What is the role of lignocaine (lidocaine) in the management of ventricular tachycardia?

Lignocaine (Lidocaine) in Ventricular Tachycardia

Lidocaine is a second-line antiarrhythmic agent for ventricular tachycardia, inferior in efficacy to procainamide, amiodarone, and sotalol, and should be reserved for recurrent VT/VF not responding to first-line therapies or when contraindications to amiodarone exist. 1, 2

Evidence for Efficacy

The evidence consistently demonstrates lidocaine's limited effectiveness:

• Lidocaine was less effective than sotalol (LOE 1), procainamide (LOE 2), and amiodarone (LOE 2) in terminating VT 1
• In a randomized trial comparing lidocaine to procainamide for hemodynamically stable monomorphic VT, procainamide terminated 12 of 15 VT episodes (80%) versus only 3 of 14 (21%) with lidocaine (p <0.01) 3
• Retrospective analyses showed lidocaine was poorly effective in patients with spontaneous sustained stable VT in the hospital setting 1
• A prospective study of 128 patients with stable VT found only 8% responded to lidocaine therapy 4

Current Guideline Recommendations

Indications for Lidocaine

The European Society of Cardiology recommends intravenous lidocaine specifically for recurrent sustained VT or VF not responding to beta-blockers or amiodarone, or when contraindications to amiodarone exist 2

• Lidocaine is indicated for recurrent sustained VT/VF associated with acute myocardial ischemia or infarction 2, 5
• For stable VT, lidocaine is considered first-choice only when other agents are contraindicated 5
• The American College of Cardiology does not recommend lidocaine as prophylactic treatment in uncomplicated acute myocardial infarction 2, as trials failed to demonstrate mortality benefit and showed increased risk of asystole 1

When NOT to Use Lidocaine

• Prophylactic use in uncomplicated MI is contraindicated due to increased asystole risk without mortality benefit 1, 2
• Lidocaine should not be used for unstable or irregular/polymorphic wide-complex tachycardia 1

Dosing Protocol

Initial Bolus Dosing

• Initial IV bolus: 1 mg/kg (maximum 100 mg) 1, 2, 5
• Additional boluses of 0.5 mg/kg every 8-10 minutes if needed, to maximum total of 4 mg/kg 1, 2
• Alternative rapid dosing for stable VT: 50 mg IV over 2 minutes, repeated every 5 minutes to total 200 mg 5

Maintenance Infusion

• Standard maintenance: 20-50 μg/kg/min (1.4-3.5 mg/min in 70 kg patient) 1, 2
• Patients requiring multiple boluses may need higher maintenance doses up to 40-50 μg/kg/min 1, 2, 5
• Target therapeutic blood level: up to 5 μg/ml 1, 2

Critical Dosage Adjustments

Elderly Patients

• Reduce infusion rate due to increased toxicity risk 2, 6

Heart Failure

• Reduce dosage significantly as half-life increases to >4 hours (versus 1-2 hours normally) 2

Cardiogenic Shock

• Substantial reduction required as half-life can exceed 20 hours 2

Hepatic Dysfunction

• Reduce dosage as lidocaine is primarily hepatically metabolized 2

After 24-48 Hours

• Reduce infusion rate as lidocaine half-life increases over time 5

Monitoring Requirements

• Monitor blood pressure and cardiovascular status closely, especially in heart failure or hypotension 2
• Consider measuring serum levels with prolonged/high infusion rates or neurologic changes 2
• Watch for CNS toxicity: nausea, drowsiness, perioral numbness, dizziness, confusion, slurred speech 5
• Severe toxicity signs: muscle twitching, seizures, respiratory depression 5
• Lidocaine depresses myocardial contractility, requiring careful monitoring in hemodynamically compromised patients 5

Treatment Algorithm for Ventricular Tachycardia

Hemodynamically Unstable VT (Systolic BP ≤90 mmHg)

1. Immediate synchronized DC cardioversion (100J, 200J, 360J) with sedation if conscious 1, 5
2. If refractory, consider amiodarone 150 mg over 10 minutes 6
3. Lidocaine as alternative if amiodarone contraindicated 2

Hemodynamically Stable Monomorphic VT

First-line agents (in order of preference):

1. Procainamide (10 mg/kg at 100 mg/min) for patients without severe CHF or acute MI 1
2. Amiodarone (150-300 mg IV) for patients with or without CHF/acute MI 1
3. Sotalol (1.5 mg/kg over 5 minutes) - avoid if prolonged QT 1

Second-line agent:

• Lidocaine only after first-line agents fail or are contraindicated 1, 2

Recurrent/Refractory VT Storm

The European Society of Cardiology recommends this sequence:

1. Beta-blockers (most effective for polymorphic VT storm) 6
2. Amiodarone 150 mg over 10 minutes, then 1.0 mg/min for 6 hours 6
3. Lidocaine as alternative or addition, particularly when VT related to myocardial ischemia 6

Common Pitfalls and Caveats

• Do not use multiple sequential antiarrhythmic drugs if first agent fails - proceed to electrical cardioversion instead 7
• Avoid prophylactic use - no mortality benefit and increased asystole risk 1, 2
• Do not use in undifferentiated wide-complex tachycardia - adenosine is safer for diagnosis 1
• Remember dose adjustments - failure to reduce dosing in elderly, heart failure, or hepatic dysfunction leads to toxicity 2
• Lidocaine use is obsolete for stable VT when other agents are available 7
• Class IC agents (flecainide, propafenone) or ajmaline are more effective alternatives when available 7

Special Clinical Context

For acute myocardial infarction with VT:

• Lidocaine remains indicated for frequent PVCs (>6/min), closely coupled beats (R-on-T), multiform PVCs, or runs of ≥3 beats 1
• Use for VF resistant to defibrillation 1
• However, prophylactic use is not recommended 1, 2