Patent Publication Number: US-2010121429-A1

Title: Stent Graft Having a Flexible, Articulable, and Axially Compressible Branch Graft

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to endoluminal stent graft structures. More particularly, the present invention relates to endoluminal stent grafts for use in a body vessel system that includes a main vessel and a branch vessel emanating from the main vessel. 
     2. Description of Related Art 
     A conventional endoluminal stent graft typically includes a radially expandable reinforcement structure, formed from a plurality of annular stent rings, and a cylindrically shaped graft material defining a main body to which the stent rings are coupled. Stent grafts are well known for use in tubular shaped human vascular or other body vessel. 
     At deployment, after intravascular insertion and transluminal transport, i.e., within the vessel, to the point of use within a damaged or diseased vessel, for example, an aneurysmal artery, a compressed stent graft is radially expanded. A stent graft is self-expandable or expandable by application of pressure applied outwardly to the interior portion of the stent graft. After deployment, the stent graft is fixed in place at the location of initial deployment within the vessel. Complications such as Type I endoleaks can occur if the stent graft migrates after deployment. 
     One approach in the prior art, used to securely fix the stent graft to the vessel at the point of initial deployment, relied on providing the stent graft with an outward biasing radial force at the contact interface between the stent graft and the interior wall of the vessel in which it was deployed. Typically, a radial force, biasing outwardly from the stent graft toward the interior wall of the vessel, was supplied by a spring element at one or both ends of the stent graft. The spring element urged the stent graft into abutting contact with the interior wall of the vessel where frictional forces between the spring element and the vessel interior wall provided both a liquid-tight seal between the stent graft and the vessel as well as fixation of the stent graft at its location of initial deployment. 
     In cases where the contact interface, sometimes called the landing zone, between the stent graft and the vessel wall is small, the surface area on the interior of the vessel available for application of outward radial force may be insufficient to firmly and permanently seal and fix the stent graft. An abdominal aortic aneurysm with a short “neck” for a landing zone is an example where the area available for application of radial force might not be enough to seal and fix a stent graft. 
     Accordingly, in the prior art, stent grafts sometimes included bare springs to extend the length of the stent graft such that the spring element contacted and could be fixed to healthy vessel tissue above or below the area of weakened or damaged vessel tissue. 
     Illustratively,  FIG. 1A  shows a partial cutaway view of a vessel system  150 , for example an artery system, containing one example of a deployed prior art stent graft  100 . Vessel system  150  includes a main vessel  152 , for example an aorta, and one or more branch vessels  154  emanating from main vessel  152 , such as renal arteries emanating from the aorta. Main vessel  152  includes an aneurysm  156 , i.e., a weakened, radially distending vessel segment, caused by disease. Aneurysm  156  is at risk of rupture resulting in, for example, extravasation of blood into the peritoneal cavity or into tissue surrounding diseased main vessel  152 . 
     An evolving method for treating aneurysmal disease of the type depicted in  FIG. 1A , is termed “endovascular aneurysmal exclusion”. The goal of endovascular aneurysmal exclusion is to exclude from the interior of aneurysm  156 , i.e., an aneurysmal sac  158 , all aorta pressurized fluid flow, thereby reducing the risk of rupture of aneurysm  156  requiring invasive surgical intervention. 
     One procedure developed to accomplish this goal entailed internally spanning affected main vessel  152  with stent graft  100 . Prior art stent graft  100  was positioned and deployed within main vessel  152  through a vessel system furcation  159 , such as an iliac artery of an artery system, with an insertion stent graft catheter (not shown) by percutaneous or cut-down procedures well know to those of skill in the art. Prior art stent graft  100  typically included a radially expandable cylindrical reinforcement structure, sometimes referred to simply as a stent  104 , formed from a plurality of annular stent rings  106  coupled to a biocompatible tubular graft material  102 . A bare spring element  108  of prior art stent graft  100  was coupled to the proximal end of stent graft material  102 . 
     Graft material  102  was configured in a tubular shape forming a main body  103  spanning across aneurysm  156 . Prior art stent graft  100  was fixed in main vessel  152  by bare spring element  108  which helped established a substantially fluid-tight seal above aneurysm  156  at a graft/vessel interface, sometimes called a landing zone  160 . Once deployed, prior art stent graft  100  provided an alternate conduit for fluid flow through main body  103  and, at the same time, excluded fluid flow into aneurysmal sac  158 . 
     In the prior art stent graft  100  of  FIG. 1A , graft material  102  did not extend beyond a branch point  162 , where branch vessel  154  begins to emanate from main vessel  152 , to the end of prior art stent graft  100  at bare spring element  108 . If graft material  102  were extended such that it passed by a vessel ostium  166  leading into branch vessel  154  from main vessel  152 , graft material  102  would block vessel ostium  166  and cut-off fluid flow into branch vessel  154 . 
     However, graft material  102  forming main body  103  may be advantageously utilized to assist in forming a liquid-tight seal between prior art stent graft  100  and healthy tissue beyond branch point  162  at landing zone  160  at the interior wall of main vessel  152  above diseased or damaged tissue at a neck  164  of aneurysm  156 .  FIG. 1B  shows a close-up, cross-section view of one branch point  162  of vessel system  150  of an embodiment similar to that shown in  FIG. 1A  containing an example of a deployed prior art stent graft  180  that further includes extended graft material  102 E beyond branch point  162 . 
     In  FIG. 1B , to address the problem of blocking of vessel ostium  166 , extended graft material  102 E included a branch opening (aperture)  110 . Thus, prior art custom configured stent graft  180  with a side window or fenestration was often referred to as a “fenestrated” stent graft. At deployment, prior art stent graft  180  was main axially and rotationally positioned within main vessel  152  such that branch opening (aperture)  110  aligned with vessel ostium  166  when prior art stent graft  180  was radially expanded. In this configuration, a portion of the fluid flow proceeded from main vessel  152 , through branch opening (aperture)  110 , through vessel ostium  166 , and into branch vessel  154 . 
     It is well known by those of skill in the art that a vessel system  150  is by nature tortuous, asymmetrical and, within limits, individually variable. Thus, when deploying prior art stent graft  180  it was often difficult to position branch opening (aperture)  110 , both main axially along main vessel  152  and rotationally about main vessel  152 , exactly at vessel ostium  166 . Misalignment between branch opening (aperture)  110  in extended graft material  102 E and vessel ostium  166  could result in partial or complete blocking of vessel ostium  166  thereby restricting or completely cutting-off fluid flow into branch vessel  154 , which is unacceptable. Even when (ring) branch opening (aperture)  110  was substantially aligned with vessel ostium  166  at initial deployment, slight migration of prior art stent graft  180  could cause subsequent misalignment and resultant fluid flow blockage. 
