An implantable device for regulating blood flow through a blood vessel comprising an elongated support dimensioned and configured to be implanted in a blood vessel. The support includes a linking member linking axially spaced apart portions to one another. A valve membrane extends between the axially spaced apart support portions and includes first region folded over the first linking member and attached thereto and a second region adjacent the first region and unattached to the first linking member. The second region is movable between a first position to enable blood flow and a second position to inhibit blood flow.