Abstract:
Methods and systems are described for creating chronic vascular access or hemodialysis. These methods and systems eliminate the insertion of needles which are now required for using the available methods of obtaining vascular access. Thus multiple complications due to needle insertion through skin, tissue, and vein or graft wall are prevented. A low-profile stable transcutaneous implant&#39;s external surface and stability minimizes infection. The implant is readily joined to a connector device that functions substantially automatically and which provides high blood flow volumes for hemodialysis.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. Nos. 61/094,745, filed Sep. 5, 2008, entitled “Methods and Apparatuses for Conducting Dialysis”, and 61/216,821, filed May 21, 2009, entitled “Method and Device For Vascular Access”. This application is also a continuation-in-part of U.S. patent application Ser. No. 12/206,674, filed Sep. 8, 2008, entitled “Method And Device For Dialysis”. All of the above applications are herein incorporated by reference in their entirety. 
     
    
     BACKGROUND 
       [0002]    The use of hemodialysis to maintain the lives of patients suffering from kidney failure was initiated in the 1960′s. It has become a widely used medical technology for patients of all ages suffering from multiple disease states that produce severe damage to the kidneys. This damage prevents the normal excretion of the toxic products of metabolism and without the use of dialysis, death will occur within a short period of time. 
         [0003]    Hemodialysis requires the use of a dialysis machine that filters the toxic substances from the patient&#39;s blood on a regular basis—generally three times each week on an every-other-day schedule for a duration of approximately four hours for each treatment. 
         [0004]    In order to successfully perform chronic hemodialysis it is necessary to have chronic access to the patient&#39;s circulatory system (vascular access). A hemodialysis treatment includes simultaneously withdrawing and infusing over 500 cc per minute of blood from and to the patient utilizing one of three forms of vascular access. 
         [0005]    In one system, a central venous catheter (CVC) is placed within a large central vein and is generally used to institute temporary emergency or urgent hemodialysis. It provides limited blood flow, causes stenosis and thrombosis of central veins, and frequently becomes non-functional due to clotting and is often the site for local and bloodstream infections. The use of the CVC may be the least desirable of the present methods for permanent vascular access. 
         [0006]    In another system a autologous arterio-venous fistula (AVF) is used which requires the presence of an adequately-sized undamaged artery and vein in an extremity. The blood vessels must be in close proximity and must be able to be anastomosed (joined) to create a dilated venous system through which flows a large volume of arterial blood. The markedly increased blood flow at increased pressure in the dilated vein is then accessed by the placement of two (2) large bore needles. These needles provide flow to and from the dialysis machine. Unfortunately, less than 50% of patients requiring hemodialysis have adequate blood vessels for the creation of a successful AVF. The increased flow and pressure within the dilated vein and the repeated insertion of needles through the skin, subcutaneous tissues and the vein wall eventually causes damage to the vein resulting in stenosis, aneurysms and thrombosis of the AVF. Nonetheless, it is currently considered the “best” method of vascular access for hemodialysis. 
         [0007]    In yet another system, an interposition graft arterio-venous fistula (IGAVF) is used when the patient does not have adequate veins for construction of an AVF. A tubular graft 6 to 7 mm in diameter, generally composed of polytetrafluroethylene (PTFE), and 25 to 40 cm in length is anastomosed to an adequately-sized extremity artery and vein and tunneled immediately beneath the skin surface. Arterial blood flows thru the graft into the venous system at high flows and pressure and, as in the AVF system, two (2) large bore needles must be inserted into the graft to perform hemodialysis. These needles result in repeated damage to the skin, subcutaneous tissues and graft wall, producing stenosis, false aneurysms, bleeding, clotting of the graft, and local and blood stream infection. 
         [0008]    Each patient with an AVF or IGAVF has to undergo the insertion of a minimum of 312 needles each year and often many more insertions, due to difficult or improper placement, in order to perform hemodialysis. Insertion of the needles at the start of hemodialysis requires skill, is painful, and results in anxiety for the patient. Removal of the needles at the completion of hemodialysis requires prolonged pressure at the puncture sites to induce clot formation and tissue coaptation to prevent bleeding. 
         [0009]    Improper needle placement results in local bleeding into the tissues (e.g., hematoma formation) and can produce false aneurysms, which are spaces within the tissues surrounding the puncture sites filled with flowing blood under high pressure. The average dialysis patient undergoes two (2) operative procedures each year to repair or create new or revise prior vascular access. 
         [0010]    Approximately thirty years ago the problems associated with repeated use of needles in patients using IGAVF for hemodialysis were recognized. A device was developed and released by Bentley Laboratories of Irvine, Calif., termed the Bio-Carbon Vascular Access Prosthesis—consisting of a permanent percutaneous port attached to a PTFE graft. The PTFE graft was inserted in the same manner as an IGAVF and the port brought through the subcutaneous tissue and skin for permanent vascular access. The device eliminated the need for needle insertion by using the percutaneous port and a connecting device as the means of providing blood inflow to and outflow from the dialysis machine. The Bentley system received FDA approval and was used in a significant number of patients worldwide and reported on in the peer-reviewed medical literature. It provided adequate blood flow rates for hemodialysis and eliminated the problems associated with the use of needles. Its major drawbacks were the formation of a sinus tract surrounding the port&#39;s exit site through the skin, a site for local infection to develop, and a cumbersome connector for connecting to the dialysis machine. Nonetheless, patients, dialysis nurses and nephrologists were enthusiastic in its use. However, the manufacturer of the device discontinued its production in the early 1980&#39;s. 
         [0011]    In addition to the Bentley device, a device was developed, e.g., a PTFE graft attached to a permanent port containing a silastic “plug” through which needles were inserted for dialysis. This device suffered from leakage through the silastic material, recirculation, sinus tract formation, and clot formation within the device. 
         [0012]    The three present methods described above for providing vascular access for hemodialysis have been in use for over 40 years. Other than attempting to influence nephrologists and surgeons to create an AVF or its several modifications, or using modified designs or materials for CVCs and IGAVFs, no new methods of creating permanent vascular access for hemodialysis are available. 
         [0013]    The maintenance of permanent and adequate vascular access for hemodialysis with minimal complications and the elimination of multiple operative procedures and/or radiologic interventional procedures is critical. The number of patients requiring dialysis continues to increase. Many of these patients are aged, obese, diabetic and often without adequate arteries or veins available for the construction of an AVF. Therefore, the standard IGAVF with its multiple complications is the only method available for providing vascular access to over 50% of patients requiring hemodialysis. In addition, if “home dialysis” or more frequent (daily) hemodialysis is ever to be realized, a simple, failsafe device for accessing the patient&#39;s circulatory system is essential. The elimination of the need to insert needles and the attendant complications may be important for such future systems. 
       SUMMARY 
       [0014]    Embodiments of the present invention provide devices and methods for maintaining permanent access to the patient&#39;s circulatory system, e.g., for the performance of hemodialysis (but any number of treatments requiring vascular access are envisioned). These embodiments provide a non-traumatic method for accessing a patient&#39;s circulatory system, providing high blood flows, and creating a simple, rapid and failsafe method for connecting to and disconnecting from the dialysis machine. 
