Use of ventriculography in assessing performance and oxygen consumption of the left ventricle: Response to altered afterload

Using ventriculography, we assessed the relationship between performance, blood flow, and oxygen consumption of the left ventricle in seven anesthetized dogs. Ventricular loading was varied between increased and decreased afterload by intra‐aortic infusion of angiotensin and acetylcholine. Intact ventricular performance was measured by computer‐based analysis of biplane left ventriculograms. Myocardial blood and flow distribution was determined by radioactive microspheres, and oxygen consumption was measured by coronary arteriovenous oxygen difference times blood flow. When left ventricular systolic pressure rose, tension‐time index, stress‐time index, stroke work, and minute work derived from the ventriculogram increased significantly; end diastolic volume increased; and ejection fraction decreased. Inverse responses occurred to a smaller degree when left ventricular pressure was reduced. With increased pressure, myocardial blood flow and oxygen consumption changed proportionately to minute work. Correlation coefficients between oxygen consumption and stroke work (0.782), oxygen consumption and minute work (0.769), oxygen consumption and tension‐time index (0.792), and between oxygen consumption and stress‐time index (0.740) all indicate that performance measures obtained from ventriculograms can be used to estimate changes in oxygen consumption during acute afterload changes. These measurements can be applied to data obtained from clinical catheterization studies in man and suggest that changes in myocardial performance and oxygen consumption can be estimated from ventriculographic data.