The Annals of Thoracic Surgery, Vol 26, 323-335, Copyright © 1978 by The Society of Thoracic Surgeons
Durability of prosthetic heart valves
RE Clark, WM Swanson, JL Kardos, RW Hagen and RA Beauchamp
Accelerated fatigue testing of clinical heart valves has been performed at
cyclic rates of 33 to 35 cycles per second at 37 degrees C using water for
non-biological valves and glutaraldehyde solutions for tissue valves. Flows
were in the physiological range, and the pressure difference across each
valve during closure was 100 +/- 25 mm Hg. The results showed that major
fatigue occurred for the Starr-Edwards 2320 at 150 million cycles, the
Hufnagel trileaflet at 124 million cycles, the Bjork-Shiley Delrin disc at
140, the Bjork-Shiley Pyrolite disc at 973, the Beall 103 at 60, the
Hancock porcine at 62, the Carpentier- Edwards porcine at 34, and the
Ionescu-Shiley porcine pericardial prosthesis at 65 million cycles. The
Lillehei-Kaster was removed after 762 million cycles without discernible
wear. Three facts emerged from the testing data: (1) the component worn in
vitro wears in vivo; (2) the sites of in vitro fatigue on the component are
identical to clinical specimens; and (3) those valves that have high
durability in vitro have given similar performance in patients. The in
vitro and clinical data for tissue valves do not correlate. The possible
reasons for the discrepancy are discussed, and a note of caution is made
regarding realistic expectations of clinical durability of tissue valves.