Congenital Long QT Syndrome:

A cardiac ion channelopathy with important anesthetic considerations

Abstract

Context: Congenital long QT syndrome (cLQTS) is the most common genetic cardiac ion channelopathy in the US. Patients with cLQTS are at risk for ventricular tachycardia (VT) in the “torsades de pointes” (TdP) pattern from physical and emotional stress, including during the perioperative period.

Purpose: This narrative review outlines the history and pathophysiology of the most common types of cLQTS, describes treatments for cLQTS, discusses the experience of anesthesia providers with cLQTS, and reports recommendations for safe administration of anesthesia to these patients.

Methods: Searches of MEDLINE (PubMed) and Google Scholar were conducted using the terms “congenital long QT syndrome”, “LQTS”, and “cardiac ion channelopathy” combined with “surgery” and “anesthesia”.

Findings: The most common types of cLQTS (LQT1-3) are caused by loss of function mutations to potassium channels responsible for ventricular repolarization or gain of function mutations to a sodium channel responsible for depolarization. cLQTS is diagnosed using the Schwartz Criteria which considers ECG findings, clinical history, and family history. It is treated with beta blocking medication, implantable cardioverter defibrillator (ICD) insertion, or left cardiac sympathetic denervation (LCSD).  Patients with cLQTS may require anesthesia for disease-related procedures (e.g. ICD insertion or LCSD), or for treatment of issues related to cLQTS (e.g. cochlear implants for congenital sensorineural deafness). To provide a safe anesthetic, providers need to avoid medications that prolong the QTc, minimize sympathetic stimulation, assure proper function of but prevent electrical interference with ICDs, correct electrolyte imbalances, and be prepared to treat TdP. 

Importance: Pre-anesthetic precautions include considering a cardiologist consultation, checking the function of the ICD, determining a baseline QTc, correcting electrolyte imbalances, premedicating to prevent anxiety, and continuing beta blocking medications on the day of surgery. Intraoperative, the anesthesia provider should apply external defibrillator pads and all monitors prior to induction, turn off ICD or adjust its settings to avoid electromagnetic interference, monitor the QT interval, have magnesium salts ready if TdP develops, consider TIVA and use sevoflurane if an inhalation agent is needed, use propofol and/or fentanyl (or an analogue) to blunt the sympathetic response of airway manipulation, and avoid ketamine, suxamethonium, and pancuronium. During emergence, the provider should consider alternatives to anticholinesterase/ anticholinergic drug combinations, avoid droperidol or ondansetron, but consider dexamethasone as prophylaxis against PONV.

Limitations: Because there are no definitive guidelines for the anesthetic management of patients with cLQTS, the anesthesia provider must rely on case studies and review articles to choose a safe anesthetic for this challenging patient population.