1st stage (of 3) in surgical correction of hypoplastic left heart syndrome; requires deep hypothermia and bypass. Excision of interatrial septum, ligation of branch pulmonary arteries, and division of ductus arteriosus is performed. Main pulmonary artery is transected and anastomosed to underside of aortic notch, and artificial tube graft is interposed between proximal right pulmonary artery and innominate artery. It is critical to maintain adequate systemic perfusion postop and to limit pulmonary blood flow.