Patent Publication Number: US-11020215-B2

Title: Venous anchor devices forming an anastomotic connector

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 14/405,088 filed on Dec. 2, 2014, which is a 371(c) application claiming priority to International Appln. Ser. No.: PCT/US2012/067561, filed on Dec. 3, 2012, which claims the benefit of priority to U.S. Prov. Appln. Ser. No.: 61/683,898, filed on Aug. 16, 2012; and which International Appln. Ser. No.: PCT/US2012/067561 claims priority to International Appln. Ser. No.: PCT/US2012/042639, filed on Jun. 15, 2012, and International Appln. Ser. No.: PCT/US2012/042666, filed on Jun. 15, 2012, and International Appln. Ser. No.: PCT/US2012/042688, filed on Jun. 15, 2012; the entireties of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention relates to medical devices for use in surgical procedures. More specifically, the present invention is related to medical devices that can be used for blood vessel anastomosis procedures. 
     Background of the Related Art 
     In the United States alone, approximately 400,000 people have end-stage renal disease requiring chronic hemodialysis. Hemodialysis replaces kidney function by removing toxins from the blood that are normally removed by healthy kidneys. In order to effectively remove toxins, blood must be passed at a high blood flow rate through a hemodialysis machine. This high blood flow is best achieved by the creation of a permanent vascular access site that includes an arteriovenous (AV) anastomosis in which a vein is attached to an artery to form a high-flow shunt or fistula. 
     Typically, a vein may be directly attached to an artery, but it can take up to twelve weeks before the fistula has sufficiently matured (time between placement and cannulation for dialysis) to provide adequate blood flow for use with hemodialysis. Moreover, a direct anastomosis may not be feasible in all patients due to anatomical considerations. Other patients may require the use of artificial graft material to provide an access site between the arterial and venous vascular systems. Because of the length of time required for a fistula to mature a patient needing dialysis will typically require a temporary access device, such as a Quinton catheter, to be inserted for hemodialysis access until the fistula has matured. The use of a temporary catheter access exposes the patient to additional risk of bleeding and infection, as well as discomfort, and is associated with a 91% higher mortality rate compared to fistulas. In trying to increase the prevalence of fistulas in the U.S., a proportional rise in catheter use has been documented. 
     Another method of using an anastomotic connector is in a coronary bypass procedure to form an end-to-side anastomosis of a saphenous vein to a coronary artery. 
     What is needed is an improved anastomosis device that addresses the foregoing problems. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention solves the foregoing problems and can find one non-limiting use in performing cardiac artery bypass grafts. In another non-limiting use the present invention can be used for procedures in which short-term and long-term vascular access is required. Another non-limiting use of the present invention is to provide an improved anastomotic connector for performing bypass operations. 
     In one non-limiting use, the present invention provides a percutaneous connection to be created between an artery and vein of a kidney failure patient without the need for surgery; which allows immediate cannulation of the shunt without reliance on catheter use; and which allows for the maturation of the outflow veins for subsequent conversion to a fistula. 
     In one aspect of the invention, an arterial anchor device is provided. Arterial anchor device includes a generally tubular main body having a distal end and a proximal end and defining a lumen therewithin. Generally tubular main body comprises a metal frame structure including struts and connector portions. The distal end, which is received within a vessel wall, includes a plurality of petal-like flanges circumferentially disposed about the distal end and integrally formed with tubular main body. The flanges may be configured to bend at an angle equal to or less than 90 degrees towards the longitudinal axis of the tubular main body portion or bend at an angle greater than 90 degrees away from the longitudinal axis of tubular main body portion. The flanges are configured to spread from a first reduced configuration to a second expanded configuration to anchor the arterial anchor device against the inner wall of an arterial fluid passageway. The distal end of the tubular main body portion is semi-rigid and configured to bend at an angle of approximately 90 degrees from the longitudinal axis of the tubular main body and maintain the bend. The struts and connectors that form the distal end, therefore, include a variable cutting pattern such that the frame-like structure of struts and connectors at the distal end are closer together than the struts and connectors that form the main body. The proximal end of tubular main body may optionally include a plurality of finger-like tines integrally formed with tubular main body. Finger-like tines extend outwardly at an acute angle from the longitudinal axis of the main body lumen. Finger-like tines are configured to securedly fasten a graft member in place when operably coupled with the tubular main body. 
     In another aspect of the present invention, a venous anchor device is provided. The venous anchor device includes a generally tubular main body having a distal end and a proximal end and defines a lumen therewithin. Generally tubular main body comprises a metal frame structure. The distal end, which is received within a vessel wall, includes first and second portions. In one embodiment the first and second portions are non-coated. Alternatively, the first portion may be coated and the second portion may be non-coated or exposed. The outer diameter of the distal end is larger than the outer diameter of the tubular main body portion. A plurality of barbs are circumferentially disposed about the second end and integrally formed with tubular main body. The plurality of barbs are configured to seat the venous anchor device in the vessel wall to ensure it does not dislodge from the vessel and also to prevent the further expansion of the vein when the barbs contact the vessel wall. A portion of the tubular main body is coated with PTFE in the manner described herein to prevent leaking. The second portion of the distal end of the venous anchor device is non-coated to ensure that barbs are free to secure the venous anchor device to the venous wall. 
