Biventricular Conversion in Unseptatable Hearts: " Ventricular Switch".

Patients with complex systemic and pulmonary venous anatomy, common atrioventricular canal defects and conotruncal anomalies have traditionally been routed to univentricular palliation and labeled as “un-septatable”. This report describes our initial experience in septation/biventricular conversion (“ventricular switch”), utilizing the left ventricle (LV) as the sub-pulmonary ventricle, essentially recapitulating the physiology of congenitally corrected transposition of the great arteries (ccTGA). Five consecutive patients with challenging anatomic configuration underwent septation. All patients were severely cyanotic and had important functional limitations. All patients required complex atrial septation. Ventricular septation was precluded by fixed pulmonary vascular resistance in two patients. Systemic venous return was diverted to the morphologic LV as part of physiological 2V (n=4) or 1.5V repair (n=1). Median conversion age was 9 years (range 11 months–46 y). Four patients had 12 previous cardiac surgical procedures in preparation for univentricular repair elsewhere. 3-D printed heart models evaluated feasibility of septation. All patients are alive at a median follow-up of 0.6 years (range 0.08 – 2.7y). Median hospital stay was 13 (range 10-60) days. LV recruitment improved functional status and significantly increased systemic oxygen saturation in all patients (79±7% vs. 95±5%, P=0.003). We report a novel paradigm for successfully utilizing both ventricles with the morphologic LV as the subpulmonary ventricle, in a complex population thought to be un-septatable. This approach is versatile and can likely be extrapolated to other complex anatomic configurations. Although we utilized this strategy in patients of variable age, earlier ventricular switch may yield the best results.