- Pathophysiology: Failure of aorticopulmonary septum formation (Neural Crest cell migration failure).
- Anatomy: Single vessel overrides a VSD; supplies Systemic, Pulmonary, and Coronary circulations.
- Genetics: Strongly associated with 22q11 deletion (DiGeorge Syndrome).
- Clinical: Cyanosis at birth (mixing of blood) + Heart Failure (pulmonary overcirculation).
- Exam: Single loud S2; bounding pulses.
- Tx: Surgical repair (close VSD, separate pulmonary arteries).