     In another aspect of the invention, an anastomotic connector is provided that includes an arterial anchor device, a venous anchor device; and a graft member. The arterial anchor device and venous anchor devices are as described hereinbefore. A graft portion comprising a generally tubular main body having a reinforced wall is structured to join the arterial and venous anchor devices within a patient&#39;s body. The tubular body including first and second ends thereof and defines a lumen therewithin. The outer diameter of the stented tubular main body of the arterial anchor device is greater than the inner diameter of the graft lumen thus providing an interference fit when in operable engagement. Optional finger-like tines on the proximal end of the arterial anchor device may also exert force against graft portion and prevent graft portion from being easily removed from the arterial connector. The second end of graft member is similarly connected to the venous anchor device, which is received within the lumen of the venous anchor device, which is configured to be placed within a second fluid passageway. The OD of the venous anchor device is greater than the ID of the graft resulting in a compression or friction fit when operably coupled. In position the arterial and venous anchor devices fluidly couple a first fluid passageway to a second fluid passageway to form an anastomotic connector. 
     In another aspect of the present invention, the arterial and venous anchor devices are coated with a PTFE coating to prevent leakage of blood or other fluids from the portion of the device that transports fluid from the first anchor device through the graft and to the second anchor device. The PTFE coating is applied by a process including forming a dispersion of polymeric nanofibers, a fiberizing polymer, and a solvent, the dispersion having a viscosity of at least about 50,000 cPs. The arterial and venous anchor devices are positioned over a tubular polymeric structure. Nanofibers from the dispersion are electrospun onto the tubular frame of the device and then the devices are heated. The process for coating the arterial and venous anchor devices is disclosed in U.S. 20110031656 and 20010030885 which are hereby incorporated by reference in their entirety. Alternatively, the arterial and venous anchor devices are coated by extruding tubes of polytetrafluoroethylene (PTFE) on the inside of the device and one on the outside. The two layers that are formed are heated to meld together. Other polymers that may be useful in coating the present devices are fluorinatedethylenepropylene (FEP), perfluoroalkoxy (PFA), polyvinylidene fluoride (PVDF), tetrafluoroethylene, hexafluoropropylene, polyethylenes such as HDPE, MDPE and LDPE, polyethylene terepthalate polyester (PET), polyetheretherketone (PEEK) and similar polymers having low coefficients of friction. 
     In another aspect of the invention, an anastomotic connector is provided that includes an arterial anchor device, a venous anchor device; and a graft member as hereinbefore described. 
     In another aspect of the present invention, a method of delivering an arterial anchor device within an arterial fluid passageway is provided. The method includes providing an arterial anchor device, the arterial anchor device including a generally tubular main body having a distal end and a proximal end, said distal end integrally defining a plurality of petal-like flanges circumferentially disposed about the distal end of said tubular main body, said tubular main body and said flanges movable between a loaded configuration and a preset expanded configuration; optionally providing a seating device comprising a wire shaft and a balloon member adapted to be inflated and deflated, said wire shaft positioned within a lumen of said tubular main body and said balloon member extending past said flanges; providing a delivery device, said delivery device including an outer sheath having a lumen; compressibly loading said seating device and said arterial anchor device within the lumen of said outer sheath; deploying the delivery device through an access site into a fluid passageway of a vessel; retracting the outer sheath to expose said flanges, wherein upon retracting the outer sheath said flanges revert to the preset expanded configuration; optionally inflating said balloon member and causing said flanges to engage an inner surface of the fluid passageway by moving said wire shaft proximally to cause said balloon member to adjacently abut said flanges thereby seating the arterial anchor device in the fluid passageway; removing said delivery device and seating device from said vessel. The tubular main body may exit the delivery device in a straight configuration and subsequently be bent into place at an angle of approximately 90 degrees by the surgeon. Alternatively, the tubular main body may be preset to bend at an approximate 90 degree angle such that when it exits the delivery device it reverts to the pre-set configuration. 
     In another aspect of the present invention, a method of delivering a venous anchor device within a venous fluid passageway is provided. The method includes providing a venous anchor device, the venous anchor device having a generally tubular main body having a distal end and a proximal end, said distal end integrally defining a plurality of barbs configured to engage a vessel wall, said tubular main body and said barbs movable between a loaded configuration and a preset expanded configuration; providing a delivery device, said delivery device including an outer sheath having a lumen; compressibly loading said venous anchor device within the lumen of said outer sheath; deploying the delivery device through an access site into a venous fluid passageway of a vessel; retracting the outer sheath to expose the distal end of the venous anchor device, wherein upon retracting the outer sheath the barbs revert to the pre-set expanded position and seat the device against the venous vessel wall; removing said delivery device. 
