A continuous "machine-like" murmur is most characteristic of which congenital heart defect?

A continuous "machine-like" murmur is most characteristic of which congenital heart defect?

• A. Atrial septal defect
• B. Coarctation of the aorta
• C. Patent ductus arteriosus
• D. Ventricular septal defect

Answer: (C)

A continuous, machinery-like murmur is produced by a persistent connection between the aorta and the pulmonary artery, known as a patent ductus arteriosus. Because blood flows from the aorta (high pressure) into the pulmonary artery throughout both systole and diastole, the murmur spans the entire cardiac cycle rather than stopping after systole. This continuous murmur classically localizes to the left infraclavicular area and may be accompanied by bounding pulses and a wide pulse pressure due to the ongoing left-to-right shunt. In contrast, other defects produce murmurs with different timing and quality: an atrial septal defect usually causes a fixed split S2 with a secondary flow murmur but not a continuous murmur; coarctation of the aorta often yields a systolic murmur best heard on the back or over the chest with diminished femoral pulses; a ventricular septal defect typically presents a harsh holosystolic murmur at the left lower sternal border.

A continuous, machinery-like murmur is produced by a persistent connection between the aorta and the pulmonary artery, known as a patent ductus arteriosus. Because blood flows from the aorta (high pressure) into the pulmonary artery throughout both systole and diastole, the murmur spans the entire cardiac cycle rather than stopping after systole. This continuous murmur classically localizes to the left infraclavicular area and may be accompanied by bounding pulses and a wide pulse pressure due to the ongoing left-to-right shunt.

In contrast, other defects produce murmurs with different timing and quality: an atrial septal defect usually causes a fixed split S2 with a secondary flow murmur but not a continuous murmur; coarctation of the aorta often yields a systolic murmur best heard on the back or over the chest with diminished femoral pulses; a ventricular septal defect typically presents a harsh holosystolic murmur at the left lower sternal border.