Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. Non-Provisional application Ser. No. 11/063,085 filed Feb. 22, 2005 now U.S. Pat. No. 8,048,140, which application in turn claims priority of provisional application Ser. No. 60/558,168, filed Mar. 31, 2004, the complete disclosures of which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention relates to a medical device and, in particular, a prosthesis for implantation within the human or animal body for the repair of damaged vessels such as blood vessels, and a method for implanting the same. 
     2. Related Art 
     Throughout this specification, when discussing the aorta or other blood vessels, the terms distal and distally with respect to a prosthesis are intended to refer to the end of the prosthesis furthest away in the direction of blood flow from the heart. Similarly, the terms proximal and proximally are intended to mean the end of the prosthesis which when implanted would be nearest to the heart. 
     The functional vessels of humans, such as blood vessels and ducts, occasionally weaken or even rupture. For example, the aortic wall can weaken, resulting in an aneurysm. Upon further exposure to haemodynamic forces, such an aneurysm can rupture. A common surgical intervention for weakened, aneurismal or ruptured vessels is the use of a prosthesis to provide some or all of the functionality of the original, healthy vessel and/or preserve any remaining vascular integrity by replacing a length of the existing vessel wall that spans the site of vessel failure. 
     The deployment of intraluminal prostheses into the lumen of a patient from a remote location by the use of a deployment device or introducer has been disclosed in a number of earlier patents and patent applications. U.S. Pat. No. 4,562,596, entitled “Aortic Graft, Device and Method for Performing an Intraluminal Abdominal Aortic Aneurysm Repair” which is herein incorporated by reference, proposes the retention of a self expanding graft within a sleeve until it is to be deployed, at which time the sleeve is withdrawn and the graft is allowed to expand. U.S. Pat. No. 4,665,918, entitled “Prosthesis System and Method” which is herein incorporated by reference, proposes a system and method for the deployment of a prosthesis in a blood vessel. The prosthesis is positioned between a delivery catheter and an outer sheath and expands outwardly upon removal of the sheath. 
     U.S. Pat. No. 4,950,227, entitled “Stent Delivery System” which is herein incorporated by reference, proposes the delivery of a stent by mounting the stent to the outside of an inflatable catheter and retaining the ends of an unexpanded stent by fitting a sleeve over either end of the stent. Expansion of the stent is caused by inflation of the catheter between the sleeves so that the ends of the stent are withdrawn from the respective sleeves and the stent released and expanded into position. 
     U.S. Pat. No. 5,387,235 entitled “Expandable Transluminal Prosthesis for Repair of Aneurysm”, discloses apparatus and methods of retaining grafts onto deployment devices. These features and other features disclosed in U.S. Pat. No. 5,387,235 could be used with the present invention and the disclosure of U.S. Pat. No. 5,387,235 is herein incorporated by reference. 
     U.S. Pat. No. 5,720,776 entitled “Barb and Expandable Transluminal Graft Prosthesis for Repair of Aneurysm” discloses improved barbs with various forms of mechanical attachment to a stent. These features and other features disclosed in U.S. Pat. No. 5,720,776 could be used with the present invention and the disclosure of U.S. Pat. No. 5,720,776 is herein incorporated by reference. 
     U.S. Pat. No. 6,206,931 entitled “Graft Prosthesis Materials” discloses graft prosthesis materials and a method for implanting, transplanting replacing and repairing a part of a patient and particularly the manufacture and use of a purified, collagen based matrix structure removed from a submucosa tissue source. These features and other features disclosed in U.S. Pat. No. 6,206,931 could be used with the present invention and the disclosure of U.S. Pat. No. 6,206,931 is herein incorporated by reference. 
     PCT Patent Publication Number No. WO99/29262 entitled “Endoluminal Aortic Stents” discloses a fenestrated prosthesis for placement where there are intersecting arteries. This feature and other features disclosed in PCT Patent Publication Number No. WO99/29262 could be used with the present invention and the disclosure of PCT Patent Publication Number No. WO99/29262 is herein incorporated by reference. 
