Abstract:
A system and method for endoluminal grafting of a main anatomic conduit in its diseased state in which it dilates to pose a life threatening condition and its various conduits that emanate from the main anatomic conduit. The grafting system comprises an endoaortic graft having at least one opening therein and at least one branch graft that is passable through the opening of the endoaortic graft into the branch anatomic conduit(s) such that the junction between the branch graft and the endoaortic graft is substantially fluid tight. A system and method for delivery of the endoaortic graft and also a system and method for efficient alignment and deployment of the branch (e.g., side branch) graft such that the coupling of the branch graft with the endoaortic graft is efficient and exact and fluid-tight; and a system and method for coupling the branch to the endoaortic graft via a coupling mechanism employing a memory metal alloy; a system and method for the proper and exact alignment of the endoaortic graft and the branch using magnetic force of a suitable nature, and which does not use the magnetic force as the coupling mechanism.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present patent application is based on, and claims priority from, U.S. provisional Application No. 60/509,904, filed Oct. 10, 2003, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to medical devices and methods, and more particularly to a system and method for endoluminal grafting of blood vessels or other tubular, main anatomic conduits which have furcations or side branches extending there from. 
     2. Related Art 
     Endoluminal grafting is a relatively noninvasive method for placing a tubular graft within the lumen of a native, main anatomic conduit, such as a blood vessel. In certain cardiovascular applications of conventional or prior art techniques for endoluminal grafting, an endovascular graft may be implanted in the aneurismal segment of a blood vessel to form a prosthetic blood flow conduit through the aneurysm, and to effectively isolate the weakened portion of the blood vessel wall from hemodynamic forces and pressures of the flowing blood. 
     The prior art has included numerous endovascular grafts of varying design. In general, these endovascular grafts typically comprise a tube made of a pliable material such as PTFE, polyester, woven Dacron®, etc., in combination with a graft anchoring component (e.g., a stent, a frame, hooks, a series of wire rings, clips, staple, etc.) that operates to hold the grafts in its intended position within the blood vessel. 
     An example of a commonly used endovascular primary stent graft is the AneuRx stent graft sold by Medtronic. A sleeve may be used at the end of the graft if the graft itself is not sufficiently long. With or without the sleeve, a conventional endovascular stent graft requires the neck (the area of the vessel between the branches and the aneurysm) to be of sufficient size to permit attachment of the graft. A conventional endovascular stent graft cannot be used if the neck is too short (this problem is described in some detail in U.S. Pat. No. 6,428,565 to Wisselink, in the paragraph bridging columns 2 and 3). 
     Endovascular grafting is a clinically-acceptablealternative to traditional surgery in patients who suffer from aneurysms of the aorta. Indeed, many patients who are diagnosed with aortic aneurysms are relatively high-risk patients and may be classed as poor-risk for traditional surgery. If allowed to remain untreated, the aneurysm will surely dissect or rupture, causing a catastrophic event leading to significant risk of death to the patient. The traditional surgery in itself incurs significant risk of morbidity and mortality to the patient, due to its inherently extensive nature, which includes excessive blood loss, intra-operative heart attacks, and organ system ischaemias due to the cross-clamping of the aorta, which is an inherent part of the procedure. Thus, endovascular grafting offers a potential means of repair of aortic aneurysm without the risks and potential complication of traditional surgery. At the present time, endoluminal grafting can be performed in patients with aneurysms isolated to the infra-renal position or at the juxta-renal position with great benefit to the high-risk patients, but is not extendable to a large population of patients that suffer with aneurismal disease of the aorta that involves its major branches. 
     Depending on which region of the aorta is/are involved, the aneurysm may extend into areas of bifurcation (i.e., the inferior end of the aorta where it bifurcates into the iliac arteries) or segments of the aorta from which smaller branches extend. In this regard, aortic aneurysms can be classified into three basic types and five sub-types on the basis of the regions of the aneurismal involvement, as follows:
         A. Thoracic Aortic Aneurysms:
           1. Aneurysms involving the ascending aorta   2. Aneurysms involving the aortic arch and branches that emanate therefrom (i.e., subclavian artery, common carotid artery, innominate artery)   
           B. Thoracoabdominal Aortic Aneurysms: Aneurysms involving the descending thoracic aorta and arteries that emanate from it (i.e., thoracic intercostals arteries) and/or the supra-renal abdominal aorta and branch arteries that emanate therefrom (i.e., renal, superior mesenteric, celiac, and/or the intercostals arteries).   C. Abdominal Aortic Aneurysm:
           1. Aneurysms involving the para-renal aorta and the branches that emanate therefrom (i.e., the renal arteries).   2. Aneurysms involving the infrarenal aorta with or without iliac involvement.   
               

     Unfortunately, not all the patients diagnosed with aortic aneurysm are presently considered to be candidates for endovascular grafting. This is largely due to the fact that most of the endovascular grafting systems are not designed for use in regions of the aorta from which side branches (i.e., carotids, innominate, subclavian, intercostals, superior mesenteric, celiac, renal) extend. In fact, most endovascular grafting systems have been in the treatment of infra-renal aneurysms, with or without the involvement of the iliac arteries. There are numerous examples in the prior art of endovascular grafting method and systems useable to treat such infra-renal aneurysms, with or without iliac artery involvement. 
