applied through the fabric and to the surfaces of both the main frame 22 and the second frame 42 in a continuous line extending between the points b of the respective legs and connecting these three points as in the previous step the adhesive material preferably does not penetrate any portion of the leaflet material lying within the main frame 22 and remains out of contact with blood passing through the valve the foregoing steps essentially complete the fabrication of the leaflet portions of the valve the remaining steps of fabrication are for the purpose of facilitating the suturing of the prosthesis within the blood vessel the excess fabric available on the outside of the frame can be rolled and consolidated along the junction line between the main and second frames to provide attachment points for stitches during surgical insertion the frame material is preferably polypropylene although other materials have also been employed with success polypropylene has excellent flex endurance and chemical stability but is difficult to attach by adhesive to other materials to facilitate adhesion the main and second frames 22 and 42 may be encapsulated with polyurethane by multiple dip coating the resulting encapsulated frame components have proved to demonstrate the desired characteristics of polypropylene without structural failures or breakdowns at the adhesive junctures valves employing the fabric described above have been tested in an accelerated fatigue tester to assess their long term endurance characteristics fatigue failures so induced have generally occurred in the region of greatest fabric flexure that is along.