     In another aspect of the invention, a method of forming an anastomotic connector between two vessels in a body of a patient is provided. The method providing an arterial anchor device, said arterial anchor device including an arterial anchor tubular main body having a distal end and a proximal end, said distal end integrally defining a plurality of flanges circumferentially disposed about the distal end of said tubular main body, said arterial anchor tubular main body and said plurality of flanges movable between a loaded configuration and preset expanded configuration; providing a delivery device, said delivery device including an outer sheath defining a lumen therewithin; compressibly loading said arterial anchor device within the lumen of said outer sheath; deploying the delivery device through an access site into a first fluid passageway of a vessel to a predetermined position; retracting the sheath to expose said flanges and said balloon member, wherein upon retracting the sheath said flanges revert to the preset expanded configuration, wherein said flanges engage the surface of a wall of said first fluid passageway; further retracting said outer sheath to cause said tubular main body to revert to the preset expanded configuration outside the vessel wall; bending said tubular main body at an angle of ninety degrees from the longitudinal axis of the device; withdrawing said delivery device from said vessel; operably connecting a first end of a length of graft material to the proximal end of said arterial anchor tubular main body; providing a venous anchor device, said venous anchor device including a venous anchor tubular main body having a distal end and a proximal end, said distal end integrally defining a plurality of barbs thereon, said tubular main body and said plurality of barbs movable between a loaded configuration and preset expanded configuration; compressibly loading said venous anchor device within the lumen of said outer sheath of said delivery device; deploying the delivery device through an access site into a second fluid passageway of a vessel to a predetermined position; retracting the sheath to expose the distal end of said venous vessel anchor and said barbs, wherein upon retracting the sheath said barbs and said distal end revert to the preset expanded configuration; further retracting said outer sheath to cause said venous anchor tubular main body to revert to the preset expanded configuration outside the vessel wall; withdrawing said delivery device from said second vessel; and forming said anastomotic connector by operably connecting a second end of said length of graft material to the proximal end of said venous tubular main body. 
     These and other features of the invention will now be described in detail with reference to the accompanying Figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a side view of one exemplary embodiment of an arterial anchor device in accordance with the invention. 
         FIG. 1B  is a detailed view of the distal end of the arterial anchor device showing petal-like flanges. 
         FIG. 1C  is a side view of the proximal end of the arterial anchor device in accordance with the invention showing optional outwardly extending tines. 
         FIG. 1D  is a detailed view of the frame work structure of the arterial anchor device laid flat in accordance with an aspect of the invention. 
         FIG. 2A  is a perspective view of the arterial anchor device of  FIG. 1  showing the device coated in accordance with the invention. 
         FIG. 2B  is a detailed view of the distal end of the arterial anchor device showing uncoated petal-like flanges. 
         FIG. 3A  is an illustration of a coated arterial anchor device positioned within an arterial fluid passageway. 
         FIG. 3B  is an illustration of the arterial anchor device with a bend between the distal end and the central portion of the tubular body which causes the distal end to be off-set from the longitudinal axis of the tubular body by about 90 degrees. 
         FIG. 4A  is a side view of an embodiment of the venous anchor device in accordance with an aspect of the invention showing the frame work structure. 
         FIG. 4B  is a view of the frame work structure of the venous anchor device laid flat in accordance with an aspect of the invention. 
         FIG. 4C  is a side view of an aspect of the venous anchor device showing the device coated in accordance with the invention. 
         FIG. 5  is a perspective view of an alternative coated venous anchor device in accordance with the invention. 
         FIG. 6  is an illustration of the venous anchor device of  FIG. 4  seated in a venous fluid passageway and connected to a graft portion. 
         FIG. 7  illustrates an exemplary delivery device utilized to deliver the arterial and venous anchor devices in accordance with the invention. 
         FIGS. 8-10  illustrate the delivery and method of placing the arterial anchor device within a vessel. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention is generally directed to an anastomotic connector structured to attach a graft between an artery and a vein, a novel arterial anchor device for anchoring the anastomotic connector to the artery and a novel venous anchor device for anchoring the anastomotic connector to the vein. The anastomotic connector in accordance with the invention may be placed percutaneously or subcutaneously and may be fabricated from any biocompatible material suitable for implantation into the human body. Further, the anchor devices preferably have a low cost and are readily replaceable. As will be appreciated by those of ordinary skill in the art based upon the following disclosure, the anastomotic connector of the invention may replace the use of catheters in those patients on hemodialysis who are permanently consigned to catheter use due to their inability (anatomically or otherwise) to sustain long-term fistula or graft options. 
     Numerous structural variations of an anastomotic connector device and arterial anchor devices are contemplated and within the intended scope of the invention. For purposes of discussion and not limitation, an exemplary embodiment will be described in detail below. As those of ordinary skill in the art will appreciate, although the anastomotic connector will be described with reference to placement within a vessel, it should be understood that the anastomotic connectors may be placed within various other fluid passageways without departing from the intended scope of the invention. 
     As best seen in  FIGS. 1 through 6  the anastomotic connector system in accordance with the invention broadly comprises an arterial anchor device, a graft and a venous anchor device. The component parts of the anastomotic connector system will now be described. 
