Abstract:
A one piece anastomosis device is disclosed which is formed of a superelastic or pseudoelastic material which self deforms or self deploys from an insertion configuration to a tissue holding configuration. The device in a deployed state preferably includes an inner tissue penetrating flange which penetrate and retains an everted graft vessel and an outer flange. The self deploying anastomosis device does not rely on a temperature transformation to achieve deployment.

Description:
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 patient&#39;s 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. 
   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 
   A superelastic or pseudoelastic one piece anastomosis device according to the present invention connects a graft vessel to a target vessel. The anastomosis device deforms from an insertion configuration to a tissue holding configuration due to the superelastic or pseudoelastic properties of the material. 
   In accordance with one aspect of the present invention, a one piece anastomosis device for connecting a graft vessel to a target vessel includes a device body formed of a superelastic or pseudoelastic material. The device body has an insertion configuration and a tissue holding configuration in which the body has an inner flange and an outer flange. At least one of the inner and outer flanges is radially constrained in the insertion configuration for insertion into the target vessel. When the device body is released it self deforms to the tissue holding configuration. 
   In accordance with another aspect of the present invention, a tube deployed anastomosis system for connecting a graft vessel to a target vessel includes a deployment tube and an anastomosis device formed of a superelastic or pseudoelastic material. The device has an insertion configuration and a tissue holding configuration in which the device has an inner flange and an outer flange. The inner and outer flanges are radially constrained in the deployment tube in the insertion configuration for insertion into the target vessel and when released from the deployment tube, the device self deforms to the tissue holding configuration. 
   In accordance with another further aspect of the present invention, a method of deploying an anastomosis system for connecting a graft vessel to a target vessel includes the steps of: connecting a graft vessel to a one piece device formed of a superelastic or pseudoelastic material; poking a portion of the one piece device through the graft vessel; and deploying the one piece device by self deformation to a tissue holding configuration in which the device has an inner flange and an outer flange and traps the target vessel tissue between the inner flange and the outer flange. 

   
     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 constrained configuration prior to use; 
       FIG. 2  is a perspective view of the anastomosis device of  FIG. 1  in a deployed configuration; 
       FIG. 3  is a side cross sectional view of the anastomosis device of  FIG. 1  with a graft vessel everted around the device and the device constrained by a tube prior to deployment; 
       FIG. 4  a side cross sectional view of the system of  FIG. 3  being inserted into a target vessel: 
       FIG. 5  is a side cross sectional view of the system of  FIG. 3  after release of an inner flange; 
       FIG. 6  is a side cross sectional view of the system of  FIG. 3  with the inner flange imbedded in an inner wall of the target vessel wall; 
       FIG. 7  is a side cross sectional view of the system of  FIG. 3  after release of the outer flange showing the deployment tube being removed; 
       FIG. 8  is a perspective view of an alternative embodiment of an anastomosis device in a constrained configuration prior to use; 
       FIG. 9  is a perspective view of the anastomosis device of  FIG. 8  in a deployed configuration; 
       FIG. 10  is side cross sectional view of the anastomosis device of  FIG. 8  after deployment shown connecting a graft and a target vessel; 
       FIG. 11  is a perspective view of an alternative embodiment of an anastomosis device in a constrained configuration prior to use; 
       FIG. 12  is a perspective view of the anastomosis device of  FIG. 11  in a deployed configuration; 
       FIG. 13  is a side cross sectional view of the anastomosis device of  FIG. 11  after deployment shown connecting a graft vessel to a target vessel; 
       FIG. 14  is a perspective view of an alternative embodiment of an anastomosis device in a constrained configuration prior to use; 
       FIG. 15  is a perspective view of the anastomosis device of  FIG. 14  in a deployed configuration; 
       FIG. 16  is a perspective view of an alternative embodiment of an expandable body anastomosis device in a constrained configuration prior to use; and 
       FIG. 17  is a perspective view of the anastomosis device of  FIG. 16  in a deployed configuration. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention relates to a superelastic or pseudoelastic anastomosis device and method for connecting a graft vessel to a target vessel without the use of conventional sutures. The quick and easy deployment of the anastomosis system according to the present invention greatly increases the speed with which anastomosis can be performed over the known sutured anastomosis methods. The anastomosis devices according to the present invention are particularly designed for use in connecting graft vessels to target vessel in a variety of anastomosis procedures, including coronary artery bypass grafting. In such procedures, a large vessel anastomotic device is used to connect a graft vessel to large diameter target vessels such as the aorta or it&#39;s major side branches and a small vessel anastomotic device is used for connecting a graft vessel to a target vessel having a small diameter such as a coronary artery. 
