A patient with severe aortic stenosis (valve area 0.6 cm², mean gradient 55 mmHg) requires hip replacement. Which haemodynamic goal is most critical during intraoperative management?

• A Maintain heart rate >100 bpm to optimise cardiac output
• B Use epidural to reduce afterload
• C Permit mild hypotension to reduce cardiac work
• D Avoid hypotension; maintain normal sinus rhythm, avoid tachycardia, and maintain adequate preload and afterload ✓

Explanation

In severe AS, the fixed cardiac output depends critically on: maintaining sinus rhythm (avoid AF/tachycardia — as tachycardia reduces diastolic filling time for the hypertrophied LV), adequate preload (hypertrophied LV requires high filling pressures), avoiding afterload reduction (the obstructed LV cannot compensate for peripheral vasodilation), and avoiding hypotension (coronary perfusion occurs in diastole and hypertrophied LV is highly susceptible to subendocardial ischaemia). Spinal or epidural anaesthesia causing rapid sympathectomy and vasodilation is hazardous. General anaesthesia with careful titration is preferred.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.