What is the immediate treatment for a patient presenting with ventricular tachycardia?

Immediate Treatment of Ventricular Tachycardia

For hemodynamically unstable ventricular tachycardia, perform immediate synchronized cardioversion starting at 100 J (biphasic) for monomorphic VT, escalating stepwise if unsuccessful; for hemodynamically stable monomorphic VT, electrical cardioversion remains first-line, but procainamide is the most efficacious pharmacologic agent if medical management is chosen. 1, 2

Initial Assessment: Determine Hemodynamic Stability

Your first critical decision point is assessing whether the patient is stable or unstable. Look specifically for:

• Hypotension (systolic BP ≤90 mmHg) 2
• Acute altered mental status 3, 1
• Ischemic chest pain or discomfort 3, 2
• Signs of acute heart failure (pulmonary edema, severe dyspnea) 3, 2
• Other signs of shock (cool extremities, poor perfusion) 3

Critical threshold: With heart rates <150 bpm and no ventricular dysfunction, the tachycardia is more likely secondary to an underlying condition rather than the primary cause of instability 3. However, any of the above signs mandate treating the VT as unstable.

Hemodynamically Unstable VT: Immediate Electrical Therapy

Proceed directly to synchronized cardioversion without delay 3, 1:

• For monomorphic VT: Start with 100 J synchronized shock (biphasic defibrillator) 3, 1, 2
• If unsuccessful, escalate to 200 J, then 360 J 2
• Provide sedation if the patient is conscious but do not delay cardioversion if the patient is extremely unstable 3, 1
• For polymorphic VT: Use unsynchronized high-energy shocks (200 J defibrillation dose) as you would treat ventricular fibrillation 3, 1

Critical pitfall: Synchronized cardioversion must not be used for polymorphic VT or pulseless VT, as the device may fail to sense a QRS and not deliver the shock 3. These require defibrillation doses.

Hemodynamically Stable Monomorphic VT: Treatment Options

While electrical cardioversion remains first-line even for stable patients 1, 4, pharmacologic options exist:

First-Line Pharmacologic Agent: Procainamide

Procainamide demonstrates the greatest efficacy among antiarrhythmic drugs for stable monomorphic VT 2, 5:

• Dosing: 10 mg/kg IV at 50-100 mg/min over 10-20 minutes (maximum 10-20 mg/kg) 2, 5
• Monitor continuously for hypotension and QRS widening during administration 2
• Contraindications: Avoid in patients with severe heart failure or acute myocardial infarction 2

Alternative Agent: Amiodarone

Use amiodarone when procainamide is contraindicated, particularly in patients with heart failure or suspected ischemia 3, 2:

• Loading dose: 150 mg (5 mg/kg) IV over 10 minutes 3, 2, 6
• Maintenance infusion: 1 mg/min for 6 hours, then 0.5 mg/min 2, 6
• FDA indication: Specifically approved for hemodynamically unstable VT and frequently recurring VF refractory to other therapy 6
• Amiodarone may be superior to lidocaine, especially in patients with recurrent sustained VT requiring cardioversion 3

Other Agents with Limited Role

• Beta-blockers: First-line for stable VT in the post-MI setting unless contraindicated 3
• Lidocaine: Only moderately effective; initial loading dose 1 mg/kg IV, followed by 0.5 mg/kg every 8-10 min to maximum 4 mg/kg, or continuous infusion 1-3 mg/min 3, 4
• Sotalol: May be considered but exercise caution due to significant beta-blocking properties 2

Critical pitfall: Never use calcium channel blockers (verapamil, diltiazem) in VT with suspected structural heart disease—they may precipitate hemodynamic collapse 4, 2.

Special Consideration: Polymorphic VT

The approach differs based on QT interval:

• Normal QT interval (likely ischemia-related): Consider IV beta-blockers and aggressively treat underlying ischemia 2
• Prolonged QT (Torsades de Pointes): Administer IV magnesium sulfate 8 mmol bolus followed by 2.5 mmol/h infusion 2
• Correct electrolyte abnormalities (potassium, magnesium) immediately 3, 2

Post-Cardioversion Management

After successful rhythm conversion:

• Continuous cardiac monitoring for VT recurrence 1
• Obtain 12-lead ECG to assess for ST-segment elevation or ischemic changes 1
• Correct electrolyte imbalances immediately, particularly potassium and magnesium 3, 2
• Start IV beta-blockers to prevent recurrent arrhythmias 1
• If VT recurs after cardioversion, administer antiarrhythmic drugs to prevent reinitiation 2

Refractory or Recurrent VT

For patients with incessant VT or electrical storm despite optimal medical therapy:

• Urgent catheter ablation is indicated for scar-related heart disease 1, 2
• Consider transvenous overdrive pacing if catheter ablation is not immediately available 1

Critical Diagnostic Distinction

Always differentiate true VT from accelerated idioventricular rhythm (ventricular rate <120 bpm), which is usually a harmless consequence of reperfusion and requires no specific therapy 3.

When in doubt with wide-complex tachycardia, treat as VT rather than assuming supraventricular tachycardia with aberrancy 2.