When the total artificial heart was implanted in the animal, only left-side inflow valve has been often damaged or destroyed in the long term survivors, which suggested that the left inflow valve was exposed to more stress of high pressure than the outflow valve. Specially designed In Vitro experiments and retrospective evaluation of longterm clinical implantation with the various types of artificial valve suggests that the aortic valve requires lower pressure tolerance than a valve in the mitral position. The tissue valves may be more suitable in the aortic position than in the mitral position and protect the myocardial functions for a long term. The mechanical valve with higher pressure tolerance may present satisfactory function as the inflow valve with a sick heart.
