Intellectual functioning of children with tetralogy of Fallot: Influence of open-heart surgery and earlier palliative operations†

Sixty children who had open-heart operations for tetralogy of Fallot were given intelligence tests preoperatively. Twenty-six had had a prior palliative aorta-pulmonary artery anastomosis (Blalock group). The mean IQ (106) was significantly higher in the Blalock than in the non-Blalock group (mean IQ 96). The Blalock group gained significantly in IQ (average 4.5 points) after open-heart surgery. The non-Blalock group gained 1.2 IQ points on the average. Of surgical factors considered, only minimum venous pH during perfusion correlated with changes in IQ. These results suggest the possible benefical effects of early operation on intellectual development.