This investigation comprises a study of venous pulse, carotid, cardiographic, and heart sound records from twenty-one men with normal hearts. The heart sounds were recorded by the method of Einthoven. When correction is made for transmission, the first heart sound begins, on an average, 0.131 of a second before the c-wave of the venous pulse, and has an average duration of 0.128 of a second. The second heart sound begins a few hundredths of a second before the v-wave and has a duration of 0.091 of a second. The third heart sound occurs shortly before or is coincident with the beginning of the h-wave. It has an average duration of about 0.03 of a second. Considerable variation from the average positions are noted in individual cases. This is especially true in the relation between the second heart sound and the v-wave.
Measurements of the venous pulse and heart sound intervals show that the a-c, c-v, and v-h venous pulse intervals, the first to second and the second to third heart sound intervals, and systole tend to remain fairly constant in length when cardiac cycles of different length are considered. The v-a, h-a, and x-a venous pulse intervals, the third to first heart sound interval, and diastole tend to vary in length with variations in total length of the cycle.
Records of the venous pulse and heart sound obtained from dogs show a similar relation to that found in man. The main difference observed was an earlier occurrence of the first heart sound before the c-wave of the venous pulse.
Hemodynamic Correlates of the Third Heart Sound and Systolic Time Intervals
