An implantable valve prosthesis is provided. The valve prosthesis includes a frame structure having first and second independent frame elements. A graft member is attached to both the first and second frame elements and includes a closure member, such as a valve leaflet. The closure member is movable between a first position that allows fluid flow through the prosthesis in a first, antegrade direction and a second position that restricts flow through the prosthesis in a second, retrograde direction.