly  630  can be extended within the aortic arch in a centered orientation. 
     A twelfth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  152  to  155   . In this embodiment, a balloon delivery rod  460  having a balloon configuration  462  is provided. The balloon delivery rod  460  is inserted into at least part of the aortic arch and the balloon configuration  462  is inflated at the superior curve of the aortic arch. See  FIG.  152   . Then, the distal end of the delivery assembly  600  is passed through the aorta and along the inflated balloon configuration  462  as shown in  FIG.  153   . The proximal end  12  of the stent graft  1100  is deployed in the aortic arch and, after satisfactory apposition of the inflow plane  300  and the implant plane  400  is verified, the balloon configuration  462  is deflated and the balloon delivery rod  460  can be removed. Finally, the stent graft  1100  is fully implanted as set forth above.  FIG.  155    illustrates one possible cross-sectional configuration for the balloon  462  of this embodiment. 
     A thirteenth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  156  to  158   . As described above, a proximal edge  12  that is perpendicular to the longitudinal edges (see  FIG.  71   ) will be difficult to position in a curved vessel and, in such a case, the inflow plane  300  will be at an angle to the implant plane  400  as shown in  FIG.  157   . To counteract this non-apposition of the proximal end  12  that does not have a bare stent, the stent graft  1100  can be formed with a non-linear proximal end  12 ′ as shown in  FIG.  158   . With this angled contour, if the shorter side (left side in  FIG.  158   ) is positioned at the inferior curved of the vessel, the proximal end  12  will fit inside the aorta to align the inflow plane  300  and the implant plane  400  as shown in  FIG.  158   . 
     A fourteenth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIG.  159   . The tip  632  or the nose cone assembly  630  is configured with a symmetric dilator  470  shown in  FIG.  159   . This dilator  470 , when closed, is merely a cylinder. However, when opened as shown in the figure, the two outer bearing surfaces  472  apply pressure to opposing sides of the vessel in which the stent graft  1100  is to be implanted, thereby centering the nose cone assembly  630  and the proximal end  12  within the vessel for implantation with apposition of the inflow plane  300  and the implant plane  400 . 
     A fifteenth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  160  and  161   . In this embodiment, a plurality (e.g., four) of wires  480  are threaded through the delivery assembly  600  and are attached to, for example, four quadrants of the apex capture device  634 . At the proximal end of the delivery assembly  600  is located an actuation knob or “joystick”  482 . By pulling or otherwise maneuvering the knob  482 , tension is applied to one or more of the wires  480  and moves the tip  632 . Such maneuvering is used to center the tip  632  as desired to ensure apposition of the inflow plane  300  and the implant plane  400 . 
     A sixteenth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  162  and  163   . Because blood is flowing through an aorta in which a stent graft  1100  is to be implanted, properties of the flow can be used for making perpendicular the stent graft&#39;s proximal opening with the tangent of the aortic arch to provide an optimal proximal seal. In particular, a tapered “windsock”  490  can be incorporated into the delivery assembly  600 . The proximal diameter of the windsock  490  is large enough so that, upon expansion due to the incoming blood flow, the proximal opening  492  of the windsock  490  opens and presses against the aortic wall. In such a configuration, the windsock  490  channels all blood flow therethrough and discharges the flow from a distal opening  494 . The distal opening  494  is made to be smaller than the proximal opening  492 . The change in opening size increases the pressure in the wind sock  490 . When the blood flow is channeled into a path that is concentric within the aorta, such as through an evenly spaced set of exit orifices  494 , the balanced (and centered) pressure would radially center the leading portion of the stent graft  1100  during deployment. 
     In one exemplary configuration shown in  FIG.  162   , the proximal end  492  of the windsock  490  is attached with sutures to the apex capture device  632 . The distal end  492  of the windsock  490  may or may not be attached to a portion of the delivery assembly  600  distal of the proximal end  12  of the stent graft  1100  to be deployed. Compare  FIGS.  162  and  163   . It is noted that having no distal attachment ( FIG.  163   ) may be more advantageous because performance of blood flow balancing may be better than with distal attachment ( FIG.  162   ). If the distal end  494  of the windsock  490  is attached, a break-away method for the sutures can be used along with the incorporation of blood flow ports as illustrated in  FIG.  162   . Performance of the windsock  490  can be evaluated with varying discharge port diameters and overall tapers. 