     However, a rigid ring branch opening (aperture)  110  was branch axially centered along a branch graft central axis L b  that is substantially perpendicular to a main body central axis L m  of main body  152 . As noted above, stent grafts were generally compressed in a radial and not axial direction prior to deployment. Also, the axial and rotational alignment difficulties described above continue to be an issue. 
     Further, branch vessel  154  is often not completely perpendicular to main vessel  152 . The branch angle between branch vessel  154  and main vessel  152  often varies from patient to patient given the tortuous and asymmetrical nature of vessels. Accordingly, prior art stent graft  180  containing a rigid (ring) branch opening (aperture)  110  was often custom fabricated, at considerable expense, to accommodate the vessel structure of a particular patient and to attempt to avoid misalignment. 
     What is needed is a stent graft containing a branch opening (aperture) or graft that is simply configurable into a compressed state prior to deployment. Further, what is needed is a branch opening (aperture) or graft that is easily aligned with, and conforms, without kinking or collapsing, to a tortuous and asymmetrical branch vessel in which it is deployed. 
     SUMMARY OF THE INVENTION 
     Examples according to the present invention provide an innovative device and method for compressing and aligning a branch graft that conforms to a tortuous, asymmetrical branch vessel, emanating from a main vessel, to provide support to, and a conduit for fluid flow into the branch vessel. 
     In one example, a stent graft includes a main body having a main body side wall, a branch opening (aperture) formed in the main body, and at least one branch graft having a branch graft side wall formed from a series of connected corrugations or pleats, and coupled to the main body at its branch opening (aperture). The branch graft is in fluid communication with the main body such that, together, they provide a conduit for fluid flow from a main vessel into a branch vessel emanating from the main vessel. Further, the series of connected pleats of graft material forming the branch graft side wall of the branch graft provide flexible, articulable, and axial compressible properties to the branch graft. 
     In one example, the main body side wall of the main body is formed from a graft material configured in a tubular shape and defining the branch opening (aperture) in the main body side wall. The branch graft is also formed from a graft material configured in a tubular shape with the branch graft side wall formed as connected annular shaped pleats. In other examples, the stent graft further includes annular shaped stent rings and bare spring elements coupled to the graft material of the main body and/or the branch graft. 
     In use, the stent graft, in a compressed configuration, is inserted into and transluminally advanced along the main vessel, for example, an aorta. Utilizing endovascular procedures and vascular imaging techniques well know to those of skill in the art, the stent graft is positioned such that the branch opening (aperture) or graft is substantially aligned, both along the main axis and rotationally within the flexible and articulable range of the branch opening (aperture) or graft, with a vessel ostium in the main vessel leading into the branch vessel. The main axial and rotational position of the branch opening (aperture) or graft is determined before deployment of the main body of the stent graft and adjusted, if necessary, to more closely position the branch opening (aperture) or graft with respect to the vessel ostium leading into the branch vessel. The main body is then radially expanded within the main vessel. Finally, the branch graft is branch axially (or laterally) expanded into the branch vessel. 
     For clarity of presentation, embodiments according to the present invention are described below in terms of a stent graft within the aorta at the intersection of a branch to the renal arteries. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a partial cutaway view of a vessel system containing one example of a deployed prior art stent graft; 
         FIG. 1B  shows a close-up, cross-section view at a branch of a vessel system similar to the one shown in  FIG. 1A  containing another example of a deployed prior art stent graft that further includes extended graft material beyond a branch point; 
         FIG. 2  shows a close-up partial cutaway view of the vessel system containing a stent graft, positioned and deployed for use, that includes an example of a branch opening (aperture) and graft; 
         FIG. 3  shows a cross sectional top view of the stent graft shown in  FIG. 2  taken along line III-III; 
         FIG. 4A  shows a cross-sectional view taken perpendicular to the branch axis of one example of a branch graft; 
         FIG. 4B  shows a cross-sectional view taken perpendicular to the central axis of another example of a branch graft; 
         FIG. 4C  shows a cross-sectional view taken perpendicular to the central axis of yet another example of a branch graft; 
         FIG. 5A  shows a side view of the example branch graft of  FIG. 4C  depicting its flexible and articulable properties in the single plane of the drawing; 
         FIG. 5B  shows a side view of the example branch graft of  FIG. 4C  further depicting its flexible and articulable properties in the single plane of the drawing; 
         FIG. 5C  shows a side view of the example branch graft of  FIG. 4C  yet further depicting its flexible and articulable properties in the single plane of the drawing; 
         FIG. 5D  shows a perspective view of  FIG. 5C ; 
         FIG. 5E  shows a perspective view depicting the flexible and articulable properties in more than one plane of the example branch graft of  FIG. 4C ; 
         FIG. 5F  shows a side view of the example branch graft of  FIG. 4C  in a compressed configuration; 
         FIG. 5G  shows a cross sectional view of the example branch graft of  FIG. 4C  in a compressed configuration taken along its central axis; 
         FIG. 6  is a key to  FIGS. 6A and 6B , which show an example process flow diagram for a method of using the stent graft; 
         FIG. 7  shows a close-up partial cutaway view of a vessel system containing an example of a stent graft in a compressed configuration and positioned along a main vessel such that a branch stent graft branch opening (aperture) is main axially misaligned below a branch point of the vessel system; 
         FIG. 8  shows a close-up partial cutaway view of vessel system containing an example of a stent graft in a compressed configuration and positioned along a main vessel such that a branch opening (aperture) and graft are substantially aligned with a vessel ostium; 
         FIG. 9  shows a first cross sectional view taken along line IX-IX of  FIG. 8  with the stent graft positioned in the main vessel such that the branch opening (aperture) and graft is rotationally misaligned with the vessel ostium; 
         FIG. 10  shows a second cross sectional view taken along line IX-IX of  FIG. 8  with the stent graft positioned about the main vessel such that the branch opening (aperture) and graft substantially aligns rotationally with the vessel ostium; 
