Determinants of aerobic capacity during exercise following complete repair of tetralogy of Fallot with a transannular patch.

Exercise capacity and the causes of its limitation following repair of tetralogy of Fallot have been studied in heterogeneous populations. Study populations have been grouped together regardless of the type of repair and residual hemodynamic abnormalities. To better understand the factors limiting aerobic exercise capacity in patients repaired with a transannular patch, 37 patients with a transannular patch and no residual pulmonary stenosis underwent resting spirometry and treadmill exercise testing. Maximal oxygen consumption and oxygen consumption at anaerobic threshold were measured in all patients to assess aerobic capacity. Patients were subdivided by gender. Resting spirometry measurements tended to be lower in both genders compared to healthy controls but did not correlate with any measurement of aerobic capacity. Maximal oxygen consumption and anaerobic threshold were significantly less in the female than the male population. A quadratic relation between maximal oxygen consumption and age at exercise testing existed for both genders but peaked at an earlier age and was significantly less in the female population. There was a significant negative correlation between maximal oxygen consumption and echocardiographically estimated right ventricular inflow volume index in the female population only. These data suggest that in patients with tetralogy of Fallot repaired with a transannular patch aerobic capacity is limited primarily by cardiac function, but that gender differences are due to noncardiac causes.