Pyrolytic carbon prosthetic heart valve occluder wear: <i>In Vivo</i> vs. <i>In Vitro</i> results for the Bjork‐Shiley prosthesis

Abstract

Abstract Pyrolytic carbon (Pyrolite ® carbon) valve occluders from 18 clinical Bjork‐Shiley prostheses recovered at necropsy were examined for wear. In situ durations extended to 12 years. Results were combined with data from 17 recovered valves in the literature to produce a data base of 35 Bjork‐Shiley valves. Cumulative in vivo results were compared to in vitro , Shiley type, accelerated life‐cycle tester results for Bjork‐Shiley prostheses. Comparative results were then interpreted using Hertzian impact wear theory. The theory provided a rational basis for the difference in wear observed in terms of applied dynamic load levels. Furthermore, Hertzian impact wear theory yielded an estimate of in vivo total dynamic loads on the order of 1 to 22 Newtons (0.2–5 lbf.) acting on the occluder of the heart valve prosthesis.