Abstract:
An aortic stent graft and a method of deploying the aortic stent graft. The method comprises providing a tapered tubular graft having a distal end and a proximal end, providing at least one stent attached to the graft at a site adjacent the distal end of the graft, loading the graft into an introducer, inserting the introducer through an incision in the aorta, deploying the graft inside the aorta; and suturing the proximal end of the graft in place.

Description:
RELATED APPLICATIONS  
       [0001]     This present patent document claims the benefit of the filing date under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 60/686,656, filed Jun. 1, 2005. 
     
    
     BACKGROUND  
       [0002]     1. Technical Field  
         [0003]     This invention relates to medical devices and, more particularly, to vascular prostheses suitable for various medical applications and the methods for making and using such vascular prostheses.  
         [0004]     2. Background Information  
         [0005]     Throughout this specification, when discussing the application of this invention to the aorta or other blood vessels, the term “distal” with respect to an abdominal device is intended to refer to a location that is, or a portion of the device that when implanted is, further downstream with respect to blood flow; the term “distally” means in the direction of blood flow or further downstream. The term “proximal” is intended to refer to a location that is, or a portion of the device that when implanted is, further upstream with respect to blood flow; the term “proximally” means in the direction opposite to the direction of blood flow or further upstream.  
         [0006]     The functional vessels of human and animal bodies, 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 hemodynamic forces, such an aneurysm can rupture. In Western European and Australian men who are between 60 and 75 years of age, aortic aneurysms greater than 29 mm in diameter are found in 6.9% of the population, and those greater than 40 mm are present in 1.8% of the population. In particular, aneurysms and dissections that extend into the thoracic aorta and aortic arch are associated with a high morbidity and are, in some situations, particularly difficult to treat.  
         [0007]     One intervention for a weakened, aneurismal, dissected or ruptured aorta is the use of an endovascular device or prosthesis such as a stent graft 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 contains the site of vessel weakness or failure. Stent grafts for endovascular deployment are generally formed from a tube of a biocompatible material in combination with one or more stents to maintain a lumen therethrough. Stent grafts effectively exclude the defect by sealing both proximally and distally to the defect, and shunting blood through its length. A device of this type can, for example, treat various arterial aneurysms, including those in the thoracic aorta or abdominal aorta.  
         [0008]     Open surgical (i.e., non-endovascular) intervention can also be an approach to treating aneurysms or other defects of the aorta. For example, a section of the aorta that spans an aneurysm can be replaced during open surgery with a woven polyester graft, or the graft may be sewn into the aorta using traditional surgical techniques. There are benefits to both endovascular and non-endovascular treatments for conditions of the aorta. Hybrid surgical-endovascular approaches have been described in the literature, including in Greenberg, et al., “Hybrid Approaches to Thoracic Aortic Aneurysms,” Circulation 2005; 112:2619-2626 and Kark, et al., “The frozen elephant trunk technique,” J Thorac Cardiovasc Surg 2003; 125:1550-3, both of which are incorporated herein by reference.  
       BRIEF SUMMARY  
       [0009]     In one aspect of the invention, there is a method of deploying an aortic stent graft that comprises providing a tapered tubular graft having a distal end and a proximal end, providing at least one stent attached to the graft at a site adjacent the distal end of the graft, loading the graft into an introducer, inserting the introducer into the aorta through an incision, deploying the graft inside the aorta; and suturing the proximal end of the graft in place.  
         [0010]     In another aspect of the invention, there is a method of deploying an aortic stent graft that comprises providing a tubular graft having a distal end and a proximal end and providing at least one stent attached to the graft at a site adjacent the distal end of the graft. Barbs extend proximally from the at least one stent. The method further comprises loading the graft into an introducer, inserting the introducer into the aorta through an incision, deploying the graft inside the aorta and suturing the proximal end of the graft in place.  
         [0011]     In yet another aspect of the invention, there is a stent graft for implantation in an aorta that comprises a tapered tubular graft having a distal end and a proximal end, and at least one stent attached to the graft at a site adjacent the distal end of the graft. The proximal end is adapted for stent-free connection to the aorta.  
         [0012]     In yet another aspect of the invention, there is a stent graft for implantation in an aorta that comprises a tubular graft having a distal end and a proximal end, at least one stent attached to the graft at a site adjacent the distal end of the graft and barbs extending from the at least one stent. The proximal end is adapted to being connected to the aorta without the assistance of a stent. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     FIGS.  1  shows a stent graft having stents at the distal end;  
         [0014]      FIG. 2  shows the stent graft of  FIG. 1  with the addition of a scallop at the proximal end;  
         [0015]      FIG. 3   a  shows a stent graft sutured at its proximal end to a preexisting graft;  
         [0016]      FIG. 3   b  shows an island sutured to a graft that extends into the ascending aorta;  
         [0017]      FIG. 4   a  shows a stent graft similar to that of  FIG. 1 , having an uncovered stent at its distal end;  
         [0018]      FIG. 4   b  shows a shorter version of the graft of  FIG. 4   a;    
         [0019]      FIG. 5   a  shows a detailed view of a stent graft with stents at its distal end;  
         [0020]      FIG. 5   b  shows an internal view of the stent graft of  FIG. 5 ;  
         [0021]      FIG. 6  shows a variation of the stent graft of  FIG. 5   a;    
         [0022]      FIG. 7  shows a sealing cuff;  
         [0023]      FIGS. 8-15  show various views of a first introducer in different stages of deployment; and  
         [0024]      FIGS. 16-17  show a second exemplary introducer. 
