To assess the immediate effects of aortic valve replacement (AVR) for valvular aortic stenosis (AS) on left ventricular (LV) systolic and diastolic function and global hemodynamics, 17 patients with AS underwent transesophageal echocardiography combined with high-fidelity LV pressure recording and thermodilution cardiac output measurements before cardiopulmonary bypass and 0.5, 6, 12, and 20 hours after AVR. Compared with results before bypass, LV systolic function had already changed 30 minutes after AVR, and remained constant thereafter: peak LV systolic wall stress decreased (from 210 +/- 60 to 130 +/- 40 g.cm-2), peak rate of dimension shortening increased (from 7.3 +/- 2.2 to 9.7 +/- 2.1 cm.s-1), both p < 0.01. Peak segmental external power thus remained constant (16.6 +/- 6.7 vs 17.7 +/- 7.6 mW.cm-3); p = NS. Changes in LV diastolic function and global hemodynamics were delayed. The peak rate of ventricular pressure decrease, normalized to developed end-systolic pressure, increased (from 15 +/- 3.2 to 19 +/- 5.2 s-1) by 6 hours. The minimal ventricular pressure of early diastole decreased (from 8.9 +/- 4.9 to 4.3 +/- 3.7 mm Hg), the peak rate of dimension lengthening of early diastole increased (from 6.0 +/- 3.0 to 8.8 +/- 2.0 cm.s-1), and LV stroke volume index increased (from 24 +/- 7 to 31 +/- 6 ml.m-2) by 12 hours, all p < 0.01. LV incoordination, defined as the dimension changes during isovolumic periods, had also improved significantly at 20 hours. Heart rate and LV enddiastolic dimension did not change.(ABSTRACT TRUNCATED AT 250 WORDS)