Lidocaine Dosing for Persistent Ventricular Tachycardia
For persistent ventricular tachycardia, administer lidocaine as an initial IV bolus of 1.0 to 1.5 mg/kg (not exceeding 100 mg), followed by supplemental boluses of 0.5 to 0.75 mg/kg every 5-10 minutes as needed up to a maximum total loading dose of 3 mg/kg, then maintain with a continuous infusion of 2-4 mg/min (30-50 mcg/kg/min). 1, 2
Critical Context: Lidocaine is Second-Line Therapy
Lidocaine is less effective than procainamide, sotalol, and amiodarone for terminating ventricular tachycardia. 1, 2 Studies demonstrate lidocaine terminates stable VT in only 8-27% of cases compared to 67-78% with amiodarone. 3, 4
Lidocaine should be reserved for VT specifically associated with acute myocardial ischemia or infarction. 1, 2 In non-ischemic settings, procainamide or amiodarone are superior first-line choices. 1
Loading Dose Protocol
Initial Bolus
Supplemental Boluses (if VT persists)
- 0.5 to 0.75 mg/kg every 5-10 minutes 1, 2
- Maximum cumulative loading dose: 3-4 mg/kg 1, 2, 6
- Alternative dosing: 50 mg every 5 minutes up to 200 mg total 5
Maintenance Infusion
After successful termination of VT:
- Standard rate: 2-4 mg/min (or 30-50 mcg/kg/min) 1, 2
- Higher doses (40-50 mcg/kg/min) may be required if multiple boluses were needed to suppress the arrhythmia 2, 6
- In a 70 kg patient, this translates to 1.4-3.5 mg/min 2, 6
Critical Dose Reductions Required
Reduce infusion rates by 50% or more in: 2, 6
- Patients >70 years of age
- Congestive heart failure or cardiogenic shock (lidocaine clearance decreases dramatically; half-life increases to >20 hours) 2
- Hepatic dysfunction
- Acute myocardial infarction 1
This is a critical safety issue—failure to reduce doses in these populations leads to toxicity. 2, 6
Duration and Monitoring
- Reduce infusion by 1 mg/min at 12-24 hours as lidocaine half-life increases with prolonged infusion 6
- Monitor plasma levels 30-120 minutes after initiation 6
- Avoid prophylactic use beyond 24 hours unless specifically indicated 6
When Lidocaine is NOT the Answer
Hemodynamically Unstable VT
Immediate synchronized cardioversion (100J, 200J, 360J) is the primary intervention—not lidocaine. 1, 5 Pharmacologic therapy is secondary. 5
Stable Monomorphic VT (Non-Ischemic)
Procainamide is the preferred agent (10 mg/kg at 20-30 mg/min), with superior termination rates compared to lidocaine. 1 Amiodarone (150 mg over 10 minutes) is reasonable for patients with heart failure or when procainamide is unavailable. 1, 2
Refractory or Recurrent VT
Amiodarone (150 mg IV over 10 minutes, then 1 mg/min for 6 hours, then 0.5 mg/min) is indicated when VT is refractory to lidocaine. 1, 5
Monitoring for Toxicity
CNS Symptoms (Most Common)
Watch for progressive signs: 2, 6
- Early: Nausea, drowsiness, perioral numbness, dizziness
- Moderate: Confusion, slurred speech, double vision
- Severe: Muscle twitching, seizures, respiratory depression
Cardiovascular Effects
Common Pitfalls to Avoid
Using standard doses in heart failure or shock without reduction—this is the most critical error leading to toxicity 2, 6
Relying on lidocaine as first-line for stable VT in non-MI settings—procainamide or amiodarone are more effective 1, 2
Increasing maintenance infusion without an additional bolus—this results in very slow increase in plasma concentration (>6 hours to reach plateau) 6
Continuing to administer multiple antiarrhythmic drugs when one fails—proceed to electrical cardioversion instead 7
Using lidocaine for wide-complex tachycardia of unknown origin—presume VT and treat accordingly, but consider procainamide or amiodarone as superior options 1