In a preterm infant with PDA, which murmur is typically heard?

• A. Coarse Systolic Murmur Best Heard Along the Left Sternal Border
• B. Continuous Machinery-Like Murmur Heard Bilaterally in the Anterior Chest
• C. Short Mid-Systolic Murmur Radiating to the Inter-Scapular Area
• D. No Murmur Audible

Answer: (A)

A patent ductus arteriosus in a preterm infant produces a continuous, machinery-like murmur that spans both systole and diastole. This audible pattern comes from the persistent flow of blood from the high-pressure aorta into the lower-pressure pulmonary artery throughout the cardiac cycle. The classic location is the left upper chest, around the left infraclavicular area, and the sound may be heard on both sides of the sternum, sometimes radiating toward the back. This continuous murmur distinguishes PDA from murmurs that are limited to systole or arise from other lesions. A systolic-only, coarse murmur along the left sternal border points more toward a ventricular septal defect or another condition, not PDA. A short mid-systolic murmur radiating to the interscapular area suggests a different pathology, and no murmur would be expected only if the ductus is very small or not hemodynamically significant. So the hallmark for PDA is the continuous, machinery-like murmur heard in the anterior chest, best near the left upper chest.