Perioperative Management of a Patient with Severe Aortic Stenosis for Hip Fracture Surgery
An 82-year-old female (weight 60 kg) with severe aortic stenosis (aortic valve area 0.8 cm², mean gradient 45 mmHg, LVEF 55%) falls and sustains a displaced femoral neck fracture. She is scheduled for hemiarthroplasty. She has a history of hypertension, type 2 diabetes, and chronic kidney disease stage 3 (eGFR 40 mL/min/1.73m²). She is on metoprolol, amlodipine, and insulin. Her BP is 150/80 mmHg, HR 70 bpm, and she is in sinus rhythm. She is anxious and in pain. You plan spinal anesthesia.
1. What are the key considerations for spinal anesthesia in this patient with severe aortic stenosis?
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The main goal in severe aortic stenosis is to maintain sinus rhythm, adequate preload, and afterload to ensure coronary perfusion. Spinal anesthesia can cause sympathectomy leading to hypotension and decreased afterload, which can be detrimental. Therefore, I would use a low-dose spinal technique (e.g., hyperbaric bupivacaine 0.5% 1.5-2.0 mL) to achieve a T10 sensory level, avoiding a high block. I would preload with 250-500 mL crystalloid and use vasopressors (phenylephrine) to maintain BP. I would avoid drugs that increase heart rate (e.g., ephedrine) because tachycardia can worsen ischemia. I would also monitor closely for any signs of myocardial ischemia. The rationale is to avoid the 'fixed cardiac output' state where hypotension can lead to severe ischemia. If spinal anesthesia is inadequate or hypotension is refractory, I would convert to general anesthesia with invasive monitoring.
2. How would you manage her chronic medications on the day of surgery?
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For metoprolol, I would continue it on the day of surgery to avoid rebound tachycardia and hypertension, which could be dangerous in aortic stenosis. For amlodipine, I would also continue it, as abrupt withdrawal can cause hypertension. For insulin, I would hold the morning dose and monitor blood glucose, treating with sliding-scale insulin as needed to maintain glucose between 140-180 mg/dL. I would also check renal function and adjust medication doses accordingly. The rationale is to maintain hemodynamic stability and avoid perioperative complications. I would involve the endocrinology team if needed.