     Patent Application Publication No. 2002/0103495 and U.S. Pat. No. 6,352,543 (Cole) disclose methods and devices for forming an anastomosis between hollow bodies using magnetic force to couple anastomotic securing components  78 ,  80  and create a fluid-tight connection between the lumens of the hollow bodies. End-to-side, side-to-side, and end-to-end anastomoses can be created without using suture or any other type of mechanical fasteners, although any such attachment means may be used in conjunction with the magnetic attachment The securing components have magnetic, ferromagnetic, or electromagnetic properties and may include one or more materials, for example, magnetic and nonmagnetic materials arranged in a laminated structure. As shown in  FIG. 9A , the securing component  78  includes two members,  78 A,  78 B disposed on opposite surfaces of a wall of one of the hollow bodies.  FIGS. 19A-19C  show an embodiment in which one of the securing components has a flange-type construction. The system of anastomotic securing components may be used in many different applications including the treatment of cardiovascular disease, peripheral vascular disease, forming AV shunts for dialysis patients, etc., and may be sized and configured for forming an anastomosis to a specific hollow body, for example, a coronary artery or the aorta. 
     Patent Application Publication No. 2002/0143347 (Cole et al.) discloses methods and devices using magnetic force to form an anastomosis between hollow bodies. End-to-side, side-to-side, and end-to-end anastomoses can be created without using sutures or any other type of mechanical fasteners, although such attachment means may be used in practicing some aspects of the invention. Magnetic anastomotic components may be attached to the exterior of a vessel, e.g., by adhesive, without extending into the vessel lumen. Various magnetic component configurations are provided and may have different characteristics, for example, the ability to match the vessel curvature or to frictionally engage the vessel.  FIG. 5B  shows sutures S used to attach the component  16  to a vessel V, although it is stated that any suitable mechanical fastener may be used, e.g., clips, stents, barbs, hooks, wires, etc.  FIG. 8B  shows a magnetic anastomotic component  50  having an opening  52  and attachment structure  54  to facilitate securing the component to a vessel (not shown). As above, the structure  54  may be used alone or in combination with other means for securing the component to the vessel. In the illustrated embodiment, the attachment structure  54  is affixed to the component  50  to define a plurality of openings  56  which may be use to receive sutures, clips, clamps, pins, barbs, or other securing or fastening means. 
     Patent Application Publication No. 2001/0041902 (Lepulu et al.) discloses anastomotic methods and devices for placing a target vessel in fluid communication with a source of blood.  FIGS. 11 and 12  show an embodiment utilizing magnets to secure the target vessel wall. In  FIG. 11 , a first securing component  90 , preferably having a rectangular shape with rounded ends, is formed of magnetic material (or provided with magnetic material), as is a second securing component  92 . The poles of the magnets are arranged to attract the components  90 ,  92  to one another and capture the tissue of the target vessel wall.  FIG. 12  shows another embodiment wherein a first securing component  94  is carried by a conduit body  96 , which is provided with a magnetic collar  98 . A second securing component  100  has a magnetic collar  102 , the poles of these magnets being arranged to repel the collars and force the components  94 ,  100  together. 
     U.S. Pat. Nos. 5,989,276 and 6,293,955 and Patent Application Publications Nos. 2003/0014061, 2003/0014062, 2003/0014063, 2001/0051809, and 2002/0052637 (Houser et al.) disclose a bypass graft incorporating fixation mechanisms at its opposite ends, for securing these ends to different locations along a blood vessel, or alternatively to different locations wherein one of the locations is a different vessel or an organ defining a cavity. Mechanical fixation features such as collets or grommets can be employed, enhanced by delivery of an electrical current sufficient to heat surrounding tissue to form a thermal bond. A graft deployment system includes a tissue dilator and a needle for perforating tissue, mounted coaxially within the dilator. Intraluminal systems further include a catheter for containing the dilator. To further assist positioning, magnets may be incorporated into the dilator near its distal tip, as indicated at  206  for a dilator  208  shown in  FIG. 25 . Such magnets may be formed of ferrite materials, or alternatively may be formed by winding conductive coils around the dilator to form electromagnets when current is supplied. The dilator magnets are used in conjunction with a guide wire  209  advanced beyond a stenosed lesion  210  within a vessel  212 . The guide wire is formed of metal, and to further enhance magnetic attraction may incorporate a magnet  214  of opposite polarity to the dilator magnet. Magnetic positioning is stated to facilitate placing bypass grafts through tortuous vessels or over long distances beyond the lesion. 
     Houser et al. also disclose tissue dilators of deployment systems for graft fixation. Magnets may be incorporated into the dilator near its distal tip, as indicated at  206  for a dilator  208  shown in  FIG. 25 . Such magnets may be formed of ferrite materials, or alternatively may be formed by winding conductive coils around the dilator to form electromagnets when current is supplied. The dilator magnets are used in conjunction with a guide wire  209  advanced beyond a stenosed lesion  210  within a vessel  212 . The guide wire is formed of metal, and to further enhance magnetic attraction may incorporate a magnet  214  of opposite polarity to the dilator magnet. Magnetic positioning is stated to facilitate placing bypass grafts through tortuous vessels or over long distances beyond the lesion. 