     PCT Patent Publication Number No. WO03/034948 entitled “Prostheses for Curved Lumens” discloses prostheses with arrangements for bending the prosthesis for placement into curved lumens. This feature and other features disclosed in PCT Patent Publication Number No. WO03/034948 could be used with the present invention and the disclosure of PCT Patent Publication Number No. WO03/034948 is herein incorporated by reference. 
     United States Patent Application Publication No. 2003/0233140 entitled “Trigger Wire System” discloses release wire systems for the release of stent grafts retained on introducer devices. This feature and other features disclosed in United States Patent Application Publication No. 2003/0233140 could be used with the present invention and the disclosure of United States Patent Application Publication No. 2003/0233140 is herein incorporated by reference. 
     United States Patent Application Publication No. 2004/0098079 entitled “Thoracic Deployment Device” discloses introducer devices adapted for deployment of stent grafts particularly in the thoracic arch. This feature and other features disclosed in United States Patent Application Publication No. 2004/0098079 could be used with the present invention and the disclosure of United States Patent Application Publication No. 2004/0098079 is herein incorporated by reference. 
     United States Patent Application Publication No. 2004/0054396 entitled “Stent-Graft Fastening” discloses arrangements for fastening stents onto grafts particularly for exposed stents. This feature and other features disclosed in United States Patent Application Publication No. 2004/0054396 could be used with the present invention and the disclosure of United States Patent Application Publication No. 2004/0054396 is herein incorporated by reference. 
     PCT Patent Publication Number No. WO03/053287 entitled “Stent Graft with Improved Graft Adhesion” discloses arrangements on stent grafts for enhancing the adhesion of such stent grafts into walls of vessels in which they are deployed. This feature and other features disclosed in PCT Patent Publication Number No. WO03/053287 could be used with the present invention and the disclosure of PCT Patent Publication Number No. WO03/053287 is herein incorporated by reference. 
     PCT Patent Publication Number No. WO98/53761 entitled “A Prosthesis and a Method and Means of Deploying a Prosthesis”, which is herein incorporated by reference, discloses various embodiments of an introducer for positioning an expandable endovascular prosthesis in a lumen of a patient. 
     One issue that arises with the use of an intraluminal prosthesis is where the damage in a vessel is at or near a branching vessel. For example, an abdominal aortic aneurysm can exist near the renal arteries, and a thoracic aortic aneurysm can exist near the left subclavian, common carotid, and/or innominate arteries. It would be desirable to prevent the prostheses from obstructing such a branch vessel. It may also be desirable to include a fenestration in a wall of an intraluminal prosthesis to allow fluid communication between the interior cavity of the prosthesis and a branch vessel adjacent to the prostheses. It may be further desirable to maintain an alignment between such a fenestration and an opening to a branch vessel. 
     SUMMARY 
     An intraluminal prosthesis is provided for strengthening a main lumen and a branch lumen in direct fluid communication with the main lumen. The prosthesis comprises a first tubular graft having a first flexible body, which includes a wall with a fenestration having a linear dimension. The prosthesis also comprises a second tubular graft having a second flexible body. The second tubular graft also includes a self-expanding stent with a terminal loop coupled that is coupled to a longitudinal end of the second flexible body. The self-expanding stent, when in an expanded state, has curvature such that the terminal loop is substantially in the same plane as the longitudinal end of the second flexible body. The second tubular graft is configured for endoluminal coupling with the first tubular graft. 
     An intraluminal prosthesis is provided for strengthening a branch lumen. The intraluminal prosthesis can comprise a flexible body made from a graft material and having a tubular interior passage. The prosthesis can also comprise a plurality of self expanding stents coupled along the length of the flexible body. A terminal stent can be coupled to and extend substantially radially outwardly from the proximal end of the flexible body. 
     A method of assembling a prosthesis intraluminally is also provided. The method can include providing a first tubular graft that has an inner passage, an outer surface, and a fenestration through the outer surface to the inner passage. The method can further include providing a second tubular graft having an inner passage, an outer surface, and a proximal end. The method can also include inserting the proximal end of the second tubular graft into the fenestration of the first tubular graft, and coupling the second tubular graft to the first tubular graft so that the inner passage of the second tubular graft is in fluid communication with the inner passage of the first tubular graft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views. 
