What is the initial treatment for a patient with sustained and symptomatic ventricular tachycardia?

Initial Treatment of Sustained and Symptomatic Ventricular Tachycardia

For hemodynamically unstable patients with sustained symptomatic VT, perform immediate synchronized direct-current cardioversion starting at 100-200 J with appropriate sedation; for hemodynamically stable patients with monomorphic VT, administer intravenous procainamide as first-line pharmacological therapy. 1, 2

Immediate Assessment

Determine hemodynamic stability first - this is the critical decision point that dictates all subsequent management:

• Unstable VT is defined by: systolic blood pressure ≤90 mmHg, acute chest pain, acute heart failure, heart rate ≥150 bpm, altered mental status, or signs of shock 3
• Stable VT means the patient maintains adequate blood pressure and perfusion without these concerning features 1, 2
• Presume any wide-QRS tachycardia to be VT if the diagnosis is unclear 1, 2
• Obtain a 12-lead ECG in stable patients to document rhythm and classify as monomorphic (consistent QRS) or polymorphic (changing QRS) 2

Treatment Algorithm for Hemodynamically Unstable VT

Do not delay - cardiovert immediately:

• Perform synchronized DC cardioversion starting at 100-200 J 1, 3
• Sedate the conscious patient immediately before cardioversion 1, 2
• Escalate energy to 360 J if initial shocks fail 3
• Have full resuscitation equipment readily available 2
• If VT is refractory to cardioversion or recurs despite countershock, administer IV amiodarone 150 mg over 10 minutes 1, 2

Treatment Algorithm for Hemodynamically Stable Monomorphic VT

Pharmacological conversion is appropriate in stable patients:

First-Line: IV Procainamide

• Procainamide is the preferred initial agent for stable sustained monomorphic VT 1, 2, 3
• Dose: 10 mg/kg IV at 50-100 mg/min over 10-20 minutes (maximum 10-20 mg/kg) 3
• Monitor blood pressure closely during infusion, especially in patients with heart failure 1

Second-Line: IV Amiodarone

• Use amiodarone when procainamide fails, in patients with heart failure, or when VT is refractory to countershock 1, 2, 3
• Loading dose: 150 mg (5 mg/kg) IV over 10 minutes 3, 4
• Maintenance infusion: 1 mg/min for 6 hours, then 0.5 mg/min 3, 4
• Amiodarone is specifically indicated for hemodynamically unstable VT and frequently recurring VF/VT refractory to other therapy 4
• Administer through central venous catheter for concentrations >2 mg/mL to avoid phlebitis 4

Alternative: IV Lidocaine

• Consider lidocaine specifically if VT is associated with acute myocardial ischemia or infarction 1, 2
• Lidocaine converts only ~20% of stable VTs, making it less effective than other options 5

Treatment for Polymorphic VT

Polymorphic VT requires different management based on QT interval:

• Normal QT (ischemia-related): Administer IV beta-blockers and treat underlying ischemia aggressively 3
• Prolonged QT (Torsades de Pointes): Give IV magnesium sulfate 8 mmol bolus followed by 2.5 mmol/h infusion 3
• IV amiodarone is useful in the absence of QT prolongation 2
• Use unsynchronized defibrillation at 200 J for unstable polymorphic VT (treat like VF) 2

Post-Conversion Management

• Evaluate and correct electrolyte abnormalities, particularly potassium and magnesium 6
• Assess for myocardial ischemia with cardiac enzymes 6
• Consider maintenance antiarrhythmic therapy to prevent recurrence 2
• Obtain cardiology consultation, especially for patients with structural heart disease 6, 2
• Monitor for 24-48 hours to detect recurrent arrhythmias 6

Refractory or Recurrent VT

• For VT refractory to cardioversion or frequently recurrent despite medications, consider transvenous catheter pace termination 1, 2
• Urgent catheter ablation is recommended for incessant VT or electrical storm in patients with scar-related heart disease 2, 3
• Evaluate for ICD implantation in patients with structural heart disease and sustained VT due to high risk of recurrence and sudden death 2, 3

Critical Pitfalls to Avoid

• Never use calcium channel blockers (verapamil, diltiazem) for wide-QRS tachycardia of unknown origin, especially with myocardial dysfunction 1
• Do not use class IC antiarrhythmic drugs in patients with history of myocardial infarction 6
• Avoid routine treatment of isolated ventricular premature beats or non-sustained VT with antiarrhythmics in asymptomatic patients without structural heart disease 6
• Do not delay cardioversion in unstable patients to attempt pharmacological conversion 1, 3
• Intravenous amiodarone at concentrations >3 mg/mL causes high incidence of peripheral vein phlebitis - use central access 4