     U.S. Pat. Nos. 6,074,416 and 6,451,048 and Patent Application Publication No. 2002/0151913 (Berg et al.) disclose connector structures  34  for attaching elongated flexible tubular grafts to the body organ tubing of a patient. The connector structures are formed from nitinol wire. 
     U.S. Pat. No. 6,068,654 (Berg et al.) discloses a two-piece graft connector having a tubular band section with its proximal end configured to attach to a tubular graft and retention loops extending from its distal end, and a tubular anchor structure configured to be placed in the patient&#39;s tubular body tissue structure. The retention loops  26  can be made of nitinol wire. In one embodiment (see  FIG. 1 ), the proximal end of the tubular band section is attached to a tubular graft. The retention loops extend from the distal end of the tubular band section of the connector, through an aperture in the side wall of a patient&#39;s tubular body tissue structure, and the tubular anchor structure is placed in the patient&#39;s tubular body tissue structure, within the retention loops. In another embodiment (see  FIG. 9 ), retention loops  26  are replaced by relatively thicker retention fingers  70 , which do not form loops, but instead form arcs, extending partially around the circumference of tubular body structure  11 . 
     Methods for graft placement are disclosed in Patent Application Publications Nos. 2002/0143383 (Parodi) and 2002/0072790 (McGuckin, Jr. et al.) and U.S. Pat. No. 6,428,565 (Wisselink). Wisselink also describes the problems associated with using a conventional endovascular stent graft when the neck is too short (see the paragraph bridging columns 2 and 3). 
     With reference to FIGS. 15 a -21, U.S. Pat. No. 6,068,637 (Popov et al.) discloses a method and devices for performing end-to-side anastomoses between the severed end of a first hollow organ and the side-wall of a second hollow organ utilizing a modified cutter catheter which is introduced into the first hollow organ in combination with a receiver catheter which is introduced into the second hollow organ. The distal end of the receiver catheter includes a receiver cavity and a selectively activatable magnetic material. The magnetic material is selected so that it will interact with a magnetically susceptible material disposed in the distal end of the modified cutter catheter when the modified cutter catheter is disposed in proximity to the proposed site for anastomosis whereby the severed end of the first hollow organ is matingly engaged with the sidewall of the second hollow organ. Thereafter, the severed end of the first hollow organ can be attached in sealing engagement with the side-wall utilizing clips, a biocompatible glue, or other suitable methods. The cutter is then activated to remove a portion of the side-wall of the second hollow organ, thereby creating an opening within the region of securement and establishing the anastomosis. In the preferred embodiment, the portion of the sidewall of the second hollow organ is engaged in the receiver cavity by the attractive force between the magnetically susceptible material and the magnetic material. The magnetically susceptible material is then released from the modified cutter catheter and withdrawn along with the portion of the sidewall removed by the cutter when the receiver catheter is withdrawn from the second hollow organ. 
     Most, if not all, of the endovascular grafts that have been designed for use in treating infra-renal aneurysms require that a proximal neck of adequate length exists inferior to the renal arteries, in order to provide a region where the superior end of the graft may be securely anchored so that blood flow to the renal arteries is not restricted. The deployment of an endovascular graft within the regions of the aorta from which the branch anatomic conduits emanate presents an additional technical challenge, because in those cases, the endovascular graft must be designed such that it can be inserted, aligned, and deployed with discrete maintenance of blood flow to the side branch anatomic conduits by means of additional branch grafts that arise from the newly-constructed endoaortic graft. This should be done in a manner that maintains sufficient blood flow to the branch anatomic conduit and yet exclude the aneurismal segment of the aorta from the haemodynamic consequences. 
     U.S. Pat. No. 5,425,765 (Tifenbrun et al.) discloses an endovascular graft that has one or more openings or fenestrations formed at specific locations, to allow blood to flow from the aorta into one or more of the branch arteries. However, such fenestrations do not form discrete connections with the branch arteries through which blood flows into the branch anatomic conduits. As a result, the area surrounding the fenestrations is prone to leakage of blood around the fenestrations, which might lead to migration of the graft as well as exposing that segment of aorta to the systemic blood pressure and other systemic hemodynamic effects. This defeats the entire concept of treatment of aneurismal disease, as the aortic wall is not entirely excluded after placement of the endoluminal graft. The migration of the endoluminal graft that might occur due to leakage around the fenestration might also compromise the blood flow to the branch anatomic conduit. 
