In vitro durability of Hancock Model 242 porcine heart valve

Two Hancock Model 242 prostheses, tissue anulus diameter 21 mm., were tested in a closed, low-volume, accelerated fatigue tester. The fluid media was sterils fresh-frozen plasma. The normal human aortic root was simulated. The cyclic rate was 20 Hz at 37 degrees C. The prostheses developed severe fatigue at 77 million cycles. Fraying of the free edges was found after 2 million cycles. Small tears near the commissures and then holes between collagen bundles at the base of the leaflets appeared at 7 million cycles. At 71 million cycles the leaflets began to tear and complete prolapse, with gross valvular insufficiency occurring at 77 million cycles. The accelerated wear of Hancock procine prosthesis is frequency dependent and independent of media and the flow geometry of the testing device.