Implantable valve prosthesis for treating venous valve insufficiency
A valve prosthesis for percutaneous placement within a vein is disclosed that includes a valve scaffold and a backflow barrier. The valve scaffold is of a shape memory or resilient material and the backflow barrier is a flap of flexible material attached to the valve scaffold. The valve prosthesis is operable to alternate between open and closed configurations in response to changes in retrograde blood flow pressure. In the open configuration, the valve scaffold has a frustoconical coil shape of consecutive windings with open spaces therebetween and the backflow barrier allows antegrade blood flow through the open spaces. In the closed configuration, the consecutive windings of the valve scaffold are collapsed such that the valve scaffold has a substantially flat profile and the backflow barrier covers the opens spaces of the flattened valve scaffold to prevent retrograde blood flow from leaking there through.
1. A valve prosthesis comprising:
a valve scaffold having a coil shape of consecutive windings with open spaces therebetween, wherein the valve scaffold is formed from a first material selected from one of a shape memory material and a resilient material; and
a backflow barrier that is a flap of a second material attached along a first edge to the valve scaffold and having an opposing second edge free of the valve scaffold, the second material being different from the first material, wherein the valve prosthesis is operable to alternate between an open configuration wherein the consecutive windings of the valve scaffold form a frustoconical coil shape and the backflow barrier allows blood flow through the open spaces between consecutive windings of the valve scaffold, and a closed configuration wherein the consecutive windings of the valve scaffold are collapsed such that the valve prosthesis has a substantially flat profile and the backflow barrier covers the open spaces of the collapsed valve scaffold to prevent blood flow through the valve prosthesis.
2. The valve prosthesis of claim 1 , wherein the valve scaffold is formed from a wire-like structure that is preset in the frustoconical coil shape.
3. The valve prosthesis of claim 1 , wherein an upstream free second edge of the flap overlaps with a downstream attached first edge of the flap when the valve prosthesis is in the closed configuration.
4. The valve prosthesis of claim 1 , wherein the valve prosthesis collapses to the closed configuration in response to retrograde blood flow pressure of a predetermined pressure threshold value that is sufficient to compress the valve scaffold into the substantially flat profile and the valve prosthesis returns to the open configuration when the retrograde blood flow pressure is insufficient to maintain the valve scaffold in the substantially flat profile such that the valve scaffold returns to the frustoconical coil shape.
5. The valve prosthesis of claim 4 , wherein the predetermined pressure threshold value is approximately 50 mmHg.
6. The valve prosthesis of claim 1 , further comprising:
an annular self-expanding anchor attached to the valve scaffold, wherein the anchor is operable to expand in radial apposition to a wall of a vessel.
7. The valve prosthesis of claim 6 , further comprising:
barbs attached to an outer surface of the anchor, wherein the barbs are operable to lodge within the vessel wall of the vein.
8. The valve prosthesis of claim 1 , wherein the backflow barrier is a continuous flap and the second material is selected from the group consisting of expanded polytetrafluoroethylene (ePTFE), polytetrafluoroethylene (PTFE), Dacron, silicone, and polyester, and wherein the backflow barrier has a thickness sufficient to allow the flap to be moveable by blood flow.
9. The valve prosthesis of claim 1 , wherein the valve scaffold has a thickness between 0.002 inches and 0.015 inches.
10. The valve prosthesis of claim 1 , wherein the valve prosthesis in the closed configuration is operable to remain closed in response to retrograde blood flow pressures of at least 150 mmHg.
11. The valve prosthesis of claim 1 , wherein the valve scaffold extends within a hem of the backflow barrier.
12. The valve prosthesis of claim 1 , wherein the valve prosthesis includes a series of consecutive windings that extend from a nose winding to a base winding and the backflow barrier extends from the nose winding to the base winding for the entire coiled length of the valve scaffold.