Tetralogy of Fallot Tetralogy of Fallot with pulmonary atresia 2013-12-08T09:44:24Z An extreme form of tetralogy of Fallot characterized by absence of flow from the right ventricle to the pulmonary arteries. UMLS:C0344882 HP:0012516 Tetralogy of Fallot with Pulmonary Atresia (TOF/PA) is a complex lesion with many different anatomic variants. The primary source of variability in this lesion is in the anatomy of the pulmonary arteries, with the spectrum ranging from well-formed, confluent pulmonary artery branches to completely absent native pulmonary arteries and major aorto-pulmonary collaterals (MAPCA's) providing all the pulmonary blood flow. The majority of cases fall somewhere in between these two ends of the spectrum, with the total pulmonary blood flow provided by a combination of diminutive native pulmonary arteries and multiple MAPCA. SNOMEDCT_US:253513005