     U.S. Pat. No. 6,428,565 (Wisselink et al.) discloses an endovascular graft that forms connections with the branch anatomic conduit with separate conduits. However, the technique and methods disclosed by Wisselink et al. have inherent deficiencies in more than one area. Wisselink et al. use conventional x-ray imaging techniques to introduce the grafts into the human body, but do not describe the delivery system and the technique of delivery such that it would make the procedure safer and most efficient. The use of conventional radiological methods to position a stent, graft, or prostheses is routine, but in this instance, the landing zone is very limited. Thus, in conjunction with fluoroscopy, an additional technique is required to align the endoaortic graft with the branch anatomic conduit and position the branch graft in such a manner that once completed, a conduit is created that supplies the branch anatomic conduit with unhampered blood flow. Wisselink et al.&#39;s method for coupling of the branch graft to the aortic graft is prone to dislodgement thus prone to leakage of blood around the prosthesis. This will also promote graft migration. Post-implant migration and leakage may lead to obstruction of blood flow to the branch anatomic conduits. 
     U.S. Pat. No. 6,352,543 (Cole et al.) discloses a method of forming anastomosis between two hollow bodies, and the use of magnetic force as a coupling force to form a fluid tight junction. Cole et al.&#39;s method in all its embodiments uses magnetic material as an anastomotic securing force and thus forms the actual fluid tight connections. However, this technique causes a rigid connection between two hollow organs that may lead to potential problems due to their fixed nature, and in the event of anastomotic narrowing are not amenable to interventional techniques in correcting the problems. Cole et al.&#39;s method uses magnetic force as a method of attachment and refers to it as the means of anastomosis. 
     Thus, in view of the above-discussed limitations and shortcomings, there remains a need in the art for development of new endovascular grafting systems and methods which (a) may be useable for endovascular grafting in regions of the aorta where branch anatomic conduits (e.g., subclavian, innominate, carotid, intercostals, celiac, mesenteric, renals and iliac arteries) extend, and/or (b) may enable more aortic aneurysms patients to be candidates for endovascular repair, and/or (c) may advance the state of the art of endovascular grafting to improve patient outcomes or lessen complications. 
     It is to the solution of these and other problems that the present invention is directed. 
     SUMMARY OF THE INVENTION 
     It is accordingly a primary object of the present invention to extend the benefit of endoluminal grafting to a large population of patients that suffer with aneurismal disease of the aorta that involves its major branches. 
     It is another object of the present invention to provide a system and method for endoluminal grafting of a blood vessel or other anatomic conduit, in a region where one or more branch anatomic conduits (e.g., side branches, furcating, etc.) extend from the main anatomic conduit. 
     It is still another object of the present invention to provide endovascular grafting systems and methods which (a) may be useable for endovascular grafting in regions of the aorta where branch anatomic conduits (e.g., subclavian, innominate, carotid, intercostals, celiac, mesenteric, renals and iliac arteries) extend, and/or (b) may enable more aortic aneurysms patients to be candidates for endovascular repair, and/or (c) may advance the state of the art of endovascular grafting to improve patient outcomes or lessen complications. 
     These and other objects of the invention are provided by a system and method for endoluminal grafting of a main anatomic conduit in its diseased state in which it dilates to pose a life threatening condition (e.g., aortic aneurysms) and its various conduits (e.g., side branch anatomic conduits such as the left common carotid, subclavian, innominate, intercostals, superior mesenteric, celiac, or renal arteries or bifurcation such as the iliac arteries) that emanate from the main anatomic conduit. 
     The grafting system comprises 1) an endoaortic graft (endoaortic cuff) having at least one opening therein and 2) at least one branch graft that is passable through the opening of the endoaortic graft into the branch anatomic conduit(s) such that the junction between the branch graft and the endoaortic graft is substantially fluid tight. 
     In one aspect, the invention comprises a system and method for delivery of the endoaortic graft and also a system and method for efficient alignment and deployment of the branch (e.g., side branch) graft such that the coupling of the branch graft with the endoaortic graft is efficient and exact and fluid-tight. 
     In another aspect, the invention comprises a system and method for coupling the branch conduit to the endoaortic graft via a coupling mechanism employing a memory metal alloy. Two different embodiments of coupling mechanisms are provided, the coupling mechanism being chosen depending on the site and anatomic location of the branch conduit. In one embodiment, the coupling mechanism is incorporated in the endoaortic graft and in the other embodiment, the coupling mechanism is incorporated in the endobranch graft. 
     In still another aspect, the invention comprises a system and method for the proper and exact alignment of the endoaortic graft and the branch conduit using magnetic force of a suitable nature, and which does not use the magnetic force as the coupling mechanism. 
     Other objects, features and advantages of the present invention will be apparent to those skilled in the art upon a reading of this specification including the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is better understood by reading the following Detailed Description of the Preferred Embodiments with reference to the accompanying drawing figures, in which like reference numerals refer to like elements throughout, and in which: 
         FIG. 1A  is a perspective view of a first embodiment of an endoaortic graft in accordance with the present invention. 
         FIG. 1B  is a cross-sectional view of the endoaortic graft of  FIG. 1 . 
         FIG. 2A  is a cross-sectional view of a delivery system for introducing the endoaortic graft of  FIGS. 1A-1B  into a native, main anatomic conduit in accordance with first and second embodiments of the present invention. 
         FIG. 2B  is a cross-sectional view taken along line  2 B of  FIG. 2A . 
         FIG. 2C  is a cross-sectional view taken along line  2 C of  FIG. 2A . 
