A COMPARISON OF WEAR PATTERNS IN-VIVO AND IN-VITRO FOR BJORK-SHILEY DELRIN(R) HEART-VALVE DISCS

Materials and methods: Wear patterns for 33 explanted Bjork-Shiley Del rin(R) heart valve discs with known implant durations were compared an d contrasted with the wear patterns for 17 discs from accelerated wear tested (AWT) valves. Previous test reports and the current study prov ided data for the maximum depth of wear grooves for a total of 56 expl anted BSD valve discs with implant durations up to 22.4 years. Results : The discs of the explanted BSD valves showed, in general, more than one type of wear pattern. Eighteen out of 33 exhibited a full indent g roove on the inflow side and 24 of the 33 discs showed well indents on the outflow side. Only two discs showed evidence of non-concentric ed ge wear. All maintained their original surface polish outside of these areas. The data indicated that wear patterns in the case of the AWT d iscs were more pronounced, and in some discs were different in type fr om those of discs from explanted valves. For example, no cracks, fract ures or perforations of the Delrin discs were observed, or reported, f or the explanted valves, while in the 17 AWT valves there were three c racked discs, four disc fractures, three disc well perforations and th ree perforating edge indents. Conclusion: It appears that the Shiley A WT conditions were more severe and imposed greater loads than those pr oduced by patients with BSD valves implanted.