Circulation, Vol 63, 200-203, Copyright © 1981 by American Heart Association
PD Stein, HN Sabbah, JB Lakier, DJ Magilligan Jr and D Goldstein
The frequency spectrum of the first heart sound (S1) was measured
noninvasively in 54 patients with porcine bioprosthetic valves inserted in
the mitral position. Phonocardiograms were recorded on magnetic tape on
line with a signal processor with which the frequency spectrum and peak
frequency of S1 were determined. In 19 patients with normal natural mitral
valves, the apparent peak frequency within the range of measured
frequencies of S1 was 46 +/- 2 Hz (mean +/- SEM). In 11 patients with
porcine bioprosthetic valves implanted in the mitral position for less than
or equal to 11/2 years, the apparent peak frequency of S1 was 43 +/- 3 Hz,
which was not significantly different from S1 in patients with normal
mitral valves. However, in 33 patients with porcine bioprosthetic valves in
place 5-7 years, the apparent peak frequency of S1 was higher, 67 +/- 2 Hz
(p < 0.001). In patients in whom the porcine bioprosthetic valve was
implanted 5 years or longer, the frequency spectrum of S1 showed a greater
proportion of sound energy at frequencies between 50-200 Hz compared with
patients in whom the prosthetic valve was implanted 11/2 years or less.
changes of the frequency of S1 in these patients may be a manifestation of
stiffening of the valve as a result of early degenerative changes.
ARTICLES
Frequency of the first heart sound in the assessment of stiffening of mitral bioprosthetic valves