fig1 a 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 fig1 a 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 fig1 b 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 . fig2 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 fig6 . regarding the introduction of reagents , fig6 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 fig3 , 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 fig5 . fig2 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 fig4 . 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 fig5 , 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 . fig4 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 . fig5 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 . fig6 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 fig2 and 3 , using endoluminal interventional techniques . for example , fig7 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 fig7 , 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 fig7 , 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 fig8 , 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 fig9 , 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 fig1 , 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 fig1 , 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 fig1 . in fig1 , 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 . fig1 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 fig1 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 . fig1 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 . fig1 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 fig1 . 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 . fig1 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 fig1 , 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 . fig1 is an isometric view of the branch prosthesis 120 . as shown in fig1 , 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 . fig1 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 . fig1 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 . fig1 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 .
an intraluminal prosthesis is provided for strengthening a main lumen and a branch lumen that branches from the main lumen . the intraluminal prosthesis can comprise two tubular grafts . the first tubular graft can have a flexible body with a fenestration . the second tubular graft can have a flexible body that is configured for intraluminal coupling to the fenestration of the first tubular graft . the flexible body of the second tubular graft can have an outer dimension that is about equal to an inner dimension of the fenestration of the first tubular graft . the second tubular graft can also have a terminal stent that curves outwardly from a proximal end of the flexible body of the second tubular graft , whereby the terminal stent acts to couple the second tubular graft to the first tubular graft .