Rare congenital heart defect, also referred to as D-transposition of the great arteries, characterized by reversed positioning of pulmonary artery rising from the left ventricle and aorta rising from the right ventricle, creating parallel circulations. The outcome is the return of oxygenated blood back to the lungs and deoxygenated blood back into circulation. May be associated with other congenital heart defects. Common signs and symptoms include cyanosis, hypoxemia, cardiomegaly, and tachypnea with or without murmur. Onset of symptoms is typically within hours to days after birth. Failure to diagnose and treat promptly almost always leads to death within 12 months.

Management includes therapies to support and stabilize cardiac and pulmonary function, followed by corrective surgery such as arterial switch operation, within the first few weeks of life. Corrective surgeries markedly improve outcomes, with many living normal adult lives.