         FIG. 1A  is an exploded perspective view of an introducer a prosthesis partially deployed. 
         FIG. 1B  is detail perspective view of a portion of the prosthesis shown in  FIG. 1A . 
         FIG. 2  is a sectional view of a portion of the introducer around the proximal end of the prosthesis. 
         FIG. 3  is a sectional view of a portion of the introducer around the distal end of the prosthesis. 
         FIG. 4  is a sectional view of a portion of the introducer around the haemostatic seal. 
         FIG. 5  is a sectional view of a portion of the introducer around the trigger wire release mechanisms. 
         FIG. 6  is a sectional view of a portion of the introducer around the pin vise clamp and the medical reagent introduction tube. 
         FIG. 7  is an exploded sectional view of the introducer of  FIG. 1A  fully loaded and ready for introduction into a patient. 
         FIG. 8  is an exploded view partially in section of the introducer of  FIG. 7  in the next stage of deployment of the prosthesis. 
         FIG. 9  is an exploded view partially in section of the introducer of  FIG. 7  with the release of the proximal end stage of deployment. 
         FIG. 10  is an exploded view partially in section of the introducer of  FIG. 7  with the release of the distal end stage of deployment. 
         FIG. 11  is an exploded view partially in section similar to  FIG. 10  showing the advancement of the distal attachment mechanism to the proximal attachment mechanism. 
         FIG. 12  is an exploded view partially in section similar to  FIG. 10  showing the withdrawal of the introducer. 
         FIG. 13  is a perspective view of a second introducer with a branch prosthesis partially deployed. 
         FIG. 14  is a sectional view of a portion of the introducer of  FIG. 13  around the proximal end of the branch prosthesis. 
         FIG. 15  is a sectional view of a portion of the introducer of  FIG. 13  around the distal end of the branch prosthesis. 
         FIG. 16  is an isometric view of the branch prosthesis shown in  FIG. 13 . 
         FIG. 17  is an elevation view of a main lumen and a branch lumen in fluid communication with the main lumen. 
         FIG. 18  is a sectional view of the main lumen and the branch lumen of  FIG. 17  after the prosthesis of  FIGS. 1A and 1B  has been implanted. 
         FIG. 19  is a sectional view of the main lumen and the branch lumen of  FIG. 17  after the branch prosthesis of  FIG. 13  has been implanted in the prosthesis of  FIG. 1A  through the fenestration shown in  FIG. 1B . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1A  shows an endoluminal prosthesis  20 , and an endovascular deployment system, also known as an introducer, for deploying the prosthesis  20  in a lumen of a patient during a medical procedure. The term “prosthesis” means any replacement for a body part or function of that body part. It can also mean a device that enhances or adds functionality to a physiological system. The terms “intraluminal” and “endoluminal” describes objects that are found or can be placed inside a lumen in the human or animal body. A lumen can be an existing lumen or a lumen created by surgical intervention. This includes lumens such as blood vessels, parts of the gastrointestinal tract, ducts such as bile ducts, parts of the respiratory system, etc. “Endoluminal prosthesis” or “Intraluminal prosthesis” thus describes a prosthesis that can be placed inside one of these lumens. 
     The introducer shown in  FIG. 1A  includes an external manipulation section  1 , a distal positioning mechanism attachment region  2  and a proximal positioning mechanism attachment region  3 . During the medical procedure to deploy the prosthesis  20 , the distal and proximal attachment regions  2  and  3  will travel through the lumen to a desired deployment site. The external manipulation section  1 , which is acted upon by a user to manipulate the introducer, remains outside of the patient throughout the procedure. 
     The prosthesis  20  comprises a tubular graft material  50 , with self expanding stents  19  attached thereto. The term “graft” means the generally cannular or tubular member which acts as an artificial vessel. A graft by itself or with the addition of other elements can be an endoluminal prosthesis. The term “stent” means any device or structure that adds rigidity, expansion force or support to a prosthesis. 
