Myocardial O2 Supply — FRCA Primary MCQ
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Correct answer: A — Coronary blood flow and arterial oxygen content
Myocardial O2 supply = coronary blood flow × arterial O2 content (CaO2). Coronary blood flow is determined by: perfusion pressure (aortic diastolic pressure - LVEDP) / coronary vascular resistance / and diastolic time. CaO2 depends on Hb concentration and SaO2. The heart has the highest O2 extraction ratio (~65%) of any organ with limited ability to increase extraction further.
Reference: Power Kam 2018 Principles of Physiology for the Anaesthetist