Which condition is associated with a continuous murmur?

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

Answer: (A)

A continuous murmur across both systole and diastole points to a conduit that remains open throughout the cardiac cycle, most classically seen with patent ductus arteriosus. When the ductus arteriosus fails to close after birth, blood flows from the high-pressure aorta to the lower-pressure pulmonary artery during both systole and diastole, creating a continuous, machinery-like murmur best heard at the left infraclavicular area. In larger PDAs you may also notice bounding pulses and a wide pulse pressure due to diastolic runoff. By contrast, atrial septal defect typically gives a systolic ejection murmur with fixed S2 splitting, ventricular septal defect produces a holosystolic murmur, and pulmonary stenosis yields a systolic ejection murmur—none of which are continuous. So the condition associated with a continuous murmur is patent ductus arteriosus.