One embodiment of the present invention provides an implantable valve prosthesis. The valve prosthesis includes a frame defining a lumen extending between a proximal frame end and a distal frame end along a longitudinal axis, and a first valve leaflet positioned within the lumen and having a distal edge attached to the frame and a proximal edge free of the frame. The first valve leaflet comprises a first and a second slit extend distally from the proximal edge and defining a free portion of the first valve leaflet between the first and second slits. The first valve leaflet is movable between a first position that allows fluid flow in a first, antegrade, direction and a second position that restricts flow in a second, retrograde direction.
