The origin of a systolic ejection murmur that radiates to the back is usually which valve origin?

• A. Pulmonary
• B. Aortic
• C. Mitral regurgitation
• D. Tricuspid

Answer: (A)

Systolic ejection murmurs come from turbulent flow across the semilunar valves, and where they radiate helps identify the valve involved. A murmur that is systolic and radiates to the back, particularly in a child, is classic for a pulmonary flow murmur originating at the pulmonary valve. This benign, innocent murmur reflects normal variation in flow across the pulmonary outflow tract and is most noticeable at the left upper sternal border with inspiration, sometimes heard radiating toward the back. It is common in healthy children and typically does not indicate valve disease.

In contrast, murmurs from the aortic valve usually radiate toward the carotids, while mitral regurgitation creates a holosystolic murmur heard best at the apex and radiates to the axilla, and tricuspid murmurs are best heard along the left lower sternal border and vary with respiration. The backward radiation pattern described fits the pulmonary valve origin.