     The tubular graft material  50  is preferably non-porous so that it does not leak or sweat under physiologic forces. The graft material is preferably made of woven DACRON® polyester (VASCUTEK® Ltd., Renfrewshire, Scotland, UK). The tubular graft can be made of any other at least substantially biocompatible material including such materials as other polyester fabrics, polytetrafluoroethylene (PTFE), expanded PTFE, and other synthetic materials known to those of skill in the art. Naturally occurring biomaterials, such as collagen, are also highly desirable, particularly a derived collagen material known as extracellular matrix (ECM), such as small intestinal submucosa (SIS). 
     Other examples of ECMs are pericardium, stomach submucosa, liver basement membrane, urinary bladder submucosa, tissue mucosa, and dura mater. SIS is particularly useful, and can be made in the fashion described in U.S. Pat. No. 4,902,508 to Badylak et al.; U.S. Pat. No. 5,733,337 to Carr; 17 Nature Biotechnology 1083 (November 1999); and WIPO Publication WO 98/22158 of May 28, 1998, to Cook et al., which is the published application of PCT/US97/14855. All of these patents and publications are incorporated herein by reference. 
     Irrespective of the origin of the graft material (synthetic versus naturally occurring), the graft material can be made thicker by making multi-laminate constructs, for example SIS constructs as described in U.S. Pat. No. 5,968,096, U.S. Pat. No. 5,955,110, U.S. Pat. No. 5,885,619, and U.S. Pat. No. 5,711,969. All of these patents are incorporated herein by reference. In addition to xenogenic biomaterials, such as SIS, autologous tissue can be harvested as well, for use in forming the graft material. Additionally elastin or elastin-like polypeptides (ELPs) and the like offer potential as a material to fabricate the graft material. 
     The self expanding stents  19  cause the prosthesis  20  to expand following its disengagement from the introducer. The prosthesis  20  also includes a self expanding zigzag stent  21  that extends from its proximal end. When it is disengaged, the self expanding zigzag stent  21  anchors the proximal end of the prosthesis  20  to the lumen. 
     One or more fenestrations  17  can be provided in the tubular graft material  50 . Radiographic markers  18  can be attached to the tubular graft material  50  adjacent to the fenestration  17  as shown in  FIG. 1B  in order to aid in the alignment of the fenestration  17  with a branch vessel. For example, the radiographic markers  18  can be small rings of metal, such as stainless steel, sewn to the tubular graft material  50  with suture, not shown. 
       FIG. 2  shows the proximal attachment region  3  in greater detail. The proximal attachment region  3  includes a cylindrical sleeve  10 . The cylindrical sleeve  10  has a long tapered flexible extension  11  extending from its proximal end. The flexible extension  11  has an internal longitudinal aperture  12 . The longitudinal aperture  12  facilitates advancement of the tapered flexible extension  11  along an insertion wire  13 . The aperture  12  also provides a channel for the introduction of medical reagents, which will flow through openings  14 . For example, it may be desirable to supply a contrast agent to allow angiography to be performed during placement and deployment phases of the medical procedure. 
     A thin walled tube  15 , which can be made of metal, is fastened to the extension  11 . The thin walled tube  15  is sufficiently flexible so that the introducer can be advanced along a relatively tortuous vessel, such as a femoral artery. The thin walled tube  15  also facilitates manipulation longitudinally and rotationally of the proximal attachment region  3 . The thin walled tube  15  extends through the introducer to the manipulation section  1 , terminating at a connection means  16 , as shown in  FIG. 6 . 
     Regarding the introduction of reagents,  FIG. 6  also shows that the connection means  16  is adapted to accept a syringe to facilitate the introduction of reagents into the tube  15 . The tube  15  is in fluid communication with the aperture  12  of the flexible extension  11 . Therefore, reagents introduced into connection means  16  flow through the aperture  12  and emanate from the apertures  14 . 
