Aortic Regurgitation Haemodynamics — FRCA Final MCQ

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ModerateGeneral AnaesthesiaAortic Regurgitation HaemodynamicsFRCA Final

A 74-year-old man with chronic moderate aortic regurgitation and preserved left ventricular systolic function undergoes elective total hip replacement under general anaesthesia. During maintenance of anaesthesia, his heart rate is 55 beats min−1. Which isolated haemodynamic change would best support forward cardiac output?

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Reveal the answer and explanation

Correct answer: B — Increase heart rate to 80 beats min−1

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

The best change is **B: increase the heart rate to 80 beats min−1**. Aortic regurgitation occurs during diastole, so bradycardia prolongs the time available for regurgitant flow. A modest increase to a high-normal heart rate shortens diastole and supports forward cardiac output. Marked tachycardia is not required and may impair ventricular filling or increase myocardial oxygen demand. Increasing systemic vascular resistance raises the aorta-to-left-ventricle pressure gradient and impedes forward ejection. Preload should generally be maintained because the dilated left ventricle depends on adequate filling to sustain stroke volume. Contractility should also be preserved; negative inotropy reduces forward output. Thus option A worsens regurgitation, while C, D and E all oppose the desired high-flow, low-afterload haemodynamic state.

Reference: Reil JC et al. Impact of heart rate, aortic compliance and stroke volume on the aortic regurgitation fraction studied in an ex vivo pig model. Open Heart. 2023;10:e002319. https://openheart.bmj.com/content/10/2/e002319