What is the safest muscle relaxant to use in a patient with an implanted defibrillator (implantable cardioverter-defibrillator, ICD)?

Safest Muscle Relaxant in Patients with Implanted Defibrillators

Rocuronium is the safest muscle relaxant for patients with implanted cardioverter-defibrillators (ICDs), as it is a non-depolarizing agent that does not interfere with device function and can be reliably reversed with sugammadex. 1, 2

Why Rocuronium is Preferred

• Rocuronium does not affect ICD sensing or defibrillation thresholds, making it the optimal choice when neuromuscular blockade is required 2, 3
• The drug provides rapid onset (60-90 seconds with 0.6 mg/kg dosing) and intermediate duration of action, allowing for controlled anesthesia without prolonged paralysis 1, 3
• Rocuronium has minimal cardiovascular effects with only mild vagolytic properties and no histamine release, even at large doses, which is critical in cardiac patients 3

Reversal Strategy is Critical

• Sugammadex provides reliable reversal at doses of 2.0 mg/kg for moderate blockade, 4.0 mg/kg for deep blockade, or 8.0 mg/kg for very deep blockade 1, 2
• Neuromuscular monitoring must be used to determine the depth of blockade and appropriate sugammadex dose, as well as to identify potential recurarization 1, 2
• Reversal efficacy may be decreased in elderly patients and those with severe renal failure (creatinine clearance <30 mL/min), requiring careful monitoring in these populations 1, 2

Avoid Depolarizing Agents

• Succinylcholine should be avoided despite its rapid onset, as depolarizing agents can theoretically interfere with ICD sensing algorithms and cause muscle fasciculations that may be misinterpreted by the device 1
• The risk-benefit ratio favors non-depolarizing agents in ICD patients, even when rapid sequence intubation is required 1, 3

Dosing Considerations

• Calculate rocuronium dose based on lean body weight in obese patients rather than actual body weight 1, 2
• Standard intubating dose is 0.6 mg/kg (2 x ED95), providing good to excellent conditions within 60-90 seconds 1, 3
• Larger doses (≥1 mg/kg) may be used for rapid sequence induction but will prolong duration of action 3

ICD-Specific Precautions During Procedure

• The ICD should be interrogated before and after any procedure requiring anesthesia to ensure appropriate function, as external electrical interference or drug effects could alter programmed parameters 1
• Antiarrhythmic drugs commonly used in ICD patients (amiodarone, sotalol, dofetilide) do not contraindicate rocuronium use, though amiodarone may increase defibrillation thresholds independently 4
• If cardioversion is required during the procedure, paddles should be positioned in anterior-posterior configuration to minimize risk to the ICD generator 1

Common Pitfalls to Avoid

• Do not use long-acting muscle relaxants (doxacurium, pipecuronium) in ICD patients, as prolonged paralysis increases risk of postoperative complications and makes assessment of device function difficult 5
• Do not rely on clinical assessment alone for reversal adequacy—objective neuromuscular monitoring is mandatory to prevent residual blockade 1, 5
• Do not position defibrillation pads directly over the ICD generator if emergency cardioversion becomes necessary, as this increases risk of device malfunction 1