Treatment of Significant Ventricular Tachycardia
For hemodynamically unstable VT, perform immediate synchronized DC cardioversion without delay; for stable monomorphic VT, intravenous procainamide is the first-line pharmacological treatment. 1
Initial Assessment: Determine Hemodynamic Stability
The critical first step is determining whether the patient is hemodynamically stable or unstable. 2
Unstable VT is defined by:
- Hypotension
- Chest pain
- Heart failure symptoms
- Heart rate ≥150 beats/min
- Altered mental status or loss of consciousness 2, 3
Key principle: When diagnosis is unclear, presume any wide-QRS tachycardia to be VT. 1
Treatment Algorithm
Hemodynamically Unstable VT
Immediate synchronized DC cardioversion is mandatory. 1
- Start at 100J, escalate to 200J, then 360J if needed 2
- Sedate the conscious patient if time permits, but do not delay cardioversion 2
- This is a Class I recommendation with the highest level of evidence 1
Hemodynamically Stable Monomorphic VT
First-line pharmacological treatment: Intravenous procainamide 1, 2, 4
Procainamide dosing:
- 10-20 mg/kg IV at 50-100 mg/min over 10-20 minutes 2, 4
- This is a Class IIa recommendation with Level B evidence 1
- Monitor continuously for hypotension and QRS widening during administration 2
- Close blood pressure monitoring is essential, especially with congestive heart failure 1
Alternative agents (when procainamide unavailable or contraindicated):
Amiodarone: Reasonable for stable monomorphic VT, though not ideal for early conversion 1, 5
- Loading dose: approximately 1000 mg over first 24 hours 5
- Initial rapid infusion: 150 mg over 10 minutes 5
- Followed by 1 mg/min for 6 hours, then 0.5 mg/min maintenance 5
- Antiarrhythmic effect may take up to 30 minutes 2
- Class IIa recommendation for unstable VT refractory to cardioversion or recurrent despite procainamide 1
Lidocaine: May be reasonable specifically for VT associated with acute myocardial ischemia or infarction 1
Sotalol: May be considered for stable sustained monomorphic VT 1
Polymorphic VT
Treatment depends on QT interval:
Normal QT interval (ischemia-related):
- Immediate DC cardioversion if hemodynamically unstable 1
- IV beta-blockers for recurrent polymorphic VT, especially if ischemia suspected 1
- IV amiodarone loading for recurrent episodes 1
- Urgent angiography with revascularization consideration 1
Prolonged QT interval (Torsades de Pointes):
- IV magnesium: 8 mmol bolus followed by 2.5 mmol/h infusion 2
- Overdrive pacing (atrial or ventricular) 1
- Beta-blockers for familial long QT syndrome 1, 2
Refractory or Recurrent VT
If initial pharmacological therapy fails:
- Proceed directly to synchronized cardioversion rather than trying multiple drugs sequentially 6
- Transvenous catheter pace termination for VT refractory to cardioversion or frequently recurrent despite medications 1
- For breakthrough episodes: 150 mg amiodarone supplemental infusions over 10 minutes 1, 5
Critical Pitfalls to Avoid
Never use calcium channel blockers (verapamil, diltiazem) for wide-QRS tachycardia of unknown origin, especially with myocardial dysfunction. 1 This is a Class III recommendation (harm).
Amiodarone is not ideal for early conversion of stable monomorphic VT despite its frequent use. 1 Procainamide is more appropriate when rapid termination is desired. 1
Correct underlying conditions early:
- Hypokalemia
- Hypomagnesemia
- Ongoing ischemia 1
Administration considerations for amiodarone:
- Must use volumetric infusion pump, not drop counters (can underdose by 30%) 5
- Concentrations >2 mg/mL require central venous catheter to avoid phlebitis 5
- Administer through dedicated central line with in-line filter 5
Post-Conversion Management
After successful conversion:
- Initiate antiarrhythmic infusion to prevent recurrence 3
- Beta-blockers reduce recurrent and refractory ventricular arrhythmias during electrical storm 1
- Consider ICD implantation for secondary prevention in structural heart disease 2
- Evaluate for coronary revascularization if obstructive disease present 1