Determination of Stroke Volume from Left Ventricular Isovolumetric Contraction and Ejection Times

Examination was made of the relationship of left ventricular isovolumetric contraction and ejection times to stroke volume. These studies were performed in humans at cardiac catheterization using the dye dilution technique and in open-chest dogs with electromagnetic flowmeters. The cardiac phases were measured from intracardiac catheters in humans and were calculated from the flow curves in dogs. While the isovolumetric and ejection periods independently gave correlations of only marginal significance with stroke volume, the ratio of these intervals was highly significant: r=0.92 for humans and r=0.86 for dogs.