Abstract
With the development of surgical techniques to replace diseased aortic valves by Bahnson et al.1 and independently by Hufnagel and Conrad,2 a quest began for the ideal, permanent substitute for the aortic valve. Various mechanical valves have been developed, but all have characteristics that produce less than optimal performance, and they necessitate permanent anticoagulant treatment. Tissue valves (such as porcine heterografts) do not require that the patient receive anticoagulants, but these valves have limited durability; even fully viable homograft transplants (recovered from a living donor at the time of cardiac transplantation) require the administration of immunosuppressive agents to prevent progressive . . .