[Sound spectrographic studies in the diagnosis of dysfunctions of mechanical heart valve prostheses (Björk-Shiley prostheses)].

A newly developed real-time sound spectroanalyzer was found to be capable of diagnosing malfunction of prosthetic heart valves (Björk-Shiley prostheses). Sound spectroanalysis was carried out 430 times on 257 patients with a prosthetic heart valve. The valvular click of prosthetic heart valves shows a typical sound spectroanalysis pattern in real time, with a high-frequency peak which diminishes beyond 25 kHz. Thrombosis of the prosthetic heart valve causes loss of the valvular click and reduction in the intensity of the high-frequency components, as shown in 4 patients. Thus the sound spectroanalysis appears to be a noninvasive technique which may allow early diagnosis of a thrombosed prosthetic heart valve. We believe this method to be superior to phonocardiography and echocardiography.