The Journal of Thoracic and Cardiovascular Surgery, Vol 78, 277-280, Copyright © 1979 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
In vitro durability of Hancock Model 242 porcine heart valve
RE Clark and WM Swanson
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.