         [0015]    One embodiment consists of a single transcutaneous port implant which may be of various heights and diameters and which contains an open central cannel which may be of various diameters. The channel is closed by a “plug-in seal” when not in use. Attached to the port may be a tubular graft of PTFE material, which may be of various lengths and diameters. One end of the graft is anastomosed to an appropriate artery and the other end is anastomosed to an appropriate vein. Blood flows continuously through the graft at high volume and pressure. The graft is placed in a deep location within the patients&#39; tissues and the port is also implanted in the patients&#39; tissues and brought out perpendicularly through the skin. A cap may be employed to provide a sterile cover for the external exposed surface of the port implant and contained “plug-in seal”. When the implant port is in use the plug-in seal is removed and a double lumen tube is inserted into the open channel of the port by means of a sterile connector device. This tube completely fills the channel lumen and extends within the lumen of the attached PTFE graft partially occluding its lumen. The use of a specially configured double lumen tube to access the blood flow within the graft allows blood flow to and from the dialysis machine and minimizes recirculation of treated blood despite the use of a single entry site to the patients circulatory system. The connector device is employed to provide a sterile, secure method for removing the “plug-in seal” and inserting the double lumen tube to initiate dialysis; then at the completion of dialysis the tube is removed and a new sterile seal inserted. The connector device is small, sterile, simple to use and disposable. 
         [0016]    The implant may have an external surface that promotes well-vascularized tissue ingrowth, by employing a mesh matrix and/or a porous configuration. This tissue ingrowth acts as a barrier to infection. In one embodiment, the surface material may be combined with an application of collagen and/or a silver polymer in order to create an additional barrier to infection. In addition the tissue ingrowth provides stability to the implant. The implant port and connector device provide a convenient, mechanical, sterile, and rapidly-deployable way to conduct dialysis. 
         [0017]    The materials that may be used for the construction of the devices may be generally biocompatible. The surfaces exposed to blood flow will generally be non-thrombogenic. 
         [0018]    Another embodiment includes two (2) implant ports substantially the same as the previously described implant port in configuration, material and surface. Each port however is attached to a circular or oval skirt of PTFE material which may be of various dimensions. The implant ports are individually anastomosed to an appropriately sized artery or vein with the graft skirt serving as a small patch sewn into the vessel wall and allowing access to the vessel lumen. When not in use the port channel is sealed and blood flows through the “patched” vessel. When in use a single lumen tube is inserted into the port channel and may or may not extend into the vessel lumen. Blood is removed from the arterial port and infused through the venous port. This arrangement allows placement of the ports at widely separated sites and eliminates recirculation and “steal” syndromes. Each port of the two port system requires a separate connector device of similar design to that used with the single port system. 
         [0019]    In one aspect, the invention is directed toward a connector device for accessing an implant coupled to a graft forming part of a patient&#39;s vasculature. The device includes a housing including: an extraction assembly to remove a plug-in seal from an implant; a blood tube to access the vasculature; and an installation assembly including a new plug-in seal to insert the new plug-in seal into the implant; and at least one locking tab to lock the housing onto the implant. 
         [0020]    Implementations of the invention may include one or more of the following. The graft may be a PTFE graft. The connector device may further include a cam dial, where rotation of the cam dial causes a distal movement followed by a proximal movement of at least one of the extraction assembly, blood tube, or installation assembly. The rotation of the cam dial may further cause a distal movement followed by a proximal movement of each of the extraction assembly, blood tube, and installation assembly. The rotation of the cam dial may cause driving posts attached to respective one of the extraction assembly, blood tube, and installation assembly to move distally and proximally along a helical barrel cam track. The installation assembly further comprising a locking pin and the locking pin may be configured to be inserted within a plug-in seal to secure the plug-in seal against movement within the implant. The connector device may further include a flush line to flush saline in a central passageway of the implant. The extraction assembly, blood tube, and installation assembly may be arranged within a turret, the turret rotating along with the cam dial. 
         [0021]    In another aspect, the invention is directed toward an implant for accessing the vasculature of a patient. The implant includes a central cylinder, a locking flange coupled to the central cylinder at a proximal end thereof; an attachment mechanism coupled to a distal portion of the central cylinder, the attachment mechanism configured to attach the implant to a graft; and an ingrowth disk surrounding at least a portion of the central cylinder. 
         [0022]    Implementations of the invention may include one or more of the following. The implant may be made of a material selected from the group consisting of: stainless steel, titanium, or combinations thereof. The locking flange may further include a protruding lip and a locking channel. The implant may further include a suture disk to secure the implant inside a patient, and the suture disk may be co-extensive with the ingrowth disk. 
         [0023]    In yet another aspect, the invention is directed towards an implant for accessing the vasculature of a patient. The implant includes a central passageway, a locking flange coupled to the central passageway at a proximal end thereof; at least one horizontal passageway extending substantially perpendicularly to the central passageway, the horizontal passageway attached to the central passageway substantially at a distal end thereof; and an ingrowth disk surrounding at least a portion of the central passageway. 
         [0024]    Implementations of the invention may include one or more of the following. The implant may be made of a material selected from the group consisting of: stainless steel, titanium, or combinations thereof. The locking flange may further include a protruding lip and a locking channel. The implant may further include another horizontal passageway extending substantially perpendicularly to the central passageway and in an opposite direction from the at least one horizontal passageway. The implant may further include a suture disk to secure the implant inside a patient, and the suture disk may be co-extensive with the ingrowth disk. 
         [0025]    In yet a further aspect, the invention is directed toward a method of accessing the vasculature of a patient, including: attaching a connector device to an implant; locking the connector device onto the implant; extracting a plug-in seal from the implant; inserting a blood tube into the implant; removing the blood tube from the implant; installing a new plug-in seal into the implant; and removing the connector device. 
         [0026]    Implementations of the invention may include one or more of the following. The method may further include priming the connector device. The method may further include flushing the implant with saline. The extracting a plug-in seal, inserting a blood tube, removing the blood tube, and installing a new plug-in seal, may be accomplished by rotating a cam dial. 
         [0027]    The advantages of the invention may include but are not limited to one or more of the following: 1)needles are not required to be inserted either into an AVF or a IGAVF to gain access to the patient&#39;s circulatory system, thus potentially damaging the skin and subcutaneous tissues, as well as reducing pain and mental stress; 2) the implant port may be used immediately after implantation; 3) the implant port design, surface materials and connector design minimize the risk of infection; 4) a single implant port provides high blood flow rates to and from the dialysis machine, minimizes recirculation and minimizes red blood cell trauma; 5) the connector device may be rapidly attached to and removed from the implant port; 6) the plug-in seal may be removed and the double lumen tube inserted to initiate dialysis and the process reversed at the completion of dialysis placing a new sterile plug-in seal in place substantially automatically by means of the connector device, thus reducing human error and breaks in sterile procedure; 7) bleeding during the initiation, performance and completion of the dialysis procedure is reduced; 8) a double implant embodiment prevents steal syndrome and recirculation, and allows placement of implants at widely separated sites; 9) both single and double port implant embodiments can be placed deep within tissues adjacent to muscle for improved tissue ingrowth into the attached PTFE material and into well-vascularized tissue ingrowth into the port&#39;s mesh matrix or porous surface, and in addition sutures may be placed between the port&#39;s suture ingrowth disk or sewing ring or flange in order to combine to produce a stable system and to minimize infection; 10) home dialysis may be performed safely, easily, and sterilely by untrained personnel; 11) angiography, thrombectomy, angioplasty, and stenting, may be performed through the implant port, by removing the plug-in seal and inserting a valved connector to the implant port central channel; 12) only a small portion of the implant port need extend above the skin surface to allow placement of the connector device; 13) many of the embodiments of the system allow their use in patients with repeated failures of vascular access and in multiple locations not available to patients limited to the current methods of vascular access; 14) the system allows the use of anticoagulants without concern for bleeding from needle insertion sites; 15) the system can be placed deep within the patient&#39;s tissues using different implant heights, and requires minimal lengths and diameters of PTFE material for its use; 16) the system may be made in a low-cost fashion; and 17) the system reduces the unsightly appearance of a device in the patient&#39;s skin as only a small portion of the implant is visible, and may be easily covered with a dressing and/or the patient&#39;s clothing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is a schematic view of a graft-attached implant and connector device according to an embodiment of the present invention. 
