Perioperative Management of Patients with Long QT Syndrome

Pre‑operative Optimization

• Maintain beta‑blocker therapy throughout the peri‑operative period; abrupt discontinuation markedly increases the risk of breakthrough arrhythmic events (Canadian Cardiovascular Society) 1.
• Continue full‑dose nadolol or propranolol on the morning of surgery to preserve adrenergic protection (Canadian Cardiovascular Society) 2.
• Obtain a baseline 12‑lead ECG and measure QTc; if QTc ≥ 500 ms, postpone elective surgery until the interval is optimized (American Heart Association) 3.
• Correct electrolyte abnormalities before induction – aim for potassium > 4.5 mmol/L, magnesium > 2.0 mg/dL, and normal calcium levels (American Heart Association) 3.

Intra‑operative Management

• Avoid bradycardia; keep heart rate > 70 bpm because pauses trigger torsades de pointes via a short‑long‑short cycle (American Heart Association) 3.
• If bradycardia occurs, treat with temporary transvenous pacing rather than atropine to raise the rate without increasing sympathetic tone (American Heart Association) 3.
• Keep intravenous magnesium sulfate (2 g) immediately available for rapid administration if torsades de pointes develops (American Heart Association) 3.

Post‑operative Care

• Avoid all QT‑prolonging medications in the recovery period, including ondansetron, erythromycin, fluoroquinolones, and haloperidol (Canadian Cardiovascular Society) 1.
• For postoperative nausea, use aprepitant or dexamethasone instead of ondansetron or droperidol (Canadian Cardiovascular Society) 2.
• For postoperative analgesia, avoid methadone and tramadol; prefer fentanyl, morphine, or hydromorphone (Canadian Cardiovascular Society) 2.

Emergency Management of Intra‑operative Torsades de Pointes

• Administer intravenous magnesium sulfate 2 g immediately as first‑line therapy, regardless of serum magnesium level (American Heart Association) 3.
• Increase heart rate to > 70 bpm using temporary pacing or isoproterenol infusion to prevent pause‑dependent triggers (American Heart Association) 3.
• Discontinue all QT‑prolonging agents and correct electrolyte disturbances promptly (American Heart Association) 3.
• Avoid amiodarone and procainamide, which further prolong the QT interval and can worsen the arrhythmia (American Heart Association) 3.
• If torsades progresses to ventricular fibrillation, deliver immediate defibrillation (American Heart Association) 3.

Critical Pitfalls to Avoid

• Beta‑blocker therapy alone does not guarantee protection; avoidance of QT‑prolonging anesthetic agents remains essential even when patients are on nadolol (Canadian Cardiovascular Society) 1.
• Do not allow bradycardia to persist, as pauses are the most common trigger for torsades de pointes in the peri‑operative setting (American Heart Association) 3.
• Systematically review all peri‑operative medications for QT‑prolonging potential (e.g., antibiotics, antiemetics, analgesics) using reliable drug‑interaction resources (Canadian Cardiovascular Society) 2.
• Never discontinue beta‑blockers peri‑operatively, as this is a leading cause of breakthrough cardiac events in patients with Long QT Syndrome (Canadian Cardiovascular Society) 2.