Determination of Fraction of Left Ventricular Volume Ejected per Beat and of Ventricular End-Diastolic and Residual Volumes

A technic has been developed for determining the fraction of left ventricular end-diastolic volume that is ejected during each cardiac cycle. Radioiodinated Diodrast was rapidly injected into the left ventricle at the time of transseptal left heart catheterization and the fraction of isotope discharged from this chamber per beat was determined with a well-shielded scintillation probe placed on the chest wall over the left ventricle. Left ventricular end-diastolic volume was estimated from the stroke volume, determined by the dye-dilution method, and the fraction of isotope discharged per beat. Difficulties resulting from inadequate mixing of isotope in the left ventricle were minimized by this technic, since the probe detected indicator in the entire left ventricular cavity. The accuracy of this technic was first demonstrated in a circulatory model and then in open-chest dogs in which ventricular dimensions were continuously monitored by means of mercury-in-rubber gages. In 21 patients without detectable abnormalities of left ventricular function the fraction of left ventricular volume discharged averaged 37±8 per cent per beat and the end-diastolic volumes averaged 89±26 ml./M. 2 B.S.A. In 21 patients with heart failure or valvular regurgitation, or both, in whom left ventricular function was compromised, the fraction of left ventricular volume discharged into the aorta averaged 16±5 per cent per beat and the end-diastolic volumes averaged 209±75 ml./M. 2 B.S.A. This technic has been found to be sensitive to changes in left ventricular function and practical to apply routinely in the course of left heart catheterization.