Patent Document

This application is a continuation of application Ser. No. 09/437,428, filed on Nov. 15, 1999, which is a continuation-in-part of application Ser. No. 09/314,278, filed on May 18, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an implantable medical device such as an anastomosis device and a deployment system for implanting the device. In a preferred embodiment, the device can be used for forming a sutureless connection between a bypass graft and a blood vessel. 
     2. Brief Description of the Related Art 
     Vascular anastomosis is a procedure by which two blood vessels within a patient are surgically joined together. Vascular anastomosis is performed during treatment of a variety of conditions including coronary artery disease, diseases of the great and peripheral vessels, organ transplantation, and trauma. In coronary artery disease (CAD) an occlusion or stenosis in a coronary artery interferes with blood flow to the heart muscle. Treatment of CAD involves the grafting of a vessel in the form of a prosthesis or harvested artery or vein to reroute blood flow around the occlusion and restore adequate blood flow to the heart muscle. This treatment is known as coronary artery bypass grafting (CABG). 
     In the conventional CABG, a large incision is made in the chest and the sternum is sawed in half to allow access to the heart. In addition, a heart lung machine is used to circulate the patients blood so that the heart can be stopped and the anastomosis can be performed. During this procedure, the aorta is clamped which can lead to trauma of the aortic tissue and/or dislodge plaque emboli, both of which increase the likelihood of neurological complications. In order to minimize the trauma to the patient induced by conventional CABG, less invasive techniques have been developed in which the surgery is performed through small incisions in the patients chest with the aid of visualizing scopes. Less invasive CABG can be performed on a beating or stopped heart and thus may avoid the need for cardiopulmonary bypass. 
     In both conventional and less invasive CABG procedures, the surgeon has to suture one end of the graft vessel to the coronary artery and the other end of the graft vessel to a blood supplying vein or artery. The suturing process is a time consuming and difficult procedure requiring a high level of surgical skill. In order to perform the suturing of the graft to the coronary artery and the blood supplying artery the surgeon must have relatively unobstructed access to the anastomosis site within the patient. In the less invasive surgical approaches, some of the major coronary arteries including the ascending aorta cannot be easily reached by the surgeon because of their location. This makes suturing either difficult or impossible for some coronary artery sites. In addition, some target vessels, such as heavily calcified coronary vessels, vessels having very small diameter, and previously bypassed vessels may make the suturing process difficult or impossible. 
     An additional problem with CABG is the formation of thrombi and atherosclerotic lesions at and around the grafted artery, which can result in the reoccurrence of ischemia. The thrombi and atherosclerotic lesions may be caused by the configuration of the sutured anastomosis site. For example, an abrupt edge at the anastomosis site may cause more stenosis than a more gradual transition. 
     Accordingly, it would be desirable to provide a sutureless vascular anastomosis device which easily connects a graft to a target vessel. It would also be desirable to provide a sutureless anastomosis device which is formed of one piece and is secured to the target vessel in a single step. 
     SUMMARY OF THE INVENTION 
     According to a preferred embodiment, the present invention relates to an anastomosis device for connecting an end of a graft vessel to a target vessel wherein the device cooperates with a deployment tool for connecting an end of the graft vessel to the target vessel. The anastomosis device comprises a first linkage deformable by the deployment tool to form a first flange (e.g., an inner flange which connects the graft vessel to an inner surface of the target vessel), an optional connecting portion extending from the first linkage, and a second linkage deformable by the deployment tool to form a second flange (e.g., an outer flange which connects the graft vessel to an outer surface of the target vessel), the second linkage including deformable links which cooperate with a distal end of the deployment tool to form the second flange. The anastomosis device is preferably sized to fit through an incision in the target vessel such that the first flange comprises an inner flange which presses a portion of the graft vessel into intimate contact with an inner surface of the target vessel and the second flange comprises an outer flange which presses another portion of the graft vessel into intimate contact with an outer surface of the target vessel. 
     The anastomosis device can include various features. For instance, a connecting portion can be provided between the first and second linkages and the first and second linkages can include axial members having weakened areas which cause the axial members to bend simultaneously during formation of the inner and/or outer flange. The deployment tool can include an expander which forms the first flange and a holder tube surrounding the expander, the holder tube engaging the deformable links and bending the deformable links outwardly to form the second flange. 
     The deployment tool can incorporate various features. For example, a deforming crown tool can include first members and the deformable links can include second members which remain connected to the first members during formation of the first flange and disconnect from the first members during formation of the second flange, the deformable members bending the deformable links outwardly during formation of the second flange and returning to a non-bent configuration after formation of the second flange. The first members can comprise tabs and the second members can comprise slots which engage the tabs and openings which disengage the tabs, the slots extending from the openings towards a proximal end of the anastomosis device. A deforming crown deployment tool can include deformable members at the distal end thereof, the deformable members being plastically deformed after bending the deformable links outwardly to form the second flange. In a third embodiment, the deployment tool breaks off part of the anastomosis device during formation of the outer flange. For example, the anastomosis device can include a deployed portion (implant) and a severable portion (discard) wherein the first and second flanges are formed on the deployed portion and the severable portion is severed from the deployed portion when the second flange is formed. The deployed portion can be connected to the severable portion by shearable connectors and the shearable connectors can be located at pivot connections between the deployed portion and the severable portion. The severable portion and the deployed portion are preferably machined from a single piece of metal and the pivot connections can comprise thin sections of the metal extending between the deployed portion and the severable portion. 
     The anastomosis device can incorporate various structural features. For instance, the first linkage can include a plurality of struts arranged in a configuration such that an axial dimension of the first linkage changes upon radial expansion of the first linkage. Further, the first linkage can include a plurality of piercing members which penetrate the graft vessel. The second linkage can include a plurality of axial members and struts arranged in a configuration such that radial expansion of the second linkage does not cause formation of the second flange. The second linkage can also include pairs of axial members which are closer together at a distal end thereof than at a proximal end thereof, the proximal ends of the axial members being joined by circumferentially extending severable links to a linkage supported by the tool, the severable links being severed when the second flange is formed. 
     An anastomosis device deployment system according to the invention can include a handle and a holder tube attached to the handle, the holder tube having a distal end configured to hold the anastomosis device with an attached graft vessel; and an expander positioned within the holder tube and slidable with respect to the holder tube to a position at which the expander is positioned within the anastomosis device and radially expands the anastomosis device. The system can further include a trocar movable with respect to the holder tube to form an opening in a target vessel to receive the anastomosis device and attached graft vessel. The trocar can be a split trocar which is slidable over the holder tube and the expanded anastomosis device. The handle can include cam grooves which cooperate with followers of the holder tube and expander to move the holder tube and expander with respect to one another upon activation of a trigger of the handle. The distal end of the holder tube can include a plurality of slits, loops and/or flexible fingers for engaging tabs of the anastomosis device during formation of the inner and outer flanges. 
