Radionuclide assessment of ventricular contraction at rest and during exercise following the Fontan procedure for either tricuspid atresia or single ventricle.

Ventricular contraction was evaluated in 18 patients studied at a mean of 2.6 years after Fontan repair. The diagnosis was tricuspid atresia in 9 patients and single ventricle in 9. Gated first-pass and gated equilibrium radionuclide ventriculography were performed at rest and during exercise. Abnormally low ventricular ejection fraction (EF) at rest was present in 8 of 18 patients by the gated equilibrium technique and 6 of 13 technically adequate gated first-pass studies. An abnormal response to exercise (failure of EF to increase less than or equal to 5% from rest to maximal exercise) was found in 10 of 16 patients by the gated equilibrium technique and in 8 of 12 by the gated first-pass technique. Only 2 patients by each radionuclide technique had both normal EF at rest and normal exercise response. Thus, this study confirms the frequent presence of abnormalities in ventricular contraction after the Fontan procedure at rest or during exercise or both despite absence of symptoms. Both EF response and the hemodynamic response during exercise were more abnormal in the presence of an atriopulmonary than an atrioventricular connection.