         FIG. 11  shows a close-up partial cutaway view the vessel containing the stent graft positioned as in  FIG. 10  but with the main body in an expanded configuration; 
         FIG. 12  shows the stent graft positioned and expanded as in  FIG. 11  and further shows a branch graft expansion catheter used to branch axially (laterally) extend the branch graft; 
         FIG. 13  shows a close-up partial cutaway view of a vessel system containing a stent graft that includes an example of a fenestration assembly; 
         FIG. 14  shows a side plan view of a portion of the stent graft of  FIG. 13  taken along the line XIV; 
         FIG. 15  shows a close-up partial cutaway view of the vessel system containing the stent graft of  FIG. 13  after securement of the fenestration assembly in a branch vessel; 
         FIG. 16  show a close-up plan view of a relaxed configuration of a main body side opening whose position is variable within flexibility limits of the surrounding corrugations or pleats laterally and vertically in the confines of the cylindrical shape that constitutes the wall structure of the main body; 
         FIG. 17  show a close-up plan view of a highly displaced configuration of a main body side opening where the opening position has been moved to a near top extreme of vertical flexibility limits of the surrounding corrugations or pleats that constitute the sidewall of the main body; 
         FIG. 18  is a close up cross sectional view of the relaxed configuration of the main body side opening of  FIG. 16 , where the centerline of the side opening in its relaxed configuration is positioned below and substantially blocked by the close adjacent wall of the main vessel; and 
         FIG. 19  is a close up cross sectional view of the vertically displaced configuration of the main body side opening of  FIG. 17 , where the centerline of the side opening in this displaced configuration is positioned substantially aligned with the center line of the branch vessel so that blood flow from the main vessel to the branch vessel is substantially clear and is not blocked by the close adjacent wall of the main vessel. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 2  shows a close-up partial cutaway view of vessel system  150  containing a stent graft  200 , positioned and deployed for use, that includes an example of a branch graft  205 .  FIG. 3  shows a cross sectional view of the stent graft of  FIG. 2  taken along line III-III. For clarity of presentation, in  FIGS. 2 and 3  the previously described stent reinforcing structures and bare spring elements are not shown, although it should be understood that the present embodiment may include some or all of these structures in certain examples. 
     Referring to  FIGS. 2 and 3  together, a main graft material  202 M is configured in a tubular shape defining a main body  203  having a main body side wall  209  spanning aneurysm  156  ( FIG. 2 ) affecting main vessel  152 . Vessel system  150  includes branch vessel  154 , for example, a renal artery, emanating from main vessel  152  at a branch point  1621  (lower edge of ostium) ( FIG. 2 ). Main vessel  152  includes a vessel ostium  166  in main vessel  152  leading into branch vessel  154 . 
     Deployed in branch vessel  154 , is a tubular shaped branch graft  205  having a branch graft side wall  206  ( FIG. 3 ) of at least one series of connected pleats  207  formed from biocompatible branch graft material  202 B. Main graft material  202 M defines a branch opening (aperture)  210  in main body  203  or, more particularly, in main body side wall  209 . Branch graft  205  is coupled to main body  203  at branch opening (aperture)  210  such that branch graft  205  is in fluid communication with main body  203 . 
     As described more fully below with reference to  FIGS. 5A-5E , branch graft side wall  206  formed of connected annularly shaped pleats  207  makes branch graft  205  flexible and articulable in the manner of a bellows. Said by way of simile, branch graft side wall  206 , formed of connected pleats  207 , provides branch graft  205  with the flexible and articulable characteristics of an “elephant trunk”. The particular properties of branch graft side wall  206  allow stent graft  200  to accommodate a relatively large degree of misalignment between branch graft opening  210  and vessel ostium  166  in main body  203  prior to deployment. Additionally, flexible and articulable branch graft  205  easily conforms, without kinking or collapsing, to the tortuous nature of branch vessel  154  after deployment. 
     Further, as also described more fully below with reference to  FIG. 5F , branch graft  205  along with branch graft side wall  206  formed of connected pleats  207 , are also compressible branch axially along a branch graft central axis, likewise in the manner of a bellows. 
     More particularly,  FIGS. 4A ,  4 B, and  4 C are cross-sectional views taken perpendicular to respective main branch graft central axes L b1 , L b2 , and L b3 , of three example branch grafts  205 - 1 ,  205 - 2 , and  205 - 3 . In  FIG. 4A , branch graft  205 - 1  is formed as a single-piece, hollow, generally cylindrically shaped tube fabricated from branch graft material  202 B- 1 . A branch graft side wall  206 - 1  of branch graft  205 - 1  is made up of a single series of uniform, connected, annularly shaped pleats  207 - 1 . Branch graft  205 - 1  further defines a fluid inlet  208 - 1  at a first end of branch graft  205 - 1  and a fluid outlet  210 - 1  at a second opposite end of branch graft  205 - 1 . Fluid inlet  208 - 1  provides for fluid flow into branch graft  205 - 1  and fluid outlet  210 - 1  provides for fluid flow out from branch graft  205 - 1 . 
     Branch graft  205 - 1  is coupled to main body  203  such that fluid inlet  208 - 1  aligns with branch opening (aperture)  210 . In use, branch graft is deployed within branch vessel  154  with fluid outlet (opening)  210 - 1  placed within the outer perimeter of the vessel ostium  166 . In this configuration, branch graft  205 - 1  is in fluid communication with branch opening (aperture)  210  and thus main body  203 . A portion of fluid flowing through main vessel  152  into main body  203  is directed into branch graft  205 - 1 , through branch opening (aperture)  210 , through branch graft inlet  208 - 1 , exiting through branch graft outlet  210 - 1  into branch vessel  154 . 
     In another example, in  FIG. 4B , branch graft  205 - 2  is formed as a hollow, generally tapered shaped tube fabricated from branch graft material  202 B- 2 . The frusto-conical surface shaped branch graft side wall  206 - 2  of branch graft  205 - 2  is made up of one series of connected annularly shaped pleats  207 - 2  of diminishing diameter from fluid inlet  208 - 2  at a first end of branch graft  205 - 2  to fluid outlet  210 - 2  at a second opposite end of branch graft  205 - 2 . Branch graft  205 - 2  is coupled to main body  203  and provides fluid flow from main vessel  152  similarly to those described above with reference to branch graft  205 - 1 , and so are not shown nor described further. 
