Abstract:
An attachment member for securing a graft material to a vessel includes a conduit portion for attachment to the graft material. The attachment member has first and second anchor wings formed on opposite sides of an end of the conduit portion. The anchor wings are biased to extend substantially perpendicular to an axis of the conduit portion. The first and second anchor wings have arcuate shapes around substantially collinear axes for the anchor wings to define a flow path within a vessel on opposite sides of the conduit portion.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention pertains to an attachment member for attaching a graft material to a coronary vessel. 
     2. Description of the Prior Art 
     U.S. Pat. No. 5,944,019 issued Aug. 31, 1999 teaches an implant for defining a blood flow conduit directly from a chamber of the heart to a lumen of a coronary vessel. An embodiment disclosed in the aforementioned patent teaches an L-shaped implant in the form of a rigid conduit having one leg sized to be received within a lumen of a coronary artery and a second leg sized to pass through the myocardium and extend into the left ventricle of the heart. As disclosed in the above-referenced patent, the conduit is rigid and remains open for blood flow to pass through the conduit during both systole and diastole. The conduit penetrates into the left ventricle in order to prevent tissue growth and occlusions over an opening of the conduit. 
     U.S. Pat. No. 5,984,956 issued Nov. 16, 1999 teaches an implant with an enhanced fixation structure. The enhanced fixation structure includes a fabric surrounding at least a portion of the conduit to facilitate tissue growth on the exterior of the implant. U.S. Pat. No. 6,029,672 issued Feb. 29, 2000 teaches procedures and tools for placing a conduit. 
     Implants such as those shown in the aforementioned patents include a portion to be connected to a coronary vessel and a portion to be placed within the myocardium. Most of the implants disclosed in the above-mentioned patents are rigid structures. Being rigid, the implants are restricted in use. For example, an occluded site may not be positioned on the heart in close proximity to a heart chamber containing oxygenated blood. To access such a site with a rigid, titanium implant, a very long implant must be used. A long implant results in a long pathway in which blood will be in contact with the material of the implant. With non-biological materials, such as titanium, a long residence time of blood against such materials increases the probability of thrombus. The risk can be reduced with anti-thrombotic coatings. Moreover, a rigid implant can be difficult to place while achieving desired alignment of the implant with the vessel. A flexible implant will enhance placement of the implant. U.S. Pat. No. 5,944,019 shows a flexible implant in FIG. 22 of the &#39;019 patent by showing a cylindrical rigid member in the heart wall and a T-shaped rigid member in the coronary artery. The cylindrical and T-shaped rigid members are joined by flexible conduit. Unfortunately, flexible materials tend to be non-biostable and trombogenic and may collapse due to contraction of the heart during systole. PCT/US99/01012 shows a flexible transmyocardial conduit in the form of a cylindrical rigid member in the heart wall and a natural vessel (artery or vein segment) connecting the rigid member to an occluded artery. PCT/US99/00593 (International Publication No. WO99/38459) also shows a flexible conduit. PCT/US97/14801 (International Publication No. WO 98/08456) shows (in FIG. 8 c ) a transmyocardial stent with a covering of expanded polytetrafluoroethylene. 
