Embryologic basis: anterior deviation of the infundibular septum
Primary 4 features (tetralogy):
(1) pulmonary stenosis with outflow obstruction from the right ventricle
(2) right ventricular hypertrophy
(3) ventricular septal defect (VSD), usually located in the posterior portion of the septum just below the aortic valve
(4) rightward shift of the aortic root, so that it overrides the ventricular septal defect
Additional findings may include:
(1) anomalies of the aortic arch (right aortic arch, other)
(2) anomalies of the coronary arteries
(3) anomalies of the pulmonary blood supply (pulmonary atresia, anomalous blood supply from the aorta, other)
(4) insufficiency of the aortic valve if valve annulus is enlarged
