American Board of Internal Medicine (ABIM) Certification Practice Exam

What is a common effect of vasodilators used in stress testing?

1. Hypotension and bradycardia

2. Hyperemia and flow disparity

3. Increased blood flow leading to arrhythmias

4. Reduction in myocardial oxygen demand

The correct answer is: Hyperemia and flow disparity

The correct response highlights the phenomenon of hyperemia and flow disparity, which are common effects observed with the administration of vasodilators during stress testing. Vasodilators work by relaxing the smooth muscle in blood vessels, leading to an increase in blood flow to areas undergoing stress, such as the myocardium during a cardiac stress test. This increased blood flow is referred to as hyperemia. In addition to the increased perfusion, vasodilators can induce flow disparity, especially when there are regions of the myocardium that may already have compromised blood flow due to atherosclerotic disease. When vasodilators are administered, they can cause more pronounced dilation in healthy vessels compared to diseased ones, leading to an unequal distribution of blood flow. This disparity is important in stress testing, as it helps to differentiate between areas of the heart that are receiving adequate blood flow and those that are not, aiding in the diagnosis of conditions like ischemia. In contrast, other options may describe potential side effects or outcomes of vasodilators, but they do not capture the hallmark effects related to the mechanism of action during stress testing as effectively as hyperemia and flow disparity do.