         FIG. 3A  is a side elevational view of a branch graft in accordance with a first embodiment of the present invention. 
         FIG. 3B  is an enlarged perspective view of the connector mechanism of the branch graft of  FIG. 3A , for coupling the branch graft with the endoaortic graft of  FIG. 1A , in the deployed position. 
         FIG. 4A  is a cross-sectional view of a delivery system for introducing the branch graft into a branch anatomic conduit of a main anatomic conduit in accordance with a first embodiment of the present invention. 
         FIG. 4B  is a cross-sectional view of the delivery system of  FIG. 4A , in which the branch graft has been deployed. 
         FIG. 5A  is a partial perspective view of the outside of an endoaortic graft in accordance with a second embodiment of the present invention. 
         FIG. 5B  is a partial perspective view of the inside of the endoaortic graft of  FIG. 5A  with the coupling mechanism for coupling with the branch graft in the open position, the struts and the magnetic ring being omitted for clarity. 
         FIG. 5C  is a partial perspective view of the inside of the endoaortic graft of  FIG. 5A  with the coupling mechanism for coupling with the branch graft in the closed position, the struts and the magnetic ring being omitted for clarity. 
         FIG. 5D  is an enlarged view of the coupling mechanism for coupling with the branch graft of  FIGS. 5B and 5C , in the closed position, the struts being omitted for clarity. 
         FIG. 6A  is a view of the coupling mechanism of  FIGS. 5B and 5C , in the open position, and its accompanying struts, the flexible magnetic ring being omitted for clarity. 
         FIG. 6B  is a view of the coupling mechanism of  FIGS. 5B and 5C , in the closed position, and its accompanying struts, the flexible magnetic ring being omitted for clarity. 
         FIG. 7A  is a side elevational view of a branch graft in accordance with a second embodiment of the present invention. 
         FIG. 7B  is a top elevational view of the branch graft of  FIG. 7A . 
         FIGS. 8A and 8B  are cross-sectional views of second embodiment of an endoaortic graft in accordance with the present invention, with different attachment mechanisms for the magnetic ring. 
         FIG. 9A  is a cross-sectional view of a delivery system for introducing the branch graft of  FIG. 7A  into a branch anatomic conduit of a main anatomic conduit in accordance with another embodiment of the present invention. 
         FIG. 9B  is an enlarged perspective view of the distal end of the delivery system of  FIG. 9A . 
       FIGS.  10 A- 10 DD illustrate the steps in the method for endoluminal grafting of blood vessels or other tubular, main anatomic conduits, in a region where one or more branch anatomic conduits extend from the main anatomic conduit, using the endoatoric graft, the endoaortic graft delivery system, the branch anatomic graft, and the branch graft delivery system in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In describing preferred embodiments of the present invention illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. 
     The present invention provides a system and method for endoluminal grafting of a blood vessel or other native, main anatomic conduit, in a region where one or more branch anatomic conduits (e.g., side branches, furcating, etc.) extend from the main anatomic conduit. 
     In accordance with a first embodiment of the present invention, the endoluminal grafting system  50  comprises an endoaortic graft  100  (also referred to herein as an “endoaortic cuff”) ( FIGS. 1A-1B ), an endoaortic graft delivery system  200  for introducing the endoaortic graft  100  into a native, main anatomic conduit  10  ( FIGS. 2A-2C ), a branch graft  300  ( FIG. 3 ), and a branch graft delivery system  400  for housing the branch graft  300  and introducing it into a branch anatomic conduit  20  extending from the main anatomic conduit  10  ( FIGS. 4A-4B ). 
     As shown in  FIGS. 1A-1B , the endoaortic graft  100  comprises a first pliable tube (i.e., a tube formed of a pliable material) having a lumen  112  extending longitudinally therethrough; at least one branch opening  114  (e.g., an aperture) formed in the first pliable tube  110 ; a flexible magnetic ring  120  incorporated around the at least one branch opening  114  of the first pliable tube  110 ; and an endoaortic graft anchoring device  130  for holding the first pliable tube  110  in substantially fixed place within the main anatomic conduit  10 , such that the branch opening  114  is in alignment with the branch anatomic conduit  20 . The pliable material can be woven polyester, expanded polytetrafluroethalene (ePTFE), and other pliable, biocompatible materials. The endoaortic graft anchoring device  130  can be, but is not limited to, such conventional devices as a radially expandable stent, a frame, a series of rings, and/or adhesive sutures, staples, etc. 
     The endoaortic graft  100  of the first embodiment of the invention can have several embodiments. In a first embodiment, shown in  FIGS. 1A-1B , the flexible magnetic ring  120  is positioned on, and is permanently secured to, the exterior surface of the first pliable tube  110 . In a second embodiment, shown in  FIGS. 8A and 8B , the flexible magnetic ring  120  is positioned on, and is removably secured to, the interior surface of the first pliable tube  110 . The second embodiment may be preferable for smaller grafts or other situations where it may not be desirable to leave the magnetic ring in place. In the second embodiment, the flexible magnetic ring  120  can be removably secured to the interior surface of the first pliable tube  110  by flexible hooks  122  ( FIG. 8A ) or by a friction fit with a flexible bushing  124  secured to the interior surface of the first pliable tube  110  ( FIG. 8B ). One or more wires  140  are attached to the removable magnetic ring  120  for separating the removable magnetic ring  120  from the flexible hooks  122  or bushing  124  and withdrawing it from patient. 
