Which defect is characterized by an aorta arising from the right ventricle and pulmonary arteries arising from the left ventricle?

• A. Transposition of the great vessels
• B. Tetralogy of Fallot
• C. Tricuspid atresia
• D. Ventricular septal defect

Answer: (A)

Transposition of the great arteries is a congenital defect in which the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle. This creates two parallel circulations instead of the normal, serial flow, so desaturated blood circulates to the body while oxygenated blood recirculates to the lungs. Survival depends on mixing between the circuits through a communication such as a patent ductus arteriosus, an atrial septal defect, or a ventricular septal defect. On ultrasound or echo, you would see the great vessels' origins swapped: the aorta comes off the right ventricle and the pulmonary artery off the left ventricle. Management in newborns aims to preserve ductal patency with prostaglandin E1 and ultimately repair with the arterial switch operation. Other defects have different patterns—Tetralogy of Fallot includes a VSD with pulmonary stenosis and an overriding aorta; Tricuspid atresia involves an absent tricuspid valve with a single functioning ventricle; a ventricular septal defect is simply a hole between the ventricles without reversed great-vessel origins.