coronary steal phenomenon
Paradoxical reduction in blood flow to ischemic myocardium when coronary vasodilators preferentially dilate vessels supplying normal tissue.
Full Definition
Coronary steal phenomenon occurs when pharmacologic vasodilators, such as adenosine or dipyridamole, cause preferential vasodilation in normal coronary vessels while leaving stenotic vessels relatively unchanged. This differential response can redirect blood flow away from areas supplied by stenotic arteries toward regions with normal vessels, potentially worsening ischemia in already compromised myocardium. The phenomenon is exploited diagnostically in pharmacologic stress testing but can be problematic therapeutically. Emergency clinicians must be aware that certain vasodilators may paradoxically worsen ischemia in patients with significant coronary artery disease, particularly when used inappropriately in acute coronary syndromes.
Usage
Usage note: Distinguish from no-reflow phenomenon, which occurs at the microvascular level post-intervention.
In Context
- "The patient experienced chest pain during adenosine administration, likely due to coronary steal phenomenon in the setting of multivessel disease." — Stress test report
- "Coronary steal phenomenon should be considered when vasodilator therapy paradoxically worsens ischemic symptoms." — Clinical teaching material