     According to another embodiment of the invention, the frangible linkage can be used to release an implant portion of a medical device at a target site in a living body. According to this embodiment, the medical device cooperates with a deployment tool for delivering and deploying the medical device to the site. The medical device includes first and second sections connected together by a frangible linkage, the frangible linkage being deformable by the deployment tool such that frangible elements of the frangible linkage are broken and the first section is separated from the second section. The frangible elements can include weakened areas which cause the frangible elements to bend when the frangible linkage is deformed by the deployment tool. For instance, the medical device can comprise an anastomosis device and the first section can include hinged axial members which bend outwardly and form first and second flanges. The deployment tool can include an expander which forms the first flange and a holder tube surrounding the expander, the holder tube engaging the second section and forming the second flange while separating the first section from the second section. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described in greater detail with reference to the preferred embodiments illustrated in the accompanying drawings, in which like elements bear like reference numerals, and wherein: 
     FIG. 1 is a perspective view of a first embodiment of an anastomosis device in a configuration prior to use with a graft vessel everted over the device; 
     FIG. 2 is a perspective view of the anastomosis device of FIG. 1 in a deployed configuration; 
     FIG. 3 is a perspective view of an anastomosis device deployment system; 
     FIG. 4 is an enlarged perspective view of the distal end of the anastomosis device deployment system of FIG. 3 with an anastomosis device prior to deployment; 
     FIG. 5 is a side cross sectional view of the anastomosis device deployment system puncturing the target vessel to advance the anastomosis device into the target vessel wall; 
     FIG. 6 is a side cross sectional view of the anastomosis device deployment system advancing the anastomosis device into the target vessel wall; 
     FIG. 7 is a side cross sectional view of the anastomosis device deployment system with an expanded first annular flange; 
     FIG. 8 is a side cross sectional view of the anastomosis device deployment system expanding a second annular flange; 
     FIG. 9 is a schematic side cross-sectional view of a deployment tool taken along line A—A of FIG. 3, the deployment tool is shown during a vessel puncturing step; 
     FIG. 10 is a schematic side cross-sectional view of the deployment tool of FIG. 9 shown during an anastomosis device insertion step; 
     FIG. 11 is a schematic side cross-sectional view of the deployment tool of FIG. 9 shown during an anastomosis device expansion step; 
     FIG. 12 is a schematic side cross-sectional view of the deployment tool of FIG. 9 shown after the anastomosis device has been fully deployed; 
     FIG. 13 is a perspective view of a frangible anastomosis device in a configuration prior to use; 
     FIG. 14 is a perspective view of the device shown in FIG. 13 after radial expansion thereof; 
     FIG. 15 shows a frangible link from the portion of FIG. 14 within the circle labeled A; 
     FIG. 16 shows the frangible link of FIG. 15 in a bent configuration; 
     FIG. 17 shows a variation of the frangible link shown in FIG. 15; 
     FIG. 18 shows another variation of the frangible link shown in FIG. 15; 
     FIG. 19 shows a deforming crown design wherein the outer flange of the device is formed from frangible helical members; 
     FIG. 20 shows a deforming crown design wherein the outer flange is formed from members which are mechanically attached to the tool; 
     FIG. 21 shows how the members forming the outer flange are released from the deforming crown during formation of the outer flange; 
     FIG. 22 shows (in planar form) a variation of the frangible anastomosis device shown in FIG. 13; 
     FIG. 23 shows details of a frangible link arrangement of the device shown in FIG. 22; 
     FIG. 24 shows (in planar form) a variation of the frangible anastomosis device shown in FIG. 13; 
     FIG. 25 shows details of a frangible link arrangement of the device shown in FIG. 24; 
     FIG. 26 shows (in planar form) a variation of the frangible anastomosis device shown in FIG. 13; 
     FIG. 27 shows details of a frangible link arrangement of the device shown in FIG. 26; 
     FIG. 28 shows (in planar form) a variation of the frangible anastomosis device shown in FIG. 13; 
     FIG. 29 shows details of a frangible link arrangement of the device shown in FIG. 28; 
     FIGS. 30 and 31 show details of a tissue anchoring arrangement; 
     FIG. 32 shows details of how an anastomotic device in accordance with the invention can be deployed; and 
     FIGS. 33 and 34 show a further embodiment of the anastomotic device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     According to the invention it is possible to perform a variety of anastomosis procedures, including coronary artery bypass grafting. The term “target vessel” is thus used to refer to vessels within the patient which are connected to either or both of the upstream and downstream end of the graft vessel. In such procedures, a large vessel anastomotic device is used with large diameter target vessels such as the aorta or its major side branches or a small vessel anastomotic device is used for a target vessel which has a small diameter such as a coronary artery. 
     In deploying a large vessel anastomotic device, the device (with one end of a graft vessel attached thereto) is inserted into an incision in a wall of the target vessel with a deformable section in a first configuration, and the deformable section is radially expanded to a second configuration to deploy a flange. The flange applies an axial force against the wall of the target vessel. Additionally, the flange can be configured to apply a radial force, substantially transverse to the device longitudinal axis, against the wall of the target vessel, to secure the device to the target vessel. For example, the device can have a plurality of deformable sections forming distal and proximal flanges. With the proximal and distal end flanges deployed, the device can be prevented from shifting proximally out of the target vessel or distally further into the interior of the target vessel. 
     The large vessel devices can be configured to connect to target vessels of various sizes having a wall thickness of at least about 0.5 mm, and typically about 0.5 mm to about 5 mm. In a preferred embodiment of the invention, the large vessel anastomotic device is configured to longitudinally collapse as the deformable section is radially expanded. The surgeon can control the longitudinal collapse to thereby position the distal end flange at a desired location at least partially within the incision in the target vessel wall. The surgeon can also control the position of the proximal end flange by longitudinally collapsing the device to a greater or lesser degree, to thereby position the proximal end flange at a desired location in contact with the target vessel. Thus, regardless of the thickness of the target vessel wall, the device can be longitudinally collapsed to position the flanges against the target vessel wall and effectively connect the device thereto. This feature is significant because the device must be connected to target vessels which have a wide range of wall thickness. For example, the aortic wall thickness is typically about 1.4 mm to about 4.0 mm and the aorta diameter can range from about 25 to about 65 mm in diameter. Therefore, regardless of the thickness of the target vessel wall, the degree of deployment of the proximal end flange, and thus the longitudinal collapse of the device, can be controlled by the physician to thereby effectively connect the device to the target vessel. For example, the surgeon may choose between partially deploying the proximal end flange so that it is positioned against an outer surface of the target vessel wall, or fully deploying the flange to position it in contact with the media of the target vessel wall within the incision in the target vessel wall. 
     In deploying a small vessel anastomotic device, the device can be used on small target vessels having a wall thickness of less than about 1.0 mm, and typically about 0.1 mm to about 1 mm in the case of coronary arteries. Despite the small size of the target vessels, the small vessel devices provide sutureless connection without significantly occluding the small inner lumen of the target vessel or impeding the blood flow therethrough. For example, the small vessel devices can include an outer flange (with the graft vessel connected thereto) loosely connected to an inner flange before insertion into the patient with the space between the loosely connected inner and outer flanges being at least as great as the wall thickness of the target vessel so that the inner flange can be inserted through an incision in the target vessel and into the target vessel lumen, with the outer flange outside the target vessel. With the outer and inner flanges in place on either side of a wall of the target vessel, tightening the flanges together compresses a surface of the graft vessel against the outer surface of the target vessel. This configuration forms a continuous channel between the graft vessel and the target vessel, without the need to suture the graft vessel to the target vessel wall and preferably without the use of hooks or barbs which puncture the target vessel. 
     In a coronary bypass operation in accordance with the invention, a large vessel device can be used to connect the proximal end of the graft vessel to the aorta, and a small vessel device can be used to connect the distal end of the graft vessel to an occluded coronary artery. However, in patients with an extreme arteriosclerotic lesion in the aorta, which may result in serious complications during surgical procedures on the aorta, the surgeon may wish to avoid this region and connect the proximal end of the graft vessel to any other adjacent less diseased vessel, such as the arteries leading to the arms or head. Further, the devices can be used with venous grafts, such as a harvested saphenous vein graft, arterial grafts, such as a dissected mammary artery, or a synthetic prosthesis, as required. 
