Nearly 100,000 heart valve surgeries are performed in the United States each year, the majority to either repair or replace the mitral or aortic valves. Cardiac valves are replaced with mechanical (synthetic) valves or bioprosthetic (tissue) valves. A major advantage of bioprosthetic valves is that no long-term oral anticoagulation is required, but their drawback is their relatively limited durability. In contrast, mechanical valves offer long-term durability but require lifelong anticoagulation therapy. The choice of valve depends on the patient's age, life expectancy, preoperative conditions, cardiac anatomy, and ability to tolerate anticoagulation therapy. Ideally, the choice of a mechanical or bioprosthetic heart valve prosthesis is made together by the patient, cardiologist, and surgeon. The existence of a safe and effective mechanical valve that reduces anticoagulant needs would expand the treatment options for patients requiring valve-replacement surgery.