What heart sound is associated with aortic stenosis?

The heart sound most commonly associated with aortic stenosis is a characteristic "plateau" or a "slow upstroke" of the carotid pulse. Aortic stenosis leads to a narrowing of the aortic valve opening, resulting in an obstructed outflow of blood from the left ventricle during systole. This obstruction produces a specific auscultatory finding: a high-pitched "crescendo-decrescendo" systolic ejection murmur best heard at the second right intercostal space.

The characteristic pulsus parvus et tardus, or diminished and delayed carotid pulse, reflects the reduced stroke volume and the prolonged ejection time typically seen in patients with severe aortic stenosis. The plateau in the upstroke indicates the increased resistance to blood flow, causing the pulse to be slow to rise and fall, compared to a normal pulse.

In summary, the association of aortic stenosis with a plateau or slow upstroke in the carotid pulse is rooted in the hemodynamic changes occurring due to the obstructed outflow, differentiating it from other conditions that might present differently in terms of heart sounds and pulse characteristics.