     Connection of the large vessel device does not require the stoppage of blood flow in the target vessel. Moreover, the anastomotic devices can be connected to the target vessel without the use of cardiopulmonary bypass. In contrast, anastomosis techniques wherein the aorta is clamped to interrupt blood flow to the area of the aortic wall to which a vein is to be anastomosed may result in liberation of plaques and tissue fragments which can lead to organ dysfunction, such as strokes, renal failure, or intestinal ischemia. However, severely diseased aortas may not provide an area suitable for clamping due to significant calcification of the aortic wall. In the anastomosis technique according to the invention, the surgeon does not need significant room inside the patient to connect the anastomotic devices to the target vessel. For example, unlike sutured anastomoses which require significant access to the aorta for the surgeon to suture the graft vessel thereto, the anastomotic devices allow the proximal end of the graft vessel to be connected to any part of the aorta. All parts of the aorta are accessible to the large vessel anastomosis devices, even when minimally invasive procedures are used. Consequently, the graft vessel may be connected to the descending aorta, so that the graft vessel would not be threatened by damage during a conventional sternotomy if a second operation is required at a later time. 
     According to the invention, a sutureless connection can be provided between a graft and a target vessel, while minimizing thrombosis or restenosis associated with the anastomosis. The anastomotic devices can be attached to the target vessel inside a patient remotely from outside the patient using specially designed applicators, so that the devices are particularly suitable for use in minimally invasive surgical procedures where access to the anastomosis site is limited. The devices allow the anastomosis to be performed very rapidly, with high reproducibility and reliability, without clamping, and with or without the use of cardiopulmonary bypass. 
     According to one preferred method of deploying the anastomosis device, the surgeon operates a deployment tool using both hands. One hand supports the tool via a handle while the other twists an actuation knob to deploy the anastomotic device. Locating the actuation knob on the tool&#39;s main axis minimizes the tendency of reaction forces to wobble the tool keeping it stable and in proper position during deployment. The twisting motion is converted to linear displacements by a set of rotating cams that engage a trocar, holder, and expander. The cams control the sequence of relative motions between the instrument&#39;s trocar and device deployment mechanisms. 
     During the foregoing procedure, a surgeon will place the tip of the instrument (the mechanical stop) in light contact with the site on the aorta to be anastomosed. Having located a suitable site, the surgeon then twists the actuation knob to fire the spring-loaded trocar and continues twisting to deploy the anastomotic device. The trocar penetrates the aortic wall at a high rate of speed to minimize any unintended deformation of the aorta and maintains a substantially fluid-tight seal at the puncture site. Having entered the aortic lumen, the trocar dilates as the anastomotic device and its holder tube (crown) are advanced through it, thus retracting the aortic tissue and serving as an introducer for the device. Once the device has fully entered the aortic lumen the trocar is withdrawn. The anastomotic device is then expanded to its full diameter and an inner flange is deployed. The device is then drawn outwards towards the instrument (mechanical stop) to seat the inner flange firmly against the intimal wall of the aorta. An outer flange is then deployed from the external side, compressing the aortic wall between the inner and outer flanges and the device is disengaged from the instrument completing the anastomosis. 
     FIG. 1 illustrates the distal portion of an anastomosis device  10  according to a first embodiment of the present invention, the proximal portion (not shown) being adapted to be deployed by a deployment tool which will be explained later. The anastomosis device  10  includes a plurality of axial members  12  and a plurality of struts  14  interconnecting the axial members. The axial members  12  and struts  14  form a first linkage  16  at a first end of the device and a second linkage  18  at a second end of the device. The first and second linkages  16 ,  18  form inner and outer flanges  20 ,  22  when the anastomosis device  10  is deployed as illustrated in FIG.  2 . The deployed flanges  20 ,  22  may be annular ring shaped or conical in shape. The first and second linkages  16 ,  18  are connected by a central connecting portion  24 . 
     In use, a graft vessel  30  is inserted through a center of the tubular anastomosis device  10  and is everted over the first linkage  16  at the first end of the device. The first end of the device may puncture part way or all the way through the graft vessel wall to hold the graft vessel  30  on the device. An opening  34  is formed in the target vessel  32  to receive the graft vessel  30  and anastomosis device  10 . Once the anastomosis device  10  with everted graft vessel  30  are inserted through the opening  34  in the target vessel  32 , the inner and outer flanges  20 ,  22  are formed as shown in FIG. 2 to secure the graft vessel to the target vessel by trapping the wall of the target vessel between the two flanges. The anastomosis device  10  forms a smooth transition between the target vessel  32  and the graft vessel  30  which helps to prevent thrombi formation. 
     The inner and outer flanges  20 ,  22  are formed by radial expansion of the anastomosis device  10  as follows. The first and second linkages  16 ,  18  are each made up of a plurality of axial members  12  and struts  14 . The struts  14  are arranged in a plurality of diamond shapes with adjacent diamond shapes connected to each other to form a continuous ring of diamond shapes around the device. One axial member  12  extends through a center of each of the diamond shapes formed by the struts  14 . A reduced thickness section  26  or hinge in each of the axial members  12  provides a location for concentration of bending of the axial members. When an expansion member of a deployment tool such as a rod or balloon is inserted into the tubular anastomosis device  10  and used to radially expand the device, each of the diamond shaped linkages of struts  14  are elongated in a circumferential direction causing a top and bottom of each of the diamond shapes to move closer together. As the top and bottom of the diamond shapes move closer together, the axial members  12  bend along the reduced thickness sections  26  folding the ends of the device outward to form the inner and outer flanges  20 ,  22  with the result that the wall of the target vessel  32  is trapped between the flanges and the everted graft vessel  30  is secured to the target vessel. 
     In the anastomosis device  10  shown in FIGS. 1 and 2, the struts  14  may be straight or curved members having constant or varying thicknesses. In addition, the axial members  12  may have the reduced thickness sections  26  positioned at a center of each of the diamond shapes or off center inside the diamond shapes. The positioning and size of the reduced thickness sections  26  will determine the location of the flanges  20 ,  22  and an angle the flanges make with an axis of the device when fully deployed. A final angle between the flanges  20 ,  22  and longitudinal axis of the device  10  is about 40-100 degrees, preferably about 50-90 degrees. 
     FIGS. 3-7 illustrate a deployment system  150  and sequence of deploying an anastomosis device  120  such as the device shown in FIGS. 1-2 with the deployment system. In FIGS. 3-5 the graft vessel  30  has been eliminated for purposes of clarity. As shown in FIGS. 3-7, the deployment system  150  includes a hollow outer trocar  152  (not shown in FIG.  3 ), a holder tube  154  positioned inside the trocar, and an expander tube  156  slidable inside the holder tube. As can be seen in the detail of FIG. 4, the anastomosis device  120  is attached to a distal end of the holder tube  154  by inserting T-shaped ends  112  of pull tabs  110  in slots  158  around the circumference of the holder tube. The trocar  152 , holder tube  154 , and expander tube  156  are all slidable with respect to one another during operation of the device. A device handle  160  is provided for moving the tubes with respect to one another will be described in further detail below with respect to FIGS. 8-11. 
