Which auscultatory finding is commonly associated with a large atrial septal defect?

Which auscultatory finding is commonly associated with a large atrial septal defect?

• A. Fixed splitting of S2
• B. No splitting of S2
• C. Murmur of tricuspid regurgitation
• D. Widely fixed splitting of S2 that does not vary with respiration

Answer: (D)

A large atrial septal defect causes a sustained left-to-right shunt that overloads the right heart and increases pulmonary blood flow. This extra flow delays the pulmonic valve closure, so the second heart sound is split and the split remains wide and fixed, not changing with breathing. That widely fixed S2 is the hallmark finding in a large ASD. While a simple fixed split can occur with smaller defects, the “widely fixed and respiration-insensitive” pattern is most characteristic of a large defect; other findings like a tricuspid regurgitation murmur point to different problems.

A large atrial septal defect causes a sustained left-to-right shunt that overloads the right heart and increases pulmonary blood flow. This extra flow delays the pulmonic valve closure, so the second heart sound is split and the split remains wide and fixed, not changing with breathing. That widely fixed S2 is the hallmark finding in a large ASD. While a simple fixed split can occur with smaller defects, the “widely fixed and respiration-insensitive” pattern is most characteristic of a large defect; other findings like a tricuspid regurgitation murmur point to different problems.