[End-systolic pressure-volume relationships obtained by conductance catheter and transient inferior vena caval occlusion: their clinical usefulness]

Abstract

Whether beneficial hemodynamic effects of cardiovascular drugs are due to changes in the inotropic or loading conditions has been difficult to determine in clinical settings. In this study, the end-systolic pressure-volume relationship, known as a load-independent measurement of cardiac contractility, was obtained by a volumetric conductance catheter and transient inferior vena caval occlusion. We applied this technique to determine the major mode of hemodynamic action of a new inotropic vasodilator, OPC-8490, in comparison to that of dobutamine. In 7 patients with anterior myocardial infarction, an 8F conductance catheter with pressure micromanometer was inserted into the left ventricle. Absolute volume calibration was accomplished by injection of hypertonic saline into the pulmonary artery. Left ventricular pressures and volumes were simultaneously and continuously measured during transient inferior vena caval occlusion using a balloon catheter. Left ventricular end-systolic pressure-volume relationships were determined during the initial 8-sec of balloon occlusion, before baroreceptor-mediated cardiac stimulation was initiated. OPC-8490 decreased both the left ventricular systolic pressure and end-systolic volume without changing the heart rate. Dobutamine increased the systolic pressure and heart rate but decreased the end-systolic volume. The reduction in the end-systolic volume with dobutamine, was caused by an increase in the slope of the end-systolic pressure-volume relationship, while with OPC-8490, it resulted from a decrease in the end-systolic pressure without an appreciable change in the slope of the end-systolic pressure-volume relationship.(ABSTRACT TRUNCATED AT 250 WORDS)