A 65-year-old man with severe aortic stenosis (valve area 0.7 cm²) is scheduled for elective hip replacement. Which haemodynamic goal is most critical intraoperatively to prevent cardiovascular collapse?

• A Maintain heart rate between 80–100 bpm to optimise cardiac output
• B Aggressively reduce afterload with vasodilators to improve stroke volume
• C Preserve sinus rhythm and maintain adequate preload; avoid tachycardia and hypotension ✓
• D Accept mild bradycardia (50–60 bpm) to prolong diastolic filling time

Explanation

In severe aortic stenosis the ventricle is stiff and pressure-overloaded; it is critically preload-dependent and cannot compensate for tachycardia (reduces filling time) or hypotension (reduces coronary perfusion pressure through a hypertrophied wall). Sinus rhythm is vital because atrial kick contributes up to 40% of cardiac output. Vasodilators causing afterload reduction precipitate catastrophic hypotension and are contraindicated. Modest bradycardia is tolerable but tachycardia is the primary enemy.

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

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Written and medically reviewed by the StethoPrep medical team.