       FIG. 1A  is a side view of one exemplary embodiment of an arterial anchor device  10  used to form the anastomotic connector in accordance with the invention. As illustrated in  FIG. 1A , arterial anchor device  10  generally includes a tubular main body  12  defining a lumen  14  therethrough. Main body  12  includes distal  16  and proximal ends  18 . In an exemplary embodiment, the outer diameter of proximal end  18  of main body  12  is greater than an outer diameter at the distal end  16  thereof. In other embodiments the outer diameter of the distal  16  and proximal  18  ends are substantially equivalent. The outer diameter of proximal end  18  may also be greater than the internal diameter of graft material  24  such that when the graft material  24  is received over the proximal end  18  of the main body  12 , the radial force exerted by the anchor device at body temperature ensures an interference fit when operably coupled to graft material  24 . One exemplary but non-limiting type of graft that may be used is a Vectra® vascular access graft (Bard Peripheral Vascular, Tempe, Ariz.). In other embodiments the outer diameter of proximal end  18  of main body  12  may be substantially equivalent to the internal diameter of the graft material so long as an interference fit is achieved, without departing from the intended scope of the invention. The varying outer diameters of the proximal end  18  of the main body  12  may depend upon numerous factors such as, for example, the desired amount of flow through the anastomotic connector. In exemplary embodiments the outer diameters of the proximal end  18  may range between about 1 mm and about 10 mm, although larger or smaller outer diameters are also contemplated and within the intended scope of the invention. 
     As illustrated in  FIGS. 1A and 1B , arterial anchor device  10  includes a plurality of flanges  22  circumferentially disposed about the distal end  16  thereof. Flanges  22  have a petal-like configuration and are integrally formed with the tubular main body  12  of arterial anchor device  10 . In forming the petal-like configuration flanges comprise a wire that in a second expanded configuration has a diameter across a central portion that is wider than the diameter across the first and second end portions. Flanges  22  may be configured to expand upon deployment at a preset angle equal to approximately 90 degrees or less. In one aspect of the invention, flanges  22  are offset at an acute angle  21  from the longitudinal axis of tubular main body  12  to seat the arterial anchor device against a vessel wall. In an exemplary embodiment, the acute angle may be approximately 50 to 60 degrees and may be preset at 55 degrees. In one aspect of the invention in a first non-expanded configuration flanges  22  are substantially parallel to a longitudinal axis of the tubular body. In another aspect of the invention, in a second expanded configuration, flanges  22  are substantially perpendicular to the longitudinal axis of the tubular body. In another aspect of the invention in a second expanded configuration, flanges  22  are offset from the longitudinal axis of the tubular main body by an acute angle. 
     As best seen in  FIG. 1B , the struts or wires  23  that form the wall of the petals are configured to expand into a wider profile to ensure that they contact the maximum area possible of the vessel wall thus ensuring the proper seating of the arterial anchor device against the wall of the arterial fluid passageway. Those of skill in the art will also appreciate that various configurations could be made to flanges  22 , without departing from the intended scope of the invention, so long as the flanges  22  are sufficiently angled and sufficiently spread apart to securely and firmly anchor the arterial anchor device  10  to a vessel wall in an arterial fluid passageway. Those of skill in the art will appreciate, however, that the petals which are formed axially will be flatter against the vessel wall and, therefore, provide greater anchoring than the petals that are otherwise formed. 
     For purposes of this disclosure, however, flanges  22  configured at an acute angle  21  offset from the longitudinal axis of main body  12  will be discussed. Tubular main body  12  comprises a metal frame structure that includes integrally formed struts  27  and connectors  26 . Referring to  FIG. 1C , arterial anchor device  10  may optionally include a plurality of finger-like tines  28  positioned at the proximal end  18  of tubular main body  12  and integrally formed therewith. Finger-like tines  28  extend outwardly from the main body  12  at an acute angle. However, those of skill in the art will appreciate that finger-like tines  28  can extend outwardly from the main body lumen  14  at any angle that will cause them to exert a compressive force on a graft when operably coupled therewith. Tubular graft portion  24  is operably coupled to proximal end  18  of main body  12  by inserting the proximal end  18  of arterial anchor device  10  into the lumen of the graft  24 . Because finger-like tines  28  extend outwardly from the tubular main body lumen  14  they exert a compressive force on graft  20  that prevents the graft  20  from being retracted in the opposite or proximal direction thus operably coupling the tubular graft portion  24  to arterial anchor device  10  assuring the graft will not dislodge after placement. 
     As further illustrated in the exemplary embodiment of  FIGS. 1A-1D , tubular main body  12  integrally transitions at the distal and proximal ends into flanges  22  and finger-like tines  28 , respectively. Tubular main body  12  includes a distal end  16  and a proximal end. As can best be seen in  FIG. 1D  the struts  27  that form the distal end  16  have a variable cutting pattern  17  resulting in struts  27  that are closer together and more tightly formed than the struts  27  that form the central portion  25  and those at the proximal end  18 . As can be seen in  FIG. 1D , the strut formation at the distal end  16  includes three sections  101 ,  102 ,  103 . The first and thirds sections  101 ,  103  include a plurality of sinusoidal-shaped struts having a length of approximately 3.77 mm. The second section  102  includes double sinusoidal-shaped struts connected at the curve by connecting member  26 . The second section  102  is connected to the first and third sections  101 ,  103  by additional connecting members  26 . The second section is approximately 8.8 mm. 