     As shown in FIG. 5, initially, the holder tube  154 , expander tube  156 , and the anastomosis device  120  are positioned within the trocar  152  for insertion. The trocar  152  has a hollow generally conical tip with a plurality of axial slots  162  which allow the conical tip to be spread apart so that the anastomosis device  120  can slide through the opened trocar. The trocar  152 , acting as a tissue retractor and guide, is inserted through the wall of the target vessel  32  forming an opening  34 . As shown in FIG. 6, the anastomosis device  120  is then advanced into or through the target vessel wall  32  with the holder tube  154 . The advancing of the holder tube  154  causes the distal end of the trocar  152  to be forced to spread apart. Once the anastomosis device  120  is in position and the trocar  152  has been withdrawn, the inner annular flange  20  is deployed by advancing the expander tube  156  into the anastomosis device. The advancing of the expander tube  156  increases the diameter of the anastomosis device  120  causing the inner flange to fold outward from the device. This expanding of the inner flange may be performed inside the vessel and then the device  120  may be drawn back until the inner flange abuts an interior of the target vessel wall  32 . 
     As shown in FIG. 8, after the inner flange has been deployed, the holder tube  154  is advanced forming the outer flange. As the holder tube  154  is advanced, the anastomosis device  120  drops into a radial groove  157  on an exterior of the expander tube  156  which holds the anastomosis device stationary on the expander tube  156 . The holder tube  154  is then moved forward to detach the entire anastomosis device by disengaging the pull tabs  130  from the slots  158  in the holder tube and causing the outer flange to be deployed. During deployment of the outer flange, shoulders  134  on the device, shown most clearly in FIGS. 5 and 6, engage a tapered distal end of the holder tube  154  causing the pull tabs  130  to be released from the slots  158 . Alternatively, and as will be explained in connection with a frangible anastomosis device according to the invention, movement of the holder tube  154  can detach a deployed portion of the device from a discard portion of the device which remains attached to the holder tube. 
     One alternative embodiment of the holder tube  154  employs a plurality of flexible fingers which receive the pull tabs  130  of the anastomosis device  120 . According to this embodiment each pull tab  130  is received by an independent finger of the holder tube  154 . To deploy the second or outer flange of the anastomosis device  120 , the flexible fingers flex outward bending the pull tabs  130  outward. For instance, the flexible fingers can be designed to flex when the pull tabs and fingers are put under axial compression in which case the fingers and tabs buckle outwards together to deploy the outer flange and release the anastomosis device from the holder tube. 
     FIGS. 9-12 illustrate the operation of the handle  160  to move the trocar  152 , the holder tube  154 , and the expander tube  156  with respect to one another to deploy the anastomosis device  120  according to the present invention. The handle  160  includes a grip  170  and a trigger  172  pivotally mounted to the grip at a pivot  174 . The trigger  172  includes a finger loop  176  and three contoured cam slots  178 ,  180 ,  182  corresponding to the trocar  152 , holder tube  154 , and expander tube  156 , respectively. Each of these tubes has a fitting  184  at a distal end thereof. A pin  186  connected to each of the fittings  184  slides in a corresponding one of the cam slots  178 ,  180 ,  182 . A fourth cam slot and tube may be added to control deployment of the outer flange. Alternatively, the handle can be modified to include fewer cam slots for deployment of the inner and outer flanges. 
     The handle  160  is shown in FIG. 8 in an insertion position in which the trocar  152  extends beyond the holder tube  154  and the expander tube  156  for puncturing of the target vessel wall  32 . Optionally, a flexible seal (not shown) such as heat shrinkable plastic or elastomeric tubing can be provided on the outer surface of the trocar  152  such that the seal covers the axial slots  162  at a location spaced from the tip of the trocar to prevent leaking of blood from the target vessel after the incision is formed. In a preferred embodiment, the trocar is actuated by a mechanism which causes the trocar to penetrate the aorta wall at a high rate of speed to minimize deformation of the aorta and maintain a fluid tight seal at the puncture site in a manner similar to biopsy gun. For instance, the spring mechanism attached to the trocar and/or the handle can be used to fire the trocar at the incision site. Any suitable actuating mechanism can be used to fire the trocar in accordance with the invention. As the trigger  172  is rotated from the position illustrated in FIG. 9 to the successive positions illustrated in FIGS. 10-12, the pins  186  slide in the cam slots  178 ,  180 ,  182  to move the trocar  152 , holder tube  154  and expander tube  156 . 
     FIG. 10 shows the handle  160  with the trigger  172  rotated approximately 30 degrees from the position of FIG.  9 . This rotation moves the holder tube  154  and expander tube  156  forward into the wall of the target vessel  32  spreading the trocar  152 . The anastomosis device  120  is now in position for deployment. FIG. 11 shows the trigger  172  rotated approximately 45 degrees with respect to the position of FIG.  9  and the cam slot  182  has caused the expander tube  156  to be advanced within the holder tube  154  to deploy the inner flange. The trocar  152  has also been withdrawn. 
     FIG. 12 shows the handle  160  with the trigger  172  pivoted approximately 60 degrees with respect to the position shown in FIG.  9 . As shown in FIG. 12, the expander tube  156  has been withdrawn to pull the inner flange against the vessel wall  32  and the holder tube  154  is moved forward to deploy the outer flange and disengage the holder tube  154  from the anastomosis device  120 . 
     The handle  160  also includes a first channel  188  and a second channel  190  in the grip  170  through which the graft vessel (not shown) may be guided. The grip  170  also includes a cavity  192  for protecting an opposite end of the graft vessel from the attachment end. 
     According to one embodiment of the invention, the anastomosis device includes a frangible linkage which allows an implant to separate from the remainder of the device upon formation of the outer flange. According to a preferred linkage design, the frangible linkage can be radially expanded and axially compressed to fracture the frangible linkage. The inner flange can be formed during radial expansion of the device and the implant can be severed while forming the outer flange. 
     FIG. 13 shows a device  200  which cooperates with a deployment tool  300  for delivering and deploying an implant  204  at a site in a living body. The device includes a frangible linkage  202  connecting the implant  204  to a discard portion  206 . As explained below, after the device is positioned at a desired location, the implant  204  can be expanded to deploy an inner flange and subsequently axially compressed to deploy an outer flange while severing the implant  204  from the discard portion  206 . The deployment tool can then be withdrawn along with the discard portion  206  which remains attached to the distal end of the deployment tool  300 . 
     FIG. 14 shows the device  200  in the radially expanded condition but prior to being axially compressed. During radial expansion of the device, axially extending barbs  208  (FIG. 13) are pivoted outwardly by struts  210  such that the outwardly extending barbs  208  and struts  210  form the inner flange. To facilitate bending of the barbs, the barbs  208  comprise points on the ends of axially extending members  212  which have narrow sections  214  located a desired distance from the free ends of the barbs  208 . For instance, the narrow sections  214  can be located at axial positions along the device corresponding approximately to the axial midpoint of the struts  210  connecting adjacent members  212  when the device is in the pre-expanded condition shown in FIG.  13 . 
     To facilitate easier bending of the struts  210  during radial expansion of the device, the distal ends of the struts can be curved at their points of attachment to the members  212 . Likewise, a curved bend can be provided at the intersection where the proximal ends of the struts are attached together. When the device is radially expanded, the members  212  move radially outward and circumferentially apart as the struts  210  move radially outward until a force on the barbs  208  by the struts  210  causes the struts to become bent at the narrow sections  214 , after which the barbs extend outwardly to form the inner flange. In this deployed condition, the barbs  208  are locked into position by an X-shaped frame formed by struts  210  and additional struts  216 . The struts  216  are similar in configuration to the struts  210  with respect to how they are shaped and attached to the members  212 . Short axially extending members  218  connect the intersection of the struts  210  to the intersection of the struts  216 . 