           [0029]      FIG. 2  is a schematic view of a graft-attached implant showing its interface with a patient&#39;s skin according to an embodiment of the present invention. 
           [0030]      FIG. 3  is a perspective schematic view of an implant and connector device according to an embodiment of the present invention. 
           [0031]      FIG. 4  is a perspective schematic view of an implant and connector device according to another embodiment of the present invention. 
           [0032]      FIG. 5  is a perspective schematic view of an implant and graft according to an embodiment of the present invention. 
           [0033]      FIG. 6  is an end-on view of the implant and graft of  FIG. 5 . 
           [0034]      FIG. 7  is a side cross-sectional view of the implant and graft of  FIG. 5 . 
           [0035]      FIG. 8  is a side cross-sectional view of an implant showing a plug-in seal and a locking pin in a first configuration. 
           [0036]      FIG. 9  is a side cross-sectional view of an implant showing a plug-in seal and a locking pin in a second configuration. 
           [0037]      FIG. 10  is a side cross-sectional view of an implant showing a plug-in seal and a locking pin with an extraction device. 
           [0038]      FIG. 11  illustrates separated outflow and inflow lumens. 
           [0039]    FIGS.  12 (A)-(D) illustrate unitary or joined outflow and inflow lumens, also termed a dual lumen or bi-lumen tube, as part of a blood tube. 
           [0040]      FIG. 13  illustrates a connector device and implant assembly according to an embodiment of the invention, joined to a graft, in a position to extract an indwelling plug-in seal. 
           [0041]      FIGS. 14(A) and 14(B)  illustrate side and top cross-sectional views of the connector device and implant of  FIG. 13 . 
           [0042]      FIG. 15  illustrates the connector device and implant of  FIG. 13 , in a position having extracted the indwelling plug-in seal. 
           [0043]      FIG. 16  illustrates the connector device and implant of  FIG. 13 , in a position to insert a blood tube. 
           [0044]      FIG. 17  illustrates the connector device and implant of  FIG. 13 , in a position with a blood tube inserted through the implant to the graft. 
           [0045]      FIG. 18  illustrates details of the driving post and mechanism by which the blood tube is inserted. 
           [0046]      FIG. 19  illustrates the connector device and implant of  FIG. 13 , in a position to install a new indwelling plug-in seal. 
           [0047]      FIG. 20  illustrates the connector device and implant of  FIG. 13 , in a position having installed the new indwelling plug-in seal. 
           [0048]      FIG. 21  illustrates the connector device and implant of  FIG. 13 , showing a perspective external view. 
           [0049]      FIG. 22  is a flowchart of a method of flushing the implant using the connector device prior to installation of a new plug-in seal. 
           [0050]      FIGS. 23(A)  and (B) illustrate views of a locking tab mechanism in a locked and unlocked configuration, respectively. 
           [0051]      FIG. 24  illustrates an AV implant, according to an embodiment of the invention. 
           [0052]      FIG. 25  illustrates an AV implant, according to another embodiment of the invention. 
           [0053]      FIG. 26  illustrates a side-by-side embodiment of the connector device. 
           [0054]    FIGS.  27 (A)-(C) illustrate a gating device for use at a distal tip of a blood tube, according to an embodiment of the invention. 
           [0055]    FIGS.  28 (A)-(B) illustrate a spherical fluid gating device for use at a distal tip of a blood tube, in a partially-expanded configuration, according to an embodiment of the invention. 
           [0056]    FIGS.  29 (A)-(B) illustrate a spherical fluid gating device for use at a distal tip of a blood tube, in an expanded configuration, according to an embodiment of the invention. 
           [0057]      FIG. 30  illustrates a flowchart of a method of use according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0058]    Embodiments of the invention are described below, generally involving an implant that accesses the vasculature and which may be in turn accessed by a connector device. First the implant is described, and then the connector device. 
       Implant 
       [0059]    Embodiments are initially described of an implant system or assembly, also termed herein just an “implant”, which may be employed for a number of procedures involving vascular access. Referring to  FIG. 1 , the implant  50  may generally connect to a PTFE graft  40 . Where the implant connects to a PTFE graft that extends between an artery and a vein, just one implant may be necessary; the one implant couples to a connector device  30  that houses and uses a dual-lumen blood tube. Where an artery and vein are used that are not connected by a graft  40 , then two implants may be employed, one for the artery and one for the vein; in this system, two connector devices  30  are then employed, and each may house and use a single-lumen blood tube. In another embodiment, an artery and a vein can be pulled together for anastomosis, and a single implant employed that couples to each, this implant termed an “AV port”. This embodiment reduces the need for a graft between the artery and vein, and is described in greater detail below. The implant itself, without connection to a connector device, is illustrated in  FIG. 2 . These different implants, and associated connector devices, are discussed below. 
         [0060]    Referring to  FIG. 3 , a system  120  is described for the case where an implant  50  connects to a PTFE graft  40  that extends between an artery and a vein. The implant  50  also couples to a connector device  30  to allow a vascular procedure to be performed. One such vascular procedure that may be performed is a dialysis procedure.  FIG. 3  also illustrates a dual lumen blood tube  60 , a dial  34  for changing phases of the procedure, and stabilizers  36  and  38  for attaching the connector device  30  to a patient, e.g., a patient&#39;s arm. A saline flush line  32  is also shown. 
         [0061]    Referring to  FIG. 4 , a system  120 ′ is described for the case where an implant  50  connects to two PTFE grafts  40 . One graft  40  forms a portion of an artery and another forms a portion of a vein. Each implant  50  also couples to a connector device  30  to allow a vascular procedure to be performed.  FIG. 4  also illustrates a single lumen blood tube  60 ′. One implant is for arterial blood and the other for venous blood. A dial  34  may be employed for changing phases of the procedure, and stabilizers  36  and  38  for attaching the connector devices  30  to a patient, e.g., a patient&#39;s arm. Connectors  42  and  44  are illustrated, the former for connecting the venous and arterial sides to a procedure device, e.g., a dialysis machine, and the latter for connecting the saline flush line to a source of saline. 
         [0062]      FIGS. 5-9  illustrate an exemplary implant  50  that is attached to a graft  40 . The implant  50  includes a central cylinder  110  that defines a passageway through which the procedure is conducted. The passageway also defines where sealing occurs to prevent infection. Attached to a proximal end of the central cylinder  110  is a locking flange  51 . Attached to a distal end of the central cylinder  110  is a suture ingrowth disk  53 . A portion of the suture ingrowth disk  53  provides for ingrowth of biological material to enhance long-term stability, and another portion of the suture ingrowth disk  53  provides an optional location for attaching sutures for short-term stability. That is, sutures may be attached after implant installation to hold the implant in a fixed location, to the adjacent fascia, until ingrowth of biological material has occurred. Where the suture portion is made of a puncturable material, the same may be directly sutured into. Where the suture portion is made of a non-puncturable material, e.g., is made of metal, the same may define holes where sutures may penetrate. In some cases, the material of the suture ingrowth disk  53  may itself be biocompatible, and its shape and constitution may allow suturing. One appropriate biomaterial is one of the STARED materials available from Healionics, Inc. of Redmond, Wash. Alternatively, the material of the suture ingrowth disk may be coated with a biocompatible material. In another alternative, the suturing section is distinct, though may be connected, to the section that promotes ingrowth. 
         [0063]    Tissue ingrowth into the external surface of the implant and into the PTFE graft material used for anastomoses to the blood vessels will, over a period of 14 to 28 days, significantly increase the stability of the device. 
