Sound spectroanalytic diagnosis of malfunctioning prosthetic heart valve.

Sound spectroanalysis was carried out for diagnosis of malfunctioning prosthetic heart valves in 50 cases, which consisted of 31 mitral, 14 aortic, 4 mitral+aortic and 1 tricuspid valve replacements with the age ranging from 17 to 57 years. Types of prosthetic valves used in this series were Starr-Edwards silicon ball valves, metal ball valves, disc valves, Kay-Shiley valves, Smeloff-Cutter valves and a Björk-Shiley valve. The system used in this study consisted of a moving coil microphone, a preamplifier, a filter (160/24 db octave) and a sound spectrograph (Rion Co. S.G. (7). Contour sound spectrograms (SSG) were drawn and peak frequency, wave pattern and frequency-intensity curves were investigated as characteristics of implanted valvular function. Peak frequencies of valvular opening and closing sounds were recorded between 1800 to 5000 Hz and differed according to the types of prosthesis. In mitral+aortic valve replacements, valvular sounds of two prostheses were clearly separated and this finding was very useful for determining the prosthesis which fell into malfunction. Decrease in peak frequency of valvular sounds or abnormal wave patterns in contour SSG were observed in 9 cases (18%). Of 9 cases, 4 cases underwent re-replacement and 2 cases died of congestive heart failure. Operative or autopsy findings gave proof to the findings in sound spectroanalysis.