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Aortic Stenosis — FRCA Final MCQ

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ModerateGeneral AnaesthesiaAortic StenosisFRCA Final

A 65-year-old man with severe aortic stenosis (valve area 0.7 cm², mean gradient 52 mmHg) requires emergency laparotomy. Before induction, he is in sinus rhythm at 70 min−1 with a mean arterial pressure of 80 mmHg and no pulmonary oedema. If all other haemodynamic variables remain unchanged, which sudden sustained change is most likely to precipitate myocardial ischaemia and haemodynamic decompensation?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — Heart rate increases from 70 to 130 min−1

Explanation lettering: C = shown as A · D = shown as C · A = shown as D

B is correct. Severe aortic stenosis produces a fixed obstruction and a hypertrophied, poorly compliant left ventricle with high oxygen demand. Marked tachycardia shortens diastole, reducing ventricular filling and the time available for coronary perfusion, while simultaneously increasing myocardial oxygen consumption. This can rapidly cause subendocardial ischaemia and decompensation. Bradycardia can reduce cardiac output because stroke volume cannot increase freely, but a rate of 55 min−1 is less immediately hazardous than a rate of 130 min−1. Modest increases in preload, systemic vascular resistance or arterial pressure are generally tolerated and may support filling or coronary perfusion; excessive increases could be harmful, but the quantified changes presented are comparatively small.

Reference: Eichlseder M, Schreiber N, Flick M, Sartori S. Perioperative management of adults with heart valve disease having noncardiac surgery: a narrative review. Current Opinion in Anaesthesiology. 2026;39(3):371–380. https://pubmed.ncbi.nlm.nih.gov/41885311/