Cardiocirculatory studies in pulsus alternans of the systemic and pulmonary circulations.

Studies carried out in 21 patients have shown for the first time that alternation of the pulse pressure in man can occur independently in either the greater or the lesser circulation without appearing in the other. Even when bilateral alternation exists, this cyclic variation may disappear in one circulation while persisting in the other. Mechanisms responsible for pulsus alternans, in particular variations in stroke volume and vascular pressures, are considered, and no single explanation satisfies the facts revealed in this study.