   Suturing a graft vessel to a target vessel with conventional procedures is difficult and time consuming, particularly in minimally invasive procedures where space may be limited and in procedures in which it may be desired to perform an anastomosis without stoppage of blood flow through the target vessel. The superelastic or pseudoelastic anastomosis device and method of the present invention allow anastomosis to be performed efficiently and effectively in tight spaces. The anastomosis may also be performed with or without stoppage of blood flow in a target vessel and with or without the use of cardiopulmonary bypass. 
     FIG. 1  illustrates an anastomosis device  10  according to a first embodiment of the present invention in a constrained insertion configuration in which the anastomosis device would be inserted into a target blood vessel.  FIG. 2  illustrates the anastomosis device  10  of  FIG. 1  in an expanded deployed configuration which holds a graft vessel to a target vessel. The superelastic or the pseudoelastic anastomosis device in  FIG. 1  includes a substantially cylindrical body  14 , a plurality of legs  16  extending from a first side of the body, and a plurality of hooks  18  extended from a second side of the body. In the insertion configuration illustrated in  FIG. 1 , the body  14 , the legs  16 , and the hooks  18 , are substantially aligned in a constrained substantially cylindrical shape. The anastomosis device  10  may be held in the constrained substantially cylindrical shape by a deployment tool, such as a substantially cylindrical deployment tube. When the deployment tool is removed from the device  10 , the device returns to a preset expanded shape illustrated in  FIG. 2  due to the superelastic or pseudoelastic properties of the material. 
   The anastomosis device  10  is made of a pseudoelastic or superelastic alloy, such as Nitenol or other pseudoelastic or superelastic material. The superelastic or pseudoelastic device  10  will self deform through superelastic or pseudoelastic behavior from the constrained insertion configuration illustrated in  FIG. 1  to the expanded configuration illustrated in  FIG. 2  when the constraining device or deployment tool is removed. The anastomosis device  10  formed of the superelastic or pseudoelastic material is formed in the final shape illustrated in  FIG. 2  and is then isothermally deformed by constraining in a tube or other deployment tool in the substantially cylindrical shape illustrated in  FIG. 1 . The need for temperature control is avoided since the anastomosis device  10  reforms the deployed shape of  FIG. 2  spontaneously when removed from the constraining tube. This allows the accurate placement of the anastomosis device  10  spontaneous and nearly instantaneously upon deployment of the device. The need for a mechanical deployment device to mechanically deform the anastomosis device from the insertion configuration to the deployed configuration is also avoided. 
   The anastomosis devices of the present invention may be made of any known superelastic or pseudoelastic material. U.S. Pat. No. 5,597,378 provides a discussion of superelastic and pseudoelastic materials and is incorporated herein by reference in its entirety. 
   The deployed anastomosis device  10  as shown in  FIG. 2  includes an inner flange formed by outwardly extruding ends  22  of the J-shaped hooks  18 . The deployed device  10  also includes an outer flange formed by the legs  16  extending outward from the body  14 . 
   In use, a graft vessel  30 , shown in  FIG. 3 , is threaded through a center of the anastomosis device  10 . An end  34  of the graft vessel  30  is everted around the hooks  18  and the hook ends  22  penetrate into or through the everted end  34  of the graft vessel retaining the graft vessel in place on the anastomosis device  10 . 
   As illustrated in  FIG. 3 , the anastomosis device  10  with the everted graft vessel  30  is positioned within a deployment tube  38  for delivery of the anastomosis device and graft vessel to an opening  40  in a target vessel  32 . In the radially constrained insertion configuration, the leading edge or hook end of the anastomosis device may be substantially cylindrical or slightly conical for ease of insertion. 