     
    
     DETAILED DESCRIPTION  
       [0025]     To help understand this description, the following definitions are provided.  
         [0026]     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.  
         [0027]     The term “endovascular” 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. An “endovascular prosthesis” is thus a prosthesis that can be placed inside one of these lumens. A stent graft is a type of endovascular prosthesis that has a graft component and a stent component.  
         [0028]     The term “stent” means any device or structure that adds rigidity, expansion force or support to a prosthesis. A “Z-stent” is a stent that has alternating struts and peaks (i.e., bends) and defines a generally cylindrical space. A “Gianturco Z-stent” is a type of self-expanding Z-stent.  
         [0029]     The term “prosthetic trunk” refers to a portion of a prosthesis that shunts blood through a main vessel. A “trunk lumen” runs through the prosthetic trunk.  
         [0030]     The term “prosthetic side branch” refers to a portion of a prosthesis that is anastomosed to the prosthetic trunk and shunts blood into and/or through a side branch vessel. An integral prosthetic side branch is one that has been connected to the trunk or formed with the trunk before deployment within the body.  
         [0031]     “Anastomosis” refers to any existing or established connection between two lumens, such as the prosthetic trunk and prosthetic branch, that puts the two in fluid communication with each other. An anastomosis is not limited to a surgical connection between blood vessels, and includes a connection between a prosthetic branch and a prosthetic trunk that are formed integrally.  
         [0032]     The term “branch extension” refers to a prosthetic module that can be deployed within a branch vessel and connected to a prosthetic branch.  
         [0033]     The term “pull-out force” means the maximum force of resistance to partial or full dislocation provided by a modular prosthesis. The pull-out force of a prosthesis having two interconnected modules may be measured by an MTS ALLIANCE RT/5® tensile testing machine (MTS Corporation, Eden Prairie, Minn.). The MTS machine is connected to a computer terminal that is used to control the machine, collect and process the data. A pressurization pump system is attached to the load cell located on the tensile arm of the MTS machine. One end of the prosthesis is connected to the pressurization pump, which provides an internal pressure of 60 mm Hg to simulate the radial pressure exerted by blood upon the device when deployed in vivo. The other end of the prosthesis is sealed. The prosthesis is completely immersed in a 37° C. water bath during the testing to simulate mean human body temperature. The MTS machine pulls the devices at 0.1 mm increments until the devices are completely separated. The computer will record, inter alia, the highest force with which the modules resist separation, i.e. the pull-out force.  
         [0034]     Biocompatible fabrics, non-woven materials and porous sheets may be used as the graft material. The graft material is preferably a woven polyester having a twill weave and a porosity of about 350 ml/min/cm 2  (available from VASCUTEK® Ltd., Renfrewshire, Scotland, UK). The graft material may also be other polyester fabrics, polytetrafluoroethylene (PTFE), expanded PTFE, and other synthetic materials known to those of skill in the art.  
         [0035]     The graft material may include extracellular matrix materials. The “extracellular matrix” is a collagen-rich substance that is found in between cells in animal tissue and serves as a structural element in tissues. It is typically a complex mixture of polysaccharides and proteins secreted by cells. The extracellular matrix can be isolated and treated in a variety of ways. Following isolation and treatment, it is referred to as an “extracellular matrix material,” or ECMM. ECMMs may be isolated from submucosa (including small intestine submucosa), stomach submucosa, urinary bladder submucosa, tissue mucosa, renal capsule, dura mater, liver basement membrane, pericardium or other tissues.  
         [0036]     Purified tela submucosa, a preferred type of ECMM, has been previously described in U.S. Pat. Nos. 6,206,931; 6,358,284 and 6,666,892 as a bio-compatible, non-thrombogenic material that enhances the repair of damaged or diseased host tissues. U.S. Pat. Nos. 6,206,931; 6,358,284 and 6,666,892 are incorporated herein by reference. Purified submucosa extracted from the small intestine (“small intestine submucosa” or “SIS”) is a more preferred type of ECMM for use in this invention. Another type of ECMM, isolated from liver basement membrane, is described in U.S. Pat. No. 6,379,710, which is incorporated herein by reference. ECMM may also be isolated from pericardium, as described in U.S. Pat. No. 4,502,159, which is also incorporated herein by reference. Other examples of ECMMs are stomach submucosa, liver basement membrane, urinary bladder submucosa, tissue mucosa and dura mater. SIS 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; U.S. Pat. No. 6,206,931 to Cook et al.; U.S. Pat. No. 6,358,284 to Fearnot et al.; 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 references are incorporated herein by reference. It is also preferable that the material is non-porous so that it does not leak or sweat under physiologic forces.  
         [0000]     Thoralon  
         [0037]     Biocompatible polyurethanes may also be employed as graft materials. One example of a biocompatible polyurethane is THORALON (THORATEC, Pleasanton, Calif.), as described in U.S. Pat. Nos. 6,939,377 and 4,675,361, both of which are incorporated herein by reference. THORALON is a polyurethane base polymer (referred to as BPS-215) blended with a siloxane containing surface modifying additive (referred to as SMA-300). The concentration of the surface modifying additive may be in the range of 0.5% to 5% by weight of the base polymer.  
