A 62-year-old man with triple-vessel coronary artery disease and angiographically proven collaterals is undergoing CABG. The anaesthetist notices ST-segment depression in the territory distal to a totally occluded vessel while being maintained on a volatile agent at 1.2 MAC. Which agent, by virtue of its potent coronary arteriolar vasodilating property, is classically associated with the 'coronary steal' phenomenon?
- A Halothane
- B Sevoflurane
- C Isoflurane ✓
- D Desflurane
Correct answer: C. Isoflurane
Explanation
Isoflurane is the most potent coronary vasodilator among the volatile agents and can produce intracoronary steal: it dilates normal resistance vessels, diverting flow away from collateral-dependent myocardium supplied by maximally dilated vessels distal to an occlusion. Sevoflurane has minimal coronary vasodilating effect, which is why it is preferred in patients with coronary steal-prone anatomy. Halothane depresses myocardium without selective arteriolar dilation, so it does not cause steal.
Reference: Morgan and Mikhail's Clinical Anesthesiology, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.