     The frangible section  202  is located at the proximal ends of axially extending members  220  which are connected to the members  212  by U-shaped links  222 . The members  220  are arranged in pairs which are attached together at only their distal ends. In particular, the distal ends of the links  222  are attached to proximal ends of the members  212  and the midpoint of each link  222  is attached to the distal ends of a respective pair of members  220 . As shown in FIG. 14, during radial expansion of the device, the individual links  222  are plastically deformed from their U-shaped configuration to form segments of a circumferentially extending annular ring. As a result, the device becomes shorter in the axial direction as links  222  form the annular ring and the distal ends of the members  220  move radially outward but not apart in the circumferential direction. At the same time, the proximal ends of the members  220  move radially outward and circumferentially apart. 
     FIG. 15 shows an expanded view of the circled portion A in FIG.  14  and FIG. 16 shows how the frangible section  202  can be bent to fracture connection points between members  220  and axial extending members  224 . As shown in FIGS. 14 and 15, proximal ends of the members  224  are attached to U-shaped links  226  which allow the proximal ends of the members  224  to move radially outward but not circumferentially apart when the device is expanded. As shown in FIG. 15, the distal ends of members  224  and connected to the proximal ends of the members  220  by a frangible joint comprised of shearable connections  228 . In the embodiment shown, the members  220  are connected at their proximal ends by a cross piece  230  and the members  224  are connected at their distal ends by a cross piece  232 . The cross piece  230  includes a recess  234  and the cross piece  232  includes a projection  236  located in the recess  234 . The frangible joint is preferably formed from a unitary piece of material (e.g., stainless steel, nickel titanium alloy, etc.) such as a laser cut tube wherein the shearable connections  228  comprise thin sections of material extending between opposite sides of the projection  236  and opposing walls of the recess  234 . As shown in FIG. 16, the recess  234  contains the projection  236  as the members  220  and  224  are pivoted about the joint formed by the shearable connections  228 . When the members  220  and  224  are pivoted to a sufficient extent, the shearable connections  228  are fractured allowing the implant to separate from the discard portion of the device. 
     The frangible link shown in FIGS. 15-16 can be modified in various ways. For instance, as shown in FIG. 17, the projection can have a slot  238  extending from the free end thereof towards cross piece  232 . The slot  238  allows the portions of the projection on either side of the slot  238  to move closer together as the proximal ends of members  224  bend away from each other during radial expansion of the device  200 . Likewise, the proximal ends of the members  220  on either side of the projection  236  can move closer together as the distal ends of the members  220  move apart during the radial expansion. Another variation is shown in FIG. 18 wherein two projections  236   a  and  236   b  extend from cross piece  232  and two projections  236   c  and  236   d  extend from cross piece  230 , projections  236   a  and  236   d  being connected by a first shearable connection  228  and projections  236   c  and  236   d  being connected by a second shearable connection  228 . As with the arrangement in FIG. 17, the arrangement in FIG. 18 allows the projections  236   a-d  to become squeezed together during radial expansion of the device  200 . 
     The device  200  can be deployed using deployment tool  300  as follows. As shown in FIGS. 13 and 14, the device  200  includes a crown  240  attached to a distal end  302  of the tool  300 . The crown includes axially extending members  242  with tabs (not shown) on the proximal ends thereof, the members  242  being held in slots  304  of the tool  300  by the tabs. A plastic sleeve (not shown) can be placed over the slots  304  to prevent the members  242  from coming out of the slots. As shown in FIG. 13, the crown is flared outwardly such that the members  242  are fully radially expanded at their proximal ends. During radial expansion of the device  200 , the diamond shaped linkage of the crown  240  is expanded from the configuration shown in FIG. 13 to the expanded configuration shown in FIG.  14 . 
     In the embodiment shown in FIGS. 13-14, the device  200  is attached to the tool  300  in a manner such that the discard portion  206  stays with the tool during deployment of the implant  204  and removal of the tool from the implant site. As previously described, the discard can include tabbed members fitted in grooves of the tool. Other suitable attachment techniques include welding the proximal end of the device to the tool using resistance welding, ultrasonic welding or the like, molding the proximal end of the device into the distal end of the tool such as by insert molding, mechanically fastening the proximal end of the device to the tool, adhesive bonding, etc. 
     In the foregoing embodiment, the device is deployed by radial expansion and axial compression. The axial compression can be accomplished by pushing the holder tube while the expander tube is held in a fixed position or vice versa. According to a further embodiment, the axial compression can be accomplished by rotation of the device. For instance, FIG. 19, showing a buckling crown  240   a  which includes helical members  244  extending from a ring  246  attached to the distal end  302  of the tool  300 . Additional helical members  248  which form the outer flange of the implant are connected to the helical members  244  by shearable connections  250 . During deployment of the outer flange, the tool  300  is rotated while preventing the implant  204  from rotating with the result that the helical members  244  and  248  bend outwardly at the location of the shearable connections  250  and form the outer flange. After formation of the outer flange, the shearable connections  250  fracture releasing the implant  204  from the crown  240   a  which remains attached to the tool. As with the previously described device, the crown  240   a  can be attached to the tool in any desired manner, e.g. welding, molding, etc. 
     According to the next embodiment, the device can be designed so as to be released from the tool without use of fracture elements. For example, the tool can include a deforming crown which mechanically disengages with the device after forming the outer flange. The device and tool can incorporate any suitable release mechanism which, for example, connects the crown to the deployment tool when a tensile force is applied to the connection but which disconnects when a compressive force is applied to the connection, e.g., hooks, tabs, spring clips, etc. FIG. 20 shows an embodiment of a tool with a deforming crown  306  comprised of struts  308  and tabs  310  connected to the struts  308  by thin necks  312 . The device  200   a  is similar to device  200  except that device  200   a  does not include frangible links. Instead, device  200   a  includes bendable members  252  which are bent outwardly by the deforming crown  306  to form the outer flange. As shown in FIG. 21, each of the members  252  includes a hole  254  sized larger than the tabs to allow the tabs to be released from the holes after the outer flange is formed. When the device  200   a  is attached to the tool  300 , the tabs  310  are fitted in the holes with the necks  312  received in the slots  256 . The struts  308  can be shorter than the members  252  so that when the outer flange is formed the members  252  extend outwardly further than the struts  308 . As a result, the necks  312  slide out of the slots  256  and the tabs  310  slide out of the holes  254  as the outer flange is formed and the implant is released from the tool. 
     FIG. 22 shows a device  400  (illustrated in planar form for ease of description but which would be used in a tubular shape) which cooperates with a deployment tool (as described earlier) for delivering and deploying an implant  404  at a site in a living body. The device includes a frangible linkage  402  connecting the implant  404  to a discard portion  406 . As explained with reference to the embodiment shown in FIGS. 13-14, after the device is positioned at a desired location, the implant  404  can be expanded to deploy an inner flange and subsequently axially compressed to deploy an outer flange while severing the implant  404  from the discard portion  406 . The deployment tool can then be withdrawn along with the discard portion  406  which remains attached to the distal end of the deployment tool. 
     During radial expansion of the device, axially extending barbs  408  are pivoted outwardly by struts  410  such that the outwardly extending barbs  408  and struts  410  form the inner flange. To facilitate bending of the barbs, the barbs  408  comprise points on the ends of axially extending members  412  which have narrow sections  414  located a desired distance from the free ends of the barbs  408 . For instance, the narrow sections  414  can be located at axial positions along the device corresponding approximately to the axial midpoint of the struts  410  connecting adjacent members  412  when the device is in the pre-expanded condition. 
