SINGLE-LEG STRUT FRACTURES IN EXPLANTED BJORK-SHILEY VALVES

A retrospective follow-up study in the Netherlands on the risk of frac ture of Bjork-Shiley convexoconcave valves concluded that prophylactic replacement is advisable for certain groups of patients. We have exam ined valves explanted from twenty-two patients because they met epidem iological criteria for reoperation, with or without the presence of mo derate cardiac impairment, or because there were other cardiac complai nts not related to the valve. No information was available before expl antation to suggest a valve defect. All patients survived their operat ions. Of the twenty-four valves, seven (29% [95% CI 13-52]) had fractu re of one of the legs of the outlet strut (single-leg strut fracture [ SLF]). Two other valves had features that suggested fatigue defects. A s in the previous study, 70-degrees valves had the highest risk of SLF (five of sixteen, two aortic and three mitral). However, two of eight 60-degrees valves (both aortic) also had SLF. Current hazard calculat ions and explantation recommendations may need to be revised. Since se veral of the defective valves were welded by the same person, knowledg e of manufacturing details may help in estimation of fracture risk for an individual patient.