Atrial septal defect may mimic which murmur?

Atrial septal defect may mimic which murmur?

• A. Pulmonic stenosis
• B. Aortic regurgitation
• C. Mitral stenosis
• D. Tricuspid regurgitation

Answer: (A)

The key concept is that an atrial septal defect causes a left‑to‑right shunt, which increases blood flow through the pulmonary valve. That extra flow creates a systolic flow murmur best heard at the left upper sternal border. Pulmonic stenosis also produces a systolic ejection murmur in the same location, so the ASD flow murmur can mimic the murmur of pulmonic stenosis. The murmur from ASD is usually softer and due to flows rather than true valve narrowing, whereas pulmonic stenosis is caused by a narrowed pulmonic valve. The other murmurs have different timing, qualities, or locations and don’t typically resemble the ASD flow murmur.

The key concept is that an atrial septal defect causes a left‑to‑right shunt, which increases blood flow through the pulmonary valve. That extra flow creates a systolic flow murmur best heard at the left upper sternal border. Pulmonic stenosis also produces a systolic ejection murmur in the same location, so the ASD flow murmur can mimic the murmur of pulmonic stenosis. The murmur from ASD is usually softer and due to flows rather than true valve narrowing, whereas pulmonic stenosis is caused by a narrowed pulmonic valve. The other murmurs have different timing, qualities, or locations and don’t typically resemble the ASD flow murmur.