Abstract:
An anastomosis device ( 12 ) for advantageously bridging an artery and a vein. The anastomosis device includes a tubular graft ( 15 ) with first and second ends ( 47  and  48 ) and a longitudinal passageway extending longitudinally through the graft. The device further includes a first stent ( 10 ) disposed about the first end of the tubular graft and a second stent ( 10 ) disposed about the second end of the tubular graft. Each of the first and second stents has a plurality of hooks or barbs ( 11 ) pointed or releasable to the point toward the other end of the graft.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority of provisional application Ser. No. 60/469,708, filed May 12, 2003. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to the field of medical devices and, in particular, an anastomosis device and method of use therefore.  
       BACKGROUND OF THE INVENTION  
       [0003]     Current devices and techniques exist which allow for open surgical attachment of an artery to a vein for vascular access or replacement of diseased vessels. This includes sewing in a graft between the internal mammary artery and a coronary vessel, the radial artery and cephalic vein, the brachial artery and cephalic vein, the brachial artery and basilica vein, the ulnar artery and basilica vein, the brachial artery to branches of the antecubital vein, and a saphenous vein loop fistula. To our knowledge, no known non-invasive methods or devices exist that employ non-invasive catheter delivery of an anastomosis device for access between these areas. Prior to using synthetic grafts, the radiologist or nephrologist&#39;s first choice is a naturally occurring vessel to act as an AV fistula for vascular access. Only after determining their inadequacy is a synthetic vessel or exogenous vessel (e.g., animal derived small intestine submucosa (SIS)) used.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention is directed to an illustrative minimally invasive anastomosis device for advantageously bridging an artery and a vein. The device is loaded into a sheath or introducer system and pushed out over a wire to the desired location following the commonly used Seldinger technique, but with ultrasound guidance. This is done on both the artery and the vein. The system is preferably placed in the sagittal plane at an angle between 0 and 40 degrees, but preferably between 25 and 40 degrees. In the transverse plane, the system is placed between 0 and 45 degrees, but preferably between 30 and 45 degrees. Many of the connection segments between the graft and the vessel are thought to be unique and should be considered as such for the use of this device without catheters as in open surgical procedures.  
         [0005]     The anastomosis device illustratively comprises a tubular graft with first and second ends and a longitudinal passageway extending therethrough. The device further comprises a first stent disposed about the first end of the tubular graft and a second stent disposed about the second end of the tubular graft. In addition, the first stent has hooks or barbs pointed or releasable to point toward the second end of the graft. Similarly, the second stent has at least hooks or barbs pointed or releasable to point toward the first end of the graft. The first and second stents are preferably self-expanding stents such as Z-stents. Alternatively, the stents can be balloon-expandable stents. These stents are resilient stents and comprise preferably nitinol or stainless steel.  
         [0006]     The device further comprises an additional stent disposed at least approximately midway along the tubular graft. In addition, the device can comprise a plurality of these additional stents disposed along the graft.  
         [0007]     The graft of the present invention comprises a biocompatible material including, for example, an extracellular collagen matrix material, a small intestine submucosa material, a synthetic material or other polymer graft material. The anastomosis device can further comprise an other tubular graft of which the first and second stents are disposed coaxially between the tubular grafts. A slidable collar can also be disposed around an end of the graft to further stabilize the graft within a blood vessel. In addition, the device can further include a surface modification or a coating inhibiting intimal hyperplasia or an exterior coating of a substance that induces homeostasis and includes at least one of fibrin, a fibrin-like substance, and thrombin.  
