In a 2-month-old infant, a machine-like continuous murmur is audible and heard loudest in the upper left sternal border (ULSB) during late systole. This finding could be suggestive of a:

Rationale: A. Pulmonary valve stenosis typically produces a systolic ejection murmur, not a continuous machine-like murmur. B. A venous hum is continuous but usually heard over the right or left supraclavicular area and is benign. C. Patent ductus arteriosus (PDA) classically produces a continuous, “machine-like” murmur best heard at the upper left sternal border. The murmur persists throughout systole and diastole due to continuous blood flow from the aorta to the pulmonary artery. D. A ventricular septal defect usually produces a holosystolic murmur heard best at the lower left sternal border, not a continuous machine-like murmur.