     As shown in  FIG. 3 , a tube  41 , which can be made of plastic, is coaxial with and radially outside the thin walled tube  15 . The tube  41  is “thick walled”, that is to say the thickness of its wall is several times that of the thin walled tube  15 . A sheath  30  is coaxial with and radially outside the thick walled tube  41 . The thick walled tube  41  and the sheath  30  extend distally to the manipulation region  1 , as shown in  FIG. 5 . 
       FIGS. 2 and 3  illustrate distal and proximal retention and release mechanisms of the introducer, respectively. During the placement phase of the medical procedure, the prosthesis  20  is retained in a compressed condition by the sheath  30 . The sheath  30  extends distally to a gripping and haemostatic sealing means  35  of the external manipulation section  1 , shown in  FIG. 4 . 
     During assembly of the introducer, the sheath  30  is advanced over the cylindrical sleeve  10  of the proximal attachment region  3  while the prosthesis  20  is held in a compressed state by an external force. A distal attachment retention section  40  is formed in the thick walled tube  41  to retain the distal end of the prosthesis  20 . Alternatively, the distal attachment section  40  can be a separate piece coupled to the thick walled tube  41 . 
     The self-expanding stent  21  is released by retracting the sheath  30 , removing the trigger wire  22 , and then sliding the proximal attachment region  3 , including the retention device  10 , proximally away from the stent  21 . Once the retention device  10  has cleared the self-expanding stent  21 , the stent  21  will expand. The trigger wire  22  and the proximal wire release mechanism  24  form a control member to selectively release the retention device  10  from the prosthesis  20  by holding the self-expanding stent  21  in the retention device  10  until the prosthesis  20  is positioned at a desired site in the lumen. 
     The distal end  42  of the prosthesis  20  is retained by the distal attachment section  40  of the thick walled tube  41 . The distal end  42  of the prosthesis  20  has a loop  43  through which a distal trigger wire  44  extends. The distal trigger wire  44  extends through an aperture  45  in the distal attachment section  40  into the annular region between the thin walled tube  15  and the thick walled tube  41 . 
     As shown in  FIG. 5 , the distal trigger wire  44  extends through the annular space between the thick walled tube  41  and the thin walled tube  15  to the manipulation region  1 . The distal trigger wire  44  exits the annular space at a distal wire release mechanism  25 . The distal trigger wire  44  and the distal wire release mechanism  25  form a control member to selectively disengage the distal retention section  40  from the prosthesis  20  when it is positioned at a desired site in the lumen. 
       FIG. 4  shows the haemostatic sealing means  35  of the external manipulation section  1  in greater detail. The haemostatic sealing means  35  includes a haemostatic seal  27  and a side tube  29 . The haemostatic seal  27  includes a clamping collar  26  that clamps the sheath  30  to the haemostatic seal  27 . The haemostatic seal  27  also includes a silicone seal ring  28 . The silicone seal ring  28  forms a haemostatic seal around the thick walled tube  41 . The side tube  29  facilitates the introduction of medical reagents between the thick walled tube  41  and the sheath  30 . 
       FIG. 5  shows a proximal portion of the external manipulation section  1 . The release wire actuation section has a body  36  that is mounted onto the thick walled tube  41 . The thin walled tube  15  passes through the body  36 . The distal wire release mechanism  25  is mounted for slidable movement on the body  36 . Similarly, the proximal wire release mechanism  24  is mounted for slidable movement on the body  36 . A pair of clamping screws  37  prevent inadvertent early release of the prosthesis  20 . 
     The positioning of the proximal and distal wire release mechanisms  24  and  25  is such that the proximal wire release mechanism  24  must be moved before the distal wire release mechanism  25  can be moved. Therefore, the distal end  42  of the prosthesis  20  cannot be released until the self-expanding zigzag stent  21  has been released and anchored to the lumen. A haemostatic seal  38  is provided so the release wires  22  and  44  can extend out through the body  36  to the release mechanisms  24  and  25  without unnecessary blood loss during the medical procedure. 