         [0064]    The suture ingrowth disk may be located at the junction of the proximal two-thirds and distal one-third of the implant length; the suture ingrowth disk extends from the implant&#39;s outer surface a distance of between about 2 and 15 mm, e.g., 8 mm, and has a thickness of approximately 1 to 10 mm, e.g., 5 mm. 
         [0065]    The external surface of the implant and suture ingrowth disk may include a mesh matrix as described above, and which may be fabricated from the same material as the implant, and which may be, e.g., metallic or another suitable material. This surface of, e.g., 2-5 mm thickness, may include a porous structure with specific size interstices and material thickness and may have a texture that encourages vascularized tissue ingrowth. 
         [0066]    The upper edge of the external surface of the mesh matrix may be coated with a collagen layer that may be parallel to the skin surface and which may be positioned immediately below the level of the epidermis, encouraging epidermal growth over the surface and limiting or preventing the development of a sinus tract adjacent to the implant at its exit site through the skin. The area where ingrowth occurs may be not only on the disk but also on a central passageway  101 , by way of the porous or mesh material extending not only over the disk but also in a cylinder around the central passageway (see element  110 ′ of  FIG. 6 ). In this way, skin growth may occur in a direction directly parallel to the skin, straight into this porous or mesh or other such material, as well as into the disk itself. The porous or mesh material may be located above the disk  53 , below the disk  53 , or both. 
         [0067]      FIG. 5  also illustrates the central passageway  101  through which procedures may be enabled by installation of a suitable catheter or other device. A sterile cap (not shown) may be employed to cover the system, although in most cases a plug-in seal is installed in a secure-enough fashion that the cap may provide only or primarily a cosmetic feature. The cap may be mounted onto the implant by way of an adhesive, by being threadingly screwed onto the implant, or via other techniques. 
         [0068]    Referring to  FIG. 6 , the implant  50  is shown in cross-section, at an end-on view, i.e., at an angle looking in a direction parallel to a blood vessel. The graft  40  is shown attached to the implant  50 . In this figure, the locking flange  51  is shown in greater detail, in particular showing a protruding lip  54  and a locking channel  56 . The locking channel  56  may have a depth of, e.g., 30-90 mils, although other depths may also be employed according to the application. The protruding lip  54  may have a depth of, e.g. 10-50 mils, although other depths may also be employed according to the application. As will be described, one or more locking tabs engage the implant in the locking channel and cause a connector device to be secured to the implant because the locking tabs are locked within the locking channel  56 . 
         [0069]    Referring to  FIG. 7 , a cross-sectional view of the implant  50  is illustrated. This view omits for clarity certain details of the locking flange  51 , but shows the central passageway  101  which is defined by the central cylinder  110 , as well as details thereof which assist in maintaining and securing a plug-in seal. 
         [0070]    The suture ingrowth disk  53  is illustrated, and one potential arrangement of material constituent layers is shown for the suture ingrowth disk  53 . In  FIG. 7 , a top layer  66  provides the suture attachment functionality, and the remaining layers act as a graft attachment mechanism  50 ′, to assist in the attachment of the implant to the PTFE graft. For example, a PTFE compression ring  67  may be employed to hold fast a section of the PTFE graft  40 , in particular a section that is wrapped around a PTFE support ring  68 . In this way, the implant may be secured to a portion of a PTFE graft. 
         [0071]    Other ways to secure the implant to the graft may also be employed. For example, a skirt may of a metal or a polymer, e.g., titanium, stainless steel, silicone, PTFE, polypropylene, or acetal, may be attached to a distal end of the central cylinder  110 , the same for attachment to a graft. Other potential ways of attaching an implant to a graft are discussed below in connection with  FIGS. 24 and 25 , these also being employable to attach implant  50  to a graft. 
         [0072]      FIG. 8  illustrates details of an implant  50  in which a plug-in seal  80  is being installed.  FIG. 9  shows the same, with the plug-in seal  80  fully installed. As is seen, the implant  50  has a locking flange  52  and an internal central passageway  101 . The internal diameter of the central passageway  101  may be, e.g., 0.1 inches to 0.3 inches, although other diameters may be employed as needed according to the patient&#39;s size and vascular requirements. 
         [0073]    In  FIG. 8 , the plug-in seal  80  has been installed but is not yet locked. The initial installation of the plug-in seal  80  has the plug-in seal  80  held in place by its locking ring  98  held by a ridge  96  defined on the implant  50 . The plug-in seal  80  may also have ribs  82   a  and  82   b  that compress during installation and thereby further secure the plug-in seal  80  in a friction fit. The components are flexible, as described below, and so the plug-in seal  80  is secured but may still be removed. To lock the plug-in seal  80  in place, a locking pin  90  is employed. The locking pin  90  is inserted into a void  84  in the plug-in seal  80 . In more detail, the locking pin  90  is mounted into the void  84  prior to use. During use, the same is fully inserted into the void  84  to securely lock the plug-in seal in the implant. 
         [0074]    The locking pin  90  includes a generally cylindrical section  86  with a frustum  88  that flares or tapers out in a proximal direction from the cylindrical section  86 . When the locking pin  90  is forced downward into the plug-in seal  80 , the frustum  88  is forced into and against a corresponding frusta&#39; section  94 . When the frustum  88  is secured in this section, as shown in  FIG. 9 , the locking ring  98  can no longer flex away from the ridge  96 . Accordingly, the plug-in seal  80  is held in the central passageway  101  in a very tight fashion, and can only be removed by a force significantly greater than that encountered in a blood vessel. The device and method by which the plug-in seal  80  is installed and removed and the locking pin  90  is installed and removed within the plug-in seal  80  is described below. 
         [0075]    To remove the plug-in seal  80 , an extraction device  102  shown in  FIG. 10  may be employed. The extraction device  102  is controlled by the connector device, as will be described, and the same is extended in a distal direction and then retracted in a proximal direction to remove an indwelling plug-in seal  80 . The extraction device  102  is generally cylindrical so as to surround the locking pin  90 , although a partial cylinder may also be used. The extraction device  102  includes at least one feature with which to engage and remove the locking pin  90 . For example, the extraction device  102  may include two tabs  104  that extend radially inwardly and proximally. These tabs act in a way similar to barbs, and when the extraction device is inserted distally far enough, the tabs  104  can engage an overhang  106  on the locking pin. By then moving the extraction device  102  proximally, first the locking pin  90  is removed, followed by the plug-in seal  80 . 
         [0076]    Before describing the connector device, general comments regarding the implant are now provided. 
         [0077]    When the patient&#39;s circulation is to be accessed for connection to the dialysis machine, a single or dual-lumen blood tube may be moved downward, i.e., in a distal direction, a sufficient distance in order to allow a distal end of the blood tube to be inserted in the graft and to engage an opposite wall thereof. The blood tube is moved in the distal direction by the action of the connector device. Referring to  FIG. 11 , two single lumen blood tubes  108   a  and  108   b  may be employed where two implants are accessed, and a dual lumen blood tube ( FIG. 12 ) may be employed in cases where just one implant is accessed. 
