The intensity of the first heart sound in auricular fibrillation with mitral stenosis

Abstract

Simultaneous phonocardiographic and electrocardiographic tracings were taken on ten patients with auricular fibrillation and mitral stenosis and two patients with auricular fibrillation without mitral stenosis. In each instance the intensity of the first heart sound, as gauged by totalling the amplitude of the three largest vibrations of the first sound, was plotted against the duration of the preceding ventricular diastole. In six of the patients with mitral stenosis there was no definite relationship between the intensity of the first sound and the duration of the preceding ventricular diastole. In four patients with mitral stenosis there was a clear-cut and striking relationship: The intensity of the first sound varied, within limits, inversely as the duration of ventricular diastole. The first sounds were loud when diastole was short and became less intense as diastole lengthened, until a low intensity was reached and maintained. The type of variation of the first heart sound seen in these four patients differs from the variation that occurs in patients with auricular fibrillation without mitral stenosis. Possible explanations for the variation in the first heart sound intensity are discussed.