Prosthetic heart valves
A prosthetic heart valve (e.g., a prosthetic aortic valve) is designed to be somewhat circumferentially collapsible and then re-expandable. The collapsed condition may be used for less invasive delivery of the valve into a patient. When the valve reaches the implant site in the patient, it re-expands to normal operating size, and also to engage surrounding tissue of the patient. The valve includes a stent portion and a ring portion that is substantially concentric with the stent portion but downstream from the stent portion in the direction of blood flow through the implanted valve. When the valve is implanted, the stent portion engages the patient's tissue at or near the native valve annulus, while the ring portion engages tissue downstream from the native valve site (e.g., the aorta).
1. A prosthetic heart valve, comprising:
a collapsible and expandable stent component formed of a shape-memory alloy, the stent component including a generally tubular first stent portion and a generally tubular second stent portion, the first stent portion having an expanded diameter that is greater than an expanded diameter of the second stent portion;
a plurality of valve leaflets coupled directly to the second stent portion but not directly to the first stent portion, the plurality of valve leaflets configured to allow blood to flow in a downstream direction, but to restrict blood from flowing in an upstream direction;
a first fabric at least partially covering an exterior surface of the first stent portion; and
a plurality of barbs coupled to the first stent portion and extending in the upstream direction, the plurality of barbs configured to pierce tissue to prevent migration of the prosthetic heart valve in the upstream direction,
wherein the first stent portion is coupled to the second stent portion to form an independent stent-in-stent design.
2. The prosthetic heart valve of claim 1 , wherein the first stent portion is coupled to the second stent portion via a plurality of individual attachment links that are positioned at spaced locations around a circumference of the stent component.
3. The prosthetic heart valve of claim 1 , wherein the first stent portion includes at least one circumferential row of closed-perimeter cells.
4. The prosthetic heart valve of claim 3 , wherein the closed-perimeter cells are diamond-shaped.
5. The prosthetic heart valve of claim 4 , wherein at least a portion of the plurality of barbs is uncovered by the first fabric to allow the plurality of barbs to embed into tissue.
6. The prosthetic heart valve of claim 5 , wherein in the expanded condition of the prosthetic heart valve, an inflow end of stent component flares radially outwardly from a central longitudinal axis of the prosthetic heart valve.
7. The prosthetic heart valve of claim 1 , wherein the first fabric is a polyester.
8. The prosthetic heart valve of claim 1 , wherein the shape-memory alloy is nitinol.
9. The prosthetic heart valve of claim 1 , wherein the second stent portion is at least partially covered by a second fabric.
10. The prosthetic heart valve of claim 9 , wherein the second fabric is formed of a polyester.
11. The prosthetic heart valve of claim 10 , wherein the second fabric covers an interior and an exterior of the second stent portion.
12. The prosthetic heart valve of claim 1 , wherein the first stent portion is spaced from the second stent portion such that the plurality of valve leaflets cannot contact the first stent portion during operation of the prosthetic heart valve.
13. The prosthetic heart valve of claim 1 , wherein the first stent portion is substantially concentric with the second stent portion.
14. The prosthetic heart valve of claim 1 , wherein the second stent portion includes three commissure regions, the plurality of valve leaflets being coupled directly to the three commissure regions.
15. The prosthetic heart valve of claim 14 , wherein, during operation of the prosthetic heart valve, the three commissures regions are spaced radially inwardly from the first stent portion so that a gap exists between an outer surface of the three commissure regions and an inner surface of the first stent portion.
16. The prosthetic heart valve of claim 14 , wherein the independent stent-in-stent design is configured to allow the first stent portion to flex independently of the three commissure regions.
17. The prosthetic heart valve of claim 16 , wherein the first stent portion is configured to anchor the prosthetic heart valve within a heart so that the plurality of valve leaflets are positioned within a native valve annulus of the heart.
18. The prosthetic heart valve of claim 17 , wherein the prosthetic heart valve is devoid of structures that span directly between the first stent portion and the second stent portion in a manner that constrains independence of motion between the first stent portion and the second stent portion.