A machinery-like murmur is most characteristic of which condition?

A machinery-like murmur is most characteristic of which condition?

• A. Atrial septal defect
• B. Patent ductus arteriosus
• C. Ventricular septal defect
• D. Pulmonic stenosis

Answer: (B)

A continuous, machinery-like murmur is the hallmark of a patent ductus arteriosus. This happens because the ductus arteriosus remains open after birth, allowing blood to flow from the aorta into the pulmonary artery throughout both systole and diastole. The result is a murmur that begins in late systole and continues through diastole, best heard at the left infraclavicular area and often accompanied by a bounding pulse and wide pulse pressure due to runoff into the pulmonary circulation. By contrast, an atrial septal defect usually shows a systolic ejection murmur with a fixed split S2 rather than a continuous murmur; a ventricular septal defect produces a harsh holosystolic murmur at the left lower sternal border; and pulmonic stenosis typically presents with a systolic ejection murmur at the left upper sternal border that does not persist into diastole.

A continuous, machinery-like murmur is the hallmark of a patent ductus arteriosus. This happens because the ductus arteriosus remains open after birth, allowing blood to flow from the aorta into the pulmonary artery throughout both systole and diastole. The result is a murmur that begins in late systole and continues through diastole, best heard at the left infraclavicular area and often accompanied by a bounding pulse and wide pulse pressure due to runoff into the pulmonary circulation. By contrast, an atrial septal defect usually shows a systolic ejection murmur with a fixed split S2 rather than a continuous murmur; a ventricular septal defect produces a harsh holosystolic murmur at the left lower sternal border; and pulmonic stenosis typically presents with a systolic ejection murmur at the left upper sternal border that does not persist into diastole.