MATERIALS DEGENERATION CAUSING LATE FAILURE OF MECHANICAL HEART VALVE PROSTHESES: PROBLEMS AND PROMISE.

Materials degradation with resultant clinically significant valvular dysfunction has been an important late complication of cardiac valvular replacement with mechanical prostheses. Major mechanisms of failure are related to either lipid absorption by silicone elastomers or abrasive wear of polymers. In a review of the necropsies of 99 patients dying late after cardiac valvular replacement, two cases of fatal valve deterioration were encountered, one involving each of the above failure modes. By scanning electron microscopy and analytical surface profilometry, seven contemporary heart valve prostheses recovered frm this series were examined. All of them had no clinical or pathological evidence of degeneration/dysfunction, contained pyrolytic carbon components and had been in-situ for 30 months or longer. Results of this analysis suggest that progressive deterioration by abrasive wear of pyrolytic carbon heart valves will not be a significant problem.