     In another example, in  FIG. 4C , branch graft  205 - 3  is formed as a first, a second, and a third hollow, generally cylindrically shaped tube  205 - 3 A,  205 - 3 B and  205 - 3 C, respectively, fabricated from branch graft material  202 B- 3 . A branch graft side wall first portion  206 - 3 A of first tube  205 - 3 A, made up of a series of connected uniform annularly shaped first pleats  207 - 3 A, is coupled to a branch graft side wall second portion  206 - 3 B of second tube  205 - 3 B, made up of a series of connected uniform annularly shaped second pleats  207 - 3 B. The diameter of second pleats  207 - 3 B is less than the diameter of first pleats  207 - 3 A. Branch graft side wall second portion  206 - 3 B of second tube  205 - 3 B is, in turn, coupled to a branch graft side wall third portion  206 - 3 C of third tube  205 - 3 C, made up of a series of connected uniform annularly shaped third pleats  207 - 3 C. The diameter of third pleats  207 - 3 C is less than the diameter of second pleats  207 - 3 B. 
     Branch graft  205 - 3  is coupled to main body  203  in a manner similar to that described above with reference to branch graft  205 - 1  and so is not shown nor described further. Further, branch graft  205 - 3  provides fluid flow from main body  203  in manner similar to that described above with additionally, a first intermediate port  212 A, at the coupling of branch graft side wall first portion  206 - 3 A and branch graft side wall second portion  206 - 3 B, providing fluid flow from first tube  205 - 3 A into second tube  205 - 3 B, and a second intermediate port  212 B, at the coupling of branch graft side wall second portion  206 - 3 B and branch graft side wall third portion  206 - 3 C, providing fluid flow from second tube  205 - 3 B into third tube  205 - 3 C. 
     The flexible, articulable, bellows-like structures of branch grafts  205 - 1 ,  205 - 2 , and  205 - 3  accommodate a relatively large degree of main axis and rotational (angular) misalignment between a main graft (e.g.,  203 ) and respective vessel ostia  166  ( FIGS. 2 and 3 ) in main vessel  152  prior to deployment. Additionally, flexible and articulable branch grafts  205 -A,  205 -B, and  205 -C easily conform, without kinking or collapsing, to the tortuous nature of their respective branch vessel  154  after deployment. 
     Illustratively,  FIGS. 5A ,  5 B, and  5 C are side views depicting the flexible and articulable properties of example branch graft  205 - 3  of  FIG. 4C  in the single plane of the drawings. In one example shown in  FIG. 5A , branch graft  205 - 3  flexibly bends upward configuring branch graft central axis L b3  in a curve C 1 . In this upwardly bent configuration, the portion of first pleats  207 - 3 A, second pleats  207 - 3 B, and third pleats  207 - 3 C at the top of branch graft  205 - 3 , partially compress and fold-in one upon the other, allowing the top of branch graft  205 - 3  to form an inside radius r 2  to curve C 1 . At the same time, the portion of first pleats  207 - 3 A, second pleats  207 - 3 B, and third pleats  207 - 3 C at the bottom of branch graft  205 - 3 , expand and stretch apart one from the other, allowing the bottom of branch graft  205 - 3  to form to form an inside radius r 1  to curve C 1 . Thus as shown, radius r 2  is less than radius r 1 , allowing branch graft  205 - 3  to bend and articulate upwardly. In this configuration, fluid outlet  210 - 3  is displaced upwardly by a displacement distance “X” and angled clockwise by a rotation angle “α” relative to the unbent configuration of branch graft  205 - 3 , indicated in dotted outline. 
     In one example shown in  FIG. 5B , branch graft  205 - 3  flexibly bends downward in mirror image to  FIG. 5A  with fluid outlet  210 - 3  displaced downwardly by a displacement distance “−X” and is angled counter-clockwise by a rotation angle “−α” relative to the unbent configuration of branch graft  205 - 3 , indicated in dotted outline. 
     In another example shown in  FIG. 5C  branch graft  205 - 3  defines a compound curve C 3  along branch graft central axis L b3 , bending first in downward direction and then in an upward direction. 
       FIG. 5D  shows a perspective view of branch graft  205 - 3  configured as in  FIG. 5C . As shown in  FIGS. 5C and 5D , branch graft side wall second portion  206 - 3 B bends downward relative to branch graft side wall first portion  206 - 3 A and branch graft side wall third portion  206 - 3 C bends upward relative to branch graft side wall second portion  206 - 3 B. 
     Further, as may be readily observed by referring to orthogonally juxtaposed  FIGS. 2 and 3  together, in one example, the bending and articulation of branch grafts is not restricted to a single plane. Illustratively,  FIG. 5E  is a perspective view depicting the flexible and articulable properties in more than one plane of branch graft  205 - 3  of  FIG. 4C . As shown, branch graft  205 - 3  defines a complex curve where branch graft side wall second portion  206 - 3 B bends downward relative to branch graft side wall first portion  206 - 3 A and branch wall side wall third portion  206 - 3 C bends laterally out of the plane defined by branch graft side wall first portion  206 - 3 A and branch graft side wall second portion  206 - 3 B. 
     Thus, the flexible, articulable, bellows-like structures of the branch graft examples described above are designed to accommodate a relatively large degree of main axial and rotational (angular) misalignment between branch graft openings and respective vessel ostia in main vessels prior to deployment. The fluid outlets of the various branch grafts may be easily flexed and articulated to accommodate a relatively large amount of misalignment with vessel ostia leading to branch vessels in which the branch grafts is deployed. Additionally, flexible and articulable branch grafts easily conform, without kinking or collapsing, to the tortuous nature of their respective branch vessels after deployment. 
     Finally, as noted briefly above, the examples of branch grafts above are also branch axially compressible. Illustratively,  FIG. 5F  shows a side view of the example branch graft  205 - 3  of  FIG. 4C  in a compressed configuration. Relative to an expanded configuration depicted in dotted outline, connected pleats  207  easily fold-in an overlie one upon the other, bellows-like, when branch graft  205 - 3  is compressed branch axially along branch graft central axis L b3 , in a direction approximately perpendicular to main body central axis L m . As can be readily appreciated, example branch graft  205 - 1  of  FIG. 4A  and example branch graft  205 - 2  of  FIG. 4B  are likewise easily configurable into a compressed state along their respective branch graft central axes L b1  and L b2 . 
