Sound spectroanalyses were carried out for diagnosis of malfunctioning prosthetic heart valves in 50 patients. Types of prostheses used in this series were Starr-Edwards silicone ball, metal ball and disc valves, Kay-Shiley valves, Smeloff-Cutter valves and Björk-Shiley valve. The system used in this study consisted of a moving coil microphone, a preamplifier, filter (160/24 db/octave) and a sound spectrograph (Rion Co. S. G. 07). Contour sound spectrograms were drawn and peak frequency, wave pattern and frequency-intensity curves were investigated as characteristics of implanted valvular function. Peak frequency of valvular opening and closing sounds were recorded between 1, 800 to 5, 000Hz and differed according to the types of prostheses. In mitral+aortic valve replacements, valvular sounds of each prosthesis were clearly separated and this findings were very useful to determine the malfunctioning prostheses.
Decrease in peak frequency of valvular sounds or abnormal wave pattern in contour soundspectrograms was observed in 9 cases. Of the 9 cases, 4 cases underwent re-replacement and two cases died of congestive heart failure. Operative or autopsy findings of these 6 cases gave proof of the findings in sound spectroanalysis.