     The central portion  25  also includes a plurality of rows  110 - 115  of openly-formed sinusoidal-shaped struts. The first row of struts  110  is connected at the curved portion  105  of the strut to the curved portion  106  of the last row of struts in the distal end. Each row of central portion struts  110 - 115  is connected to the subsequent row by two connecting members  126  that extend from a mid-portion of the strut to the curved portion of the strut in the subsequent row. Central portion  25  is approximately 28 mm. 
     The elongated proximal end includes a strut formation of two rows  201 ,  202 . Each row includes a plurality of sinusoidal-shaped struts  227  with the second section  202  including double sinusoidal-shaped struts  228 . First row  201  is connected by a plurality of connecting members  226  to the central portion  25 . First row  201  is connected at the curved portion to the second double row  228 . 
     Those of skill in the art will appreciate that the number of rows utilized in the anchor device can vary depending on the length of the anchor device desired. 
     The arterial anchor device in accordance with the invention is expandable from a first retained configuration to a second expanded configuration as seen in  FIG. 1A . The variable cutting pattern of the distal end  16  allows for the second configuration in which the distal end  16  may be bent or preset at an angle that is approximately 90 degrees offset from the longitudinal axis LA of the tubular main body  12  as best seen in  FIG. 3B . In addition, the tighter variable cutting pattern of the distal end provides a stronger radial force when in the expanded position which helps in preventing leakage when positioned within an arterial vessel. The stronger radial force at the distal end also prevents the arterial anchor device from collapsing and cutting off or reducing flow through the anastomotic connector. 
     Plurality of flanges  22  are structured to move between a loaded position (inside a delivery sheath, not shown) prior to deployment and an expanded in situ position as illustrated in  FIG. 1A  and  FIG. 3 . As will be appreciated by those of ordinary skill in the art, the arterial anchor device  10  in accordance with the invention, and as best seen in  FIGS. 2A, 2B and 3 , is structured to provide a secure, leak-free connection to an arterial vessel passageway. Therefore, it is contemplated that a fluid impermeable, biocompatible polymer  23  may be deposited on the arterial anchor device to fill the interstices of the struts comprising the tubular main body to ensure a leak-tight seal when implanted in the arterial fluid passageway. Such biocompatible materials may include, but are not limited to, expanded Polytetrafluoroethylene (“ePTFE”), polyester, silicone composites, or various other plastics and elastomers or combinations thereof. In an exemplary embodiment, the arterial anchor device is coated with a PTFE coating to prevent leakage of blood or other fluids from the portion of the device that transports fluid from the first anchor device through the graft and to the second anchor device. The PTFE coating is applied by a process including forming a dispersion of polymeric nanofibers, a fiberizing polymer, and a solvent, the dispersion having a viscosity of at least about 50,000 cPs. The arterial anchor device is positioned over a tubular polymeric structure. Nanofibers from the dispersion are electrospun onto the tubular frame of the device and then the devices are heated.  FIG. 3  depicts a further aspect of an anchor device in accordance with the invention having petal-like flanges  22  coated with the PTFE electrospun coating, those of skill in the art will appreciate that flanges  22  may remain uncoated as shown in  FIGS. 2A and 2B  to ensure a tight compression fit against the wall of the arterial fluid passageway. In addition, endothelialization of the flanges will be promoted by leaving flanges  22  uncoated. Further, it may to desirable to leave proximal end  18  uncoated so that the coating does not fray when it is compress into graft material  24  thus ensuring a fluid impermeable fit. 
     Alternatively, the arterial and venous anchor devices may be coated by extruding tubes of polytetrafluoroethylene (PTFE) on the inside of the device and one on the outside. The two layers that are formed are heated to meld together. Other polymers that may be useful in coating the present devices are fluorinatedethylenepropylene (FEP), perfluoroalkoxy (PFA), polyvinylidene fluoride (PVDF), tetrafluoroethylene, hexafluoropropylene, polyethylenes such as HDPE, MDPE and LDPE, polyethylene terepthalate polyester (PET), polyetheretherketone (PEEK) and similar polymers having low coefficients of friction. 
     Arterial anchor device  10  may be either self-expanding, such as so-called shape-memory materials, or non self-expanding, such as stainless steel. One benefit of using a self-expanding material is that plurality of flanges  22  will expand when deployed within a vessel without the need for a separate expansion device, thus eliminating additional equipment and steps during the deployment process. 
     As best seen in  FIG. 1D , in forming the exemplary arterial anchor device  10 , a tubular length of metal is used to cut the arterial anchor device  10  and integrally form the struts  24  and connectors  26  of tubular main body  12  as well as flanges  22  and finger-like tines  28 . As discussed previously, the metal material used in the exemplary arterial anchor device  10  should be both resilient and capable of being heat treated to substantially set a desired shape. Preferably, the metal from which arterial anchor device  10  is cut exhibits a high modulus of elasticity that is biocompatible and has superior compressibility allowing the arterial anchor device  10  to be self-expandable. 
     One class of materials which meet these qualifications is so-called shape memory alloys. Such alloys tend to have a temperature induced phase change which will cause the material to have a preferred configuration which can be fixed by heating the material above a certain transition temperature to induce a change in the phase of the material. When the alloy is cooled back down, the alloy will “remember” the shape it was in during the heat treatment and will tend to assume that configuration unless constrained from so doing. 