         [0038]     The SMA-300 component (THORATEC) is a polyurethane comprising polydimethylsiloxane as a soft segment and the reaction product of diphenylmethane diisocyanate (MDI) and 1,4-butanediol as a hard segment. A process for synthesizing SMA-300 is described, for example, in U.S. Pat. Nos. 4,861,830 and 4,675,361, which are incorporated herein by reference.  
         [0039]     The BPS-215 component (THORATEC) is a segmented polyetherurethane urea containing a soft segment and a hard segment. The soft segment is made of polytetramethylene oxide (PTMO), and the hard segment is made from the reaction of 4,4′-diphenylmethane diisocyanate (MDI) and ethylene diamine (ED).  
         [0040]     THORALON can be manipulated to provide either porous or non-porous THORALON. Porous THORALON can be formed by mixing the polyetherurethane urea (BPS-215), the surface modifying additive (SMA-300) and a particulate substance in a solvent. The particulate may be any of a variety of different particulates or pore forming agents, including inorganic salts. Preferably the particulate is insoluble in the solvent. The solvent may include dimethyl formamide (DMF), tetrahydrofuran (THF), dimethyacetamide (DMAC), dimethyl sulfoxide (DMSO) or mixtures thereof. The composition can contain from about 5 wt % to about 40 wt % polymer, and different levels of polymer within the range can be used to fine tune the viscosity needed for a given process. The composition can contain less than 5 wt % polymer for some spray application embodiments. The particulates can be mixed into the composition. For example, the mixing can be performed with a spinning blade mixer for about an hour under ambient pressure and in a temperature range of about 18° C. to about 27° C. The entire composition can be cast as a sheet, or coated onto an article such as a mandrel or a mold. In one example, the composition can be dried to remove the solvent, and then the dried material can be soaked in distilled water to dissolve the particulates and leave pores in the material. In another example, the composition can be coagulated in a bath of distilled water. Since the polymer is insoluble in the water, it will rapidly solidify, trapping some or all of the particulates. The particulates can then dissolve from the polymer, leaving pores in the material. It may be desirable to use warm water for the extraction, for example, water at a temperature of about 60° C. The resulting pore diameter can also be substantially equal to the diameter of the salt grains.  
         [0041]     The porous polymeric sheet can have a void-to-volume ratio from about 0.40 to about 0.90. Preferably the void-to-volume ratio is from about 0.65 to about 0.80. The resulting void-to-volume ratio can be substantially equal to the ratio of salt volume to the volume of the polymer plus the salt. Void-to-volume ratio is defined as the volume of the pores divided by the total volume of the polymeric layer including the volume of the pores. The void-to-volume ratio can be measured using the protocol described in AAMI (Association for the Advancement of Medical Instrumentation) VP20-1994, Cardiovascular Implants—Vascular Prosthesis section 8.2.1.2, Method for Gravimetric Determination of Porosity. The pores in the polymer can have an average pore diameter from about 1 micron to about 400 microns. Preferably, the average pore diameter is from about 1 micron to about 100 microns; more preferably, it is from about 1 micron to about 10 microns. The average pore diameter is measured based on images from a scanning electron microscope (SEM). Formation of porous THORALON is described, for example, in U.S. Pat. No. 6,752,826 and U.S. patent application Publication No. 2003/0149471 A1, both of which are incorporated herein by reference.  
         [0042]     Non-porous THORALON can be formed by mixing the polyetherurethane urea (BPS-215) and the surface modifying additive (SMA-300) in a solvent, such as dimethyl formamide (DMF), tetrahydrofuran (THF), dimethyacetamide (DMAC) or dimethyl sulfoxide (DMSO). The composition can contain from about 5 wt % to about 40 wt % polymer, and different levels of polymer within the range can be used to fine tune the viscosity needed for a given process. The composition can contain less than 5 wt % polymer for some spray application embodiments. The entire composition can be cast as a sheet, or coated onto an article such as a mandrel or a mold. In one example, the composition can be dried to remove the solvent.  
         [0043]     THORALON has been used in certain vascular applications and is characterized by thromboresistance, high tensile strength, low water absorption, low critical surface tension, and good flex life. THORALON is believed to be biostable and to be useful in vivo in long term bloodcontacting applications requiring biostability and leak resistance. Because of its flexibility, THORALON is useful in larger vessels, such as the abdominal aorta, where elasticity and compliance is beneficial.  
         [0044]     A variety of other biocompatible polyurethanes may also be employed. These include polyurethanes that preferably include a soft segment and include a hard segment formed from a diisocyanate and diamine. For example, polyurethane with soft segments such as PTMO, polyethylene oxide, polypropylene oxide, polycarbonate, polyolefin, polysiloxane (i.e. polydimethylsiloxane), and other polyether soft segments made from higher homologous series of diols may be used. Mixtures of any of the soft segments may also be used. The soft segments also may have either alcohol end groups or amine end groups. The molecular weight of the soft segments may vary from about 500 to about 5,000 g/mole.  
