Unequal right and left ventricular ejection with ectopic beats

Abstract

Simultaneous right and left ventricular stroke volumes were measured with electromagnetic flow probes in open-chest, anesthetized dogs. Atrial ectopic beats with normal ventricular depolarization produced differences between right and left ventricular stroke output, although the right and left ventricular pressures were proportionately reduced to an equal extent. This imbalance in volume ejected was a result of the differences in diastolic level, related to peak systolic pressure, in the aorta compared with pulmonary artery. With ventricular ectopic beats, the stimulated ventricle failed to develop the same percentage of control pressure as did the contralateral ventricle. The difference between aortic and pulmonary flow was thus less marked with right ventricular ectopic beats, and exaggerated with left ventricular ectopic beats.