What type of murmur is characteristic of aortic stenosis (AS)?

Aortic stenosis typically presents with a harsh, systolic, crescendo-decrescendo murmur. This type of murmur occurs during the ejection phase of the cardiac cycle, specifically when blood is being ejected from the left ventricle into the aorta through the narrowed aortic valve. The crescendo-decrescendo quality refers to the murmur's intensity increasing to a peak and then decreasing, which is characteristic of the turbulent flow across a stenotic valve.

The timing of this murmur is important as it corresponds to the phase of ventricular contraction (systole) when the left ventricle is working harder to push blood through the obstructed opening. The harsh quality of the sound reflects the marked turbulence caused by the narrowed opening of the aortic valve, making the murmur distinct and recognizable during a physical exam.

Other types of murmurs described in the options do not align with the characteristics found in aortic stenosis. For instance, a soft diastolic murmur would not represent the turbulence caused by a structural obstruction but rather suggest a different pathophysiological condition. A continuous murmur across all phases is more typical of conditions such as arteriovenous fistulas or patent ductus arteriosus, where