   One embodiment of a method for deploying the anastomosis device  10  of the present invention will be described with reference to  FIGS. 3-6 . As shown in  FIG. 3 , the graft vessel  30  is prepared by everting an end  34  of the graft vessel around the hooks  18  of the anastomosis device  10 . The hook ends  22  penetrate the graft vessel tissue to maintain the everted configuration of the graft vessel. The hooks  18  and the legs  16  of the anastomosis device  10  are radially constrained by inserting the anastomosis device  10  and everted end of the graft vessel  30  into a deployment tool  38  in the shape of a tube. When positioned inside the deployment tool  38 , the anastomosis device  10  is in a generally cylindrical configuration for insertion into the target vessel  32 . 
   As shown in  FIG. 4 , the deployment tool  38  is used to insert the anastomosis device  10  and the graft vessel  30  into the target vessel  32  until the hook ends  22  have passed through the opening  40  and are positioned within an interior of the blood vessel. As shown in  FIGS. 3 and 4 , a retainer tube  36  is positioned around the graft vessel  30  and inside the deployment tool  38  for holding and extruding the anastomosis device  10 . A distal end  48  of the retainer tube  46  is positioned adjacent to a proximal end of the anastomosis device  10 . The distal end  48  of the retainer tube  46  may be attached to or abut the anastomosis device  10  to hold the anastomosis device in place inside the deployment tube  38  during the insertion step of  FIG. 4 . 
   As shown in  FIG. 5 , the anastomosis device  10  is held in place by the retainer tube  46  while the deployment tube  38  is withdrawn or retracted to release the radial constraining force from the hooks  18 . Upon removal of the deployment tube  38  from the hooks  18 , the hook ends  22  and hook base portion  24  spontaneously spring outward due to the superelasticity or pseudoelasticity of the material. 
   As shown in  FIG. 6 , after the release of the hooks  18  the anastomosis device  10  is withdrawn by the deployment tool  38  against the interior wall of the target vessel  32  causing the hook ends  22  to be compressed against or penetrate into the tissue of the interior wall of the target vessel. The deployment tube  38  is then completely withdrawn as shown in  FIG. 7  allowing the legs  16  to spontaneously spring outward to trap the wall of the target vessel  32  between the hooks  18  which form an inner flange and the legs  16  which form an outer flange for the deployed anastomosis device  10 . 
     FIGS. 8-10  illustrate an alternative embodiment of an anastomosis device  50  having a central body portion  54 . A first set of legs  56  extend from one end of the body  54  and a second set of pointed legs  58  extend from the second side of the body. In a constrained configuration illustrated in  FIG. 8 , the anastomosis device  50  is substantially tubular for insertion into a target vessel. In an expanded deployed configuration, illustrated in  FIGS. 9 and 10 , the anastomosis device  50  is substantially C-shaped in cross section with the legs  56  forming an outer flange and the pointed legs  58  forming an inner flange of the anastomosis device  50 . 
   The embodiment shown in  FIGS. 8-10  may be deployed in a manner similar to that of the anastomosis device described above with respect to  FIGS. 1-7 . As shown in  FIG. 10 , the graft vessel  62  is everted around the anastomosis device  50 . The anastomosis device  50  and graft vessel  62  are then inserted into an opening in the target vessel  64  in a constrained configuration. A constraining device such as the deployment tool  38  is then removed from the anastomosis device  50  and graft vessel  62  allowing the legs  56  and  58  to spontaneously spring outward by the superelastic or pseudoelastic properties of the material to form inner and outer flanges which trap the tissue of the target vessel  64  between the inner and outer flanges. 
   According to one preferred embodiment of the anastomosis device  50  the pointed legs  58  each include a pointed tissue penetrating end  66  and a rectangular stop member  68  for limiting the tissue penetration of the penetrating end. As shown in  FIG. 10 , the tissue penetrating end  66  of the pointed legs  58  penetrates into or through the graft vessel  62  to ensure the graft vessel is retained on the anastomosis device  50  during and after deployment. 
   In the deployed configuration illustrated in  FIG. 10 , the intima of the graft vessel  62  abuts an intima of the target vessel  64 . Thus, the expansion of the inner flange of the anastomosis device  50  forms a vein gasket to seal the graft and target vessels together. 
