Frequency spectra of the first heart sound and of the aortic component of the second heart sound in patients with degenerated porcine bioprosthetic valves.

To determine the usefulness of the frequency of heart sounds in the assessment of porcine bioprosthetic valve degeneration, frequency spectra of phonocardiograms of the first heart sound and the aortic component of the second sound were analyzed in 31 patients with degenerated porcine bioprosthetic valves. Comparisons were made with 35 control patients whose valves were inserted 1 month or less. Among 23 patients with degenerated porcine bioprosthetic valves in the mitral position, the dominant frequency of the first heart sound was 95 +/- 11 Hz, which exceeded the first sound in 18 controls (51 +/- 3 Hz) (p less than 0.01). The degenerated mitral porcine bioprosthetic valves of 14 patients showed calcification or fibrosis and the first heart sound in these patients was 115 +/- 16 Hz, which exceeded that of control subjects (p less than 0.001). The degenerated mitral porcine bioprosthetic valves of 9 patients showed torn leaflets only, and the first heart sound in these patients was 64 +/- 9 Hz, which did not differ from that of control subjects. In the aortic position, 8 valves were degenerated and the aortic component of the second sound was 109 +/- 12 Hz, which was higher than that in 17 control subjects (63 +/- 4 Hz) (p less than 0.001). Only 2 of these degenerated valves showed tears unaccompanied by calcific deposits or fibrosis, and the frequencies were comparable to that of control subjects. These observations indicate that the frequency of heart sounds in patients with degenerated porcine bioprosthetic valves becomes abnormally elevated when degeneration is accompanied by calcification or fibrosis, which causes the cusps to stiffen.