Treatment of Ventricular Tachycardia
The treatment of ventricular tachycardia (VT) should prioritize early electrical cardioversion for hemodynamically unstable patients, while pharmacological therapy with intravenous lidocaine is the first-line drug treatment for stable VT. 1
Initial Assessment and Management
Hemodynamic Stability Assessment
- First determine if the patient has a pulse and assess hemodynamic stability 1
- Check for adverse signs: systolic BP ≤90 mmHg, chest pain, heart failure, or heart rate ≥150 beats/min 1
Unstable VT (with pulse but hemodynamically compromised)
- Immediate synchronized DC cardioversion is recommended (100J, 200J, 360J) 1
- Sedate patient prior to cardioversion if conscious 1
- For refractory cases, consider double sequential cardioversion to avoid medication-induced hypotension 2
Pulseless VT
- Follow VF/pulseless VT protocol with immediate defibrillation as the priority 1
- Early defibrillation is more important than initial drug therapy 1
Pharmacological Management
First-Line Drug Therapy for Stable VT
- Lidocaine (lignocaine) is the first-choice antiarrhythmic for VT 1
- Dosing: 50 mg IV over 2 minutes, repeated every 5 minutes to total dose of 200 mg 1
- If successful, maintain with infusion at 2-4 mg/min 1
Second-Line Drug Therapy
- Amiodarone is indicated for VT refractory to lidocaine 1, 3
- FDA-approved for hemodynamically unstable VT refractory to other therapy 3
- Dosing: 5 mg/kg (300 mg) over one hour for stable patients; can be given over 15 minutes in life-threatening situations 1
- Maintenance: Further loading dose of 15 mg/kg (up to 900 mg) over 24 hours 1
- Note: Amiodarone has a delayed onset of action (up to 30 minutes) and is associated with significant side effects 1, 4
Other Pharmacological Options
- Procainamide can be considered for stable VT without severe heart failure or acute MI 1, 5
- Magnesium (8 mmol bolus followed by 2.5 mmol/h infusion) may be effective for VT associated with acute myocardial infarction 1
- Bretylium (5 mg/kg) can be used for refractory VT that does not respond to other agents 1
Comparative Efficacy
- Head-to-head studies show amiodarone is more effective than lidocaine for shock-resistant VT (78% vs 27% immediate termination rate) 6
- However, amiodarone has a relatively slow onset and is only moderately effective for acute termination of VT (29% success rate in one study) 4
Long-Term Management
- Catheter ablation is recommended for:
Important Considerations
- Always administer IV drugs with a 20 ml saline bolus to aid delivery to central circulation 1
- Monitor for hypotension with antiarrhythmic drugs, especially in already compromised patients 2, 6
- Lidocaine can cause CNS side effects including paraesthesia, drowsiness, and seizures at toxic levels 1
- Amiodarone has a long half-life (up to 100 days) and serious long-term side effects 1