     One particularly preferred shape memory alloy for use in the present method is Nitinol, an approximately stoichiometric alloy of nickel and titanium, which may also include other minor amounts of other metals to achieve desired properties. NiTi alloys such as nitinol, including appropriate compositions and handling requirements, are well known in the art and such alloys need not be discussed in detail here. 
     Such NiTi alloys are preferred, at least in part, because they are commercially available, have a high yield strain and more is known about handling such alloys than other known shape memory alloys. NiTi alloys are also very elastic—they are said to be “superelastic” or “pseudoelastic.” This elasticity will help a device of the invention return to a present expanded configuration for deployment into a blood vessel. However, any suitable self-expanding material may be used as will be appreciated by those of ordinary skill in the art. 
     As hereinafter described, prior to implantation the arterial anchor device  10  is collapsed inside a delivery device or sheath. Upon introduction into a vessel, the distal end of the anchoring structure freely self-expands to its original dimensions. The self-expanding behavior of the arterial anchor device  10  is due to the relatively high modulus of elasticity of the shape-memory material, which imparts superior spring-like properties to the arterial anchor device  10 . 
       FIG. 3A  illustrates an exemplary arterial anchor device  10  deployed through vessel wall W.  FIG. 3B  illustrates the approximate 90 degree bend in the arterial anchor device. 
     Referring now to  FIGS. 4-6  a venous vessel anchor  400  in accordance with the invention is shown. As illustrated in  FIG. 4A , venous vessel anchor  400  generally includes a tubular main body  412  defining a lumen  414  therethrough. Main body  412  includes distal  416  and proximal ends  418 . In one exemplary embodiment, the outer diameter of distal end  416  of main body  12  is greater than the outer diameter of proximal end  418  to ensure it is property seated in a venous fluid passageway. Generally tubular main body  412  comprises a metal frame structure. In an exemplary embodiment depicted in  FIG. 4C  the distal end  416 , which is received within a vessel wall, includes first and second portions  415 ,  417 . The first  415  and second  417  portions are non-coated. Alternatively, as best seen in  FIG. 5  the first portion  415  may be coated and the second portion may be non-coated to expose a plurality of barbs  421  circumferentially disposed about the second end and integrally formed with tubular main body. The plurality of barbs  421  are configured to seat the venous anchor device in the vessel wall to ensure it does not dislodge from the vessel wall. In addition, upon deployment barbs  421  restrict further expansion of the venous anchor device when the barbs  421  anchor it against the vessel wall. A portion of the tubular main body  412  is coated in the manner hereinafter described to prevent leaking. Preferably, the first and second portions  415 ,  417  of the distal end  416  of the venous anchor device are non-coated to ensure that barbs  421  are free to secure the venous anchor device  400  to the venous wall. When forming the anastomic connector in accordance with the invention, the venous vessel anchor  400  is operably coupled to graft material  424 , as best seen in  FIG. 6 . One exemplary but non-limiting type of graft that may be used is a Vectra® vascular access graft (Bard Peripheral Vascular, Tempe, Ariz.). The outer diameter of proximal end  418  of main body  412  may be greater than the internal diameter of the graft material  424  to ensure a tight interference fit. Alternatively, the outer diameter of the proximal end  18  may be substantially equivalent to the internal diameter of the graft material, without departing from the intended scope of the invention, so long as an interference fit is achieved. The varying outer diameters of the proximal end  418  of the main body  412  may depend upon numerous factors such as, for example, the desired amount of flow through the anastomotic connector. In exemplary embodiments the outer diameters of the proximal end  418  may range between about 1 mm and about 10 mm and preferably about 8 mm on the proximal end when fully expanded, although larger or smaller outer diameters are also contemplated and within the intended scope of the invention. The outer diameter of the distal end  416  is approximately 10 mm to 12 mm and preferably 11 mm so long as it is larger than the proximal end  418 . 
     As best seen in  FIGS. 4A and 4B  the frame-like structure of the tubular main body  412  has a loose configuration or in other words a column pitch that is substantially equivalent along the length of the device. In one aspect of the invention, the column pitch (‘CP’) is approximately 0.185 inches which allows the tubular body to easily bend. Those of skill in the art will appreciate, however, that other column pitches can be used and still be within the scope of the invention. When the tubular main body  412  is exposure to arterial pressure the loosely configured tubular main body  412  will stretch. When first deployed into the venous vessel it will assume an outer diameter equal to the inner diameter of the venous vessel into which it is deployed up to an approximate maximum of about 10 mm. As barbs  421  engage the vessel wall (as best seen in  FIG. 6 ) the barbs prevent the vein from further expansion. 
     As can be seen in  FIG. 4B  the frame like structure is substantially the same as the central portion  425  of the arterial anchor device  10 . Thus, frame of the venous anchor device includes a plurality of rows  410  of openly-formed sinusoidal-shaped struts. Each row of struts  410  is connected to the subsequent row by two connecting members  426  that extend from a mid-portion of the strut to the curved portion of the strut in the subsequent row. 
