In transposition of the great arteries, which statement is true?

• A. Aorta arises from the right ventricle and the pulmonary artery from the left ventricle
• B. Aorta arises from the left ventricle and the pulmonary artery from the right ventricle
• C. There is a large left-to-right shunt through the foramen ovale
• D. Oxygenated blood circulates systemically without mixing

Answer: (A)

Transposition of the great arteries means the great vessels originate from the opposite ventricles, so the aorta comes off the right ventricle and the pulmonary artery comes off the left ventricle. This creates two parallel circulations, and survival depends on mixing of oxygenated and deoxygenated blood through an opening like a patent foramen ovale, a VSD, or a PDA. The other statements don’t describe this abnormal origin pattern: normal anatomy would have the aorta from the left ventricle and the pulmonary artery from the right ventricle, and while mixing can occur via shunts, the defining feature is the swapped vessel origins and the resulting need for mixing to oxygenate systemic circulation.