Which statement best explains the rationale for advising rest before surgery in aortic stenosis?

• A. To prevent syncope during exertion
• B. To increase heart rate
• C. To enhance oxygen delivery during activity
• D. To strengthen leg muscles

Answer: (A)

In aortic stenosis the left ventricle has to push blood through a narrowed aortic opening, creating a fixed, limited cardiac output. With exertion, the heart cannot significantly increase flow to meet higher demands. That mismatch can cause transient cerebral hypoperfusion, leading to syncope. Resting before surgery reduces the heart’s workload and oxygen demand, helping maintain stable hemodynamics and lowering the risk of fainting during anesthesia and perioperative stress.

Increasing heart rate or contractility would worsen the situation by further decreasing diastolic filling time and coronary perfusion, and the ideas of merely strengthening leg muscles or improving oxygen delivery during activity don’t address the primary risk in severe aortic stenosis, which is exertional syncope.