     As shown in  FIGS. 2A-2C , in accordance with the first embodiment of the invention, the endoaortic graft delivery system  200  comprises a flexible outer sheath  210 , which functions as a delivery catheter, a flexible inner central sheath  220 , at least one flexible inner side sheath  230 , and a tapered and flexible tip  240  at the distal end of the inner central sheath  220 , the tip  240  forming the nose cone of the delivery system. The inner central sheath  220  is substantially concentric with the outer sheath  210  for carrying an axial guide wire  30  (shown in  FIGS. 10A-10J ). The at least one inner side sheath  220  is radially positioned between the inner central sheath  220  and a corresponding branch opening  114  in the first pliable tube  110  for carrying a corresponding separate branch anatomic conduit guide wire  40  (shown in  FIGS. 10C-10J ) that is to be passed into a corresponding side branch anatomic conduit  20 . The tapered, flexible tip  240  has an aperture  242  to allow the passage of the axial guide wires  30  therethrough. The endoaortic graft  100  is loaded in the endoaortic graft delivery system  200  such that the central sheath  220  carrying the axial guide wire  30  is centrally located therethrough, and the at least one inner side sheath  220  carrying a corresponding branch guide wire  40  to a corresponding branch anatomic conduit  20  is positioned within the first pliable tube  110  downstream of the branch opening  114  and traverses through the branch opening  114 . 
     As shown in  FIG. 3A  the branch graft  300  in accordance with the first embodiment of the invention comprises a second pliable tube  310  (i.e., a tube formed of a pliable material) having a lumen  312  extending therethrough and having a proximal end  314 , a mid-portion  3 l 6 , and a distal end  318 ; a connector mechanism  320  at the proximal end; and a branch graft anchoring device  330  at the distal end  318 . The second pliable tube  310  is sized to be receivable through the flexible magnetic ring  120  of the endoaortic graft  100  such that the junction between the branch graft  300  and the endoaortic graft  100  is substantially fluid tight. The pliable material can be woven polyester, expanded polytetrafluroethalene (ePTFE), or other pliable, biocompatible material. The connector mechanism  320  is made from a memory metal (such as nitinol) and is associated with the proximal end of the second pliable tube. When activated, the connector mechanism  320  is able to form a connection with the corresponding branch opening  114  in the first pliable tube  110 , such that the fluid that flows through the lumen  112  of the first pliable tube  110  can pass through the branch opening  114  in the first pliable tube  110  and into the lumen  312  of the branch graft  300 . The mid-portion  316  is configured with a corrugated section  316   a  to maintain a patent lumen of the second pliable tube  310 , such that the branch graft  300  is kink-resistant in an angular situation. The branch graft anchoring device  330  is operative to hold at least the distal end  318  of the branch graft  300  in contact with the surrounding wall of the branch anatomic conduit  20 . The branch graft anchoring device  330  can be, but is not limited to, a radially expandable stent, a frame, hooks, rings, sutures, staples, and/or adhesive, staples. 
     As shown in  FIGS. 4A-4B , in accordance with the first embodiment of the invention, the branch graft delivery system  400  comprises an arrangement of three substantially concentric, flexible, hollow sheaths, an outer sheath  410 , an inner sheath  420 , and a middle sheath  430  between the outer and inner sheaths  410  and  420 . Prior to deployment, the distal ends  422  and  432  of the inner and middle sheaths  420  and  430  are substantially coterminous, and the branch graft  300  is housed between the inner sheath  420  and the middle sheath  430 , so that the middle sheath  430  also covers the branch graft  300 . The outer sheath  410  cannot be retracted. At its distal end  412 , the outer sheath  410  carries a magnet  440 . The magnet  440  can have either a natural or an induced magnetic field, and can include an electromagnet, a ferromagnet, or a ferromagnetic fluid contained within a collar. The outer sheath  410  can also rotate so as to change the polarity of the magnet  440  in a particular plane, in order to disengage the branch graft delivery system  400  from the endoaortic graft  100 . The inner sheath  420  accommodates the guide wire going  40  into the branch anatomic conduit  20  so that the entire branch graft delivery system  400  can be passed over the guide wire  40 . The distal end  422  of the inner sheath  420  terminates in a tapered and flexible tip  450  forming the nose cone of the branch graft delivery system  400 . The tapered, flexible tip  450  has an aperture  452  therein to allow the passage of a guide wire  40  therethrough. 
     Because the middle sheath  430  covers both the inner sheath  420  and the branch graft  300 , when the middle sheath  430  is retracted, it will uncover the branch graft  300  such that the branch graft  300  is deployed fully to form the new connection with the endoaortic graft  100 . 
     The branch graft delivery system  400  in accordance with the first embodiment of the invention is suited primarily for use in axial (straight line) situations, because the distal end is not particularly flexible. 
