To clarify differences between pre- and postoperative volumetric and hemodynamic variables from patients with clinically good and poor outcomes after a Fontan procedure, 40 patients with univentricular heart (double inlet left ventricle) (mean age: 5.7 +/- 3.3 years) were studied using the ventricular cineangiography. According to postoperative clinical findings, patients were classified into two groups: 26 patients with good outcomes and 14 patients with poor outcomes (including five with early and two with intermediate deaths) and compared with a control population. Age at surgery, pre-operative cardiac index, wall mass and systolic ejection phase parameters were not different between the two patient groups, however, end-diastolic volume index in poor outcomes was significantly smaller than those with good outcomes (100 +/- 24, 78 +/- 22, 64 +/- 14 ml/m2: good, poor outcomes and controls, respectively, p less than 0.05), and the mass/volume ratio in this group significantly elevated (1.00 +/- 0.18, 1.19 +/- 0.33, 0.97 +/- 0.19 g/ml, p less than 0.05). Postoperatively, both ventricular volume and mass in good outcomes returned toward the normal and the mass/volume ratio remained within normal range (1.07 +/- 0.22). In contrast, the hypertrophied ventricular mass in those patients with poor outcomes did not decrease in parallel with ventricular volume, thus contributing to a further increased ratio (1.48 +/- 0.19). Although there were no significant differences between pre-operative hemodynamic variables among the two groups, the mass/volume ratio in those with poor outcomes was increased pre-operatively and further increased after the Fontan procedure due to rapid and acute reduction of preload.(ABSTRACT TRUNCATED AT 250 WORDS)