         [0078]    Referring to  FIG. 12 , two varieties of dual lumen blood tubes are illustrated. In  FIG. 12(A) , skives may be made in a dual-lumen catheter blood tube  112  to define an outflow lumen  116  and an inflow lumen  118 . In a dialysis vascular procedure, the outflow lumen  116  would direct the blood to a dialysis machine and the inflow lumen  118  would return the blood to the vessel from the same machine. In  FIG. 12(B) , skives and a tapered cut may be made in a dual-lumen catheter blood tube  114  to define an outflow lumen  116 ′ and an inflow lumen  118 ′. In some cases, depending on configuration, the blood tube of  FIGS. 12  (B) and (C) may allow greater blood flow around the blood tube in order to provide, e.g., a washing or rinsing effect. As shown in the end-on view of  FIG. 12(D) , in which the graft  40  is also illustrated, the portion of blood transported out of the body by the blood tube may be, e.g., about 90% of the total blood flow in the vessel. The other 10% is directed around the blood tube to achieve a cleaning effect. 
         [0079]    This configuration occludes, e.g., over 90% of the GAVF lumen and directs a large volume of blood flow into the outflow channel and substantially prevents the recirculation of blood returned from the dialysis machine through the inflow channel. The partial occlusion of the lumen allows a small amount of continuous blood flow around the blood tube and through the GAVF, providing a washing effect during dialysis. 
         [0080]    The implant may be attached to tubular PTFE grafts of various diameters and lengths. The method of attachment of the graft to the implant may use the same technique whether for a single implant system or whether for a dual implant system. An elliptical opening of an appropriate shape and size to match the internal circumference of the implant may be defined and a sleeve employed that extends outward a distance, e.g., 5 mm from the opening, both of which may be constructed during manufacture of the tubular PTFE graft. The method of attachment described below provides a tight seal of the PTFE graft to the implant. 
         [0081]    The tubular PTFE graft may be anastomosed by standard vascular surgical techniques to a suitable artery and vein, creating a functional GAVF. The combination of various implant lengths (heights) and graft diameters and lengths allows implantation of the system in various locations in the patient&#39;s body. In particular, the system may be placed at deeper locations dependent only on the length, i.e., the height, of the implant. The length used will depend on the patient&#39;s size, thickness of the subcutaneous tissues, and depth of the blood vessels to which the implant is attached. The external diameter of the implant may be approximately 1.5 cm. Its proximal end may be configured for placement of a cap that provides a sterile cover for the implant and its contained plug-in seal when not in use. The implant may extend above the surrounding skin approximately 1.0-4.0 mm. 
         [0082]    The implant may be fabricated from a material that can withstand the repeated stresses placed upon it when the cap or connector device is placed and removed. 
         [0083]    The implant at its lower or distal end may incorporate a lip, e.g., a 1 mm lip, to provide a way to attach the skirt of, e.g., PTFE graft material. The PTFE graft material may be elliptical in shape with the long axis oriented to the long axis of the vessel to which it will be anastomosed and the short axis oriented to the transverse diameter of the vessel to which it will be anastomosed. The skirt may be available in several dimensions appropriate to the size of the vessels to which it will be anasotomosed. The skirt may have a central opening substantially commensurate with the internal diameter of the implant, and a sleeve extending a distance, e.g., 5 to 10 mm, from the central opening. The sleeve may be stretched to fit over the lip at the distal end of the implant. The sleeve may be fixed to the implant with a tight circumferential wrap of multiple strands of monofilament PTFE thread of small diameter. The same may then secure the PTFE graft skirt to the implant and eliminate space between the PTFE graft skirt and the distal edge of the implant. 
         [0084]    The skirt may be anastomosed to the blood vessel using a standard vascular surgical technique after excising a minimal elliptical portion of the wall of the vessel. This in effect widens the vessel at the interface between the implant PTFE skirt and the blood vessel. This configuration, in conjunction with the “washing” effect of repeated outflows and inflows of large volumes of blood through the implant, prevents the growth of tissue and/or thrombus across the interface. 
         [0085]    When the implant is not in use, the plug-in seal made of blood-compatible materials may be placed within the lumen of the implant as a seal as has been described. The plug-in seal fits tightly within the implant and may have a smooth blood compatible surface. The fit of the plug-in seal within the implant and its smooth blood compatible surface assists in the prevention of thrombus formation at the interface. 
         [0086]    A sterile cap of appropriate material may be seated securely over the upper surface of the implant and plug-in seal to preserve sterility and to prevent the plug-in seal from being inadvertently snagged by garments or the like. An antimicrobial circular gasket may be placed on the bottom surface of the cap that extends beyond the outer surface of the implant. To further enhance the stability of the implant, an optional ingrowth bowl  215  (illustrated in  FIG. 24  in connection with an AV implant) may be employed, the same allowing surface epidermis tissue to radially terminate into the mesh structure, growing down into the ingrowth mesh and creating a tight vascularized infection barrier. A combination of porosity and weave network enables the creation of varying density configurations. 
         [0087]    The disclosed implant systems provide small implants that have very little foreign body material exposed. The same are configured to be stable, both vertically as well as rotationally, allowing the surface interfaces to be safe and trauma-free. Ingrowth around the structures and through the ingrowth mesh at least in part is responsible for the stability of the systems. 
       Connector Device 
       [0088]    The connector device is a disposable catheter unit that is designed to initiate and terminate the desired functions for blood access. The same has a semi-automated design to allow the various functions to occur. These different modes of operation complete the entire blood access procedure, e.g., for dialysis. The connector device may employ a control dial that positions its components in specific ways into the implant for the procedure. One advantage may be that seating pressures and alignments may be automatic with this design, allowing constant, safe, infection-free and low manipulation of the implant and the connector device. 
         [0089]    The connector device may accomplish the following five main objectives. First, it can be locked circumferentially and securely onto an upper surface of the implant. Next, it extracts and removes the plug-in seal positioned within the central passageway of the implant, into the housing of the connector device. Next, it inserts a blood conduit or tube from the connector device into the implant&#39;s central passageway a sufficient distance to create a partially obstructing gate within an attached PTFE graft. This conduit connects with the connector device&#39;s inflow and outflow tubing and provides separate channels for blood flow to and from the PTFE graft and a dialysis machine. Next, the connector device retracts the blood conduit from the central passageway of the implant at the completion of the procedure. Finally, the connector device installs a new sterile plug-in seal into the central passageway of the implant as the central passageway and top of the implant are flushed with saline from, e.g., a saline flush line in the connector device. 
         [0090]    In more detail, and referring to  FIG. 13 , a system  120  includes a connector device  30  having a number of components. The connector device  30  is coupled to an implant  50 , and it is understood that the implant  50  may accommodate a single or dual lumen blood tube  60 . In  FIG. 13 , an interface seal  76  is illustrated that forms an airtight seal between the connector device  30  and the implant  50 . Certain elements of the implant  50  are shown with the same reference numerals as noted above, including a suture ingrowth disk  53  and the implant&#39;s attachment to a graft  40 . 
         [0091]    The connector device  30  includes an arterial blood line  71  and a venous blood line  72 , which combine to form an AV blood tube  60 . The blood tube  60  may be open as shown, or enclosed in a protective cover (not shown) to prevent inadvertent operator interference. A connector  77  is provided for a flush line  61 , the flush line  61  for delivering saline to the central passageway  101  of the implant. A stabilizer  56  may be provided on one or more sides in order to inhibit movement of the connector device  30 . A dial assembly  58  forms the core of the device  30 , and the same includes a rotating turret  65  which presents different subsystems to the implant  50  in a prescribed order. 
         [0092]    The turret  65  includes three internal cylinders  73   a ,  73   b , and  73   c  (see  FIGS. 13 ,  14 (B),  15 - 17 , and  19 ) each spaced generally at a 120-degree angle from each other. Each cylinder has at least one vertical groove  78  to guide the pistons up and down; and each piston has at least one guide post  78 ′ (see  FIG. 20 ) which is inserted into, and which rides in, the corresponding vertical groove  78 . The three cylinders each have a different purpose for the procedure, e.g., a dialysis procedure. For example, the first cylinder extracts the plug-in seal from within the implant&#39;s central passageway in a manner described below. This vertical movement is repeated within all three cylinders in order to lower and raise their contained assemblies or tubes as the cylinder housing rotates during the use of the connector device at the start, during, and at the completion of the procedure. Conveniently, all internal components stay within the connector device, and the turret and cam dial may be made to rotate in only one direction. 
