The present-day clinical evaluation of heart sounds is unsatisfactory. The physical factors concerned in the production of the normal sounds, particularly the first sound, are imperfectly understood. Furthermore, little is known of the mechanisms by which modifications of these sounds are accomplished. It seemed possible, therefore, that studies of patients showing variations of the first heart sound in successive beats might be of interest. This report deals principally with certain of the effects of auricular contraction on the first sound. In this connection it became necessary to consider also the effect of auricular contraction on the amplitude of the pulse wave because of a possible relation between the intensity of the first heart sound and the ventricular output per beat. Wiggers1 was able to furnish evidence to the effect that when the systolic discharge is increased the first sound is reduced in intensity.
INFLUENCE OF AURICULAR SYSTOLE ON THE FIRST