A systolic murmur that radiates to the left axilla and lower back is most characteristic of which condition?

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

Answer: (A)

This question hinges on how regurgitant murmurs radiate depending on which valve is leaking. In mitral regurgitation, blood spurts backward from the left ventricle into the left atrium during systole, producing a holosystolic, high-pitched blowing murmur. It’s typically heard best at the apex (left midclavicular line) and characteristically radiates toward the left axilla, sometimes even to the back as the regurgitant jet and transmitted sound travel along the chest wall.

This pattern helps distinguish it from other systolic murmurs: aortic stenosis gives a harsh, crescendo-decrescendo murmur best at the right upper sternal border with radiation to the carotids; pulmonary stenosis is heard best at the left upper sternal border; tricuspid regurgitation is holosystolic best at the left lower sternal border and tends to radiate to the right or xiphoid area, not to the axilla or back. Therefore, the described radiation to the left axilla and lower back is most characteristic of mitral regurgitation.