         [0008]     Additionally, the device can include flares at one or more of the ends of the graft. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0009]      FIG. 1A  depicts a side view of a ZILVER® stent with barbs at the ends thereof that is utilized in the anastomosis device of the present invention;  
         [0010]      FIG. 1B  depicts an enlarged end view of the stent of  FIG. 1A  from inside an anastomosed vessel;  
         [0011]      FIG. 1C  depicts the anastomosis device of the present invention with the stent of  FIG. 1A  at each end of a tube of SIS material and connecting an artery and a vein;  
         [0012]      FIG. 2  depicts a pictorial view of a tube of SIS material that can form the inner and outer layers of the anastomosis device of the present invention;  
         [0013]      FIG. 3A  depicts one end of the anastomosis device of the present invention attached to a vessel;  
         [0014]      FIG. 3B  depicts the ZILVER stent of  FIG. 1A  sandwiched between two tubes of SIS material;  
         [0015]      FIG. 3C  depicts the stent-graft of  FIG. 3B  with the stent having one or more eyelets at the end thereof;  
         [0016]      FIG. 4A  depicts a side view of one end of the anastomosis device of the present invention being inserted into a vessel;  
         [0017]      FIG. 4B  depicts a side view of one end of the anastomosis device of  FIG. 4A  with the barbs of the stent folded over and engaging a vessel wall;  
         [0018]      FIG. 4C  depicts a top view of the opened anastomosis device of  FIG. 4B ;  
         [0019]      FIG. 5A  depicts a percutaneous stent grabber for holding the top stent closed with the strut tips at the center until released;  
         [0020]      FIG. 5B  depicts the stent grabber of  FIG. 5A  after depression;  
         [0021]      FIG. 6A  depicts the deployed anastomosis device of the present invention with the stent of  FIG. 1A  outside the SIS graft material tube;  
         [0022]      FIG. 6B  depicts the anastomosis device of the present invention with the stent barbs placed inside the device;  
         [0023]      FIG. 6C  depicts an end view of the deployed device of  FIG. 6A ;  
         [0024]      FIG. 6D  depicts an end view of the device of  FIG. 6B ;  
         [0025]      FIG. 7  depicts external barbs positioned on the outside of the anastomosis device of the present invention for maintaining the device against the blood vessel;  
         [0026]      FIG. 8A  depicts a spring loaded exterior stent for assisting placement of the graft material of the anastomosis device of the present invention;  
         [0027]      FIG. 8B  depicts the anastomosis device of  FIG. 8A  with the springs deployed;  
         [0028]      FIG. 9  depicts a collar around the external portion of the anastomosis device of the present invention pushed up against the outside wall of the vessel to secure the graft material against the vessel; and  
         [0029]      FIG. 10  depicts an anastomosis device of the present invention with an internal stent approximately midway between the graft to minimize kinking. 
     
    
     DETAILED DESCRIPTION  
       [0030]      FIG. 1A  depicts a side view of a laser cut, modified ZILVER® stent  10  with barbs  11  at each end. This stent is utilized in the anastomosis device  12  of the present invention. The ZILVER stent is available from COOK Inc., Bloomington, Ind. The barbs may be cold formed or heat set to fold over or bend down towards the main body of the stent.  
         [0031]      FIG. 1B  depicts an enlarged end view of the ZILVER stent  10  of  FIG. 1A  from inside a vessel.  
         [0032]      FIG. 1C  depicts anastomosis device  10  of the present invention attached to artery  13  and vein  14  with ZILVER stents  10  including barbs  11  of  FIG. 1A . The device includes first and second stents  10  at first and second ends  47  and  48  of a tube of small intestine submucosa (SIS) material  15 .  
         [0033]      FIG. 2  depicts a tube  15  of SIS material. This tube is formed from a flat sheet of SIS material sewn with suture material  16  longitudinally therealong to form a tube. Small intestine submucosa (SIS) or another extracellular collagen matrix material is commercially available from COOK Biotech, West Lafayette, Ind. In addition, a small portion of the SIS sheath extends beyond the seam (black lines).  
         [0034]     The graft, preferably made of small intestine submucosa, but not limited to commonly used synthetic graft materials, is the conduit that bridges the artery and the vein. At each end of the graft are stents  10  that are preferably made from nitinol and cold formed or heat set at greater than 400 F. The stents are anchored to the inside of the graft wall and provide a retention force when inserted into the blood vessel. The SIS material is preferably vacuum pressed around the stents, rehydrated, and then lyophilized before being placed in the introducer system to provide for optimal compliance. The SIS material must have enough layers, preferably three or more, in the graft to accommodate arterial blood pressure. The layers of SIS material may be adhered together with Fibrin glue. The SIS material may be sewn into a tubular form from a sheet as depicted in  FIG. 2 . Alternatively, the SIS material may be lyophilized, then slid over the stent or inside the stent. The SIS material may also be vacuum pressed inside the stent or without a stent present, then slid onto or inside the stent.  
         [0035]      FIG. 3A  depicts one end  17  of another embodiment of the anastomosis device  12  of the present invention attached to vessel  13 . End  17  of graft  15  is flared to help maintain the seal of the graft in blood vessel  13 . The ends of the graft are preferably flared to an outside diameter greater than the hole in the blood vessel. This should help to form a tight fit and minimize blood loss when the device is advanced into, then pulled back against the inside wall of the blood vessel.  
         [0036]      FIG. 3B  depicts stent  10  of  FIG. 1A  sandwiched between first and second tubes  15  of SIS material to form anastomosis device  12 . Tubular SIS material is flanged at one end and four barbs  11  of a sandwiched stent penetrate through SIS downwards towards the stent body. The other end is cut to reveal the cross section of the device. Both ends are flanged in the final product.  
         [0037]      FIG. 3C  depicts anastomosis device  12  of  FIG. 3B  with stent  10  having one or more eyelets  18 .  