     Further,  FIG. 5G  shows a cross sectional view of example branch graft  205 - 3  of  FIG. 4C  taken along branch graft central axis L b3  with first, second, and third tubes  205 - 3 A,  205 - 3 B, and  205 - 3 C, respectively, telescoped into one another. Referring to  FIGS. 4C and 5G  together, when compressed into the configuration shown in  FIG. 5G , third tube  205 - 3 C of example branch graft  205 - 3  telescopes through second intermediate port  212 B and nests within second tube  205 - 3 B, which, as a unit, likewise telescopes through first intermediate port  212 A and nests within first tube  205 - 3 A of branch graft  205 - 3 . Advantageously, in this highly compressed nested configuration, branch graft  205 - 3  presents a very thin side profile when coupled to main graft material  202 M of main body  203  ( FIG. 4A ). 
     Thus, as described above, flexible, articulable, and branch axially compressible branch graft  205  is formed from at least one series of connected annular pleats  207 , and is coupled to and in fluid communication with main body  203  at branch opening (aperture)  210 . Further, as shown in  FIG. 7  and as described more fully below, prior to deployment, stent graft  200  in its entirety, including main body  203  and branch graft  205 , is easily configurable into a compressed state. Main body  203  is compressible radially in directions inward and perpendicular with respect to main body central axis L m . At the same time, branch graft  205  is compressible branch axially in a direction along branch graft central axes L b , also in a direction perpendicular with respect to a main body central axis L m , i.e., also in a direction of radial compression of main body  203 . Main body  203  is compressible radially and branch graft  205  is compressible branch axially by application of forces directed perpendicular toward main body central axis L m . 
     A method of use of the stent graft is next described.  FIG. 6  is a key to  FIGS. 6A and 6B , which show a process flow diagram for a Method  600  of using stent graft  200  of  FIGS. 2 and 3 .  FIG. 7  shows a close-up partial cutaway view of vessel system  150  containing stent graft  200  in a compressed configuration and positioned along main vessel  152  such initial opening of branch graft  205  is main axially misaligned and located below branch point  162  of vessel system  150 . Referring to  FIGS. 6 and 7  together, Start Operation  602  of Method  600  commences use of stent graft  200  containing flexible articulable branch grafts  205 . Start Operation  602  transfers to Insert/Advance Stent Graft Operation  604 . When it is stated herein that a first operation transfers to a second operation, those of skill in the art understand that the first operation is completed and the second operation is started. 
     In one embodiment, at Insert/Advance Stent Graft Operation  604 , a stent graft catheter (not shown) sheathing stent graft  200  in a compressed configuration is inserted into and advanced along vessel system  150 , for example an artery system, through furcation  159  ( FIG. 1A ), for example an iliac artery, until stent graft  200  is in the general area of branch point  162  of vessel system  150 . The insertion and advance of compressed stent grafts through intravascular procedures utilizing a guide wire (not shown) to direct the coursing of the stent graft catheter through vessel system  150  are well known to those of skill in the art and therefore are not described further. 
     In one embodiment, the advance and axial positioning of the stent graft catheter sheathing stent graft  200  through furcation  159  and main vessel  152  to the general location of branch point  162  is monitored through well-know vascular imaging and radiographic techniques, using one or more radiopaque markers (not shown) coupled to a known location on the stent graft catheter. Upon the stent graft catheter, or more particularly stent graft  200 , reaching the general location of branch point  162 , Operation  604  transfers to Position Stent Graft Axially Operation  608 . 
     In Position Stent Graft Axially Operation  608 , the axial position of stent graft  200  is adjusted along the direction of main body central axis L m  so that branch graft  205  more closely aligns main axially with vessel ostium  166 . After the adjustment, Operation  608  transfers to Stent Graft Accurately Positioned Axially Determination Operation  612 . 
     In Stent Graft Accurately Positioned Axially Determination Operation  612 , it is determined whether branch graft  205  is accurately positioned main axially with respect to vessel ostium  166 . In Determination Operation  612 , an axial misalignment distance “Z”, ( FIG. 7 ), between branch graft  205  and vessel ostium  166  is determined using radiographic or other visioning techniques. 
     If the outcome of Determination Operation  612  indicates that axial misalignment distance “Z” is greater than a distance that would provide effective deployment of branch graft  205  within branch vessel  154 , Determination Operation  612  transfers back to Position Stent Graft Axially Operation  608  so that stent graft  200  may be repositioned within main vessel  203 , main axially along main body central axis L m , such that branch graft  154  more closely main axially aligns with vessel ostium  166 . 
     Operations  608  and  612  makeup a Stent Graft Axial Repositioning Loop  616 . Several iterations of Stent Graft Axial Repositioning Loop  616  may be needed to provide accurate axial positioning of stent graft  200  so that branch graft opening of the main body is main axially aligned with vessel ostium  166  within the flexible and articulable range of branch graft  205 . Thus, Stent Graft Axial Repositioning Loop  616  is repeatedly performed until stent graft  200  is main axially positioned within main vessel  152  such that branch graft  205  may be effectively deployed within branch vessel  154  through vessel ostium  166 . 
     At some point following Operation  608  within Loop  616 , stent graft  200  is positioned as illustrated in  FIG. 8 .  FIG. 8  shows a close-up partial cutaway view of vessel system  150  containing stent graft  200  in a compressed configuration and positioned along main vessel  152  such that branch graft  205  substantially aligns main axially with vessel ostium  166 . When it is said that branch graft  205  substantially aligns main axially with vessel ostium  166  it is meant that main axially misalignment distance “Z” is within the flexibility and articulation range of branch graft  205 . 
     Referring to  FIGS. 6 and 8  together, as indicated above, in this final iteration of Loop  616 , Operation  608  transfers to a final iteration of Determination Operation  612 . In this final iteration of Stent Graft Accurately Positioned Axially Determination Operation  612 , axial misalignment distance “Z” between branch graft  205  and vessel ostium  166  is determined to be sufficiently small that an effective deployment of branch graft  205  within branch vessel  154  may be accomplished if branch graft  205  is also properly aligned rotationally while branch graft  205  maintains this current main axial position relative to vessel ostium  166 . In  FIG. 8 , substantial main axial alignment along the direction of main body central axis L m  between branch graft  205  and vessel ostium  166  is represented by a nominal “zero” value for axial misalignment distance “Z”. 
     When stent graft  200  is main axially position as just described and shown in  FIG. 8 , the angular relationship about main body central axis L m  between vessel ostium  166  and branch graft  205  may also be determined. Hence, since Stent Graft Accurately Positioned Axially Determination Operation  612  is now true (YES), with stent graft  200  maintained main axially in its current position, Determination Operation  612  transfers to Position Stent Graft Rotationally Operation  618 . 
