Late-onset hypercyanotic spells in duct-dominant Tetralogy of Fallot with pulmonary atresia from juxtaductal PDA-LPA stenosis: CT angiography for preoperative mapping.

Tetralogy of Fallot with pulmonary atresia (ToF-PA) requires precise delineation of extracardiac pulmonary blood supply to guide optimal palliation, especially in duct-dependent physiology. We report an 8-month-old infant with late-onset central cyanosis and recurrent cry-triggered hyper cyanotic spells. Computed tomography (CT) thoracic angiography showed classic ToF with short-segment pulmonary atresia, a malaligned perimembranous ventricular septal defect, and hypoplastic yet confluent branch pulmonary arteries. A long, tortuous patent ductus arteriosus (PDA) provided dominant pulmonary flow, with severe focal juxtaductal stenosis just before insertion into the left pulmonary artery and reduced distal pulmonary arborization. A small ostium secundum atrial septal defect was identified. Minor systemic collaterals were seen, without large dominant major aortopulmonary collateral arteries, suggesting duct-dominant physiology potentially amenable to pulmonary artery rehabilitation. This case highlights late deterioration from progressive PDA-left pulmonary artery narrowing and underscores CT angiography as a key decision map for catheter or surgical palliation and operative planning.