         [0045]     The diisocyanate used as a component of the hard segment may be represented by the formula OCN—R—NCO, where —R— may be aliphatic, aromatic, cycloaliphatic or a mixture of aliphatic and aromatic moieties. Examples of diisocyanates include MDI, tetramethylene diisocyanate, hexamethylene diisocyanate, trimethyhexamethylene diisocyanate, tetramethylxylylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, dimer acid diisocyanate, isophorone diisocyanate, metaxylene diisocyanate, diethylbenzene diisocyanate, decamethylene 1,10 diisocyanate, cyclohexylene 1,2-diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, xylene diisocyanate, m-phenylene diisocyanate, hexahydrotolylene diisocyanate (and isomers), naphthylene-1,5-diisocyanate, 1-methoxyphenyl 2,4-diisocyanate, 4,4′-biphenylene diisocyanate, 3,3′-dimethoxy-4,4′-biphenyl diisocyanate and mixtures thereof.  
         [0046]     The diamine used as a component of the hard segment includes aliphatic amines, aromatic amines and amines containing both aliphatic and aromatic moieties. For example, diamines include ethylene diamine, propane diamines, butanediamines, hexanediamines, pentane diamines, heptane diamines, octane diamines, m-xylylene diamine, 1,4-cyclohexane diamine, 2-methypentamethylene diamine, 4,4′-methylene dianiline and mixtures thereof. The amines may also contain oxygen and/or halogen atoms in their structures.  
         [0047]     Other applicable biocompatible polyurethanes include those using a polyol as a component of the hard segment. Polyols may be aliphatic, aromatic, cycloaliphatic or may contain a mixture of aliphatic and aromatic moieties. For example, the polyol may be ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, propylene glycols, 2,3-butylene glycol, dipropylene glycol, dibutylene glycol, glycerol, or mixtures thereof.  
         [0048]     Biocompatible polyurethanes modified with cationic, anionic and aliphatic side chains may also be used, as in U.S. Pat. No. 5,017,664.  
         [0049]     Other biocompatible polyurethanes include: segmented polyurethanes, such as BIOSPAN; polycarbonate urethanes, such as BIONATE; and polyetherurethanes, such as ELASTHANE; (all available from POLYMER TECHNOLOGY GROUP, Berkeley, Calif.).  
         [0050]     Other biocompatible polyurethanes include polyurethanes having siloxane segments, also referred to as a siloxane-polyurethane. Examples of polyurethanes containing siloxane segments include polyether siloxanepolyurethanes, polycarbonate siloxane-polyurethanes, and siloxanepolyurethane ureas. Specifically, examples of siloxane-polyurethane include polymers such as ELAST-EON 2 and ELAST-EON 3 (AORTECH BIOMATERIALS, Victoria, Australia); polytetramethyleneoxide (PTMO) and polydimethylsiloxane (PDMS) polyether-based aromatic siloxanepolyurethanes such as PURSIL-10, -20, and -40 TSPU; PTMO and PDMS polyether-based aliphatic siloxane-polyurethanes such as PURSIL AL-5 and AL-10 TSPU; aliphatic, hydroxy-terminated polycarbonate and PDMS polycarbonate-based siloxane-polyurethanes such as CARBOSIL-10, -20, and -40 TSPU (all available from POLYMER TECHNOLOGY GROUP). The PURSIL, PURSIL-AL, and CARBOSIL polymers are thermoplastic elastomer urethane copolymers containing siloxane in the soft segment, and the percent siloxane in the copolymer is referred to in the grade name. For example, PURSIL-10 contains 10% siloxane. These polymers are synthesized through a multi-step bulk synthesis in which PDMS is incorporated into the polymer soft segment with PTMO (PURSIL) or an aliphatic hydroxy-terminated polycarbonate (CARBOSIL). The hard segment consists of the reaction product of an aromatic diisocyanate, MDI, with a low molecular weight glycol chain extender. In the case of PURSIL-AL, the hard segment is synthesized from an aliphatic diisocyanate. The polymer chains are then terminated with a siloxane or other surface modifying end group. Siloxane-polyurethanes typically have a relatively low glass transition temperature, which provides for polymeric materials having increased flexibility relative to many conventional materials. In addition, the siloxane-polyurethane can exhibit high hydrolytic and oxidative stability, including improved resistance to environmental stress cracking. Examples of siloxane-polyurethanes are disclosed in U.S. patent application Publication No. 2002/0187288 A1, which is incorporated herein by reference.  
         [0051]     In addition, any of these biocompatible polyurethanes may be end-capped with surface active end groups, such as, for example, polydimethylsiloxane, fluoropolymers, polyolefin, polyethylene oxide or other suitable groups. See, for example, the surface active end groups disclosed in U.S. Pat. No. 5,589,563, which is incorporated herein by reference.  
         [0052]      FIG. 1  shows a stent graft  10  designed for implantation in the thoracic aorta. The stent graft is formed from a section of graft material shaped into a tube. Stents  12  are positioned at the distal end  14  of the graft  10 . The graft tube may be made of any of the graft materials described above, preferably woven polyester twill. The fabric may be crimped so that the graft may be able to bend without excessive kinking. The graft tube is preferably sized to correspond to a particular patient&#39;s anatomy. An exemplary graft  10  may have a length of about 140-280 mm, and may be designed to extend from a point just distal of the subclavian artery  16  to a point proximal to the celiac artery  18 , as shown in  FIG. 1 . The stent graft  10  may be manufactured to a maximum length, and be subsequently trimmed to suit a particular patient. The diameter of an exemplary graft  10  is about 30 mm. The graft  10  is preferably tapered. For example, the proximal end  20  of the graft  10  may have a diameter of 30 mm, while the distal end  14  of the graft  10  may have a diameter of 28, 32, 36 or 44 mm. Thus, the graft  10  either tapers distally (i.e., is narrower in the distal region of the graft  10 ), or tapers proximally (i.e., is narrower in the proximal region of the graft  10 ). The taper can better allow the stent graft  10  to form a sealing interconnection with preexisting grafts.  