       FIG. 6  shows a distal portion of the external manipulation section  1 . A pin vise  39  is mounted onto the distal end of the body  36 . The pin vise  39  has a screw cap  46 . When screwed in, the vise jaws  47  clamp against (engage) the thin walled tube  15 . When the vise jaws  47  are engaged, the thin walled tube  15  can only move with the body  36 , and hence the thin walled tube  15  can only move with the thick walled tube  41 . With the screw cap  46  tightened, the entire assembly, except for the external sleeve  30 , can be moved as one. 
     The prosthesis  20  can be deployed in any method known in the art, preferably the method described in WO98/53761 in which the devise is inserted by an introducer via a surgical cut-down into a femoral artery, and then advanced into the desired position over a stiff wire guide  13 , shown in  FIGS. 2 and 3 , using endoluminal interventional techniques. For example,  FIGS. 7 through 12  show various stages of the deployment of the prosthesis  20  during an illustrative medical procedure. A guide wire  13  is introduced into the femoral artery and advanced until its tip is beyond the region into which the prosthesis  20  is to be deployed. 
     In  FIG. 7 , the introducer assembly is shown fully assembled ready for introduction into a patient. The prosthesis  20  is retained at each of its ends by the proximal and distal retaining assemblies respectively, and compressed by the external sleeve  30 . If it is an aortic aneurism which is to be grafted, the introducer assembly can be inserted through a femoral artery over the guide wire  13  in the form as shown in  FIG. 7 , and positioned by well known radiographic techniques not discussed here. The fenestration  17  of the prosthesis  20  can be aligned with a branch vessel, such as a renal artery, during this positioning. 
     In  FIG. 8 , the introducer assembly is in a desired position for deployment of the prosthesis  20 . The external sheath  30  is withdrawn to just proximal of the distal attachment section  40 . This action releases the middle portion of the prosthesis  20  so that it can expand radially. The proximal self-expanding stent  21 , however, is still retained within the retention device  10 . Also, the distal end  42  of the prosthesis  20  is still retained within the external sheath  30 . 
     By release of the pin vise  39  to allow small movements of the thin walled tubing  15  with respect to the thick walled tubing  41 , the prosthesis  20  can be lengthened or shortened or rotated or compressed for accurate placement in the desired location within the lumen. X-ray opaque markers, not shown, can be placed along the prosthesis  20  to assist with placement of the prosthesis. 
     In  FIG. 9 , the proximal trigger wire  22  has been removed, allowing the retention device  10  to be separated from the self-expanding zigzag stent  21 , as explained above. At this stage, the proximal trigger wire release mechanism  24  and the proximal trigger wire  22  can be removed completely. 
     Also, the screw cap  46  of the pin vise  39  has been loosened so that the thin walled tubing  15  can been pushed in a proximal direction to move the proximal attachment means  10  in a proximal direction. When the proximal attachment means  10  no longer surrounds the self-expanding stent  21  at the proximal end of the prosthesis  20 , the self-expanding stent  21  expands. When the self-expanding stent  21  expands, the hooks or barbs  26  on the self-expanding stent  21  grip into the walls of the lumen to hold the proximal end of the prosthesis  20  in place. 
     At this point, the distal end  42  of the prosthesis  20  is still retained by the distal attachment means  40 , with the loop  43  retained therein. The external sheath  30  is then withdrawn to distal of the distal attachment section  40  to allow the distal end  42  of the prosthesis  20  to expand. At this point, the distal end  42  of the prosthesis  20  can still be moved. Consequently, the prosthesis  20  can still be rotated or lengthened or shortened or otherwise moved to for accurate positioning. 
     In  FIG. 10 , the distal end  42  of the prosthesis  20  has been released by removal of the distal trigger wire  44 . At this stage, the distal trigger wire release mechanism  25  and the distal trigger wire  44  can be removed completely. This removal can be accomplished by passing the distal wire release mechanism  25  over the pin vise  39  and the connection means  16 . The loop  43  of the terminal distal self-expanding zigzag stent  19  is hence released, and the prosthesis  20  is now free to expand to the wall of the lumen. At this point, the introducer is ready to be removed. 
