This study examines the relative contribution of early (E) and atrial (A) filling of the left ventricle. Ten patients were studied under anesthesia before and after coronary artery bypass grafting (CABG) using measurements of the mitral velocity-time integral (VTI) with transesophageal pulsed Doppler echocardiography and nuclear angiocardiography simultaneously. Thermodilution cardiac output measurements were made simultaneously in order to express the E and A filling in quantitative terms. The mean difference between methods in estimating E filling was -1.0 mL and the figures for the mean +/- 2 SD were 5.7 and -7.8 mL, r = 0.98 using regression analysis. The mean difference during A filling was 0.9 mL and the corresponding figures for the mean +/- 2 SD were 7.9 and -6.1 mL, r = 0.88. There was a reduction in the volume entering the left ventricle during the E filling (42-26 mL) and in the A phase (27-22 mL) from before surgery in comparison to after CABG. There was good agreement between transesophageal Doppler echocardiographic and nuclear angiocardiographic methods concerning the volume contribution during E and A phases of left ventricular filling.