Atrial and ventricular septal defects are classified as acyanotic because the shunt is usually left-to-right.

Atrial and ventricular septal defects are classified as acyanotic because the shunt is usually left-to-right.

• A. They are cyanotic defects
• B. They are acyanotic defects due to left-to-right shunt
• C. They cause right-to-left shunt causing cyanosis
• D. They never cause heart failure

Answer: (D)

Atrial and ventricular septal defects create a left-to-right shunt, meaning oxygenated blood from the left side leaks into the right heart and back to the lungs. This increases pulmonary blood flow but preserves systemic oxygen levels, so there is no cyanosis. That’s why these defects are described as acyanotic. However, a large shunt can overload the pulmonary circulation and the left heart, leading to congestive heart failure in infancy. If pulmonary hypertension develops over time, the shunt can reverse to right-to-left, causing cyanosis later (Eisenmenger syndrome). So saying they never cause heart failure isn’t accurate.

Atrial and ventricular septal defects create a left-to-right shunt, meaning oxygenated blood from the left side leaks into the right heart and back to the lungs. This increases pulmonary blood flow but preserves systemic oxygen levels, so there is no cyanosis. That’s why these defects are described as acyanotic. However, a large shunt can overload the pulmonary circulation and the left heart, leading to congestive heart failure in infancy. If pulmonary hypertension develops over time, the shunt can reverse to right-to-left, causing cyanosis later (Eisenmenger syndrome). So saying they never cause heart failure isn’t accurate.