Fate of Outflow Tract in Tetralogy of Fallot

Cardiac catheterization studies were performed in 37 selected patients with tetralogy of Fallot. In 25 patients the ratio of right ventricular to left ventricular systolic pressures (RV/LV ratio) decreased between completion of repair and restudy by a mean of 36% (range, 10 to 53%). In 4 patients the ratio was unchanged, and in 8 patients it increased by a mean of 33% (range, 10 to 73%). Patients with patch graft reconstruction of the outflow tract showed significantly less likelihood (p = 0.02) of a late increase in RV/LV ratio than patients without a patch graft. A greater late decrease in RV/LV ratio occurred in patients who had good immediate relief of outflow tract obstruction. The most common site of outflow tract obstruction at restudy was the pulmonary valve and valve ring. Stenosis of the pulmonary valve recurred in 5 patients despite the fact that a patch traversed the valve ring in 2 of them.