       FIG. 9  shows a first cross sectional view taken along line IX-IX of  FIG. 8  of stent graft  200  positioned about main vessel  152  such that branch graft  154  is misaligned rotationally with vessel ostium  166 . Referring to  FIGS. 6 and 9  together, with stent graft  200  still in a compressed configuration to permit movement, in Position Stent Graft Rotationally Operation  618 , the angular position of stent graft  200  is adjusted about the direction of main body central axis L m  so that branch graft  205  more closely aligns rotationally with vessel ostium  166 . After the adjustment, Operation  618  transfers to Stent Graft Accurately Positioned Rotationally Determination Operation  624 . 
     As shown in  FIG. 9 , at Stent Graft Accurately Positioned Rotationally Determination Operation  624 , a rotational misalignment angle “θ” is an angle between branch graft  205  and vessel ostium  166  about main body central axis L m . Hence, a first pass through Determination Operation  624  determines that, as shown in  FIG. 9 , when viewed by radiographic or other visioning along main body central axis L m  from above, branch graft  205  is rotationally misaligned clockwise with vessel ostium  166  by rotational misalignment angle “θ”. 
     In this example, branch graft  205  is sufficiently rotationally misaligned with vessel ostium  166  such that deployment of branch graft  205  within branch vessel  154  is not possible. Accordingly, upon completion of Determination Operation  624 , Operation  624  transfers back to Position Stent Graft Rotationally Operation  618 . 
     Operations  618  and  624  makeup a Stent Graft Rotational Repositioning Loop  628 . Several iterations of Stent Graft Rotational Repositioning Loop  628  may be needed to provide accurate rotational alignment of branch graft  205  with vessel ostium  166 . 
     At each Stent Graft Accurately Positioned Rotationally Determination Operation  624 , rotational misalignment angle “θ” is re-determined. If, at the completion of Determination Operation  624 , stent graft  200  must be repositioned rotationally about main vessel central axis L m , Operations  618  and  624  are repeated. 
       FIG. 10  shows a second cross sectional view taken along line IX-IX of  FIG. 8  of stent graft  200  positioned about main vessel  152  such that branch graft  205  substantially aligns rotationally with vessel ostium  166 . Referring to  FIGS. 6 and 10  together, by completing sufficient iterations of Stent Graft Rotational Repositioning Loop  628 , branch graft  205  is rotated counter-clockwise so that branch graft  205  is rotationally aligned with vessel ostium  166 , as shown in  FIG. 10 . Substantial Rotational Alignment about the direction of main body central axis L m  between branch graft  205  and vessel ostium  166  is represented by a nominal “zero” value for rotational misalignment angle “θ”. Substantial rotational alignment occurs when branch graft  205  and vessel ostium  166  are relatively positioned rotationally, within the flexibility and articulation range of branch graft  205 , such that branch graft  205  may be effectively deployed in branch vessel  154  through vessel ostium  166 . Hence, at this point Determination Operation  624  is true (YES) for the example of  FIG. 10  and Determination Operation  624  transfers to Expand Main body Radially Operation  626 . 
       FIG. 11  shows a close-up partial cutaway view the vessel containing the stent graft positioned as in  FIG. 10  but with the main graft body in an expanded configuration.  FIG. 12  shows stent graft  200  positioned and expanded as shown in  FIG. 11  and further shows a branch graft expansion catheter  1100  used to axially expand branch graft  205 . Referring to  FIGS. 6 ,  11  and  12  together, at Expand Main body Radially Operation  626  ( FIG. 6 ) following Determination Operation  624 , a stent graft catheter sheath (not shown) constraining stent graft  200  in a compressed configuration ( FIGS. 9 and 10 ) is drawn back from or removed from the stent graft catheter (not shown) used to position stent graft  200  as described above. Stent graft  200 , or more particularly main body  203 , radially expands outward from main body central axis L m  to contact the interior wall of main vessel  152  ( FIGS. 11 and 12 ). In one example, main body  203  is self expanding and, in another example, main body  203  is expanded by means of an expansion balloon (not shown) inserted into main vessel  152  and advanced to main body  203  in a manner well known to those of skill in the art. 
     With main body  203  in an aligned and expanded configuration, in one example, Operation  626  ( FIG. 6 ), transfers to Insert/Advance Branch graft Catheter Operation  630 . In this example, a flexible branch graft expansion catheter  1100  is used to axially expand branch graft  205  ( FIGS. 11 and 12 ) into branch vessel  154 . Branch graft expansion catheter  1100  includes a hollow main piece  1102  of generally straight tubular shape, and a turning piece  1104  formed as a hollow tubular shaped bend of approximately 90° coupled at a turner piece first end  1106  ( FIG. 11 ) to a distal end of main piece  1102 . A flexible deployment wire  1108 , is slidibly movable within branch graft expansion catheter  1100 . 
     At Insert/Advance Branch graft Expansion Catheter Operation  630 , branch graft expansion catheter  1100  is inserted into main vessel  152  and advanced to branch graft  205  in a manner analogous to that described with respect to Insert/Advance Stent Graft Operation  604  above and is therefore not repeated here with respect to Operation  630 . 
     Next, after completion of Insert/Advance Branch graft Expansion Catheter Operation  630 , to substantially align turning piece second end  1108  with branch graft  205 , Position Branch graft Expansion Catheter Axially Operation  634  followed by Branch graft Expansion Catheter Accurately Positioned Axially Determination Operation  636 , together making up Branch graft Expansion Catheter Axial Repositioning Loop  638 , is iterated in the manner described above with reference to Stent Graft Axial Repositioning Loop  616  and so are not repeated here. 
     Next, to rotationally substantially align turning piece second end  1108  with branch graft  205 , at Position Branch graft Expansion Catheter Rotationally Operation  640  followed by Branch graft Expansion Catheter Accurately Positioned Rotationally Determination Operation  642 , together making up Branch graft Expansion Catheter Rotational Repositioning Loop  644 , is iterated as also described above with reference to stent graft  200 . 
     Thus, at some point following a last iteration of Determination Operation  642  turning piece second end  1108  of branch graft expansion catheter  1100  substantially aligns main axially and rotationally with branch graft  205  as shown in  FIGS. 11 and 12 . When it is said that turning piece second end  1108  substantially aligns main axially and rotationally with branch graft  205 , it is meant that branch graft expansion catheter  1100  may be used to effectively expand branch graft  205  along branch graft central axis L b . 