         [0053]     The proximal end  20  of the stent graft  10  is preferably unstented, as it is designed to be anastomosed to the native artery with sutures  22 , as shown in  FIG. 1  and described in further detail below. The distal end  14 , however, is preferably stented so that a seal may be formed between the stent graft  10  and the native artery following deployment of the stent graft  10 , without the addition of sutures.  
         [0054]     As shown in  FIG. 1 , there are preferably three self expanding Z-stents  12 , 13 ,  15  sutured to the distal end  14  of the graft  10 . The distal stent  15  is preferably sutured to the inside of the graft  10 , as shown in  FIG. 1 . This may improve the circumferential apposition of the stent graft  10  to the surrounding vessel wall. The other stents  12 , 13  can be sutured to the outside of the graft  10 . Alternatively, two distal-most stents may be sutured to the inside of the graft and the third stent can be sutured to the outside of the stent graft  10 , as shown at the distal end  162  of the graft  152  in  FIG. 6 . Thus, in an embodiment that has three Z-stents, the stents can have an approximate amplitude of 17.5 mm, such that the three of them, sutured to the distal end of the graft, occupy about a 60 mm length of the graft. The remainder of the graft can be about 80-85 mm, for a total length of about 140 -145 mm. There may be more stents added to the distal end, depending on the overall length of the graft, the requirements of the anatomy, etc.  
         [0055]     Barbs or hooks  24  preferably extend in the proximal (cephalad) direction from the distal-most stent  15 . Barbs  24  may also extend from the other stents  12 , 13 . The barbs  24  may help anchor the distal end  14  of the graft  10  in place, thereby improving sealing at the distal end  14 . The barbs  24  may extend from the struts or the bends of the Z-stent  15 . There may be a single ring of barbs  24  extending from the stent  15 , or a more extensive array of barbs as shown in  FIG. 1 . A single row of barbs  130  extending from the distal bends of a Z-stent is shown in  FIG. 5 .  
         [0056]     As shown in  FIG. 2 , the proximal end  20  of the stent graft  10  may have a scallop  28  that accommodates the subclavian artery  16 , allowing the stent graft  10  to be sutured at a more proximal location in the aortic arch  30 , while not impeding flow to the subclavian artery  16 . A proximal fenestration or an integral prosthetic branch (not shown) may also be employed for a similar purpose.  
         [0057]     An extension for an integral prosthetic branch may be deployed. As shown in  FIG. 3   a,  the stent graft  34  may be sutured to a preexisting prosthetic module  36 . The preexisting prosthetic module  36  may have been deployed surgically or endovascularly during the same surgical procedure or a previous procedure.  
         [0058]     The graft can also extend further proximally with the use of an open surgical procedure using the “island” surgical technique. In that technique, the aorta is clamped proximally to the innominate, left common carotid, and left subclavian arteries. An island  25  encompassing those aortic arch side branches is cut from the aorta. A graft  17  having a fenestration  27  that approximates the shape and size of the island is deployed into the aortic arch. Alternatively, the fenestration  27  can be cut after the graft&#39;s deployment. The island  25  is then sutured to the fenestration  27  and the location in the aorta from which the island was resected.  
         [0059]      FIG. 4   a  shows that the distal end  52  of the graft  40  may be modified to accommodate the branch vessels of the thoraco-abdominal aorta, such as the celiac, SMA and renal arteries. As with the subclavian, these can be accommodated with, for example, fenestrations, scallops, or integral prosthetic branches.  FIG. 4   a  shows a stent graft  40  extending to the renal arteries  42 . A celiac fenestration  44  and SMA fenestration  46  preserve blood flow to their respective arteries. The distal end  48  of the stent graft  40  features an uncovered stent  50  that extends over the renal arteries  42  without occluding them. Barbs  52  extend proximally from the uncovered stent  50 .  
         [0060]      FIG. 4   b  shows a shorter graft than that of  FIG. 4   a.  In  FIG. 4   b,  the uncovered stent transverses the SMA  45  and celiac  47  arteries so that they are not occluded.  
         [0061]      FIGS. 5   a  and  5   b  show external and internal views of an embodiment of an exemplary stent graft. The stent graft  101  includes a tubular body  103  formed from a biocompatible woven or non-woven fabric, or other material. The tubular body  103  has a proximal end  105  and a distal end  107 . The stent graft  101  may be tapered, as described above, depending upon the topography of the vasculature and flow considerations.  
         [0062]     Towards the distal end  107  of the tubular body  103 , there are a number of self-expanding Z-stents  109 , 111  such as the Z-stent on the outside of the body. In this embodiment there are two external stents  109  spaced apart by a distance of between 0 mm to 10 mm. The external stents  109  are joined to the graft material by means of stitching or suturing  110 , preferably using a monofilament or braided suture material.  
