Influence of ventricular morphology on aerobic exercise capacity in patients after the Fontan operation

OBJECTIVES This study investigated the influences of ventricular morphology, hemodynamics and clinical findings on exercise capacity in patients after the Fontan operation. BACKGROUND Determinants of exercise capacity after the Fontan operation remain unclear. METHODS Peak oxygen uptake (Pvo2) was determined in 105 patients by exercise test and compared to hemodynamics and clinical findings. Patients were divided into three groups based on ventricular morphology: those with a right ventricle (group RV), a biventricle (group BV) and a left ventricle (group LV). RESULTS Ten patients with atrioventricular valve regurgitation (AVVR) or hypoxia exhibited a low Pvo2. After excluding these patients, although Pvo2 did not correlate with hemodynamics, except ventricular ejection fraction (p < 0.02), it correlated with age at the Fontan operation and exercise test (p < 0.002). The Pvo2 was higher in group LV (63 ± 9%) than in groups RV (55 ± 9%) and BV (55 ± 12%) (p < 0.01), while an inverse correlation between Pvo2 and age at operation was demonstrated only in group RV (p < 0.05). Groups RV or BV and age at exercise test were associated with a lower Pvo2, whereas group LV was an independent predictor of a higher Pvo2 (p < 0.01). During 4.2 years of follow-up, a decrease in peak heart rate was related to a decrease in Pvo2 (p < 0.05). The Pvo2 decreased in group RV (p < 0.01). CONCLUSIONS In addition to AVVR, hypoxia, and heart rate response, ventricular morphology is related to exercise capacity. Early Fontan operation may be beneficial in terms of exercise capacity, especially in the group RV patients.