A heart valve prostheses includes an annular member implantable within a biological annulus, a collar extending upwardly from the annular member, and a sewing ring extending from the annular member. A spring structure couples the collar to the annular member and biases the collar to align with the annular...http://www.google.de/patents/US7967857?utm_source=gb-gplus-sharePatent US7967857 - Gasket with spring collar for prosthetic heart valves and methods for making and using them
