What is the likely cause of agrade 4/6 crescendo systolic murmur heard and radiating to the carotids?

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

Answer: (B)

The presence of a grade 4/6 crescendo systolic murmur, especially one that radiates to the carotids, is highly indicative of aortic stenosis. In aortic stenosis, blood flow is obstructed during systole as the left ventricle ejects blood into the aorta through a narrowed valve. This obstruction causes turbulence, resulting in a distinctive murmur that is often described as "crescendo" due to its increasing intensity as it progresses through systole.

As the heart muscle works harder to pump blood through the aortic valve, the murmur not only becomes more pronounced, but the radiation of sound to the carotids is also a classic feature. This is due to the proximity of the pathways by which the sound waves travel, particularly given the anatomical arrangement of the heart and major blood vessels. The degree of stenosis often correlates with the intensity of the murmur, and a grade 4 murmur is considered quite significant, suggesting a clinically relevant degree of obstruction.

Other heart conditions like aortic regurgitation or mitral regurgitation produce different murmur characteristics that do not involve the same pattern or radiation to the carotids. In aortic regurgitation, for instance, the murmur is