Which defect best describes the combination of pulmonary stenosis, right ventricular hypertrophy, overriding aorta, and ventricular septal defect?

Which defect best describes the combination of pulmonary stenosis, right ventricular hypertrophy, overriding aorta, and ventricular septal defect?

• A. Transposition of the great arteries
• B. Tricuspid atresia
• C. Tetralogy of Fallot
• D. Total anomalous pulmonary venous connection

Answer: (C)

This combination is tetralogy of Fallot. The four features arise together because of anterior malalignment of the conal septum during development, which creates obstruction of the right ventricular outflow tract (pulmonary stenosis) and a malaligned ventricular septal defect. The aorta ends up straddling the VSD (overriding the VSD) and can receive blood from both ventricles. The outflow obstruction drives more deoxygenated blood across the VSD into the systemic circulation, producing a right-to-left shunt and cyanosis, while the right ventricle enlarges to cope with the increased workload. This quartet of findings is characteristic of TOF and defines the condition. Other congenital heart defects don’t present with this exact fourfold combination. Transposition of the great arteries features discordant ventriculoarterial connections rather than an overriding aorta with a VSD. Tricuspid atresia centers on absence of the tricuspid valve with a hypoplastic right ventricle, often with a VSD but not the full tetralogy. Total anomalous pulmonary venous connection involves pulmonary veins draining into the right heart, not an overriding aorta with the classic VSD and outflow tract obstruction.

This combination is tetralogy of Fallot. The four features arise together because of anterior malalignment of the conal septum during development, which creates obstruction of the right ventricular outflow tract (pulmonary stenosis) and a malaligned ventricular septal defect. The aorta ends up straddling the VSD (overriding the VSD) and can receive blood from both ventricles. The outflow obstruction drives more deoxygenated blood across the VSD into the systemic circulation, producing a right-to-left shunt and cyanosis, while the right ventricle enlarges to cope with the increased workload. This quartet of findings is characteristic of TOF and defines the condition.

Other congenital heart defects don’t present with this exact fourfold combination. Transposition of the great arteries features discordant ventriculoarterial connections rather than an overriding aorta with a VSD. Tricuspid atresia centers on absence of the tricuspid valve with a hypoplastic right ventricle, often with a VSD but not the full tetralogy. Total anomalous pulmonary venous connection involves pulmonary veins draining into the right heart, not an overriding aorta with the classic VSD and outflow tract obstruction.