     Next, after turning piece second end  1108  is positioned as just described, Operation  642  transfers to Expand Branch graft Axially Operation  646  where deployment wire  1110  is slidibly advanced within branch graft expansion catheter  1100 , flexibly bending toward compressed branch graft  205  when advanced within turning piece  1104 . With further advance of deployment wire  1110  beyond turning piece second end  1108 , a deployment wire distal end  1112  of deployment wire  1110  contacts and branch axially expands branch graft  205  along branch graft central axis L b . 
     As described, by Method  600 , branch graft  205  is previously positioned both main axially ( FIG. 12 ) and rotationally ( FIG. 11 ) adjacent vessel ostium  166  leading into branch vessel  154 . Thus, at Expand Branch graft Axially Operation  646 , branch graft  205  deploys within branch vessel  154 , as shown in  FIGS. 2 and 3 , when it is axially expanded along branch graft central axis L b  by operation of deployment wire distal end  1112 . 
     After branch graft  205  is axially expanded and deployed within branch vessel  154 , deployment wire  1110  is retracted from its deployment configuration and is returned within branch graft expansion catheter  1100  by slidibly moving deployment wire  1110  in a direction opposite of that used to expand and deploy branch graft  205 . After, deployment wire  1110  is retracted, branch graft expansion catheter  1100  is withdrawn from vessel system  150 , which completes Expand Branch graft Axially Operation  646 , thereby ending Method  600  at End Operation  648 . At this point stent graft  200  is fully deployed as shown in  FIGS. 2 and 3 . 
     In examples of stent graft  200  that include branch grafts  205  that are self expanding, branch graft  205  is branch axially self expanded and deployed within branch vessel  154  without use of branch graft expansion catheter  1100 . Accordingly, Operation  630  through  644  are not implemented and Expand Main body Radially Operation  626  is followed directly by Expand Branch graft Axially Operation  646  where branch graft  205  self expands. 
     Thus, stent grafts include branch grafts that are flexible and articulable. Method  600  provides a process that, prior to deployment, easily accommodates compression of the entire stent graft and easily accommodates a relatively large degree of main axial and angular misalignment between branch grafts and the branch vessel into which the branch grafts are deployed. Further, after the operations of Method  600  are successfully completed, the flexible and articulable branch grafts easily conform, without kinking or collapsing, to the tortuous nature of the respective branch vessels into which they are deployed. 
     The sequence of operations and the operations in Method  600  are illustrative only and are not intended to limit either the sequence of operations or the specific operations. For example, the axial and radial positioning operations could be done together rather than as separate operational loops. 
     In another example Method  600  may be utilized to place a bifurcated stent graft including a separate fenestrated main body, having a branch opening (aperture) in the main graft material making up the main body, and a separate branch graft. By Method  600  the fenestrated main body is longitudinally aligned with a vessel ostium leading to the branch graft and deployed in the main vessel of the vessel system. The separate branch graft is next aligned with the branch opening (aperture) of the main body and branch axially expanded, by Method  600 , through the main body branch opening (aperture) through the vessel ostium and into the branch vessel. The branch graft is coupled to the main body at the main body branch opening (aperture) by techniques well know to those of skill in the art. 
     In general, those of skill in the art can alter the sequence and operations so long as the sequence of operations positions the branch graft substantially adjacent to the vessel ostium of a branch vessel into which the flexible and articulable branch graft is to be deployed. 
       FIG. 13  shows a close-up partial cutaway view of a vessel system  1350  containing a stent graft  1300  that includes an example of fenestration assembly  1380  in accordance with one embodiment of the present invention.  FIG. 14  shows a side plan view of a portion of stent graft  1300  of  FIG. 13  taken along the line XIV. For clarity of presentation, in  FIGS. 13 and 14 , the previously described stent reinforcing structures and bare spring elements are not shown, although it should be understood that stent graft  1300  may include some or all of these structures in certain examples. Generally, stent graft  1300  may include self expanding or balloon expandable stents as is well known to those of skill in the art. 
     Referring to  FIGS. 13 and 14  together, a main graft material  1302 , sometimes called a wall, is configured in a tubular shape defining a main body  1303  spanning across an aneurysm  156  affecting a main vessel  152 , for example, an artery. Vessel system  1350  includes one or more branch vessels (e.g.,  154 ), for example, renal arteries, emanating from main vessel  152  at branch point (e.g.,  162 ). Main vessel  152  includes a vessel ostium  166  in main vessel  152  leading into branch vessel  154 , thereby placing branch vessel  154  in fluid communication with main vessel  152 . 
     Positioned for deployment in branch vessel  154 , is a fenestration assembly  1380 , sometimes called a corrugated hole. Fenestration assembly  1380  includes at least one series of connected pleats  1307  formed from biocompatible material, e.g., graft material. Fenestration assembly  1380  defines an branch opening (aperture)  1310  in main body  1303 . Fenestration assembly  1380  is coupled to or integral with main graft material  1302  such that fenestration assembly  1380  is in fluid communication with main body  1303 . 
     As described more fully below with reference to  FIG. 15 , fenestration assembly  1380  formed of connected pleats  1307  makes fenestration assembly  1380  flexible and articulable in the manner of a bellows. Said by way of simile, fenestration assembly  1380 , formed of connected pleats  1307 , provides fenestration assembly  1380  with the flexible and articulable characteristics of an “elephant trunk”. The particular properties of fenestration assembly  1380  allow stent graft  1300  to accommodate a relatively large degree of misalignment between fenestration assembly  1380  and vessel ostium  166  prior to deployment. Additionally, flexible and articulable fenestration assembly  1380  easily conforms, without kinking or collapsing, to the tortuous nature of branch vessel  154  after deployment. 
     Connected pleats  1307 , sometimes called corrugations, are formed as ring structures, one within another, of decreasing diameter. To illustrate, an outer pleat  1307 A of connected pleats  1307  is attached, i.e., connected to or integral with, main graft material  1302 . Outer pleat  1307 A defines a first branch opening (aperture) (ring) in main graft material  1302  of stent graft  1300 . 
     Outer pleat  1307 A has the greatest diameter D 2  of pleats  1307 , i.e., fenestration assembly  1380  has a diameter D 2 . Conversely, an inner pleat  1307 B of connected pleats  1307  defines branch opening (aperture) (ring)  1310 . Inner pleat  1307 B, sometimes called a second ring, defines a smaller branch opening (aperture), e.g., branch opening (aperture)  1310 , within outer pleat  1307 A. 