         [0093]    Each cylinder encloses a separate assembly, and each assembly has a piston with a driving post  62   a ,  62   b , and  62   c , which allows a cam to cause vertical movement. The driving posts for each piston ride in a top track  122  until such time as an internal cam cylinder, driven by the cam dial, contacts an engagement pin  124 , at which point the driving post is pushed down (by riding down the engagement pin  124 ) into a helical barrel cam track  69 . The helical barrel cam track  69  forces the driving post (and thus the piston) first down in a distal direction and then up in a proximal direction. Between the down and up movements is a travel distance or stall mode, e.g., for 120 degrees, where the piston is going neither up nor down. 
         [0094]    In the position shown in  FIG. 13 , a plug-in seal  64  is about to be extracted from the implant  50  using a plug-in seal extraction assembly  63 , which includes a piton  63 ′ and an extraction device  102 . The extraction piston  63 ′ and the extraction device may be inserted around the plug-in seal  64  by the action of the connector device  30 , in particular by operating or rotating a turret cylinder  73   a  into position (this position may be a default or initial position, i.e., the position when shipped) and rotating the cam dial, thereby causing a driving post  62   a  to traverse down a helical barrel cam track  69  (of course, it is the helical barrel cam track  69  that rotates). As the plug-in seal extraction piston  63 ′ is constrained by the guide track  78  and guide post  78 ′, it has only one degree of freedom, i.e., up or down, and the same is forced downward into the plug-in seal  64 . As described above, the extraction device  102  may be employed to engage and, upon movement in a proximal direction, remove the plug-in seal  64  from the implant  50 . 
         [0095]    In more detail, and referring in addition to  FIGS. 14(A) and 14(B) , the system  120  and connector device  30  are illustrated ( FIG. 14(B)  is a cross-section along lines A-A of  FIG. 14(A) ). A cam dial  57 , shown with serrations for ease of turning, is a constituent part of the dial assembly  58 . The cam dial  57  is integral with an internal cam cylinder  59 , on the inside cylindrical wall of which is the helical barrel cam track  69 . By rotating the cam dial  57 , an operator may cause one or more pistons to move up or down within one of the three cylinders  73   a ,  73   b , or  73   c , disposed within the turret  65 . 
         [0096]    The rotation drives these pistons, and the rotation may be configured to be in the same direction by use of an appropriate clutching mechanism discussed below, e.g., a clutch cam device  130  shown in  FIG. 14(B) . The internal cam cylinder  59  is discontinuous with discontinuity  128 , and the cylinder  59  further includes a head section  82  with a spline section, e.g., radially inward-facing teeth  82 ′. The head section  82  is cammed, e.g., bulbous or otherwise extended in a radially outward direction. In this way, the head section  82  may engage a corresponding ramp on the interior of the cylinder  59 , the ramp extending, e.g., 120 degrees, although many variations of the amount of ramp may be provided. When the head section  82  engages the ramp, the head section  82  is bowed inward such that the teeth  82 ′ engage a spline on the turret  65 , e.g., teeth  85  on the exterior of the turret  65 . When they are so engaged, cam dial rotation moves the vertical driver cam  59  and the turret  65  together for a 120-degree displacement  83  for the next cylinder, then releases for a 240-degree rotation  84 , this 240-degree rotation being employed for vertical movement of the cylinder pistons. Like with the 120-degree rotation, the 240-degree rotation may vary significantly, e.g., a 5-degree overtravel (or more or less) may be provided. Each 120-degree rotation may be temporarily arrested by way of a detent. 
         [0097]    Returning to the sequential movement of the turret  65 ,  FIG. 15  illustrates the connector device  30  and implant  50  following a turret rotation in which the rotation has caused the extraction of the plug-in seal  64 . In a way opposite to that in which the extraction assembly  63  was engaged onto the plug-in seal  64 , the rotation moves the extraction assembly  63  in the upward (proximal) direction because the same causes the driving post  62  to traverse up the helical barrel cam track  69 . 
         [0098]      FIG. 16  illustrates the next sequential stage of rotation. In  FIG. 16 , the extraction assembly  63  and plug-in seal  64  have been rotated away from the implant  50  and in their place is the AV blood tube  60  in a raised position. It will be understood that, in a two-implant system, the blood tube  60  need only have or employ a single lumen, while in a single implant system, the blood tube  60  will have two (or more) lumens. In  FIG. 16 , the AV blood tube  60  is in a retracted position. Other details of the AV blood tube have been discussed above. 
         [0099]    As with the plug-in seal extraction, the driving post  62   b  is forced down the helical barrel cam track  69  via rotation of the internal cam cylinder, forcing the blood tube  60  through the cylinder  73   b  and into the implant  50  as illustrated in  FIG. 17 . The rotation causes the insertion in the same way as the descending engagement of the plug-in seal extraction assembly. The blood tube  60  may be generally provided with enough slack to allow the blood tube to be inserted into the graft as well as enough slack to accommodate the rotation itself. 
         [0100]    The configuration of the driving post  62   b  is substantially similar to that of driving posts  62   a  and  62   c ; however, what the same attaches to is somewhat different since the blood tube  60  requires a continuous lumen throughout the cylinder  73   b , unlike the situation with the plug-in seal extraction and insertion. Referring to  FIG. 18 , a driving post  62   b  is illustrated as attached to a driving torus  134 . The driving torus defines an inner void in which may be disposed a blood tube driving annulus  136 . Using such a configuration, movement of the driving post  62   b  can result in movement of the blood tube  60 . 
         [0101]    After insertion, the procedure, e.g., dialysis, may be conducted. During the procedure, the dial assembly  58  may be in the stall mode. 
         [0102]    Following the procedure, the blood tube  60  is retracted and rotated away from the implant  50 , again via a cam dial and turret rotation. In particular,  FIG. 19  illustrates the connector device  30  following another rotation of the turret  65 . In this orientation, the blood tube  60  has finished accessing the vasculature, and has been rotated away from the implant  50 . In its place is another cylinder  73   c , this cylinder  73   c  containing an installation assembly including a new unused and sterile plug-in seal  64 ′ mounted on a plug-in seal installation piston  63 ′. By rotating the turret  65  in the same direction as before, the seal installation piston  63 ′ may be forced in a downward direction via the post  62   c  having the helical barrel cam track  69  rotating about the same, and thus sealing the implant  50 . The installed position is illustrated in  FIG. 20 . As discussed above in connection with  FIGS. 8 and 9 , installation of the plug-in seal  64 ′ is accomplished not only by inserting the same into the implant but also by inserting a locking pin  90  into the plug-in seal  64 ′. 
         [0103]    Retraction of the plug-in seal installation piston  63 ′ is accomplished in the same way as removal of the plug-in seal extraction piston  63 , by rotation of turret  65 . 
         [0104]      FIG. 21  illustrates a perspective view of the system  120  including the connector device  30  coupled to the implant  50 . 
