Venous valve prostheses

A venous valve prosthesis comprising:

• a frame defining a longitudinal axis;
• a prosthetic valve coupled to the frame and disposed about an exterior of the frame, the prosthetic valve defining a valve conduit extending from an upstream opening to a downstream opening, an outer surface, an inner surface, and one or more slits extending from the outer surface to the inner surface, the prosthetic valve having a closed configuration wherein the one or more slits are closed and an open configuration wherein the one or more slits are open;
• and
• a nose-piece configured to couple the prosthetic valve to the frame, wherein the nose-piece defines a nose piece conduit in fluid communication with the valve conduit to enable fluid flow through the valve conduit when the one or more slits are in the closed configuration,
• wherein, with the venous valve prosthesis implanted in a vein, the prosthetic valve in the closed configuration is configured to block blood from flowing past the prosthetic valve between a wall of the vein and the outer surface of the prosthetic valve, and
• wherein, with the venous valve prosthesis implanted in the vein, the prosthetic valve is configured to move to the open configuration in response to antegrade blood flow through the vein to enable at least a portion of the antegrade blood flow to flow through the one or more slits, into the valve conduit, and past the prosthetic valve.