     To facilitate easier bending of the struts  410  during radial expansion of the device, the distal ends of the struts can be curved at their points of attachment to the members  412 . Likewise, a curved bend can be provided at the intersection where the proximal ends of the struts are attached together. When the device is radially expanded, the members  412  move radially outward and circumferentially apart as the struts  410  move radially outward until a force on the barbs  408  by the struts  410  causes the struts to become bent at the narrow sections  414 , after which the barbs extend outwardly to form the inner flange. In this deployed condition, the barbs  408  are locked into position by an X-shaped frame formed by struts  410  and additional struts  416 . The struts  416  are similar in configuration to the struts  410  with respect to how they are shaped and attached to the members  412 . Short axially extending members  418  connect the intersection of the struts  410  to the intersection of the struts  416 . 
     The frangible section  402  is located at the proximal ends of axially extending members  420  which are connected to the members  412  by U-shaped links  422 . The members  420  are arranged in pairs which are attached together at midpoints of links  422 . During radial expansion of the device, the individual links  422  are plastically deformed from their U-shaped configuration to form segments of a circumferentially extending annular ring. As a result, the device becomes shorter in the axial direction as links  422  form the annular ring and the distal ends of the pairs of members  420  attached to an individual link  422  move radially outward but not apart in the circumferential direction. At the same time, the proximal ends of the members  420  move radially outward and circumferentially apart. 
     The frangible section  402  is located between axial members  420  and axially extending members  424 . As shown in FIG. 22, the members  420  are closer together at their distal ends and this condition remains after expansion of the device. The proximal ends of the members  424  are attached to mid-points of U-shaped links  426  by a pair of short and closely spaced apart axially extending links  427 . The distal ends of members  424  are connected to the proximal ends of the members  420  by a frangible joint comprised of shearable connections  402  which operate in a manner similar to the previously discussed connections  228 , i.e., as shown in FIG. 23, the members  420  are connected at their proximal ends by a cross piece  430  and the members  424  include a projection  436  received in a recess  434 . The frangible joint is formed from a unitary piece of material such as a laser cut tube wherein the shearable connections  402  comprise thin sections of material extending between opposite sides of the projection  436  and opposing walls of the recess  434 . When the members  420  and  424  are pivoted to a sufficient extent, the shearable connections  402  are fractured allowing the implant to separate from the discard portion of the device. 
     The device  400  can be deployed in the same manner that the device  200  is deployed using deployment tool  300 . That is, the device  400  includes a crown attached to a distal end of the deployment tool. The crown includes axially extending members  442  with tabs  443  on the proximal ends thereof, the members  442  being held in slots  304  of the tool  300  by the tabs  443 . A plastic sleeve (not shown) can be placed over the slots  304  to prevent the members  442  from coming out of the slots. When mounted on the deployment tool, the crown is flared outwardly such that the members  442  are fully radially expanded at their proximal ends. During radial expansion of the device  400 , the diamond shaped linkage of the crown  440  is expanded from an unexpanded condition like the configuration shown in FIG. 13 to an expanded condition like the expanded configuration shown in FIG.  14 . 
     FIG. 24 shows a device  500  (illustrated in planar form for ease of description but which would be used in a tubular shape) which cooperates with a deployment tool (as described earlier) for delivering and deploying an implant  504  at a site in a living body. The device includes a frangible linkage  502  connecting the implant  504  to a discard portion  506 . As explained with reference to the embodiment shown in FIGS. 13-14, after the device is positioned at a desired location, the implant  504  can be expanded to deploy an inner flange and subsequently axially compressed to deploy an outer flange while severing the implant  504  from the discard portion  506 . The deployment tool can then be withdrawn along with the discard portion  506  which remains attached to the distal end of the deployment tool. 
     During radial expansion of the device, axially extending barbs  508  are pivoted outwardly by struts  510  such that the outwardly extending barbs  508  and struts  510  form the inner flange. To facilitate bending of the barbs, the barbs  508  comprise points on the ends of axially extending members  512  which have narrow sections  514  located a desired distance from the free ends of the barbs  508 . For instance, the narrow sections  514  can be located at axial positions along the device corresponding approximately to the axial midpoint of the struts  510  connecting adjacent members  512  when the device is in the pre-expanded condition. 
     To facilitate easier bending of the struts  510  during radial expansion of the device, the distal ends of the struts can be curved at their points of attachment to the members  512 . Likewise, a curved bend can be provided at the intersection where the proximal ends of the struts are attached together. When the device is radially expanded, the members  512  move radially outward and circumferentially apart as the struts  510  move radially outward until a force on the barbs  508  by the struts  510  causes the struts to become bent at the narrow sections  514 , after which the barbs extend outwardly to form the inner flange. In this deployed condition, the barbs  508  are locked into position by an X-shaped frame formed by struts  510  and additional struts  516 . The struts  516  are similar in configuration to the struts  510  with respect to how they are shaped and attached to the members  512 . Short axially extending members  518  connect the intersection of the struts  510  to the intersection of the struts  516 . 
     The frangible section  502  is located at the proximal ends of axially extending members  520  which are connected to the members  512  by U-shaped links  522 . The members  520  are arranged in pairs which are attached together at only their distal ends. In particular, the distal ends of the links  522  are attached to proximal ends of the members  512  and the midpoint of each link  522  is attached to the distal ends of a respective pair of members  520 . During radial expansion of the device, the individual links  522  are plastically deformed from their U-shaped configuration to form segments of a circumferentially extending annular ring. As a result, the device becomes shorter in the axial direction as links  522  form the annular ring and the distal ends of the members  520  move radially outward but not apart in the circumferential direction. At the same time, the proximal ends of the members  520  move radially outward and circumferentially apart. 
     The frangible section  502  is located between pairs of the axial members  520  and pairs of axially extending members  524 . As shown in FIG. 24, each pair of members  520  attached to an individual link  522  are closer together at their distal ends and this condition remains when the device is expanded. The proximal ends of pairs of the members  524  are attached at locations intermediate mid-points and ends of U-shaped links  526  by a pair of curved links  527 . During expansion of the device, the U-shaped links  526  deform into a circumferentially extending ring and cause the proximal ends of the members  524  to spread apart such that a gap  528  between the members  524  becomes wider at the proximal ends of the members  524 . To aid spreading of the members  524 , the members include a curved recess  529  at the distal ends thereof. The distal ends of members  524  are connected to the proximal ends of the members  520  by a frangible joint comprised of shearable connections  502  which operate in a manner similar to the previously discussed connections  228 , i.e., as shown in FIG. 25, the members  520  are connected at their proximal ends by a cross piece  530  and the members  524  are connected by a cross piece  535  which includes a projection  536  received in a recess  534 . The frangible joint is formed from a unitary piece of material such as a laser cut tube wherein the shearable connections  502  comprise thin sections of material extending between opposite sides of the projection  536  and opposing walls of the recess  534 . When the members  520  and  524  are pivoted to a sufficient extent, the shearable connections  502  are fractured allowing the implant to separate from the discard portion of the device. 
     The device  500  can be deployed in the same manner that the device  200  is deployed using deployment tool  300 . That is, the device  500  includes a crown attached to a distal end of the deployment tool. The crown includes axially extending members  542  with tabs  543  on the proximal ends thereof, the members  542  being held in slots  304  of the tool  300  by the tabs  543 . A plastic sleeve (not shown) can be placed over the slots  304  to prevent the members  542  from coming out of the slots. When mounted on the deployment tool, the crown is flared outwardly such that the members  542  are fully radially expanded at their proximal ends. During radial expansion of the device  500 , the diamond shaped linkage of the crown  540  is expanded from an unexpanded condition like the configuration shown in FIG. 13 to an expanded condition like the expanded configuration shown in FIG.  14 . 