     SUMMARY OF THE INVENTION 
     According to a preferred embodiment of the present invention, an attachment member is disclosed for securing a graft material to a vessel. The attachment member includes a conduit portion for attachment to said graft material. The attachment member has first and second anchor wings formed on opposite sides of an end of said conduit portion. The anchor wings are biased to extend substantially perpendicular to an axis of the conduit portion. The first and second anchor wings have arcuate shapes around substantially collinear axes for the anchor wings to define a flow path within a vessel on opposite sides of the conduit portion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side sectional view of an implant according to the present invention; 
     FIG. 2 is a side sectional view of an implant according to the present invention shown in place in a human heart wall with the implant establishing a direct blood flow path from a heart chamber to a coronary vessel; 
     FIG. 3 is a perspective view of the implant of FIG. 1; 
     FIG. 4 is a perspective view of a novel attachment member for attachment to a vessel in lieu of a conventional anastomosis; 
     FIG. 5 is the view of FIG. 4 shown attached to a vessel; 
     FIG. 6 is a side sectional view of a tube prior to formation of the attachment member of FIG. 4; 
     FIG. 7 is a side elevation view of the tube of FIG. 6 with phantom lines indicating a manner of formation of the attachment member of FIG. 4; 
     FIG. 8 is a side elevation view of the attachment member following the formation of FIG. 7; 
     FIG. 9 is a top plan view of the attachment member of FIG. 8; 
     FIG. 10 is the view of FIG. 8 with an optional sewing cuff; and 
     FIG. 11 is the view of FIG. 8 with an alternative embodiment of the attachment member showing an open cell mesh construction in the vessel. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With initial reference to FIGS. 1-3, an implant  10  is shown including a composite of a hollow, rigid cylindrical conduit  12  and a flexible conduit  14 . The conduit  12  may be formed of any suitable material. In a preferred embodiment conduit  12  is formed of low density polyethylene (“LDPE”). The material of the conduit  12  is preferably a rigid material in order to withstand contraction forces of the myocardium and hold open a path through the myocardium during both systole and diastole. 
     The conduit  12  is sized to extend through the myocardium MYO of the human heart to project into the interior of a heart chamber HC (preferably, the left ventricle) by a distance of about 5 mm. The conduit  12  extends from a first (or upper) end  16  to a second (or lower) end  18  (FIG.  1 ). 
     As discussed more fully in the afore-mentioned U.S. Pat. No. 5,984,956, the conduit  12  may be provided with tissue-growth inducing material  20  adjacent the upper end  16  to immobilize the conduit  12  within the myocardium MYO. The material  20  surrounds the exterior of the conduit  12  and may be a polyester woven sleeve or sintered metal to define pores into which tissue growth from the myocardium MYO may occur. 
     The flexible conduit  14  has first and second ends  30 ,  32  (FIG.  1 ). The first end  30  of the flexible conduit  14  is inserted through the interior of the conduit  12 . The first end  30  is wrapped around the lower end  18  of the conduit  12  such that the first end  30  of the flexible conduit  14  covers the exterior of the conduit  12  adjacent the lower end  18  of the conduit  12 . The first end  30  terminates spaced from the upper end  16  of the conduit  12  to expose the tissue-growth inducing material  20 . 
     The first end  30  of the flexible conduit  14  is secured to the rigid conduit  12  by heat bonding along all surfaces of opposing material of the rigid conduit  12  and the flexible conduit  14 . At elevated temperatures, the material of the rigid conduit  12  flows into the micro-pores of the material of the flexible conduit  14 . The rigid material has a lower melting point than the flexible material. 
     The rigid conduit  12  and attached flexible conduit  14  are placed in the myocardium MYO with the lower end  18  protruding into the left ventricle HC. The implant  10  thus defines an open blood flow path  60  having a first end  62  in blood flow communication with the left ventricle  82 . A second end  64  of the blood flow path  60  communicates directly with the lumen LU of the coronary vessel CA lying at an exterior of the heart wall MYO. To bypass an obstruction in a coronary artery, the end  32  of the flexible conduit  14  is attached to the artery in any suitable manner. For example, the end  32  may be anastomosed to the artery CA with sutures (not shown) in an end-to-side anastomosis as is done in conventional coronary artery bypass procedures. The end  32  is secured to the artery CA distal to the obstruction. 
