Long QT Syndrome (LQTS)

Avoid QT-prolonging drugs - The single most important rule. Steer clear of ondansetron, droperidol, haloperidol, methadone, and macrolide and fluoroquinolone antibiotics, among others on the QT list. Sevoflurane modestly prolongs the QT; propofol does not and is a reasonable primary agent.

Blunt sympathetic surges - Adrenergic stimulation triggers torsades, especially in LQT1 and LQT2. Ensure deep anesthesia before laryngoscopy, treat pain and light anesthesia promptly, and avoid ketamine and other sympathomimetics. Continue home beta-blockers through the morning of surgery.

Optimize electrolytes - Correct potassium, magnesium, and calcium before induction and keep them in the normal-to-high range; hypokalemia and hypomagnesemia lengthen the QT. Prophylactic magnesium is reasonable.

Avoid bradycardia and pauses - Pause-dependent torsades occurs in LQT2 and LQT3; avoid abrupt bradycardia and long sinus pauses, and keep chronotropic and pacing backup available.

Torsades management - Treat with magnesium sulfate 2 g IV, defibrillate if unstable, and use overdrive pacing or isoproterenol for pause-dependent runs. Have a defibrillator with pads on before induction.

Reversal choice - Neostigmine with glycopyrrolate causes abrupt heart-rate swings; where a rocuronium or vecuronium block was used, sugammadex avoids that autonomic disturbance.

Implanted devices - If an implantable cardioverter-defibrillator (ICD) is present, manage it perioperatively per protocol (magnet or reprogramming) and keep external defibrillation ready.

A disorder of prolonged ventricular repolarization - a long QT interval on the ECG - that predisposes to torsades de pointes, syncope, and sudden cardiac death. Congenital forms arise from cardiac ion-channel mutations: LQT1 and LQT2 affect potassium channels and LQT3 the sodium channel; Romano-Ward is isolated while Jervell and Lange-Nielsen also causes deafness. An acquired form results from QT-prolonging drugs and electrolyte derangements (hypokalemia, hypomagnesemia, hypocalcemia). Adrenergic surges trigger events in LQT1 and LQT2, whereas pauses and bradycardia trigger LQT2 and LQT3. The perioperative period is high-risk because sympathetic stimulation, drugs, and electrolyte shifts all converge.