     FIG. 26 shows a device  600  (illustrated in planar form for ease of description but which would be used in a tubular shape) which cooperates with a deployment tool (as described earlier) for delivering and deploying an implant  604  at a site in a living body. The device includes a frangible linkage  602  connecting the implant  604  to a discard portion  606 . As explained with reference to the embodiment shown in FIGS. 13-14, after the device is positioned at a desired location, the implant  604  can be expanded to deploy an inner flange and subsequently axially compressed to deploy an outer flange while severing the implant  604  from the discard portion  606 . The deployment tool can then be withdrawn along with the discard portion  606  which remains attached to the distal end of the deployment tool. 
     During radial expansion of the device, axially extending barbs  608  are pivoted outwardly by struts  610  such that the outwardly extending barbs  608  and struts  610  form the inner flange. To facilitate bending of the barbs, the barbs  608  comprise points on the ends of axially extending members  612  which have narrow sections  614  located a desired distance from the free ends of the barbs  608 . For instance, the narrow sections  614  can be located at axial positions along the device corresponding approximately to a position slightly distal of the axial midpoint of the struts  610  connecting adjacent members  612  when the device is in the pre-expanded condition. 
     To facilitate easier bending of the struts  610  during radial expansion of the device, the distal ends of the struts can be curved at their points of attachment to the members  612 . Likewise, a curved bend can be provided at the intersection where the proximal ends of the struts are attached together. When the device is radially expanded, the members  612  move radially outward and circumferentially apart as the struts  610  move radially outward until a force on the barbs  608  by the struts  610  causes the struts to become bent at the narrow sections  614 , after which the barbs extend outwardly to form the inner flange. In this deployed condition, the barbs  608  are locked into position by an X-shaped frame formed by struts  610  and additional struts  616 . The struts  616  are similar in configuration to the struts  610  with respect to how they are shaped and attached to the members  612 . Short axially extending members  618  connect the intersection of the struts  610  to the intersection of the struts  616 . 
     The frangible section  602  is located at the proximal ends of axially extending members  620  which are connected to the members  612  by U-shaped links  622 . The members  620  are arranged as circumferentially spaced apart pairs which are attached together at midpoints of links  622 . During radial expansion of the device, the individual links  622  are plastically deformed from their U-shaped configuration to form segments of a circumferentially extending annular ring. As a result, the device becomes shorter in the axial direction as links  622  form the annular ring. At the same time, the proximal ends of each pair of members  620  attached to an individual link  622  move radially outward and apart in the circumferential direction. 
     The frangible section  602  is located between pairs of the axial members  620  and pairs of axially extending members  624 . As shown in FIG. 26, the members  620  are substantially parallel to each other when the device is in its unexpanded condition, i.e., prior to formation of the inner flange. However, when the device is radially expanded the distal ends of the members  620  will remain closer together than their proximal ends since the distal ends are attached to a midpoint of the links  622 . The proximal ends of pairs of the members  624  are attached at mid-points of U-shaped links  626  by a pair of thin links  627 . During expansion of the device, the U-shaped links  626  deform into a circumferentially extending ring while proximal ends of pairs of the members  624  spread apart such that a gap  628  between the pairs of members  624  becomes wider at the proximal ends of the members  624 . To aid spreading of the pairs of members  624 , the members  624  include a curved recess  629  at the distal ends thereof. The distal ends of members  624  are connected to the proximal ends of the members  620  by a frangible joint comprised of shearable connections  602  which operate in a manner similar to the previously discussed connections  228 , i.e., as shown in FIG. 27, the members  620  are connected at their proximal ends by a cross piece  630  and the members  624  are connected by a cross piece  635  which includes a projection  636  received in a recess  634 . The frangible joint is formed from a unitary piece of material such as a laser cut tube wherein the shearable connections  602  comprise thin sections of material extending between opposite sides of the projection  636  and opposing walls of the recess  634 . When the members  620  and  624  are pivoted to a sufficient extent, the shearable connections  602  are fractured allowing the implant to separate from the discard portion of the device. 
     The device  600  can be deployed in the same manner that the device  200  is deployed using deployment tool  300 . That is, the device  600  includes a crown attached to a distal end of the deployment tool. The crown includes axially extending members  642  with tabs  643  on the proximal ends thereof, the members  642  being held in slots  304  of the tool  300  by the tabs  643 . A plastic sleeve (not shown) can be placed over the slots  304  to prevent the members  642  from coming out of the slots. When mounted on the deployment tool, the crown is flared outwardly such that the members  642  are fully radially expanded at their proximal ends. During radial expansion of the device  600 , the diamond shaped linkage of the crown  640  is expanded from an unexpanded condition like the configuration shown in FIG. 13 to an expanded condition like the expanded configuration shown in FIG.  14 . 
     FIG. 24 shows a device  700  (illustrated in planar form for ease of description but which would be used in a tubular shape) which cooperates with a deployment tool (as described earlier) for delivering and deploying an implant  704  at a site in a living body. The device includes a frangible linkage  702  connecting the implant  704  to a discard portion  706 . As explained with reference to the embodiment shown in FIGS. 13-14, after the device is positioned at a desired location, the implant  704  can be expanded to deploy an inner flange and subsequently axially compressed to deploy an outer flange while severing the implant  704  from the discard portion  706 . The deployment tool can then be withdrawn along with the discard portion  706  which remains attached to the distal end of the deployment tool. 
     During radial expansion of the device, axially extending barbs  708  are pivoted outwardly by struts  710  such that the outwardly extending barbs  708  and struts  710  form the inner flange. To facilitate bending of the barbs, the barbs  708  comprise points on the ends of axially extending members  712  which have narrow sections  714  located a desired distance from the free ends of the barbs  708 . For instance, the narrow sections  714  can be located at axial positions along the device corresponding approximately to the axial midpoint of the struts  710  connecting adjacent members  712  when the device is in the pre-expanded condition. 
     To facilitate easier bending of the struts  710  during radial expansion of the device, the distal ends of the struts can be curved at their points of attachment to the members  712 . Likewise, a curved bend can be provided at the intersection where the proximal ends of the struts are attached together. When the device is radially expanded, the members  712  move radially outward and circumferentially apart as the struts  710  move radially outward until a force on the barbs  708  by the struts  710  causes the struts to become bent at the narrow sections  714 , after which the barbs extend outwardly to form the inner flange. In this deployed condition, the barbs  708  are locked into position by an X-shaped frame formed by struts  710  and additional struts  716 . The struts  716  are similar in configuration to the struts  710  with respect to how they are shaped and attached to the members  712 . Short axially extending members  718  connect the intersection of the struts  710  to the intersection of the struts  716 . 
     The frangible section  702  is located at the proximal ends of axially extending members  720  which are connected to the members  712  by U-shaped links  722  and U-shaped links  723 . The members  720  are arranged in pairs which are attached at their distal ends to proximal ends of the links  723  and the midpoints of the links  723  are attached to midpoints of the links  722 . The ends of the links  722  are attached to the proximal ends of adjacent members  718 . During radial expansion of the device, the individual links  722 ,  723  are plastically deformed from their U-shaped configuration to form segments of two circumferentially extending annular rings. As a result, the device becomes shorter in the axial direction as links  722 ,  723  form the annular rings and the distal ends of each pair of the members  720  attached to an individual link  723  move radially outward but not apart in the circumferential direction. At the same time, the proximal ends of pairs of the members  720  move radially outward and circumferentially apart. 
