Scintigraphic study of relation between left ventricular peak systolic pressure and end-systolic volume in patients with coronary artery disease and normal subjects.

Abstract

The relation between left ventricular peak systolic pressure and end-systolic volume was studied in 12 normal subjects and 12 patients with coronary artery disease. Peak systolic pressure was measured with a cuff sphygmomanometer and left ventricular volumes were determined by radionuclide ventriculography. Observations were made at rest, after 1 mg atropine, and during at least 3 increments of an infusion of phenylephrine which raised systolic blood pressure by 45 mm Hg while heart rate was held constant. The relation between peak systolic pressure and end-systolic volume at a constant heart rate was linear in all subjects. The slope of this line was steeper in normal subjects than in patients with coronary artery disease and correlated exponentially with the ejection fraction determined simultaneously. The end-systolic volume extrapolated to zero pressure (V0) was not significantly different between the 2 groups and correlated poorly with the ejection fraction. The simple ratio of peak systolic pressure to end-systolic volume, at rest and after drug interventions, was of similar sensitivity to the ejection fration in the detection of patients with left ventricular dysfunction caused by coronary artery disease. In normal subjects this ratio rose after atropine whereas the ejection fraction was unchanged. The apparent superiority of the ratio of peak systolic pressure to end-systolic volume over the ejection fraction in the detection of the positive inotropic response to increasing heart rate, coupled with the linearity of this relation over a wide range of systolic blood pressure, suggests that the systolic pressure-volume relation will be useful in the evaluation of cardiac drug effects in man. None of the indices derived from the systolic pressure volume relation, however, was more sensitive than the ejection fraction derived simultaneously in the detection of patients with left ventricular dysfunction resulting from coronary artery disease.