         [0063]     At the distal end  107  of the prosthetic module  101  there is provided an internal Z-stent  111  which provides a sealing function for the distal end  107  of the stent graft  101 . The outer surface of the tubular body  103  at the distal end  107  presents an essentially smooth outer surface, which, with the assistance of the internal Z-stent  111 , can engage and seal against the wall of the aorta when it expands and is deployed.  
         [0064]     The internal stent  111  is comprised of struts  115  with bends  116  at each end of the struts. Affixed to some or all of the struts  115  are barbs  130  which extend proximally from the struts  115  through the graft material. When the stent graft is deployed into an aortic arch, the barbs  130  engage and/or penetrate into the wall of the aorta and prevent proximal movement of the stent graft  101  caused by pulsating blood flow through the stent graft  101 . It will be noted that the stent  111  is joined to the graft material by means of stitching  112 , preferably using a monofilament or braided suture material.  
         [0065]      FIG. 6  shows a stent graft  152  that has the two distal stents attached to the inside  162  of the stent graft  152 . Additional stent grafts are described in U.S. patent application Publication Nos. 2003/0199967 A1 and 2004/016978 A1, which are incorporated herein by reference.  
         [0066]      FIG. 7  shows a three-stent cuff  150  that can be used in conjunction with the stent grafts described above. The cuff  150  may be about 55 mm in length and can have any of a variety of suitable diameters including, for example 28, 30 or 32 mm. It is preferably sized to form a-sealing interconnection with a stent graft. The stents  158  may be place internally or externally, relative to the main graft. It can be introduced with a 30 cm variation of one of the introducers described below. Once the stent graft described below is deployed, the cuff shown in  FIG. 7  may be used to seal the distal or proximal end of the stent graft if it becomes apparent that the stent graft itself does not exhibit optimal sealing against the aortic wall. In particular, the sealing cuff may be used at the site of surgical anastomosis (i.e., the proximal portion of the graft), if it is discovered that the surgical anastomosis exhibits imperfect sealing. By placing a sealing cuff using endovascular techniques, surgical repair of the anastomosis may be rendered unnecessary. Such a cuff  150  may also be manufactured using two or four stents, for example.  
         [0067]     The devices described above are implanted using a hybrid surgical procedure—one that employs aspects of open surgical repair in addition to endovascular techniques. In summary, the aortic arch is surgically exposed; then an incision is made in the aortic arch or associated branch vessel so that an introducer containing the stent graft can be inserted into the aorta. The aortic arch can be exposed using a conventional median sternotomy. The introducer is advanced distally through the aortic arch into the thoracic aorta, until it is in a proper distal position. At that point, the stent graft is released from the introducer. At the distal end of the stent graft, the stents expand, with or without the assistance of a balloon catheter, thereby forming a seal at the distal end. Then, the proximal end of the stent graft—which is preferably stent-free—is sutured to the native aorta using standard surgical techniques. Finally, the incision in the aortic arch is closed, followed by the closure of the surgical access.  
         [0068]     Thus, using this hybrid procedure, a second surgical operation through a separate entry point—e.g., a left thoracotomy—is rendered unnecessary to ensure sealing at the distal end of the stent graft.  
         [0069]     Exemplary introducers are described further below.  
         [0000]     Introducer  
         [0070]      FIGS. 8 and 9  show an exemplary introducer which may be used to deploy the stent graft described above. The introducer may be about 40 cm in length, which is shorter than the delivery systems that are used to deploy stent grafts through femoral cut-downs. For example, the TX-2 delivery system (Cook Incorporated, Bloomington, Indiana) is generally about 75 cm. The introducer, shown in  FIGS. 8 and 9 , is preferably about 20/22 French in diameter.  
         [0071]     The introducer may comprise, working from the inside towards the outside, a guide wire catheter  201  which extends the full length of the device from a syringe socket  202  at the far distal end of the introducer to a nose dilator  203  at the proximal end of the introducer. The introducer may also be employed without the assistance of a guide wire, and thus will lack a guide wire catheter and associated features.  
         [0072]     The nose cone dilator  203  is fixed to the guide wire catheter  201  and moves with it; the dilator may be about  40 mm and is preferably blunt tipped. The nose cone dilator has a through bore  205  as an extension of the lumen of the guide wire catheter  201  so that the introducer can be deployed over a guide wire (not shown). To lock the guide wire catheter  201  with respect to the introducer in general, a pin vice  204  is provided. Again, a version of the introducer shown in  FIGS. 8 and 9  may be designed so that it works without a guide wire, and thus, does not have the bore  205  and other features used with a guide wire.  
         [0073]     The trigger wire release mechanism generally shown as  206  at the distal end of the introducer includes a distal end trigger wire release mechanism  207  and a proximal end trigger wire release mechanism  208 . The trigger wire release mechanisms  207  and  208  slide on a portion of the fixed handle  210 . Until such time as they are activated, the trigger wire mechanisms  207  and  208  are fixed by thumbscrews  211  ( FIG. 9 ) and remain fixed with respect to the fixed portion of the fixed handle. The controlled deployment afforded by use of the trigger wires helps to ensure accurate placement of the distal portion of the graft.  
