Which factor might typically increase the intensity of an aortic stenosis murmur?

Leaning forward enhances the intensity of an aortic stenosis murmur due to the changes it causes in the heart's hemodynamics and the position of the chest wall. When a patient leans forward, it can help to bring the heart closer to the chest wall, improving sound transmission from the heart through the chest. This position also enhances the flow of blood across the narrowed aortic valve, which can cause an increase in turbulence and thus amplify the murmur associated with aortic stenosis.

Additionally, leaning forward can increase venous return to the heart, potentially increasing the gradient across the aortic valve when it is stenotic, further contributing to the more pronounced sound of the murmur. This positioning is a common technique in clinical practice to better auscultate heart sounds, especially when assessing for conditions like aortic stenosis where sound dynamics play a crucial role.

Other factors mentioned, like standing up quickly or lying flat, do not increase the intensity of the murmur to the same extent. Increased systemic vascular resistance can affect the heart's workload but does not specifically enhance the murmur's audibility.