Relation of intensity of cardiac sounds to age

Abstract

The absolute intensity of the first (S 1), third (S 3), and fourth (S 4) heart sounds (in mm Hg) and the relative intensity of S 4 compared with S 1 were measured in 146 normal persons, aged 8 to 91 years, using an infinite time-constant, calibrated pressure mechanocardiograph applied to the chest wall with a loading pressure of 400 mm Hg. The absolute intensity of S 1 (r = 0.28) and S 3 (r = 0.43) decreases with age, but the absolute intensity of S 4 does not increase with age (r = 0.06). Therefore, the relative intensity of S 4 compared with S 1 increases with age (r = 0.31). This finding may explain the increased frequency of S 4 in qualitative phonocardiograms in older persons.