Ventricular performance measured during ejection: Studies in patients of the rate of change of ventricular power

An expression indicative of the rate of change of ventricular power was derived and applied to the evaluation of left ventricular performance of patients with angina. Patients were categorized as having normal or abnormal ventricular performance on the basis of the ejection fraction, mean velocity of circumferential fiber shortening, and left ventricular end-diastolic volume index. In those with normal performance, the ejection rate of change of power was (25 +/- 2) times 108 dyne cm. sec. (-2); in patients with abnormal performance it was (11 +/- 1) times 10(8) dyne cm. sec. (-2) (P less than 0.001). There was no overlap of values between categories of patients. Such a clear distinction between categories was not seen with any of the commonly utilized isovolumic indices of performance. The rate of change of ventricular power measured during ejection is free of assumptions, yet has a fluid dynamic as well as a physiological meaning. It serves in an intergrative fashion by incorporating terms previously shown to be of functional significance. Previous studies in dogs showed that it reflected alterations of the inotropic state, yet it was relatively independent of alterations of preload or afterload. It appears, therefore, that it is an indicator of ventricular performance that has desirable characteristics.