Risk of valve re- placement in this setting is high. 4.4.3. Hypoplastic Left Heart Syndrome/Norwood Repair The Norwood repair is the first of 3 steps in palliation for hypoplastic left heart syndrome and consists of a- trial septectomy, transection, and ligation of the distal main PA with construction of a systemic-to-PA shunt, and anastomosis of the proximal stump of the main PA to the hypoplastic ascending aorta with augmentation of the entire aortic arch from the sinotubular junction to beyond the ductus arteriosus. Hypoplastic left heart syndrome is fatal unless surgical palliation is performed in the neonatal period. Subsequent surgeries include a bidirectional cavopulmonary anastomosis (often per- formed around 6 months of age), followed finally by a Fontan procedure (often at approximately 2 to 4 years of age). Sequelae of hypoplastic left heart syndrome are largely those of the Fontan palliation, but additional concerns related to the underlying anatomy and the Norwood repair is important in patients with hypoplas- tic left heart syndrome. These include aortic obstruction related to anastomosis of the PA and aorta, and neo- aortic dilation. Additionally, native anatomy wherein coronary arteries arise from a small aortic root make coronary ischemia a greater concern than in other un- derlying disorders managed with Fontan repair. The fre- quency and spectrum of long-term sequelae specific to the Norwood repair are not yet known. 4.4.4. Truncus Arteriosus Truncus arteriosus in the adult has almost invariably been repaired in childhood, and in the rare circum- stances when an adult has unrepaired truncus arte- riosus, Eisenmenger physiology is typical. Pulmonary hypertension may be present in repaired patients. The types of operative repairs may involve VSD clo- sure, right ventricle to-PA conduit placement, recon- struction of the pulmonary arteries, and replacement of the truncal (neoaortic) valve. 