Which description best characterizes a pulmonary flow murmur?

• A. Harsh, late systolic murmur at the upper left sternal border
• B. Soft, blowing murmur radiating to the lung fields
• C. Continuous machinery murmur
• D. Loud, harsh systolic crescendo-decrescendo murmur

Answer: (B)

Pulmonary flow murmurs arise from increased blood flow through the pulmonary valve and are a common benign finding in children. They are typically soft, with a blowing quality, and are heard best at the left upper sternal border, often radiating to the lung fields. This description—soft, blowing and radiating to the lungs—fits a pulmonary flow murmur well. Other tones point elsewhere: a harsh late systolic murmur at the left upper sternal border suggests other valve problems such as mitral valve issues or related murmurs; a continuous machinery murmur indicates patent ductus arteriosus, which is heard throughout systole and diastole; and a loud, harsh systolic crescendo-decrescendo murmur at that area suggests outflow tract stenosis, not a benign flow murmur.