The first onflow and diastolic waves in the venous pulse

Simultaneous records of the contractions of the auricle and ventricle, intraventricular pressure, arterial pulse, and the pulse of the superior vena cava were made.

Previous investigators have not agreed as to the time relations of the 3d positive (Mackenzie's “v”) wave, some placing its appearance during ventricular systole, and others believing that it occurs in diastole. This confusion has arisen from the fact that Mackenzie's “v” wave in reality consists of two positive waves which are separate both in time and origin. (Bard described two such waves, but was not definite concerning the time relations.)

The first of these waves has been called the “onflow” wave, and the second, the “diastolic” wave. They are preceded, of course, by the auricular and systolic (“c”) waves.

In a series of some fifty dogs, the onflow wave has always appeared just at the end of auricular relaxation, and therefore, during the first half of ventricular systole. The wave is terminated at the very beginning of ventricular diastole. The origin of the wave cannot be ascribed to the passive auricle, nor to the ventricle, the base of which is still moving downward, and which would tend, therefore, to produce a negative, rather than a positive wave. The wave must simply represent the increased pressure resulting from the onflowing blood, which can now no longer enter the completely relaxed auricle, and must necessarily “back up” into the great veins. The instant ventricular relaxation commences, the base of the ventricle pushes up against the column of blood in the auricle and veins, and thus produces a still greater pressure—i.e., the diastolic rise. In all of the experiments this diastolic rise has occurred synchronous with the beginning of ventricular relaxation, before the closure of the semilunar valves.