     In  FIG. 11 , the first stage of removal is shown. First, the distal attachment section  40  is advanced until it is received in the rear of the proximal attachment device  10 . Next, the proximal attachment device  10 , the tapered flexible extension  11 , and the distal attachment device  40  are removed together, as shown in  FIG. 11 . 
     In  FIG. 12 , the sheath  30  has been advanced to uncover the joint between the proximal attachment device  10  and the distal attachment section  40 . The sheath  30  can be removed with the proximal attachment device  10 , the tapered flexible extension  11 , and the distal attachment device  40 . Alternatively, these items could be removed separately, followed by removal of the external sleeve  30 . 
       FIG. 13  shows an endoluminal branch prosthesis  120 , and an endovascular introducer for deploying the branch prosthesis  120 . The branch prosthesis  120  is configured to have an outer diameter approximately equal to the diameter of the fenestration  17  of the prosthesis  20 , so that the branch prosthesis  120  can be tightly coupled to the prosthesis  20 . 
     The introducer includes an external manipulation section  101 , a proximal positioning mechanism  102  and a distal positioning mechanism  103 . The deployment of the prosthesis  120  and the actions of the distal and proximal attachment regions  103  and  102 , and the manipulation section  101  are fundamentally the same as for the deployment of the prosthesis  20  described above. 
     As shown in  FIGS. 14 and 15 , one major difference between the branch prosthesis  120  and the prosthesis  20  is that the branch prosthesis  120  is loaded into the introducer “backwards”, such that a self-expanding zigzag stent  121  is retained by the proximal positioning mechanism  102 . Additionally, the “proximal” end of the branch prosthesis  120  is nearest to the external manipulation section  101 , whereas the “proximal” end of the prosthesis  20  is farthest from the external manipulation section  1 . 
     The branch prosthesis  120  comprises a tubular graft material  150 , with self expanding stents  119  attached thereto. The tubular graft material  150  is preferably a non-porous material similar to the tubular graft material  50 . The self expanding stents  119  cause the branch prosthesis  120  to expand following its disengagement from the introducer. 
     The branch prosthesis  120  also includes a self expanding zigzag stent  121  that extends from its proximal end. When it is disengaged, the self expanding zigzag stent  121  anchors the proximal end of the branch prosthesis  120  to the internal wall of the prosthesis  20 . 
       FIGS. 14 and 15  illustrate proximal and distal retention and release mechanisms  102  and  103  of the introducer, respectively. During the placement phase of the medical procedure, the branch prosthesis  120  is retained in a compressed condition by a sheath  130 . 
     During assembly of the introducer, the sheath  130  is advanced over a cylindrical sleeve  110  of the distal attachment region  103  while the branch prosthesis  120  is held in a compressed state by an external force. A proximal attachment retention section  140  is formed in a thick walled tube  141  to retain the proximal end of the branch prosthesis  120 . Alternatively, the proximal attachment section  140  can be a separate piece coupled to the thick walled tube  141 . 
       FIG. 14  shows the proximal attachment region  102  in greater detail. The tube  141  is coaxial with and radially outside a thin walled tube  115 . The tube  141  is “thick walled”. The sheath  130  is coaxial with and radially outside the thick walled tube  141 . The thick walled tube  141  and the sheath  130  extend proximally and then distally to the manipulation region  101 , as shown in  FIG. 13 . 
     The proximal end  142  of the prosthesis  120 , including the self-expanding zigzag stent  121 , is retained by the proximal attachment section  140  of the thick walled tube  141 . The proximal end of the self-expanding zigzag stent  121  has a loop  143  through which a proximal trigger wire  144  extends. The proximal trigger wire  144  extends through an aperture  145  in the proximal attachment section  140  and into the annular region between the thin walled tube  115  and the thick walled tube  141 . 
       FIG. 15  shows the distal attachment region  103  in greater detail. The distal attachment region  103  includes a cylindrical sleeve  110 . The cylindrical sleeve  110  has a long tapered flexible extension  111  extending from its distal end. The flexible extension  111  has an internal longitudinal aperture  112 . The thin walled tube  115  is fastened to the extension  111 . 