     As will be appreciated by those of ordinary skill in the art, the venous anchor device  400  in accordance with the invention, and as best seen in  FIGS. 4 through 6 , is structured to provide a secure, leak-free connection to a venous vessel passageway. Therefore, it is contemplated that a fluid impermeable, biocompatible polymer  423  may be deposited on the venous anchor device  400  to fill the interstices of the struts comprising the tubular main body to ensure a leak-tight seal when implanted in the venous fluid passageway. The fluid impermeable, biocompatible polymer  423  may be woven. Such biocompatible materials may include, but are not limited to, expanded Polytetrafluoroethylene (“ePTFE”), polyester, silicone composites, or various other plastics and elastomers or combinations thereof. In an exemplary embodiment, the venous anchor device is coated with a PTFE coating to prevent leakage of blood or other fluids from the portion of the device that transports fluid from the first anchor device through the graft and to the second anchor device. The PTFE coating is applied by a process including forming a dispersion of polymeric nanofibers, a fiberizing polymer, and a solvent, the dispersion having a viscosity of at least about 50,000 cPs. The venous anchor device  400  is positioned over a tubular polymeric structure. Nanofibers from the dispersion are electrospun onto the tubular frame of the device and then the devices are heated. Alternatively, the venous anchor device is coated by extruding tubes of polytetrafluoroethylene (PTFE) on the inside of the device and one on the outside. The two layers that are formed are heated to meld together. Other polymers that may be useful in coating the present devices are fluorinatedethylenepropylene (FEP), perfluoroalkoxy (PFA), polyvinylidene fluoride (PVDF), tetrafluoroethylene, hexafluoropropylene, polyethylenes such as HDPE, MDPE and LDPE, polyethylene terepthalate polyester (PET), polyetheretherketone (PEEK) and similar polymers having low coefficients of friction. 
     As described previously and as alternatively depicted in  FIG. 4C  the entire distal end  416  of the venous anchor device  400  may be left uncoated while the tubular main body is coated. Alternatively, as shown in  FIG. 5 , the venous anchor device  400  may have the first portion  415  coated while the second portion  417  including plurality of barbs  421  is uncoated to ensure barbs  421  are free to lie against vessel wall. 
     Those of skill in the art will appreciate that although it is contemplated that the venous anchor device  400  is coated there is no backflow in the venous device due to the arterial pressure of the blood flowing through it. This minimizes any leakage that may occur at the entry point of the device in the venous wall. 
     Venous anchor device  400  may be either self-expanding, such as so-called shape-memory materials, or non-self-expanding, such as stainless steel. In forming the exemplary venous anchor device  400 , a tubular length of metal is used to cut the venous anchor device  400  and integrally form the struts and connectors of tubular main body  412  as well as barbs  421 . As discussed previously, the metal material used in the exemplary venous anchor device  400  should be both resilient and capable of being heat treated to substantially set a desired shape. Preferably, the metal from which venous anchor device  400  is cut exhibits a high modulus of elasticity that is biocompatible and has superior compressibility allowing the venous anchor device  400  to be self-expandable. 
     One class of materials which meet these qualifications is so-called shape memory alloys. Such alloys tend to have a temperature induced phase change which will cause the material to have a preferred configuration which can be fixed by heating the material above a certain transition temperature to induce a change in the phase of the material. When the alloy is cooled back down, the alloy will “remember” the shape it was in during the heat treatment and will tend to assume that configuration unless constrained from so doing. 
     One particularly preferred shape memory alloy for use in the present method is Nitinol, an approximately stoichiometric alloy of nickel and titanium, which may also include other minor amounts of other metals to achieve desired properties. NiTi alloys such as nitinol, including appropriate compositions and handling requirements, are well known in the art and such alloys need not be discussed in detail here. 
     Such NiTi alloys are preferred, at least in part, because they are commercially available, have a high yield strain and more is known about handling such alloys than other known shape memory alloys. NiTi alloys are also very elastic—they are said to be “superelastic” or “pseudoelastic.” This elasticity will help a device of the invention return to a present expanded configuration for deployment into a blood vessel. However, any suitable self-expanding material may be used as will be appreciated by those of ordinary skill in the art. 
     As hereinafter described, prior to implantation the venous anchor device  400  is collapsed inside a delivery device or sheath. Upon introduction into a vessel, the distal end of the anchoring structure freely self-expands to its original dimensions. The self-expanding behavior of the venous anchor device  400  is due to the relatively high modulus of elasticity of the shape-memory material, which imparts superior spring-like properties to the venous anchor device  400 . 
     Referring generally to  FIGS. 8 through 11 , the method of implanting the arterial anchor device and venous anchor device to form the anastomotic connector in accordance with the invention will now be discussed. In a technique known to those of skill in the art to gain access to a fluid passageway of a vessel, an introducer including a stylet having a micropuncture tip puncture is introduced into the patient body. The stylet is used to puncture a small access opening through a vessel wall. The stylet is then removed with the introducer remaining in position in the fluid passageway of the vessel through the vessel wall. 