         [0038]      FIG. 4A  depicts a preformed stent  19  at one end of device  12  of the present invention that will open like a flower with petals  21 - 24 , which will hold to vessel wall  20 . The stent may be formed at room temperature. The stent may be heat set to fold out at body temperature (e.g. nitinol). The stent may have strings attached at the petals through which follow around the outside of the graft and are pulled by hand outside the body to deploy the stent. The stent may use a percutaneous grabber to hold the tip of each petal or strut at the center of the graft, but can be unlocked by pushing at the proximal end. The stent may consist of Z-stent rings on top of each other. The top Z-stent is placed about half way into the lumen of the blood vessel to which the anastomosis will be made, then opens out like a blossoming flower against the side inside walls of the vessel. Strings pulled from outside the patient or a percutaneous grabber may be used to help deploy the stent.  
         [0039]      FIG. 4B  depicts a side view of end  17  of anastomosis device  12  of  FIG. 4A  with petals  21 - 24  of stent  19  folded over and engaging a vessel wall  20 .  
         [0040]      FIG. 4C  depicts an end view of an opened anastomosis device  12  of  FIG. 4B  with petals and barbs  21 - 24  folded over to engage a vessel wall.  
         [0041]      FIG. 5A  depicts a percutaneous stent grabber  25  holding a top stent closed with strut tips at center until released.  
         [0042]      FIG. 5B  depicts stent grabber  25  of  FIG. 5A  after depression.  
         [0043]      FIG. 6A  depicts a side view of barbs  26  attached to top stent  27  of anastomosis device  28  to facilitate anchoring into blood vessel  32 . The stent may have hooks attached by soldering or laser cut with the stent from cannula that bend down and are parallel to the graft or up to a 45 degree angle from the graft. The hooks may also be attached with a cannula over them and then soldered or laser welded. The hooks may be nitinol or stainless steel.  
         [0044]      FIG. 6B  depicts formed barbs  29  connected to stent  30  placed inside device  31 . Internal stent  30  is a Z-stent or a ZILVER stent.  
         [0045]      FIG. 6C  depicts an end view of the deployed device of  FIG. 6A .  
         [0046]      FIG. 6D  depicts an end view of the deployed device of  FIG. 6B .  
         [0047]      FIG. 7  depicts external metal barbs or struts  33  holding graft  34  in place against blood vessel  35 . Barbs  33  may be bonded to external stent  36  or attached with a plastic wrap. The device further comprises mechanical anchors to hold the graft against the outside wall of the blood vessel. The anchors pull the stent inside the blood vessel towards the graft and into the wall of the blood vessel and may be employed to further limit dislodgement of the graft. The mechanical anchors help to achieve a normal force to the outside of the roughly perpendicular blood vessel. The mechanical anchors may be achieved by external metal barbs from a stainless steel or nitinol stent wrapped around the outside graft that hold onto subcutaneous tissue and prevents pull out of the graft; a spring loaded stent placed around the outside of the graft that pushes outward in both directions; and a tight fitting collar placed around the outside of each end of the graft and snugged up against the perpendicular vessel to prevent migration of the inside stent.  
         [0048]      FIG. 8A  depicts a spring loaded exterior stent  37  prior to deployment to help push graft  38  against vessel wall  39  after deployment.  
         [0049]      FIG. 8B  depicts the anastomosis device of  FIG. 8A  with the springs deployed. Dashed marks denote internal stent  40 .  
         [0050]      FIG. 9  depicts collar  41  disposed around graft  42  tightly fitted and pushed up against outside vessel wall  43  to secure the graft in place.  
         [0051]      FIG. 10  depicts an anastomosis device  44  of the present invention with an internal stent  45  midway between graft  46  to minimize kinking. The anastomosis device of the present invention at the middle of the graft is a stent placed to help prevent kinking of the device. These grafts are anchored to the side of an artery, then often extend in a straight section  10  cm before a 180 degree loop. After the loop, another 10 cm straight segment of the graft runs parallel to the first leg and its end is connected to the side of a vein. This invention presents the novel idea of using a stent at the loop portion to prevent kinking. Polytetrafluoroethylene (PTFE), is a commonly used graft material and is not subject to kinking. Most other graft materials, including the preferred material in this invention, SIS, are subject to kinking. The stents of this embodiment are preferably nitinol and of the ZILVER stent geometry, but may be of the Z-stent geometry and also made from stainless steel. The stent may be surface modified and paclitaxel coated too, to limit long term intimal hyperplasia.  
         [0052]     The device of the present invention at each end of the graft may also include thrombin, or preferably fibrin or a fibrin-like substance that is applied to the exterior surface of the graft to assist with homeostasis. Fibrin is a naturally occurring substance that, when in contact with blood, causes a platelet plug to form and controls bleeding. Eyelets may also be placed at each bend of the stent or eyelets only at the connection points of the base stent and the top stent to help reduce stress at the bends. Adhesive bonding of the graft around the outside of the base stent may be used by folding the graft from the outside to the inside, gluing, then cutting off any excess.