     The frangible section  702  is located between pairs of the axial members  720  and pairs of axially extending members  724 . As shown in FIG. 28, the members  720  attached to an individual link  722  are somewhat closer together at their distal ends than their proximal ends, a condition which remains after expansion of the device. The proximal ends of pairs of the members  724  are attached to mid-points of U-shaped links  726  by a pair of short links  727 . During expansion of the device, the U-shaped links  726  deform into a circumferentially extending ring and cause the proximal ends of the members  724  to spread apart such that a gap  728  between the members  724  becomes wider at the proximal ends of the members  724 . To aid spreading of the members  724 , the members include a curved recess  729  at the distal ends thereof. The distal ends of members  724  are connected to the proximal ends of the members  720  by a frangible joint comprised of shearable connections  702  which operate in a manner similar to the previously discussed connections  228 , i.e., as shown in FIG. 29, the members  720  are connected at their proximal ends by a cross piece  730  and the members  724  are connected by a cross piece  735  which includes a projection  736  received in a recess  734 . The frangible joint is formed from a unitary piece of material such as a laser cut tube wherein the shearable connections  702  comprise thin sections of material extending between opposite sides of the projection  736  and opposing walls of the recess  734 . When the members  720  and  724  are pivoted to a sufficient extent, the shearable connections  702  are fractured allowing the implant to separate from the discard portion of the device. 
     The device  700  can be deployed in the same manner that the device  200  is deployed using deployment tool  300 . That is, the device  700  includes a crown attached to a distal end of the deployment tool. The crown includes axially extending members  742  with tabs  743  on the proximal ends thereof, the members  742  being held in slots  304  of the tool  300  by the tabs  743 . A plastic sleeve (not shown) can be placed over the slots  304  to prevent the members  742  from coming out of the slots. When mounted on the deployment tool, the crown is flared outwardly such that the members  742  are fully radially expanded at their proximal ends. During radial expansion of the device  700 , the diamond shaped linkage of the crown  740  is expanded from an unexpanded condition like the configuration shown in FIG. 13 to an expanded condition like the expanded configuration shown in FIG.  14 . 
     FIGS. 30 and 31 show details of a tissue anchoring arrangement which can optionally be incorporated in the anastomosis device according to the invention. In particular, FIG. 30 shows a distal end of a device  800  (illustrated in planar form for ease of description but which would be used in a tubular shape) wherein axially extending members  802  having points  804  for penetrating the graft vessel (as described earlier) also include a tissue anchoring arrangement  806 . The tissue anchoring arrangement  806  comprises one or more projections (e.g., tangs or barbs) extending from one or both sides of the members  802 , the projections providing anchor points against the inner surface  810  of the target vessel  812 , as shown in FIG. 31 (wherein illustration of the graft vessel has been omitted). The projections  806  can include points  808  which embed themselves in the tissue of the target vessel with or without penetrating the tissue. It is desirable that the projections provide enough of an anchoring effect to prevent sudden increases in blood pressure in the target vessel (after the anastomosis operation) from rupturing the seal between the graft vessel and the target vessel created by the anastomosis device. The outer flange can also include anchoring projections which can be used in lieu of or addition to anchoring projections on the inner flange. 
     A preferred method of loading an expander  156  in a holder tube  154  and placing a graft vessel over the anastomosis device is explained with reference to FIG. 32, wherein expander  156  has been inserted in holder tube  154 . However, prior to insertion of the expander, the barbed ends  824  of device  820  preferably are bent outwardly so as to form an angle such as 5 to 60° to the central axis of the device. Afterwards, the expander  156  can be advanced within the holder tube  154  to a location at which a proximal portion  822  of anastomosis device  820  is expanded over the expander. As a result of contact of the beveled end of the expander  156  with axial members  826 , the barbed ends  824  can be rotated inwardly somewhat to form a smaller angle with the central axis of the device  820 . Then, after a graft vessel is threaded through the anastomosis device  820 , the end of the graft vessel can be everted over the distal end of the anastomosis device and the barbed ends  824  can be poked through the graft vessel. Details of how this eversion process can be carried out are set forth in commonly assigned U.S. patent application Ser. No. 09/440,166 filed on Nov. 15, 1999. With the anastomosis device and everted graft vessel in such a condition, the holder tube  154  can be loaded in a trocar (not shown). Details of preferred trocar designs and an explanation of how the trocar creates an incision in a target vessel can be found in commonly assigned U.S. patent application Ser. No. 09/440,263 (filed Nov. 15, 1999). 
     In order to deploy the device  820 , the inner flange can be expanded by pushing the expander  156  a set distance while maintaining the holder tube  154  in a fixed position. As a result, the linkage of the inner flange rotates the barbed ends  824  about the hinged connections  828  such that the barbed ends  824  from an angle of 40 to 140° with the central axis. Then, the holder tube  154  is pushed a set distance while holding the expander  156  in a fixed position to deploy the outer flange. As a result, the linkage of the outer flange and the discard portion of the anastomosis device is axially compressed such that the linkage fractures as the outer flange is rotated outwardly and towards the already deployed inner flange. 
     Each of the anastomosis devices described above are preferably single piece devices which are formed by laser cutting or punching from a tube or sheet of material. The devices may be provided in varying sizes to join vessels such as arteries, veins, bile ducts, etc., of different sizes. Although various linkage arrangements have been shown wherein the devices include struts which extend between two circumferentially spaced apart locations and axial members which extend between two axially spaced apart locations, the linkages which form the flanges could also be formed by V-shaped links arranged in diamond like patterns. For example, FIG. 33 shows an example of a tubular mesh  830  which can be axially compressed to form an outwardly extending flange. The mesh  830  includes short links  832  and  838  and long links  834  and  836 , the links  832  and  834  being joined to form a first diamond shaped pattern, the links  834  and  836  being joined to form a second diamond shaped pattern, and the links  836  and  838  being joined to form a third diamond shaped pattern. With such an arrangement, axial compression of the tubular mesh  830  will cause the links  834  and  836  to pivot about joints  835  connecting the links  834  to the links  836  and thus form a flange as illustrated in FIG.  34 . 
     The mesh  830  can be joined to another mesh with the same or different linkage arrangement with or without a connecting linkage therebetween. If the same linkage arrangement is used, in order to obtain deployment of one flange prior to deployment of the other flange, one of the linkages can be made with wider and/or thicker links. For example, by using a distal linkage of thin links and a proximal linkage of thick links, it is possible to deploy the inner flange prior to deployment of the outer flange. In other words, axial compression of the tubular mesh can cause the weaker distal linkage to deploy first and form the inner flange after which the outer flange can be formed by axial compression of the stronger proximal linkage. 
     Although the invention has been principally discussed with respect to coronary bypass surgery, the anastomosis devices of the present invention may be used in other types of anastomosis procedures. For example, the anastomosis device may be used in femoral—femoral bypass, vascular shunts, subclavian-carotid bypass, organ transplants, and the like. 
     The anastomosis devices may be made of any known material which can be bent and will retain the bent shape such as stainless steel, nickel titanium alloys, and the like. The hinges or pivot joints which have been discussed above in the various embodiments of the present invention may be designed to concentrate the bending at a desired location. 
     While the invention has been described in detail with reference to the preferred embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made and equivalents employed, without departing from the present invention.

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