Conflicting data are available concerning left ventricular (LV) function in patients after total correction of tetralogy of Fallot (TOF). The response to afterload stress determined by methoxamine challenge and the peak systolic blood pressure-end-systolic volume relationship were evaluated echocardiographically in 20 postoperative TOF patients (age range 9 to 15 years, mean 12 +/- 2). All patients were without significant residual shunts or pulmonary stenosis. Results were compared with those in 10 control subjects (age range 9 to 15 years, mean 11 +/- 2). The TOF group had higher mean end-diastolic (76.9 +/- 14.4 vs 66.2 +/- 7.2 ml.m-2 P less than 0.05) and mean end-systolic (36.7 +/- 8.5 vs 29.6 +/- 3.9 ml.m-2, P less than 0.05) volumes than controls. Stroke volume index (SVI) and LV ejection fraction were similar in the two groups. In normal subjects, methoxamine caused a decrease in SVI in seven out of 10 patients and a mild increase in three; the mean value of SVI at rest was not significantly different from the mean value at peak pressor effect (36.5 +/- 4.4 vs 35.9 +/- 4.0 ml.m-2, P = NS). In the TOF group, methoxamine induced a reduction in SVI in all patients; the mean value of SVI at peak pressor effect was significantly lower than the mean value at rest (31.3 +/- 5.4 vs 40.2 +/- 6.9 ml.m-2, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)