Twenty patients were studied with simultaneous left ventricular cavity echocardiograms and apex cardiograms during the first two weeks after correction of severe aortic regurgitation. Endocardial echoes and apex cardiograms were digitized, so that left ventricular dimensions, their rates of change, and echo dimension-apex cardiogram relations could be studied. After aortic valve replacement, there was an early reduction in end-diastolic dimension, within 2 days, from 7-0 +/- 0-8 cm to 5-7 +/- 1-0 cm (P less than 0-001), while peak normalized shortening rate (peak Vcf) dropped from 1-9 +/- 0-6 to 1-4 +/- 0-6 S-1 (P less than 0-01), and remained unchanged for the remainder of the study. Immediately after operation, striking abnormalities of isovolumic contraction and, to a lesser extent, of early relaxation, could be seen, which regressed over 4 to 7 days, except in 2 patients who developed a low output state. These changes in left ventricular dimension, Vcf, and isovolumic contraction could not have been described by an single "measure" of left ventricular function.