     A seventeenth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  164  to  169   . In this embodiment, a plurality of memory shape metal (e.g., Nitinol) hypo-tubes  500  are attached to the delivery assembly  600  and act as a mechanism to center the tip and, therefore, the stent graft  1100  during stent graft positioning and deployment. In one exemplary embodiment, two control tubes or lumens  502 ,  504  are placed somewhere between, around, or over the apex release lumens  620 ,  640 . Each of the hypo-tubes  500  is secured at its distal end  506  to the inner control tube  502  at or near the tip  632 . Each of the hypo-tubes  500  is further secured at its proximal end  508  to the outer control tube  504  at a distance from the tip  632 . As illustrated in the comparison of  FIGS.  165  and  166   , forward (advancement) motion of the outer control tube makes the hypo-tubes  500  expand into a “basket” shape that contacts the walls of the aorta and centers the proximal end  12  of the stent graft  1100  within the vessel. When in this advanced position of the outer control tube  504 , as shown in  FIG.  164   , the hypo-tubes  500  are used to create an arc during positioning and, thereby, facilitate the centering function. Backwards (retraction) motion of the outer control tube  504  decreases the profile of the hypo-tubes  500  to lie longitudinally along the length of the inner control tube  502 . 
     To incorporate this feature into the stent grasping device that connects with each of the proximal apices  1132  of the clasping stent  1130 , each hypo-tube  500  has a small “notch”  510  (slightly larger than the diameter of the wire of the clasping stent  1130 . This “notch” is located at the center of the pre-formed arc of the hypo-tubes  500  (see  FIGS.  166 ,  167   ). Inside the diameter of the hollow hypo-tube  500  is a rigid release wire that acts to engage the proximal apices  1132  to attach releasably the clasping stent  1130  to the delivery system. See, e.g.,  FIGS.  133  to  135   . The releasable clasping shown in  FIGS.  168  and  169    ensures a secure lock of the stent graft  1100  to the delivery assembly  600 . During attachment of the stent graft  1100  to the delivery assembly  600 , the apices  1132  of the clasping stent  1130  are positioned into each notch  510  and the rigid release wire is fed over the clasping stent  1130  to capture (secure) the clasping stent  1130  and secure it to the delivery assembly  600  (see  FIG.  169   ). Release of the stent graft  1100  from the delivery assembly  600  is obtained by withdrawing the rigid wire within the hypo-tubes  500 . Expansion of the pre-formed nitinol hypo-tube  500  can be performed manually (slide action) or through a self-expanding configuration. 
     An eighteenth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIGS.  170  to  172   . In this embodiment, the tip  632 ′″ has been given expandable exterior segments  6322 ′, in this case, three segments. The tip  632 ′″ also contains an interior expansion mechanism, for example, a spring actuated or pusher actuated mechanism, that extends the exterior segments  6322 ′ from the position shown in  FIGS.  170  and  171    to the position shown in  FIG.  172   . When the tip  632 ′″ is so expanded, it becomes centered within the curved vessel, thereby also centering the proximal end  12  of the stent graft  1100 . 
     The tip-centering embodiments are not limited to the distal end of the delivery assembly  600 . The guidewire  610  can also be utilized. More specifically, in a nineteenth exemplary embodiment of the proximal end apposition improvement device, the guidewire  610  can be provided with an expanding “basket”  520  at the distal end thereof as shown in  FIGS.  173  to  175   . This basket  520  can be either self-expanding or manually expanded and opens within the aorta when the basket  520  is just upstream of the implant plane  400 . The delivery assembly  600  is, then, introduced over the guidewire  610  to the deployment site. After delivery of the stent graft  1100 , the guidewire  610  is withdrawn into the guidewire lumen  620  of the delivery assembly  600  and withdrawn along with the assembly  600 . 
     A twentieth exemplary embodiment of the proximal end apposition improvement device is illustrated in  FIG.  176   . This embodiment provides an alternative to the bio-absorbable bare stent  30  by including a removable bare stent  30 ′. Utilizing such a bare stent  30 ′ during deployment but removing it after apposition of the inflow plane  300  and the implant plane  400  is confirmed provides the self-centering features of the original bare stent  30  but without the detrimental affects that can be caused by the long-term exposure of the bare stent  30  to the interior wall of the vessel in which the stent graft  1100  is implanted. This removable bare stent  30 ′ can be fixed onto or be a part of the apex capture device  634 . The bare stent  30 ′ can be fixedly secured to the proximal end of the distal apex head  636 , for example, and removably secured to the proximal end  12  of the stent graft  1100 . Detachment of the bare stent  30 ′ can be accomplished in a variety of ways. One exemplary embodiment can collapse the bare stent  30 ′ with a collection ring that slides over the bare stent  30 ′ in a proximal direction. As the ring progresses proximally along the individual turns of the bare stent  30 ′, a radially inward force is imparted to each proximal apex  32 ′ sufficient to release or break the contact between the apex  32 ′ and the stent graft  1100 . Another exemplary bare stent removal device reverses the orientation of a hook that connects each apex  32 ′ to the stent graft  1100  so that the apex capture device  634  is moved distally to release the bare stent  30 ′ from the stent graft  1100 . 
     It is envisioned that any of the nineteen exemplary embodiments described above can be used individually or in any combination. 
     While exemplary embodiments of the invention have been illustrated and described, it will be clear that the invention is not so limited. Numerous modifications, changes, variations, substitutions, and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.