Fatigue analysis of clinical bioprosthetic heart valves manufactured usingphotooxidized bovine pericardium

Background and aim of the study: Recent reports have given details of early clinical failures of bioprosthetic heart valves manufactured using dye-med iated photooxidized bovine pericardium. These failures were attributed to a brasion of the inflow surface of the leaflets against the cloth-covered inn er face of the outer valve frame. These failures had not been detected duri ng preclinical testing of such valves. The aim of this study was to determi ne if such failure modes could be replicated during fatigue testing of the photooxidized valves, and whether lining of the inflow face of the outer fr ame with pericardium could eliminate these failures. Methods: The fatigue properties of six lined and six unlined PhotoFix(R) al pha valves was determined using two Rowan Ash fatigue testers which were cy cled at 15 Hz for a maximum of 210 million cycles. The closing pressure wit hin in each chamber was 110 +/- 10 mmHg. Each valve was inspected every 40 million cycles for any signs of fatigue failure. All valves were tested to at least 210 million cycles, Results: In all six lined PhotoFix alpha valves there was no evidence that wear, tear or abrasion of the inflow aspect of the leaflets adjacent to the inflow face of the outer frame had occurred. Only one unlined valve showed any signs of damage adjacent to the outer frame, as evidenced by loss of l oose connective tissue, but this did not have the imprint of the cloth cove ring, which would have suggested actual wear. Effectively, after 200 millio n cycles, no fatigue failures of either the lined or the unlined PhotoFix c r valves had occurred. Moreover, the leaflet tears that had been observed c linically were not replicated in this study. Conclusion: Previous studies have shown a good qualitative, quantitative as sociation between fatigue failure in Rowan Ash accelerated fatigue testers, and clinical experience in glutaraldehyde-treated bovine pericardial valve s. The accelerated fatigue tester did not provide an adequate model for the prediction of clinical failure for the photooxidized pericardial valves.