     The distal most stent  119  is released by retracting the sheath  130 , removing the trigger wire  122 , and then sliding the distal attachment region  103 , including the retention device  110 , distally away from the distal most stent  119 . Once the retention device  110  has cleared the distal most stent  119 , the distal most stent  119  will expand. The distal most stent  119  can include barbs, as shown in  FIG. 16 , to facilitate anchoring the stent  119  to the lumen. 
     The trigger wire  122  and the distal wire release mechanism  124  form a control member to selectively release the retention device  110  from the prosthesis  120  by holding the distal most stent  119  in the retention device  110  until the prosthesis  120  is positioned at a desired site in the lumen. 
       FIG. 16  is an isometric view of the branch prosthesis  120 . As shown in  FIG. 16 , when fully expanded the self-expanding zigzag stent  121  has a curvature to facilitate anchoring of the branch prosthesis  120  to an interior wall of the prosthesis  20 . Outer portions of the self expanding stent  121  are seen to extend substantially radially outwardly from the tubular graft  150 . The self-expanding zigzag stent  121  allows the branch prosthesis  120  to resist the force of blood flow, which may tend to dislodge the branch prosthesis  120  from the prosthesis  20 . 
     The self-expanding zigzag stent  121  can have a parabolic or round curvature so that an end  125  of a loop  126  is located in about the same plane as an opening  127  of the branch prosthesis  120 . The self-expanding zigzag stent  121  can be mounted near the opening  127  of the branch prosthesis  120 , so the curvature of one loop  126  of the stent  121  is between about 120° and 200°, and preferable between about 170° and 190°. 
     The distal most stent  119  can have barbs  128  attached thereto. The barbs  128  can anchor the stent  119  to the lumen so that the branch prosthesis  120  does not slide into the prosthesis  20 . As mentioned above, hydrostatic forces in arteries, where blood flows from main vessels to branch vessels, will be significantly greater in the proximal to distal direction than in the reverse direction. Therefore, the self-expanding zigzag stent  121  will resist the greater force, and the barbs  128  coupled to the stent  119  will resist the lesser force, so that the branch prosthesis  120  remains securely anchored within the fenestration  17  of the main prosthesis  20 . 
     Radiographic markers  129  can be attached to the self-expanding zigzag stent  121 , to one of the stents  119  or to the tubular graft material  150 . For example, the radiographic markers  129  can be small rings of metal, such as stainless steel, wrapped around the stent  121  or one of the stents  119 , or sewn to the tubular graft material  150  with suture. Preferably, at least one radiographic marker  129  is located near the opening  127 , so that the opening  127  can be aligned with the fenestration  17  of the graft  20 . 
       FIG. 17  is a front view of a main lumen  175  and a branch lumen  176 , wherein the lumens  175  and  176  are in fluid communication with each other. The main lumen  175  has an aneurism, or weakness, which exists at the attachment point of the branch lumen  176 .  FIG. 18  shows the lumens  175  and  176  after the prosthesis  20  has been successfully implanted. The fenestration  17  is aligned with the opening of the branch lumen  176 . 
       FIG. 19  shows the lumens  175  and  176  after the prosthesis  120  has been successfully implanted. The prosthesis  20  reinforces the main lumen  175 . The branch prosthesis  120  performs two main functions. First, the branch prosthesis  120  keeps the fenestration  17  aligned so that the lumens  175  and  176  remain in fluid communication. Second, the branch prosthesis  120  reinforces the branch lumen  176 , which may also be weakened because of the aneurism. 
     Throughout this specification, unless the context requires otherwise, the words “comprise” and “include” and variations such as “comprising” and “including” will be understood to imply the inclusion of an item or group of items, but not the exclusion of any other item or group items. 
     While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Furthermore, although various indications have been given as to the scope of this invention, the invention is not limited to any one of these but can reside in two or more of these combined together. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.

Technology Category: 1