         [0074]     Immediately proximal of the trigger wire release mechanism  206  is a sliding handle mechanism generally shown as  215 . The sliding handle mechanism  215  generally includes a fixed handle extension  216  of the fixed handle  210  and a sliding portion  217 . The sliding portion  217  slides over the fixed handle extension  216 . A thumbscrew  218  fixes the sliding portion  217  with respect to the fixed portion  216 . The fixed handle portion  216  is affixed to the trigger wire mechanism handle  210  by a screw threaded nut  224 . The sliding portion of the handle  217  is fixed to the deployment catheter  219  by a mounting nut  220 . A deployment catheter extends from the sliding handle  217  through to a capsule  221  at the proximal end of the deployment catheter  219 .  
         [0075]     Over the deployment catheter  219  is a sheath manipulator  222  and a sheath  223 , which slide with respect to the deployment catheter  219  and, in the ready to deploy situation as shown in  FIGS. 8 and 9 , extend from the sheath manipulator  222  forward to the nose cone dilator  203  to cover a prosthetic module  225  retained on the introducer distally of the nose cone dilator  203 .  
         [0076]     In the ready to deploy condition shown in  FIGS. 8 and 9 , the sheath  223  assists in retaining stent graft  225 , which includes self-expanding stents  226  in a compressed condition. The proximal covered stent  227  is retained by a fastening at  228  which is locked by a trigger wire (not shown) which extends to trigger wire release mechanism  208 . The distal exposed stent  229  on the stent graft  225  is retained within the capsule  221  on the deployment catheter  219  and is prevented from being released from the capsule by a distal trigger wire (not shown), which extends to the distal trigger wire release mechanism  207 .  
         [0077]      FIG. 9  shows the same view as  FIG. 8 , but after withdrawal of sheath  223 , and  FIG. 11  shows the same view as  FIG. 10 , but after activation of sliding handle mechanism  215 .  
         [0078]     In  FIG. 10 , the sheath manipulator  222  has been moved distally so that its proximal end clears the stent graft  225  and lies over the capsule  221 . Freed of constraint, the self expanding stents  226  of the stent graft  225  are able to expand. However, the fastening  228  still retains the uncovered stent  229 , and the capsule  221  still retains the other stents. At this stage, the proximal and distal ends of the stent graft  225  can be independently repositioned, although if the distal stent  229  included barbs as it has in some embodiments, the proximal end can only be moved proximally.  
         [0079]     Once repositioning has been done, the distal end of the stent graft  225  should be released first. The distal trigger wire release mechanism  207  on the handle  210  is removed to withdraw the distal trigger wire. Then the thumb screw  218  is removed, and the sliding handle  217  is moved distally to the position shown in  FIG. 11 . This moves the capsule  221  to release the exposed stent  229 . As the fastening  228  is retained on the guide wire catheter  201 , just distal of the nose cone dilator  203 , and the guide wire catheter  201  is locked in position on the handle  210  by pin vice  204 , then the proximal trigger wire release mechanism  208 , which is on the handle  210 , does not move when moving the sliding handle, deployment catheter  219  and capsule  221 , so the proximal end of the prosthetic module  225  remains in a retained position. The proximal end of the prosthetic module  225  can be again manipulated at this stage by manipulation of the handle. Although, if the uncovered stent  229  included barbs as discussed above, the proximal end can only be moved proximally. The proximal fastening  228  can then be released by removal of the proximal trigger wire release mechanism  208 .  
         [0080]     As shown in  FIGS. 12 and 13 , the detailed construction of a particular embodiment of a sliding handle mechanism according to this invention is shown.  FIGS. 12 and 14  show the sliding handle mechanism in the ready to deploy condition.  FIGS. 13 and 15  show the mechanism when the deployment catheter and hence the capsule has been withdrawn by moving the sliding handle with respect to the fixed handle. The fixed handle extension  216  is joined to the trigger wire mechanism handle  210  by screw threaded nut  224 .  
         [0081]     The sliding handle  217  is fixed to the deployment catheter  219  by screw threaded fixing nut  220  so that the deployment catheter moves along with the sliding handle  217 . The sliding handle  217  fits over the fixed handle extension  216  and, in the ready to deploy situation, is fixed in relation to the fixed handle by locking thumbscrew  218 , which engages into a recess  230  in the fixed handle extension  216 . On the opposite side of the fixed handle extension  216  is a longitudinal track  231  into which a plunger pin  232  spring loaded by means of spring  233  is engaged. At the distal end of the track  231  is a recess  234 .  
         [0082]     A guide tube  235  is fixed into the proximal end of the sliding handle  217  at  236  and extends back to engage into a central lumen  241  in the fixed handle extension  216  but is able to move in the central lumen  241 . An O ring  237  seals between the fixed handle extension  216  and guide tube  235 . This provides a hemostatic seal for the sliding handle mechanism. The trigger wire  238 , which is fixed to the trigger wire releasing mechanism  208  by means of screw  239 , passes through the annular recess  242  between the fixed handle extension  216  and the guide wire catheter  201  and then more proximally in the annular recess  244  between the guide wire catheter  201  and the guide tube  235  and forward to extend through the annular recess  246  between the guide wire catheter  201  and the deployment catheter  219  and continues forward to the proximal retaining arrangement. Similarly, the distal trigger wire (not shown) extends to the distal retaining arrangement.  
