Endovascular prostheses are disclosed that are configured to repair a native venous valve having improper or non-existent valve leaflet coaptation caused by vessel weakness and/or distention. The prostheses are configured to be implanted in the venous system immediately downstream of the malfunctioning valve and act as repair devices to restore proper function to the venous valve by reconfiguring and supporting the valve leaflets and thereby improving their coaptation.
