In a child, a low-pitched murmur best heard at the left lower sternal border is most consistent with which finding?

• A. Innocent murmur
• B. Pulmonary hypertension murmur
• C. Atrial septal defect murmur
• D. Pulmonary stenosis murmur

Answer: (A)

Low-pitched, musical murmurs heard best at the left lower sternal border in a child are classic for an innocent murmur, typically the Still’s murmur. This pattern comes from normal turbulent blood flow in a healthy heart and is usually midsystolic, soft in intensity, and confined to the left lower sternal border without radiation or other concerning signs. There are no symptoms, normal growth, and no abnormal heart sounds elsewhere, which supports a benign finding. In contrast, pathologic murmurs have distinguishing features: pulmonary hypertension would show a loud P2 and signs of right‑sided strain; an atrial septal defect murmur is often a fixed split S2 with a systolic flow murmur at the left upper sternal border due to increased pulmonary flow; pulmonary stenosis yields a harsh systolic murmur at the left upper sternal border, sometimes with a click and radiation. Therefore, the described murmur most consistently fits an innocent murmur.