A 32-year-old white man is referred for evaluation of a murmur noted on a pre-employment physical. He has no specific complaints. He is physically active and runs 4-5 miles almost every day. His older brother died of presumed sudden cardiac arrest at age 37 years. On physical examination, there is a wide, fixed splitting of the second heart sound. A faint mid-systolic ejection murmur is heard best over the left second intercostal space. Otherwise, his physical examination is unremarkable. An echocardiogram confirms the presence of a large secundum atrial septal defect.
Which of the following is the most likely explanation for the murmur?

Question

A 32-year-old white man is referred for evaluation of a murmur noted on a pre-employment physical.  He has no specific complaints.  He is physically active and runs 4-5 miles almost every day.  His older brother died of presumed sudden cardiac arrest at age 37 years.  On physical examination, there is a wide, fixed splitting of the second heart sound.  A faint mid-systolic ejection murmur is heard best over the left second intercostal space.  Otherwise, his physical examination is unremarkable.  An echocardiogram confirms the presence of a large secundum atrial septal defect.
Which of the following is the most likely explanation for the murmur?

Quizplus · Accepted Answer

Patients with atrial septal defect (ASD) and moderate-to-large left-to-right shunt have increased flow through the pulmonic valve. This produces a mid-systolic ejection murmur resulting from increased flow across the pulmonic valve. Another characteristic finding is the presence of wide and fixed splitting of the second heart sound. (Choice A) Dilatation of the pulmonary artery is associated with pulmonic regurgitation and a low-pitched diastolic murmur. (Choice C) Patients with large ASD and significant left-to-right shunting have increased flow across the tricuspid valve that produces a mid-diastolic murmur that does not increase with inspiration. (Choice D) Mitral valve prolapse produces a single or multiple clicks, followed by a late systolic murmur. (Choice E) The low-velocity left-to-right shunt flow across the atrial septal defect produces no audible murmur. Educational objective: Atrial septal defect with moderate-to-large left-to-right shunt causes a mid-systolic ejection murmur due to increased flow through the pulmonic valve. __________

A 32-Year-Old White Man Is Referred for Evaluation of a Murmur