     Inner pleat  1307 B has the smallest diameter D 3  of pleats  1307 . The other pleats between outer pleat  1307 A and inner pleat  1307 B have a decreasing diameter from outer pleat  1307 A to inner pleat  1307 B. Further, in one example, pleats  1307  are one within another, e.g., are concentric ring structures. For example, pleats  1307  lie along the cylindrical surface defined by main graft material  1302 . More specifically, outer pleat  1307 A and inner pleat  1307 B are concentric in one example. 
     In one example, pleats  1307  are formed of a graft material extending between outer pleat  1307 A and inner pleat  1307 B. The graft material enables movement, e.g., orbital, eccentric, and/or angular movement, of inner pleat  1307 B with respect to outer pleat  1307 A. Stated another way, the graft material is concentrically corrugated into pleats  1307 , allowing flexible positioning of inner pleat  1307 B within outer pleat  1307 A. Illustratively, the graft material includes biocompatible flexible material allowing flexible positioning of inner pleat  1307 B within outer pleat  1307 A. 
     As shown in  FIG. 13 , vessel ostium  166  of branch vessel  154  has a diameter D 1 . As set forth above, fenestration assembly  1380  has a diameter D 2 . In one example, diameter D 2  of fenestration assembly  1380  is greater than diameter D 1  of branch vessel  154  accommodating a greater amount of acceptable misalignment between fenestration assembly  1380  and branch vessel  154 . More particularly, as long as vessel ostium  166  of branch vessel  154  is aligned with the area defined by fenestration assembly  1380 , more particularly, defined by outer pleat  1307 A, fenestration assembly  1380  is sufficiently aligned with vessel ostium  166  of branch vessel  154  for proper deployment of fenestration assembly  1380  within branch vessel  154  as shown in  FIG. 15 . 
     To illustrate, branch opening (aperture)  1310  defined by inner pleat  1307 B has a branch axis  1310 L. Vessel ostium  166  of branch vessel  154  has a branch axis  166 L. Branch axis  166 L of vessel ostium  166  is misaligned with branch axis  1310 L of branch opening (aperture)  1310 , branch axis  1310 L of branch opening (aperture)  1310  being below branch axis  166 L of vessel ostium  166  as shown in  FIG. 13 . However, as set forth above, this misalignment of branch axis  1310 L of branch opening (aperture)  1310  with branch axis  166 L of vessel ostium  166  is acceptable since vessel ostium  166  of branch vessel  154  is aligned with the area defined by outer pleat  1307 A. 
       FIG. 15  shows a close-up partial cutaway view of vessel system  1350  containing stent graft  1300  of  FIG. 13  after securement of fenestration assembly  1380  in branch vessel  154 . As shown in  FIG. 15 , the lower portion of pleats  1307  is stretch apart further than the upper portion of pleats  1307  allowing fenestration assembly  1380  to be inserted within branch vessel  154 . Fenestration assembly  1380  is inserted within branch vessel  154  in a manner similar to that discussed above, and so is not repeated. In accordance with this example, a securement member  1502 , e.g., a self-expanding stent, anchors fenestration assembly  1380 , e.g., inner pleat  1307 B, within branch vessel  154 . 
       FIG. 16  show a close-up plan view of a relaxed configuration of a fenestration assembly  1680 : a main body side opening (small ring)  1610  having a surrounding pleat (or ring)  1607 B whose position is variable within flexibility limits of the surrounding corrugations or pleats, e.g.,  1607 , laterally and vertically (within the confine of an outer pleat (or ring)  1607 A in the confines of the tubular cylindrical shape that constitutes the wall structure of the main body near the location of branch vessels emanating from the main vessel as shown in  FIGS. 18 and 19 .  FIG. 16  pictures elements similar to those discussed for  FIG. 14  above. In this relaxed configuration, the upper portion of the fenestration assembly have a pleats spanned dimension  1607 U that is approximately equal to the lower portion of the fenestration assembly pleats spanned dimension  1607 L. 
       FIG. 17  show a close-up plan view of the fenestration assembly of  FIG. 16  with a highly displaced configuration of the main body side opening  1610  whose position has been moved to a near top extreme of vertical flexibility limits of the surrounding corrugations or pleats  1607  that constitute the fenestration assembly in the sidewall of the main body. The side opening  1610  has been displaced upwards an offset distance  1650  from its relaxed position as shown in  FIG. 16 . In this configuration the upper portion of the fenestration assembly has pleats spanned dimension  1607 U which has substantially diminished from that shown in  FIG. 16 , while the lower portion of the fenestration assembly pleats spanned dimension  1607 L is substantially greater than from that shown in  FIG. 16 . The change in each of the upper and lower pleats spanned dimensions  1607 U,  1607 L is substantially equal to the center offset distance  1650 . 
       FIG. 18  is a close up cross sectional view of the relaxed configuration of the main body side opening  1610  of  FIG. 16 , where the centerline of the fenestration assembly side opening in its relaxed configuration is positioned below and substantially blocked by the close adjacent wall (neck)  164  of the main vessel. As can be seen in  FIGS. 16 and 18  the stent graft is shown deployed where a central axis  186 L of the branch opening  1610  has been implanted an offset distance  1650  below the center line  1810 L of the branch vessel  154 . 
       FIG. 19  is a close up cross sectional view of the vertically displaced configuration of the main body side opening shown in  FIG. 17 , where the centerline  186 L of the side opening  1610  in this displaced configuration is positioned substantially aligned with the center line  1810 L of the branch vessel  154  so that blood flow from the main vessel to the branch vessel is substantially clear and is not blocked by the close adjacent wall (neck)  164  of the main vessel. A guidewire or catheter (not shown) used to guide and/or deploy a branch graft through the side branch opening is used to provide the vertical force needed to achieve the vertical offset distance  1650  shown here. In the configurations shown in  FIG. 16-19 , the ostium of the branch vessel is located approximately at the diameter of the main body at the location of the branch vessel. In this configuration there is no opportunity for portions of a fenestration assembly to extend laterally outward because of the closely adjacent main vessel wall (neck). So in this configuration as in others where a lateral extension of the corrugations are not desired, a branch graft assembly, e.g., those shown in the Wisselink U.S. Pat. Nos. 5,984,955 and 6,428,565. incorporated herein by reference, can be used to attach to the branch opening  1610  of the present fenestration assembly. 
     While particular embodiments have been described, those skilled in the art will understand that these embodiments are exemplary of the spirit and scope of the invention.