Influence of age on the effect of bidirectional cavopulmonary anastomosis on left ventricular volume, mass and ejection fraction

Objectives. We sought to identify age-related differences in the ventricular response of patients after bidirectional cavopulmonary anastomosis (CPA) and to compare changes in the ventricular response among children <3 years of age who underwent CP with that of age-matched control subjects who had systemic to pulmonary artery shunt alone. Background. Pre-Fontan CP has been advocated over systemic to pulmonary artery shunt alone in patients with single ventricle to facilitate ventricular volume unloading and minimize risk of the Fontan operation. Methods. Our study evaluated 23 patients who initially received systemic to pulmonary artery shunt as an initial procedure before subsequent Fontan palliation. In eight of these patients (group I), bidirectional CP was performed before age 3 years, and in four (group II), it was performed after age 10 years. The remaining 11 patients (group III, age and weight control group for group I) were maintained with their initial shunt until they underwent Fontan palliation. Serial echocardiographic analysis was used retrospectively to evaluate left ventricular volume and mass and systolic pump function (ejection fraction) before and after bidirectional CPA. Results. Through 10 months of follow-up, group I patients showed significant decreases in indexed end-diastolic volume both after CP (120 ml/m1.5 body surface are vs. 78 ml/m1.5, p = 0.001) and in comparison with values in patients in groups II and III, who showed no changes in end-diastolic volume (p < 0.001). Indexed ventricular mass decreased moderately after bidirectional CP in group I (from 228 g/m1.5 body surface are to 148 g/m1.5) but remained unchanged in groups II and III. The differences in trends between groups I and III were significant (p = 0.03). Ejection fraction decreased significantly in group II versus group I patients (0.48 to 0.27 vs. 0.51 to 0.52, p < 0.05) after CPA. Oxygen saturation measurements before and after bidirectional CP revealed significant increase in group I (73% to 86%, p < 0.001) and decrease in group II (82% to 73%, p < 0.01). Conclusions. Bidirectional CP facilitates ventricular volume unloading and promotes regression of left ventricular mass in younger children (<3 years) in preparation for Fontan operation. In contrast, bidirectional CP is of questionable value in older children as staging procedure for Fontan palliation.