Severe aortic stenosis and hip fracture surgery
An 82-year-old woman (58 kg, 155 cm) is admitted with a displaced left femoral neck fracture after a fall. She has severe aortic stenosis: transthoracic echocardiography two weeks ago showed an aortic valve area of 0.7 cm², mean gradient 48 mmHg, peak velocity 4.2 m/s, LVEF 55%, and mild mitral regurgitation. She reports two episodes of exertional syncope in the past month and is NYHA class III. Her medications are aspirin 75 mg daily, atorvastatin 40 mg, and bisoprolol 2.5 mg. Blood pressure is 138/72 mmHg, heart rate 64/min in sinus rhythm. Haemoglobin is 92 g/L, platelets 210 ×10⁹/L, INR 1.0, creatinine 96 µmol/L. The multidisciplinary team plans cemented hemiarthroplasty within 24 hours. She is anxious and asks whether she can be awake for the operation. There is no critical care bed immediately available, but a level 2 bed can be arranged postoperatively.
1. Compare a single-shot spinal, a general anaesthetic, and a combined technique for this patient. State your preferred plan and the haemodynamic targets that guide it.
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The key physiological problem is a fixed cardiac output. Coronary perfusion depends on diastolic pressure, so the goals are to preserve sinus rhythm, preload, afterload, and avoid tachycardia.
- Single-shot spinal: rapid, avoids airway instrumentation, and allows an awake patient. However, sympathectomy causes venodilation and a fall in SVR; in severe aortic stenosis this can precipitate profound hypotension and myocardial ischaemia. A low-dose spinal (e.g. hyperbaric bupivacaine 7.5 mg plus fentanyl 20 µg) given incrementally, with immediate phenylephrine support, is defensible.
- General anaesthesia: gives control of ventilation and airway but induction agents cause vasodilation; laryngoscopy causes sympathetic stimulation. It is preferred if the patient cannot lie flat, is uncooperative, or has a contraindication to neuraxial block.
- Combined spinal-epidural: allows titration but is slower and leaves a catheter in a patient who may need postoperative anticoagulation.
My preferred plan is a low-dose single-shot spinal with invasive arterial monitoring, a phenylephrine infusion ready, and general anaesthesia immediately available. Targets: systolic BP within 20% of baseline, MAP at least 65–70 mmHg, heart rate 60–80/min in sinus rhythm, and avoidance of aortocaval compression. If hypotension cannot be controlled, convert to general anaesthesia with careful induction rather than persisting with an inadequate block.
2. Ten minutes after spinal injection, blood pressure is 84/40 mmHg and heart rate is 52/min. What is your immediate management, and what physiological reasoning guides it?
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Call for help, give 100% oxygen, confirm the block height and that the patient is conscious, and check the arterial trace and surgical field for bleeding. This is a high-risk combination because bradycardia plus vasodilation critically reduces coronary perfusion in severe aortic stenosis.
Immediate steps:
- Phenylephrine 50–100 µg IV to restore SVR and diastolic pressure.
- If bradycardia persists, glycopyrrolate 0.2 mg IV or ephedrine 3–6 mg IV. Ephedrine increases heart rate and contractility but may cause tachycardia and increase myocardial oxygen demand; use the smallest effective dose.
- A cautious 250 mL crystalloid bolus only if there is evidence of hypovolaemia; avoid indiscriminate fluid loading in fixed-output physiology.
- If refractory, start an adrenaline infusion 0.01–0.05 µg/kg/min and consider converting to general anaesthesia.
The reasoning is that phenylephrine treats the fall in SVR but can worsen reflex bradycardia. In aortic stenosis, a slow heart rate is poorly tolerated because cardiac output cannot increase, so restoring a normal sinus rate and diastolic pressure is as important as restoring SVR.
3. Where should this patient be monitored postoperatively, and what are the main risks you would actively manage?
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She needs level 2 care with continuous ECG, invasive arterial pressure monitoring, hourly urine output, and regular neurological and pain assessment. Severe aortic stenosis plus hip fracture surgery carries a high risk of perioperative myocardial infarction, arrhythmia, and acute kidney injury.
Postoperative priorities:
- Haemodynamics: avoid hypovolaemia and hypotension; continue the beta-blocker unless bradycardia or shock intervenes; do not stop aspirin abruptly after recent syncope and vascular risk.
- Myocardial injury: serial troponin and ECG; treat tachycardia and anaemia promptly. A restrictive transfusion threshold is reasonable, but in severe aortic stenosis a haemoglobin around 80–90 g/L may be inadequate if there is ongoing bleeding or ischaemia.
- Delirium and analgesia: multimodal analgesia, avoid excessive opioids, and mobilise early with physiotherapy.
- Venous thromboembolism and bleeding: mechanical prophylaxis initially, then LMWH when surgical bleeding risk allows.
- Follow-up: document the aortic stenosis and arrange cardiology review; if she develops syncope, chest pain, or heart failure, escalate urgently.