Quantitative and qualitative cineangiographic analysis of the left ventricle (LV) was performed in 26 patients with isolated Ebstein's malformation, having a mean age of 23 +/- 17 years. Nine autopsied hearts with isolated Ebstein's malformation were submitted to morphologic and morphometric analysis. In 4 of the cases, it was possible to make a direct correlation between the angiographic data obtained during life and the autopsy findings. On the basis of the LV end-diastolic volume we identified 3 groups of patients: 7 with volume <60 ml/m2, another 7 with volume between 60 and 80 ml/m2, and 12 with volume >80 ml/m2. The LV ejection fraction was reduced in 2 patients with normal LV end-diastolic volume and in 6 with increased LV end-diastolic volume. The ratio of ventricular mass to LV end-diastolic volume was always adequate, but a reduction of the ventricular contractive performance (end-systolic pressure to end-systolic volume ratio <3 mm Hg/ml/m2) was found only in patients with a dilated left ventricle. No correlation was demonstrated between the extent of the atrialized component of the right ventricle (mean value 67 +/- 31 cm2, range 13 to 133) and the LV dimensions. All but 2 patients showed a leftward diastolic displacement of the ventricular septum, but in only 1 did this produce an elongated shape of the left ventricle. Sixteen had anomalies of LV dynamics: 10 with hypokinesia (3 of the posterior wall, 4 of the apex, 1 of the inferior wall, 1 of the septum, and 1 global), 6 with dyskinesia (1 of the posterior wall, 2 of the apex, 1 of the posterior wall and apex, 1 of the superior part of the septum, and 1 of the anterior wall), and 8 with premature diastolic distension of the anterobasal wall. Morphometric analysis produced mean values for myocytes of 59 +/- 10%, for the interstitium of 21 +/- 4%, and for fibrous tissue of 20 +/- 9% (normal 4 +/- 1%). Five autopsied hearts had a prolapsing and/or dysplastic mitral valve.