ACOUSTIC ASSESSMENT OF THE PHYSICAL INTEGRITY OF BJORK-SHILEY CONVEXO-CONCAVE HEART-VALVES

Background Several lines of evidence indicate a two-stage failure mode for the Bjork-Shiley convexo-concave (C/C) heart valve, in which one of the two outlet strut legs separates from the flange before the othe r, potentially providing an opportunity to identify and prophylactical ly replace failure-prone valves. Radiographic single leg separation (S LS) detection, although successful, is subjective and skill intensive, implying a need for both an objective preliminary screen and subseque nt corroboration of the radiographic findings. Methods and Results We developed a time-windowed, power density analysis of C/C valve closing sounds to detect the vibrational resonance that characterizes the pre sence of an intact outlet strut in clinically functioning, 29-mm-flang e size C/C valves. Recordings from more than 800 patients enrolled in radiographic SLS detection studies were analyzed, and the assessment a lgorithm was evaluated through a blinded test of 32 study valves for w hich the true status became known consequent to an autopsy or surgical explantation. Valves were objectively scored on a 0-to-1 scale, with 1 being assuredly intact and scores of <0.50 indicating a probable SLS . All except five valves (incorrectly designated probable SLS) were cl assified correctly, for a sensitivity of 1.00 (95% confidence interval , 0.79 to 1.00) and a specificity of 0.69 (0.41 to 0.89). Conclusions This level of accuracy is sufficient to serve as an effective prelimin ary screen, potentially allowing a threefold concentration of SLS prev alence among the C/C valves of patients undergoing radiographic assess ment. The value of acoustic classification in avoiding unnecessary ope rations prompted by false-positive radiographs is less certain.