     With the above-described embodiment, the implant  10  permits revascularization from the left ventricle HC to a coronary vessel such as a coronary artery CA (or a coronary vein in the event of a retrograde profusion procedure). The use of an elongated, flexible conduit  14  permits revascularization where the vessel CA is not necessarily in overlying relation to the chamber HC. For example, the implant  10  permits direct blood flow between the left ventricle HC and a vessel CA overlying the right ventricle (not shown). The use of a PTFE flexible conduit  14  results in blood flowing through path  60  being exposed only to PTFE which is a material already used as a synthetic vessel with proven blood and tissue compatibility thereby reducing risk of thrombosis and encouraging endotheliazation. As shown in FIG. 1, the flexible conduit  14  is wrapped around the conduit  12  so that no portion of the rigid conduit  12  is in contact with blood within the left ventricle HC. 
     An interior radius  15  (FIG. 1) is provided on a side of the rigid conduit  12  at end  16 . The radius  15  provides support for the flexible conduit  14  and pre-forms the flexible conduit at a preferred 90° bend (a bend of differing degree or no bend could be used). 
     A plurality of discrete rigid rings  17  are provided along the length of the flexible conduit not otherwise opposing the rigid conduit. Preferably, the rings are LDPE each having an interior surface heat bonded to an exterior surface of the flexible conduit  14 . At the radius  15 , LDPE rings  17   a  are integrally formed with the radius  15  with the cross-sectional planes of the rings  17   a  set at a fixed angle of separation (e.g., about 20 degrees) to support the flexible conduit throughout the 90 degree bend. Again, an interior surface of rings  17   a  is heat bonded to an exterior surface of the flexible conduit. The rings  17 ,  17   a  provide crush resistance. Between the rings  17 ,  17   a , the flexible conduit may flex inwardly and outwardly to better simulate the natural compliance of a natural blood vessel. By way of a further non-limiting example, the discrete rings  17  could be replaced with a continuous helix. 
     With the foregoing design, an implant of accepted implant material (i.e., LDPE and ePTFE) is formed with blood only exposed to the higher blood compatibility of ePTFE. The constantly open geometry permits a smaller internal diameter of the ePTFE previously attainable with conventional grafts. 
     FIGS. 4-11 illustrate an invention for attaching a conduit to a vessel in other than a traditional end-to-side anastomosis while permitting blood to flow from the conduit and in opposite directions with a vessel. The embodiment of the invention is illustrated with respect to use with the conduit  10  of FIG. 1 but may be used with any suitable conduit or graft material. 
     The invention utilizes an attachment member  50  having a generally T-shaped configuration. In a preferred embodiment, the member is formed from a tube  52  of LDPE (FIG. 6) which has interior and exterior lining  54  of ePTFE as described above. In the flexible conduit embodiment described above, the PTFE of the attachment member  50  is an extension of the flexible conduit  14 . 
     The free end  55  of the tube is cut with cuts  56  formed from the center of the free end and angling outwardly to (but not through) the sidewalls of the tube. So cut, two anchor wings  58  are formed on opposite sides of centrally positioned triangular portion  60 . The triangular portion  60  is aligned with a cylindrical conduit portion  62 . The material can be preformed for the anchor wings  58  to be biased to an outwardly flared position extending perpendicular to the longitudinal axis of the conduit portion  62 . The anchor wings  58  and triangular portion  60  are arcuate portions of a cylinder bending around an axis perpendicular to the longitudinal axis of the conduit portion  62 . 
     To attach the member, an incision IN is formed in the artery CA. The free end  55  is placed in the vessel CA and the wings  58  flare outwardly capturing the tube in the artery. A sewing cuff  70  (FIG. 10) may be provided on the tube  62  for stitching to the artery to prevent leakage. Also, a bio-glue may be provided at the incision IN to prevent leaks. 
     With the embodiment described, ePTFE only is exposed to blood flow. As an alternative, the wings  58  could be formed of open cell mesh material (e.g., nitinol, stainless steel, etc.) (FIG. 11) and left exposed for promoting tissue in-growth similar to that of open cell stents. 
     Having disclosed the present invention in a preferred embodiment, it will be appreciated that modifications and equivalents may occur to one of ordinary skill in the art having the benefits of the teachings of the present invention. It is intended that such modifications shall be included within the scope of the claims are appended hereto.