         [0083]     A further hemostatic seal  240  is provided where the guide wire catheter  201  enters the trigger wire mechanism handle  210  and the trigger wires  238  pass through the hemostatic seal  240  to ensure a good blood seal.  
         [0084]     As can be seen in  FIGS. 13 and 15 , the locking thumbscrew  218  has been removed and discarded, and as the sliding handle is moved onto the fixed handle, the plunger pin  232  has slid back along the track  231  to engage into the recess  234 . At this stage, the sliding handle cannot be moved forward again.  
         [0085]     As the trigger wire release mechanisms  207  and  208  are on the trigger wire mechanism handle  210 , which is fixed with respect to the fixed handle  216 , then the proximal trigger wire  238  is not moved when the deployment catheter  219  and the sliding handle  217  are moved so that it remains in position and does not prematurely disengage.  
         [0086]      FIGS. 16 and 17  show an alternative introducer  301  that has a distal end  303  which in use is intended to remain outside a patient and a proximal end  305  which is introduced into the patient. This introducer is further described in U.S. patent application Publication No. 2004/0106974, which is incorporated herein by reference. The curved nose cone dilator  317  may help guide the introducer  301  through the aortic arch or tortuous anatomy.  
         [0087]     Towards the distal end there is a handle arrangement  307  which includes trigger wire release apparatus  309  as will be discussed later. The main body of the introducer includes a tubular carrier  311  which extends from the handle  307  to a proximal retention arrangement, generally shown as  313 .  
         [0088]     Within a longitudinal lumen  314  in the central carrier  311  extends a guide wire catheter  315 . The guide wire catheter  315  extends out through the proximal retention arrangement  313  and extends to a nose cone dilator  317  at the distal end of the introducer  301 . The nose cone dilator  317  is curved, and in the embodiment shown in  FIG. 39 , the guide wire catheter  315  is also curved towards its distal end so that the distal end  305  of the introducer has a curve which may have a radius of curvature  319  of between 70 to 150 mm. This curvature enables the introducer of the present invention to be introduced through the aortic arch of a patient without excessive load being placed on the walls of the aorta.  
         [0089]     A stent graft  321  is retained on the introducer between the distal end  323  of the nose cone dilator  317  and the distal retention arrangement  313 . A sleeve  325  fits over the tubular carrier  311 , and, by operation of a sleeve manipulator  327 , the sleeve can be extended forward to extend to the nose cone dilator  317 . By the use of the sleeve  325 , the stent graft  321  can be held in a constrained position within the sleeve.  
         [0090]     At the distal end of the stent graft just proximal of the proximal end  323  of the nose cone dilator  317 , a distal retention arrangement  331  is provided.  
         [0091]     The distal retention arrangement  331  includes a trigger wire  333 , which engages a knot  335  of suture material, which is fastened to the trigger wire  333  and the guide wire catheter  315 . When the trigger wire  333  is withdrawn as will be discussed later, the suture knot  325  is released and the distal end of the stent graft can be released. The nose cone dilator  317  can have one or more apertures extending longitudinally, and the proximal trigger wire  333  can extend into one of these apertures.  
         [0092]     The proximal retention arrangement  313 , as shown in detail in  FIG. 40 , includes a capsule  340 , which is part of a capsule assembly  341 , which is joined by a screw thread  343  to the distal end  342  of the central carrier  311 . The capsule  340  includes a passageway  344  within it with a proximal closed end  346  and an open distal end  348 . The open distal end  348  faces the nose cone dilator  317  and the guide wire catheter  315  passes through the center of passageway  344 .  
         [0093]     The stent graft  321  has a distal stent  348  that is received within the capsule  340 , which holds it constrained during deployment. If the distal stent  348  has barbs extending from its struts, then the capsule keeps the barbs from prematurely engaging the walls of the vessel it is being deployed in and also prevents them from catching in the sleeve  325 . A trigger wire  350  passes through aperture  352  in the side of the capsule, engages a loop of the exposed stent  348  within the capsule and then passes along the annular recess  354  between the guide wire catheter  315  and the tubular carrier  311  to the trigger wire release mechanism  309 .  
         [0094]     The trigger wire release mechanism  309  includes a proximal release mechanism  356  and a distal end release mechanism  358 .  
         [0095]     To release the stent graft after it has been placed in the desired position in the aorta, the sleeve  325  is withdrawn by pulling back on the sleeve manipulator  327  while holding the handle  307  stationary. The distal release mechanism  358  on the handle  307  is then released by loosening the thumb screw  364  and completely withdrawing the distal release mechanism  358 , which pulls out the trigger wire  333  from the capsule  340 . Pin vice  362 , which fixes the position of the guide wire catheter with aspect to the handle  307  and central carrier  311 , is then loosened so that the guide wire catheter  315  can be held stationary, which holds the nose cone dilator and hence the distal retention arrangement  331  stationary while the handle is pulled back to remove the capsule  340  from the exposed stent  348 , which releases the distal end of the stent graft.  
         [0096]     Once the position of the distal end of the stent graft  321  has been checked, the proximal release mechanism  358  can then be removed by release of the thumb screw  364  and complete removal of the proximal release mechanism  358 .  
         [0097]     The tubular central carrier  311  can then be advanced while holding the nose cone dilator  317  stationary so that the introducer can be made more compact for withdrawal. Then the proximal end of the stent graft can be sutured in place, as described above.  
         [0098]     It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.