Safest Skeletal Muscle Relaxant in Patients with Implanted Defibrillators
Rocuronium is the safest skeletal muscle relaxant for patients with implanted cardioverter-defibrillators (ICDs), as it is a non-depolarizing agent that does not interfere with device sensing or defibrillation thresholds and can be reliably reversed with sugammadex. 1
Why Rocuronium is the Preferred Agent
Rocuronium does not affect ICD sensing algorithms or defibrillation thresholds, making it the optimal choice when neuromuscular blockade is required in this population 1. 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.
Critical: Avoid Depolarizing Agents
Succinylcholine must 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 strongly favors non-depolarizing agents in ICD patients, even when rapid sequence intubation is required 1.
Dosing Strategy
- Standard intubating dose is 0.6 mg/kg (2 x ED95), providing good to excellent intubating conditions within 60-90 seconds 1
- Calculate dose based on lean body weight in obese patients rather than actual body weight 1
Reversal Protocol is Mandatory
Sugammadex provides reliable reversal and is essential for safe use of rocuronium in this population 1:
Neuromuscular monitoring must be used to determine the depth of blockade and appropriate sugammadex dose, as well as to identify potential recurarization 1. 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.
ICD-Specific Precautions During the 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 2, 1. This is standard practice for all patients with implanted cardiac devices undergoing procedures 2.
If cardioversion is required during the procedure, paddles should be positioned in anterior-posterior configuration to minimize risk to the ICD generator 2, 1. The anterior-posterior electrode configuration reduces the risk of exit block compared to positioning one paddle near the impulse generator and the other over the cardiac apex 2.
Common Pitfalls to Avoid
- Do not position defibrillation pads directly over the ICD generator if emergency cardioversion becomes necessary, as this increases risk of device malfunction 1
- Do not rely on clinical assessment alone for reversal adequacy—objective neuromuscular monitoring is mandatory to prevent residual blockade 1
- Gloves should be worn by healthcare providers coming into contact with patients during potential device discharge to limit risk of electrification 3
- A ring magnet must be available to inactivate the ICD unit if necessary during the procedure 3
Alternative Muscle Relaxants Are Not Recommended
While other skeletal muscle relaxants like cyclobenzaprine, carisoprodol, and tizanidine are used for musculoskeletal conditions 4, 5, these oral agents are not appropriate for procedural neuromuscular blockade and lack the specific safety profile established for rocuronium in ICD patients 1. The evidence supporting rocuronium's safety in this population is based on its lack of interference with device function, which has not been established for other agents 1.