     The above-described endoluminal grafting system  50  in accordance with the first embodiment of the present invention can be implanted within the branched anatomic conduit by a method comprising the following steps:
         1) Advancing an axial guide wire  30  into the body of the aneurysm ( FIGS. 10A-10B ), and then advancing at least one other, more pliable balloon tipped guide wire  40  into the branch anatomic conduit using the endoaortic graft delivery system  200  ( FIGS. 10C-10I );   2) Transluminally advancing the endoaortic graft  100  over the guide wires  30  and  40  into the branched, main anatomic conduit  10  using the endoaortic graft delivery system  200  ( FIGS. 10J-10M ;   3) Positioning the endoaortic graft  100  within the anatomic conduit  10  using the endoaortic graft delivery system  200  such that the branch opening  114  is aligned with the branch anatomic conduit  20  ( FIGS. 10N-10P );   4) Utilizing the endoaortic graft anchoring device  130  to anchor the endoaortic graft  100  within the main anatomic conduit  10  (not shown);   5) Transluminally advancing the branch graft  300  loaded in the branch graft delivery system  400  over the guide wire  40  to the branch anatomic conduit  20  ( FIGS. 10Q-10R );   6) Passing the distal end of the branch graft delivery system containing the branch graft  300  through the branch opening  114  and into the branch anatomic conduit  20 , until the magnetic ring  120  of the endoaortic graft  100  and the magnet  440  on the branch graft delivery system  400  attach ( FIG. 10S );   7) Operating the branch graft delivery system  400  such that the branch graft  300  is deployed in the branch anatomic conduit  20 , until such time as the retractable middle sheath  430  of the branch graft delivery system  400  is fully retracted ( FIGS. 10T-10V );   8) Once the retractable middle sheath  430  of the branch graft delivery system  400  is fully retracted, rotating the outer sheath  410  of the branch graft delivery system  400  by 180 degrees to switch the magnetic poles to allow the two magnets  120  and  440  to disengage as well as deploy the most proximal part of the nitinol connector mechanism  320 , allowing the leak proof connection between the branch graft  300  and the endoaortic graft  100  (FIGS.  10 W- 10 DD).       

     In accordance with a second embodiment of the present invention, the endoluminal grafting system  50 ′ comprises an endoaortic graft  100 ′ ( FIGS. 5A-5D ), an endoaortic graft delivery system  200  for introducing the endoaortic graft  100 ′ into a native, main anatomic conduit  10  ( FIGS. 2A-2C ), a branch graft  300 ′ ( FIGS. 7A-7B ), and a branch graft delivery system  400  for housing the branch graft  300 ′ and introducing it into a branch anatomic conduit  20  extending from the main anatomic conduit  10  ( FIGS. 4A-4B ). 
     As shown in  FIGS. 5A-5D , the endoaortic graft  100 ′ comprises a first pliable tube  110  (i.e., a tube formed of a pliable material) having a lumen  112  extending longitudinally therethrough; at least one branch opening  114  (e.g., an aperture) formed in the first pliable tube  110 ; a flexible magnetic ring  120  incorporated around the at least one branch opening  114  of the first pliable tube; a coupling mechanism  150  for coupling the branch graft  300 ′ to the flexible magnetic ring  120 ; and an endoaortic graft anchoring device  130  for holding the first pliable tube  110  in substantially fixed place within the main anatomic conduit  10 , such that the branch opening  114  is in alignment with the branch anatomic conduit  20 . The pliable material can be woven polyester, expanded polytetrafluroethalene (ePTFE), and other pliable, biocompatible materials. The coupling mechanism  150  is as shown in  FIG. 5D  and  FIGS. 6A-6B , and comprises a plurality of staples  152  extending outwardly from the perimeter of the flexible magnetic ring  120 , and a plurality of struts  154  that hold the staples  152  in the open position and are releasable to allow the staples  152  to close. The staples  152  preferably are made from a memory metal (such as nitinol). The endoaortic graft anchoring device  130  can be, but is not limited to, such conventional devices as a radially expandable stent, a frame, a series of rings, and/or adhesive sutures, staples, etc. 
     The endoaortic graft delivery system  200  of the second embodiment of the present invention is the same as shown and described in connection with the first embodiment. 
     As shown in  FIGS. 7A-7B , the branch graft  300 ′ comprises a second pliable tube  310 ′ (i.e., a tube formed of a pliable material) having a lumen  312  extending therethrough, and having a collapsible, toroidal-shaped proximal end  314 ′ defining a connector mechanism, a mid-portion  316 , and a distal end  318 ; and a branch graft anchoring device  330  at the distal end. The pliable material can be woven polyester, expanded polytetrafluroethalene (ePTFE), or other pliable, biocompatible material. The toroidal proximal end  314 ′ can be a hollow silastic ring filled with a ferro-fluid (that is, a fluid with magnetic particles suspended therein). The second pliable tube  310 ′ is sized to be receivable through the flexible magnetic ring  120  of the endoaortic graft  100 ′ such that the junction between the branch graft  400  and the endoaortic graft  100 ′ is substantially fluid tight, and the ferro-fluid has sufficient magnetic properties to be attracted to the flexible magnetic ring  120  yet still be easily movable relative thereto. The mid-portion  316  is configured with a corrugated section  316   a  to maintain a patent lumen of the second pliable tube  310 ′, such that the branch graft  300 ′ is kink-resistant in an angular situation. The branch graft anchoring device  330  is positioned at the distal end  318  and is operative to hold at least the distal end  318  of the branch graft  300 ′ in contact with the surrounding wall of the branch anatomic conduit  20 . The branch graft anchoring device  330  can be, but is not limited to, a radially expandable stent, a frame, hooks, rings, sutures, staples, and/or adhesive, staples. 
