What murmur is characteristic of aortic stenosis?

Aortic stenosis is associated with a systolic crescendo/decrescendo murmur, which is characterized by a sound that starts softly, increases in intensity, and then decreases before the next heart sound. This murmur occurs due to turbulent blood flow across a narrowed aortic valve during systole, when the left ventricle contracts to eject blood into the aorta.

The crescendo portion reflects the increased velocity of blood flow as it accelerates through the narrowed valve, and the decrescendo portion corresponds to the decrease in flow as the left ventricle relaxes and blood no longer accelerates through the valve. It is typically best heard at the right second intercostal space and often radiates to the carotid arteries.

This distinguishing feature of the murmur helps to differentiate aortic stenosis from other types of murmurs, such as holosystolic murmurs that are common in conditions like mitral regurgitation, diastolic murmurs which occur due to conditions like aortic regurgitation, and continuous murmurs seen in patent ductus arteriosus or arteriovenous fistulas. Recognizing the specific characteristics of these murmurs is crucial for accurate diagnosis and management of cardiac conditions.