         [0105]    Termination of the dialysis may include a sterile saline flush as the plug-in seal  64 ′ is inserted into the implant central passageway  101 . The flush line  61  infuses the saline in order to rinse all blood components from the implant central passageway  101 . In more detail, and referring to the flowchart of  FIG. 22 , a first step in the method  180  is to prime both lines to be attached to the connector device  130 , i.e., the arterial and venous sides, with saline from, e.g., a syringe (step  172 ). A next step is to attach the lines to the connector device  130  and thus to the patient (step  174 ). A next step is to rotate the turret in the manner described above so as to remove the plug-in seal (step  175 ) and further rotate the turret in the manner described above to put the blood tube above the implant central passageway  101  (step  176 ). Further rotation inserts the same into the implant (step  177 ). A next step, to ensure there is no clotting of the implant, is to check the blood flow by aspirating or pulling back on an inserted syringe (the syringe may be inserted into the manifold to which the arterial and venous lines attach (step  178 ). Assuming no clotting, the syringe is removed (step  182 ) and the arterial and venous lines may be attached to a dialysis machine for a dialysis procedure (step  184 ). 
         [0106]      FIGS. 23(A) and 23(B)  illustrate a locking mechanism which may be employed to lock the connector device  30  onto an implant  50 . Of course, it will be understood that other locking mechanisms may also be employed. In particular,  FIG. 23(A)  illustrates the locking mechanism in a rest configuration, in which the same is locked onto an implant locking flange  51 . The locking mechanism includes a first locking tab  160  and a second locking tab  170  which rotate around a pivot  152 . The locking tabs may be, e.g., 10-40 mils thick, although other thicknesses may also be employed. The first locking tab  160  includes a finger tab  148 , a flange engagement tab  142 , and a tensioner  154 . The tensioner  154  engages an abutment  162  to bias the locking tab  160  in a counterclockwise direction. The second locking tab  170  includes a finger tab  146 , a flange engagement tab  144 , and a tensioner  158 . The tensioner  158  engages an abutment  156  to bias the locking tab  170  in a clockwise direction. By an operator squeezing the finger tabs  148 , the biases are overcome and the flange engagement tabs  142  and  144  rotate away from the locking flange  51 , as shown in  FIG. 23(B) , allowing the connector device to be removed from the implant. Of course, the same technique allows the connector device to be attached to the implant. 
       Variations 
     AV Implant 
       [0107]    An AV implant system may be employed, in another embodiment, and used in place of the implant  50 . The AV implant system requires that one implant be joined to an appropriately-sized artery and a second implant joined to an appropriately-sized vein in a manner described below. The implants generally do not attach directly to arteries and veins but rather attach to grafts, or artificial vessel portions, which have been installed surgically. Sometimes, an entire vessel portion is replaced with a graft. Other times, just a portion of the vessel is replaced, e.g., just an elliptical portion, so as to allow the implant to achieve a substantial purchase on the vessel. In some cases, a circular annulus of graft material, e.g., PTFE, may be wrapped around an element on the implant, allowing the blood to only contact PTFE or the interior of the implant, minimizing the chance of infection or other maladies. 
         [0108]    Referring to  FIG. 24 , an AV implant system  20  is illustrated that is an implanted structure made of, e.g., titanium, but which may be made of any biocompatible material. The AV implant system  20  is a small three-way structure with two horizontal passageways and a vertical lumen  201  that travels upward (or in a proximal direction) toward the surface tissue where the implant protrudes with an external implant interface. The system  20  may include a locking flange  52 ′ to which a connector device  30  may be attached in the same manner as that of implant  50  above. 
         [0109]    The vertical lumen  201  is defined by a central cylinder  210 , and allows access by a catheter to two separate vascular grafts, one which forms part of an artery and one which forms part of a vein. The catheter in turn may have two channels, e.g., may be a split-channel catheter. 
         [0110]    The AV implant system  20  includes two horizontal lumens  202  and  204 , these lumens  202  and  204  defined by walls  206  and  208 , respectively, which are attached to skirt segments  212  and  214 , respectively. The skirt segments are coupled to or mounted to the arterial and venous grafts. The skirts may be made of, e.g., PTFE. In this way, the skirts can anastomose to the artery and vein, replacing a portion of the body&#39;s vessel wall. The skirts become covered with the body&#39;s natural endothelial cells, which in time become part of the vessel lumen. 
         [0111]      FIG. 24  shows the AV implant system  20  with two different ways of attaching to grafts, while  FIG. 25  shows the AV implant system  20  with two of the same ways of attaching to grafts. 
         [0112]    In  FIG. 24  (on the left hand side of the implant), a wall device  206  includes a cylindrical section  205  which mates with a hole in the central cylinder  210 . This mating may be by way of a press-fit. At a distal end of the cylinder  205  is a frusto-conical section  207 . The PTFE skirt  103  may be made elastic enough to allow a hole or sleeve section of the same to be moved over the frusto-conical section  207 . The hole or sleeve section is then trapped between the frusto-conical section  207  and a wall  209  of the AV implant  20 . By further pressing the cylinder  205  into the hole of the central cylinder  210 , the PTFE sleeve becomes incapable of removal. 
         [0113]    Also in  FIG. 24  (on the right hand side of the implant), a PTFE skirt is illustrated as attached to the implant  20  via another technique. A sleeve  214  of the PTFE skirt is inserted and wrapped around an element  208  and held in place by a friction fit, by another ring, or by puncturing the sleeve with a pin formed integrally with the implant. Other ways will also be seen given this teaching. These configurations may create more of a natural lumen surface, exposing less titanium to the blood stream. 
         [0114]      FIG. 25  shows insertion of a blood tube  60 ′. Arterial blood flows into a blood tube  60 ′ by way of an arterial port  44 , and flows back into the patient&#39;s vasculature following dialysis by way of a venous port  44 ′, these ports forming the two aforementioned horizontal lumens.  FIG. 25  also illustrates wall  206 ′, which functions in a way similar to wall  206 , and which couples to a skirt section  214 , which is in turn anastomosed to a graft  40 ′. 
         [0115]      FIGS. 24 and 25  show other elements, these similar to those of implant  50 , and indicated by primed components. For example, a suture ingrowth disk  53 ′ is illustrated, which as before may include a titanium mesh with a treated coating and/or a circular support such as for suturing.  FIG. 24  also illustrates various other components, which may also be employed in implant  50 . These include a seal seat  218  and locking tabs  212  and  213 , which may be employed in other types of locking configurations. An ingrowth bowl  215  may be optionally included, the same allowing tissue to more gently fill in around the implant as ingrowth occurs. 
         [0116]    A distal end of the central passageway  201  is a location at which the arterial and venous ports intersect, and may incorporate a slight taper, e.g., of between 2 and 10 degrees, e.g., 5 degrees. This taper assists in sealing the lumen, e.g., with a plug-in seal, as well as sealing the split-channel or dual lumen catheter  60 ′ when the same is installed for a vascular procedure such as for dialysis. 
       Side-by-Side Design 
       [0117]    Referring to  FIG. 26 , a side-by-side connector device design is illustrated which may be useful when the vertical height of the turret is desired to be lessened. Referring to this figure, a connector device  300  includes an outside housing  326  and a stabilizer  356 . A cam dial  357  is integral with a cylinder  359 , which has an accompanying spline  382 . Rotation of the spline  382  rotates a spline  385  on a turret  365 . The turret  365  includes three cylinders  373   a ,  373   b , and  373   c . Rotating the cam dial  357  performs similar functions as in the design of connector device  30 . In particular, splines  382  and  385  can be engaged or disengaged to rotate the turret, and rotation of the cam dial  357  also causes rotation of a helical barrel cam track  369 , moving pistons within cylinders  373   a ,  373   b , and  373   c  to move up and down. In this case, the driving posts for the cylinders are exterior of the cylinders, and extend to the cylinder  359  so as to engage a track  369  within the same. 
