LEFT-VENTRICULAR FUNCTION AFTER TOTAL CORRECTION OF TETRALOGY OF FALLOT

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 P<0·05) and mean end-systolic (36·7±8 vs 29·6±3·9 ml. m-2 P<0·05 volumes than controls. Stroke volume index (SVI) and LV ejection fraction were similar in the two groups. In normal subjects, mnethoxamine 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 induceda reduction in SVI in all patients, the mean value of SVl 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<0·001). Ejection fraction decreased in both groups with the afterload challenge, but in the TOF patients the reduction was significantly higher than in the normal subjects (from 53±4 to 38±5% vs from 55±3 to 49±3%, P<0·001). Peak systolic blood pressure-end- systolic volume relationships were constructed. The slope (m) of the relationship was significantly lower in the TOF group than in the control subjects (2·85±0·77 vs 6·21+0·58, p<0·001);in the TOE group m was below the 95% confidence limit in all studied patients. There was a significant correlation between aortic oxygen saturation preoperatively and the slope of the peak systolic pressure-end-systolic volume relation. Thus, LV function after successful total correction of TOFmay be abnormal, with larger than normal LV size and decreased contractile function. © 1991 The European Society of Cardiology.