     Referring to  FIGS. 7 through 10 , the delivery device  710  used to deliver and seat the anchor devices  10 ,  400  in accordance with the invention in a fluid passageway broadly includes a seating device  712  comprising a wire shaft portion  713  terminating in an inflatable balloon member  714  on a distal end thereof and an outer sheath  716  into which the anchor device  10 ,  400  is loaded. The wire shaft  712  with donut-shaped balloon member  714  is positioned within the lumen  14  of, for example, arterial anchor device  10  with the balloon member  714  extending past aperture  36  formed by flanges  22 . The combination, i.e. arterial anchor device  10  and wire shaft  512  with balloon member  714  is then housed within the outer sheath  716  of the delivery device  510  for introduction into the fluid passageway. The delivery device  710  may include radiopaque markings on the outer sheath at the proximal end which extends outside the body to enable the physician to visualize the placement of the arterial anchor device  10  in accordance with the invention. The physician guides the delivery device into the fluid passageway up to the first mark on the outer shaft, which extends the distal end of the delivery device into the fluid passageway of vessel V. The sheath  716  is then retracted to a second marking to expose the balloon member  714  and flanges  22  in the vessel fluid passageway. Flanges  22  revert to an expanded position (due to the shape memory properties and by mechanical actuation) to secure the connector  10  to an inner surface (IS) of vessel wall W. Balloon member  714  is inflated and retracted against the annular flange aperture  36  by manipulating the wire shaft  713  in a proximal direction. As the balloon member contacts the flanges  22 , flanges  22  are moved to seat the anchor device to an inner surface (IS) of vessel wall W. The sheath is further retracted proximally to expose the remaining portion  518  of the arterial anchor device extending outside the vessel wall W. The tubular main body may then be bent at the distal end to an about 90 degree angle to the longitudinal axis of the distal end. Alternatively, the about 90 degree bend may be pre-set such that when the anchor device is deployed it assumes the about 90 degree configuration. The graft material  24  is then slidably coupled to the proximal end  18  of the vessel anchor  10  having a greater outer diameter to create a fluid tight seal. Those of skill in the art will appreciate; however, that arterial anchor device  10  may be integrally formed with graft material  24  or may be pre-loaded onto the graft material  24  prior to delivery in an arterial fluid passageway. Those of skill in the art will also appreciate that the anchor device may be deployed by puncturing the raft at the mid-section, wherein the graft material would be self-sealing or a surgeon would sew it closed. Alternatively, a valve may be built into the side of the graft material and the anchor device deployed through the valve. 
     Wire shaft  713  is removed from the system leaving the arterial anchor device  10  seated in the arterial vessel fluid passageway and operably coupled to graft material  24 . The foregoing process is then repeated with the venous vessel anchor  400  in a venous fluid passageway to form the anastomotic connector in accordance with the invention. However, the balloon member is optionally eliminated from seating the venous device as the barbs  421  will self-expand to anchor the device against the venous wall.  FIG. 3  depicts the arterial anchor device in accordance with the invention implanted in an arterial fluid passageway and  FIG. 6  depicts the venous anchor device in accordance with the invention implanted in a venous fluid passageway. As illustrated, the distal portion of the venous anchor device resides within the vessel lumen with barbs  421  lying adjacent to or embedded in the venous wall as opposed to the arterial anchor device which is seated against a vessel wall. 
     Additionally, it may be preferable to provide the anastomotic connectors of the invention with an inner surface that is contoured to allow smooth arterial or venous blood flow into and out of the connector device. As those of ordinary skill in the art will appreciate, providing a non-thrombogenic surface minimizes the creation of recirculation or stagnation zones with high shear or dwell times that could otherwise lead to clotting. 
     It is also contemplated that the inner or outer surface of the anastomotic connectors of the invention be configured to deliver and release therapeutic substances such as anti-microbial agents, anti-inflammatory agents, anti-proliferative agents (e.g. taclipaxel), growth factors, stem cells, collagen and the like. Those of ordinary skill in the art will appreciate that these therapeutic agents may be coupled with the connector and/or the external or internal surface of the connector by means such as being encased or embedded in a polymeric or other biocompatible coating, applied to a textured external surface of the connector; contained within pockets of the connector on either an internal or external surface, and the like. 
     As will be appreciated by those of ordinary skill in the art, the same general process described herein may be followed in order to place a connector within other types of fluid passageways. Although a method of deploying an anastomotic connector having a self-expanding anchor member has been generally described herein, the method may be adapted for deploying an anastomotic connector having a non self-expanding anchor member. 
     Based upon the present disclosure and after viewing the exemplary embodiment of the anastomotic connector presented herein, the many advantages and benefits provided by the invention will be appreciated by those of ordinary skill in the art. One advantage is that the geometry of the anastomotic connector allows continuous and uninterrupted arterial or venous flow during use for dialysis or other applications, thereby eliminating or substantially reducing any loss of circulation to the downstream, distal extremities. Stated alternatively, the geometry of the anastomotic connectors allows “full” flow into the graft as well as “full” flow to the downstream anatomy. Thus, distal arterial flow is not “cut-off” due to the presence of the anastomotic connector. Another advantage is that the anastomotic connectors of the invention are true percutaneous devices that do not require a “cut down” as in an “open surgery” approach. The implantation method is therefore less invasive for the patient and faster for the surgeon. Yet another advantage is that the present invention allows for maturation of the distal vein in preparation for secondary AVF while avoiding a central dialysis catheter. 
     Although the present invention has been described with reference to preferred embodiments, those of ordinary skill in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.