       Gating Assemblies 
       [0118]    In many cases, structuring the blood tube in accordance with  FIG. 12  is enough to ensure sufficient blood flow is sent to dialysis and sufficient blood flow is available for flushing the implant during the procedure. In some cases, however, a small implant is installed in a large blood vessel, and in these and other cases it becomes necessary to gate the flow so that appropriate flow is achieved for both purposes. 
         [0119]    Referring to FIG.  27 (A)-(C), a vascular gate  400  is illustrated which descends into the interior of the blood stream in the region of the graft. This gating is accomplished with a single piston  440  that can descend and occlude approximately 90% of the blood flow during dialysis. The gate has an arterial channel  478  with entry hole  477  on one side and a venous port  472  with an exit hole (not shown) on the other. A retracted configuration is shown in  FIG. 27(A)  and a partially deployed configuration is shown in  FIG. 27(B) . 
         [0120]    This cylinder gate  400  intersects the graft at a distal end  442  which also has a cylindrical shape, and blocks off the majority of the blood flow. These two intersecting cylinders conform to the gate because the outside collar of the implant changes the shape of the graft in this location. This changes the orientation from cylindrical in a horizontal sense to cylindrical in a vertical sense. This sliding gate design is a high tolerance mechanism that reduces or eliminates leakage of blood through any adjacent channels, generally by means of an automated flushing system (see port  441  in  FIG. 27(B) ) which is designed to fill the space and prevent blood from traveling between the housing and the gate piston. This auto-flush acts as a fluid bearing and keeps the respective surfaces clean. 
         [0121]    The gate configuration may be slightly out-of-round, and enables the gate to maintain proper positioning, and eliminates the need for additional guides to prevent the gates from rotating. The lower portion of the gate has a large diameter, and the upper section has a smaller diameter which occupies the main passageway of the implant structure. This acts as an actuator device which allows the connector device to manipulate the gate. The actuation of the gate implant device is accomplished by the connector device, which locks onto the gate implant and positions an internal port system to interface with the gate implant. The positioning may be accomplished in the same manner as the descending of any of the aforementioned assemblies.  FIG. 27(C)  illustrates the fully-extended configuration. 
         [0122]    FIGS.  28 (A)-(B) and  29 (A)-(B) illustrate another gate assembly, this embodiment including a fluid bladder and in particular a spherical fluid gate. Fluid flexible bladder systems may be employed to inflate and gate the blood flow in the vessel to prevent arterial and venous mixing. The bladders may be formed of rubber or the like and may be filled with saline for expansion and inflation. 
         [0123]    FIGS.  28 (A)-(B) illustrate the gate during expansion and FIGS.  29 (A)-(B) illustrate the gate after expansion. A spherical balloon  480  is inflated via a fluid inflation passageway  432 , which may be valved to the saline flush line  61 . When inflated, lumens  477  and  478  are defined for arterial and venous blood. The remainder of the blood vessel or graft, or a substantial portion thereof, is occluded. Other elements are also shown of implant  50 , including a suture ingrowth disk  53 . An optional support collar  431  is shown, which may provide additional support to the PTFE graft  40 . 
         [0124]    This configuration allows for a spherical ball to dominate the interior of the blood vessel. Saline is injected, e.g., from the connector device, into the implant via the fluid inflation passageway above. The preformed arterial and venous passageways expand open until the sphere has inflated. The attachment of the sphere to the distal portion of the catheter area allows the rigid section to port from the outer perimeter to the interior of the catheter. The ports molded from the catheter allow arterial blood flow into the connector device and back to the opposite side of the sphere. 
         [0125]    In an alternative embodiment, a structure may be placed around the balloon so as to direct the balloon inflation in specific directions, e.g., to more effectively occlude the vessel. For example, the balloon may be between two parallel plates, each with a window formed therein. During inflation, the balloon may be configured to expand through the windows, thereby tending to occlude the vessel in a planar fashion. If passageways are formed in the balloon leading to a blood tube, the same may be effectively employed in a vascular procedure. 
         [0126]    In yet another embodiment, a vascular ring bladder design may be employed which expands a fluid bladder from the exterior of a vascular ring which surrounds the vessel or graft. The external balloon applies pressure to the outside of the vessel, closing around the positioned catheter and narrowing the blood flow through the area. A portion of the vessel wall may then drop down through a portion of the support ring that is open. An injection of saline, to inflate the bladder, travels through the structural housing of the implant from the connector device. 
       Shape Variations 
       [0127]    Implants may differ in many ways; e.g., implants for use with dual-lumen blood tubes may have more of an elliptical shape in their central passageway or graft sleeves, as well as a larger proximal, i.e., upper, surface area to accommodate both the outflow and inflow blood channels present. 
         [0128]    One potential purpose of the elliptical shape for the implant is to maintain the correct orientation of the implant and its outflow and inflow channels, as well as any gate and plug-in seal, when the implant is in use. One correct orientation of the plug-in seal may be such that its long diameter is perpendicular to the direction of blood flow within the GAVF. This allows occlusion of the GAVF, providing maximum flow rates and preventing re-circulation. 
         [0129]    The distal or lower openings may be larger than the proximal openings and may also be elliptical. The elliptical shapes of the openings and the large channels result in maximum blood flow volumes with lessened turbulence. 
         [0130]    A central portion of the plug-in seal may include a gate and may be continuous with an attached foot. The foot is generally thin, flexible, elliptical in shape, and of sufficient surface area to cover and seal the site of the implant attachment to the GAVF. The plug-in seal also may cover and seal the lower openings of the outflow and inflow channels when they are not in use. 
         [0131]    Referring to the flowchart of  FIG. 30 , a method  500  according to an embodiment of the invention is illustrated. A first step is to attach the connector device to the implant and to lock the two together by way of the locking tabs or via another variety of locking mechanism (step  502 ). A next step is to perform a priming procedure as described above (step  504 ). Steps  502  and  504  may be switched if desired. A next step is to rotate the cam dial so as to extract a plug-in seal (step  506 ). A next step is to rotate the cam dial so as to move a blood tube into position and to further rotate the cam dial so as to insert the blood tube (step  508 ). A vascular procedure, e.g., dialysis, may then be performed (step  512 ). The cam dial is then rotated so as to retract the blood tube (step  514 ). The cam dial is then rotated so as to move a new plug-in seal into position for installation (step  516 ). The implant is then flushed with saline (step  518 ) so as to minimize the risk of infection as well as to reduce the chance of air bubble inclusion upon insertion of a new plug-in seal. Following the flush, the cam dial may then be rotated so as to insert the plug-in seal (step  522 ). The connector device may be unlocked and removed (step  524 ). An optional final step is to cover the implant with a sterile cap (step  526 ). 
         [0132]    The materials employed in the connector device and implant may be as follows, although other materials will also be understood to be employable. The material of the turret, internal cylinder having the helical barrel cam track, as well as plug-in seal extraction device and insertion device, may be delrin, nylon, or other polymer materials. The plug-in seal may be, e.g., silicone, and the locking ring may be made of delrin or the like. The support and suture ring may be, e.g., silicone as well as metals such as titanium. The housing of the connector device may be, e.g., polycarbonate. O-rings may be, e.g., silicone or the like. The saline flush line may be, e.g., PVC. The locking pin may be made of various metals, e.g., stainless steel or the like. The locking tabs may be made of spring steel, e.g.,  17 - 7  spring steel, brass alloys, polymeric materials, or the like. In general, where two components are in contact or moving against one another, they should be of different materials. One of ordinary skill in the art will recognize that other materials may also be employed. 
         [0133]    The above description has been with respect to certain specific embodiments. The invention, however, is not to be limited to those specifics. Accordingly, the invention is to be limited solely by the claims appended hereto, and equivalents thereof.