     The branch graft delivery system  400  of the second embodiment of the present invention is the same as shown and described in connection with the first embodiment. 
     The above-described endoluminal grafting system  50 ′ in accordance with the second embodiment of the present invention can be implanted within the branched anatomic conduit  10  by a method comprising the same steps (1) through (7) as in accordance with the first embodiment, and the following additional steps:
         8) Once the retractable middle sheath  430  of the branch graft delivery system  400  is fully retracted, rotating the outer sheath  410  of the branch graft delivery system by 180 degrees to switch the magnetic poles to allow the two magnets  120  and  440  to disengage.   9) Withdrawing the branch graft delivery system  400 ;   10) Advancing another guidewire with a hook or snare mechanism through the lumen  112  of the endoaortic graft  100 ′;   11) Under fluoroscopy, using the hook or snare mechanism to engage the struts  154  of the endoaortic graft coupling mechanism  150  and apply traction to them to deploy the staples  150  and engage the toroidal proximal end  314 ′ of the branch graft  300 ′.       

     In accordance with a third embodiment of the present invention, the endoluminal grafting system  50 ″ comprises the endoaortic graft  100  of  FIGS. 1A-1B ,  5 A- 5 D or  8 , the endoaortic graft delivery system  200  shown in  FIGS. 2A-2C , a branch graft  300  as shown in  FIG. 3 , and a branch graft delivery system  400 ′ shown in  FIGS. 9A and 9B  for housing and introducing the branch graft  300 . The branch graft delivery system  400 ′ of  FIGS. 9A and 9B  is similar to that of  FIGS. 4A-4B  in also comprising an arrangement of three substantially concentric, flexible, hollow sheaths, an outer sheath  410 , an inner sheath  420 , and a middle sheath  430  between the outer and inner sheaths, a magnet  440  carried at the distal end  412  of the outer sheath  410 , and a nose cone  450  terminating the distal end  422  of the inner sheath  420 . However, in the endoaortic graft delivery system  200  in accordance with the third embodiment of the invention, prior to deployment, the distal end  422  of the inner sheath  420  extends outwardly of the distal ends  412  and  432  of the outer and middle sheaths  410  and  430 , with the branch graft  300  loaded over the distal end  432  of the middle sheath  430  with only the connector mechanism  320  housed between the outer and middle sheaths  410  and  430 . Further, the branch graft delivery system  400 ′ includes means  460  for maintaining the branch graft  300  in a contracted condition prior to deployment. 
     In the third embodiment of the invention, the means  460  for maintaining the branch graft  300  in a contracted position includes a deployment wire  462  radially positioned between the inner and middle sheaths  420  and  430 , and a thread  464  wrapped around both the contracted branch graft  300  and the deployment wire  462 . The thread  464  is made of a biodegradable, absorbable material (for example, PTF or synthetic, absorbable suture sold under the trademarks Vicryl® and Monocryl®). One end  464   a  of the thread  464  is left as a tail extending at least the length of the outer sheath  412  and the other end (not shown) is secured on itself, for example by a half-knot, to prevent the wrapping from unraveling. The thread  464  is wrapped about the deployment wire  462  and the branch graft  300  in a figure-eight configuration, so that when the deployment wire  462  is retracted, the wrapping unravels, allowing the branch graft  300  to assume an expanded condition. 
     The third embodiment of the invention, in which the branch graft delivery system  400 ′ employs a wrapping, is particularly suited to use in a non-axial (curved) situation, as the distal end of the branch graft delivery system  400 ′ is relatively flexible, although it can also be used in axial situations. 
     The above-described endoluminal grafting system  50 ″ in accordance with the third embodiment of the present invention can be implanted within the branched anatomic conduit  10  by a method comprising the same steps (1) through (6) as in accordance with the first embodiment, and the following additional steps:
         7) Operating the branch graft delivery system  400 ′ such that the branch graft  300  is deployed in the branch anatomic conduit  20 , until such time as the retractable middle sheath  430  of the branch graft delivery system  400 ′ is fully retracted;   8) Once the retractable middle sheath  430  of the branch graft delivery system  400 ′ is fully retracted, rotating the outer sheath  410  of the branch graft delivery system  400 ′ by 180 degrees to switch the magnetic poles to allow the two magnets  120  and  440  to disengage as well as deploy the most proximal part of the nitinol connector mechanism  320 , allowing the leak proof connection between the branch graft  300  and the endoaortic graft  100 .       

     Modifications and variations of the above-described embodiments of the present invention are possible, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described.