Fenestrated fontan with delayed catheter closure: Effects of volume loading and baffle fenestration on cardiac index and oxygen delivery

Background. The fenestrated Fontan operation has been applied to high-risk patients with univentricular hearts, resulting in improved survival. The purpose of this study was to determine the hemodynamic factors responsible for these improved results. Methods and Results. We performed the fenestrated Fontan operation in 17 high-risk patients with univentricular hearts (median age, 3 years; age range, 1.2-25 years). High-risk characteristics were depressed ventricular function and/or hypertrophy (n=12), atrioventricular valve insufficiency (n=5), pulmonary artery distortion (n=6), elevated pulmonary vascular resistance (>2 units/m²) (n=4), previously failed Fontan operation (n=2), or associated Wolff-Parkinson-White syndrome (n=1). Intraoperative hemodynamic measurements (n=8) included cardiac index (by aortic flow probe), peripheral arterial O₂ saturations, and left and right atrial pressures during inflow occlusion, followed by volume loading with open versus closed fenestration. Mean baffle fenestration was 3.5 mm (range, 2.7-5.0 mm). Multiple regression analysis (cardiac index versus atrial pressure) revealed cardiac index was greater with open than with closed fenestration (p<0.001) during volume loading. Oxygen delivery (cardiac index multiplied by oxygen content) was also greater with open than with closed fenestration (p<0.001). Survival was 100% with a mean follow-up of 10.4 months; pleural drainage was high in two patients. Subsequent transcatheter fenestration closure resulted in increased O₂ saturation (87±1% to 96±0.3%, p<0.05). Conclusions. The fenestrated Fontan operation improves survival in high-risk patients by increasing cardiac index and maintaining oxygen delivery, despite mild arterial O₂ desaturation. Subsequent transcatheter fenestration closure can be performed after hemodynamic assessment.