Abstract
The closing sound of the SJM cardiac valve prosthesis was analysed both in vitro and in vivo, using the technique of the fast Fourier transform. In vitro, the power-spectrum curve of the closing sound contains a peak at 0.6 KHz, and the power gradually decline to 7 KHz. It also has small peaks at about 1.2, 1.8, 2.4 and 3.6 KHz. In vivo, the spectra of the normally functioning SJM cardiac valve prostheses show the same curve as the curve in vitro. In the case of the cardiac valve prosthesis attached with fibrin glue on the housing, the power declined to between 0.6 and 3 KHz. The same curve was shown clinically in two cases of the thrombosed SJM cardiac valve prosthesis and thromboembolism. The decline of the power between 0.6 and 3 KHz suggests the throm-bus or pannus formation of the SJM cardiac valve prosthesis.