     FIGS. 11-13  illustrate an alternative embodiment of the superelastic or pseudoelastic anastomosis device  80  in a radially constrained configuration illustrated in  FIG. 11  and in an expanded tissue retaining configuration illustrated in  FIGS. 12 and 13 . The anastomosis device  80  includes a device body  84  formed of a plurality of substantially parallel spring elements  86  interconnecting to end members  88 . Extending from the end members  88  are a plurality of prongs  90  which in the expanded tissue supporting configuration illustrated in  FIG. 13 , form inner and outer flanges to trap the tissue of the target vessel  96 . As in the previous embodiments, a graft vessel  94  is inserted through a center of the anastomosis device body  84  and is everted around the prongs  90  of at least one end the device body. The prongs  90  penetrate into or through the graft vessel tissue to retain the graft vessel on the anastomosis device. 
   The anastomosis device  80  with the graft vessel  94  everted around the anastomosis device is inserted in a radially constrained configuration illustrated in  FIG. 11  into an opening in the target vessel  96 . When the radially constraining member such as a retainer tube is removed from the anastomosis device  80 , the anastomosis device spontaneously self deforms and returns to the configuration of  FIG. 12  due to the superelastic or pseudoelastic properties of the material. 
   As shown in  FIG. 13 , a first set of the prongs  90  forms a flange at the inner wall of the target vessel. The spring elements  86  allow the distance between the end members  88  to adjust somewhat to target vessels  96  having walls of different thicknesses. The spring elements  86  may also apply a compression force to the wall of the target vessel  96  once the anastomosis device  80  has been deployed to provide improved sealing. 
   In an alternate embodiment of the anastomosis device  80  of  FIGS. 11-13 , the graft vessel  94  may be attached to the anastomosis device without everting. This may be done by providing axial prongs, hooks, or barbs on the inner rail member  88  and hooking an end of the graft vessel on the hooks, prongs, or barbs without everting. 
   An alternative embodiment of an anastomosis device  100  includes an anastomosis device body  104 , legs  106 , and hooks  108 , as in the embodiment of  FIGS. 1 and 2 . The embodiment of  FIGS. 14 and 15  differs from the embodiment of  FIGS. 1 and 2  in that the legs  106  are folded outward and downward adjacent the body  104  in the radially constrained insertion configuration illustrated in  FIG. 14 . The legs  106  will spontaneously spring out to the flange forming configuration of  FIG. 15  when the radially constraining member such as a retainer tube is removed for deployment of the anastomosis device  100 . 
     FIGS. 16 and 17  illustrate an alternative embodiment of an anastomosis device  200  including a device body  204 , legs  206  and pointed legs  208 . The body  204  is formed of axially extending members  210  interconnected by struts  212  which allow the body to expand radially. Positioned between the body  204  and the pointed legs  208  are hinges  214 .  FIG. 16  illustrates the anastomosis device  200  in a radially constrained insertion configuration with a graft vessel  220  extending through an interior of the device body  204  and everted over the pointed legs  208 . The pointed legs  208  penetrate and hold the everted end of the graft vessel  220  on the device  200 . 
   For insertion, the anastomosis device  200  of  FIG. 16  is radially constrained in a deployment tube (not shown). As the deployment tube is withdrawn from the device  200 , the pointed legs  208  fold outward to form an inner flange, the device body  204  expands radially, and the legs  206  fold outward to form an outer flange. The radially expanding body  204  helps to stretch and support an opening in the target vessel. 
   Each of the anastomosis devices according to the present invention are preferably single piece devices which are formed in a substantially tubular shape. The anastomosis devices may be formed by laser cutting or punching from a tube or sheet of superelastic or pseudoelastic material. Alternatively, the devices may be formed from superelastic or pseudoelastic wire. The devices may be provided in varying sizes to join vessels of different sizes. The legs, hooks, prongs, and other device elements which have been discussed above with regard to the various embodiments may be used in varying numbers and arrangements depending on the particular application. 
   The invention has been described as an anastomosis device which is constrained for insertion in a radially constrained configuration with a deployment tool such as tube. However, the deployment tube may take other non-tubular shapes. 
   Although the invention has been primarily discussed with respect to coronary artery bypass surgery, the anastomosis devices of the present invention may by 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 devices according to the present invention may be used with venous grafts such as a harvested saphenous vein graft, arterial graft, such as a dissected mammal artery, or a synthetic prosthesis, as required. 
   Finally, the anastomosis devices according to the present invention have been illustrated as substantially cylindrical members. However, the devices can also be shaped into ovals, football shapes, or other shapes. Oval shapes can be particularly useful for accommodating small target vessels. 
   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.