What is the immediate management for a patient presenting with ventricular tachycardia on an electrocardiogram (ECG)?

Immediate Management of Ventricular Tachycardia on ECG

For hemodynamically unstable ventricular tachycardia, perform immediate synchronized direct current cardioversion without delay; for stable monomorphic VT, intravenous procainamide is the preferred first-line pharmacological agent, while amiodarone is preferred in patients with heart failure or impaired left ventricular function. 1, 2

Initial Assessment: Hemodynamic Stability

Immediately assess for signs of hemodynamic instability including hypotension, altered mental status, signs of shock, chest pain, or acute heart failure symptoms. 1, 2, 3 This single determination drives all subsequent management decisions.

• If the patient is hypotensive yet conscious, provide immediate sedation before cardioversion 2
• Obtain a 12-lead ECG for all hemodynamically stable patients with sustained VT 4
• When in doubt about the diagnosis of wide-complex tachycardia, always treat as VT - never assume it is supraventricular 2

Management Algorithm for Unstable VT

Proceed directly to synchronized cardioversion without attempting pharmacological conversion in unstable patients. 1, 2, 3

• Use 100 J synchronized discharge for monomorphic VT with rates >150 bpm 2
• Use unsynchronized 200 J discharge for polymorphic VT that appears similar to VF 2
• Begin with maximum output for defibrillation to ensure successful termination 4
• If initial cardioversion fails, repeat attempts after adjusting electrode location, applying pressure over electrodes, or administering antiarrhythmic medication 3

For recurrent VT after cardioversion, administer amiodarone 150 mg IV over 10 minutes before subsequent cardioversion attempts. 2, 3, 5

Management Algorithm for Stable Monomorphic VT

First-Line Pharmacological Therapy

Intravenous procainamide is the preferred first-line agent for hemodynamically stable monomorphic VT due to greatest efficacy for rhythm conversion. 2

• Administer procainamide 10 mg/kg IV at 50-100 mg/min over 10-20 minutes 2
• Maximum rate: do not exceed 50 mg per minute 6
• Maximum initial dose: 500-600 mg, with 1 gram as absolute maximum 6
• Monitor blood pressure and ECG continuously during infusion 2, 6
• Stop infusion if persistent conduction disturbances or hypotension develop 6

Alternative Agent: Amiodarone

Use intravenous amiodarone instead of procainamide in patients with heart failure, suspected myocardial ischemia, or impaired left ventricular function. 1, 2

• Loading dose: 150 mg IV over 10 minutes 1, 2, 5
• Maintenance infusion: 1 mg/min for 6 hours, then 0.5 mg/min 5
• Maximum initial infusion rate: 30 mg/min 5
• Administer through central venous catheter for concentrations >2 mg/mL 5
• Use volumetric infusion pump, not drop counter sets 5

Second-Line Options

• Sotalol: 1.5 mg/kg IV over 5 minutes may be considered for stable monomorphic VT 3
• Lidocaine: Only moderately effective, consider second-line 2, 4

Management of Polymorphic VT

Direct current cardioversion is first-line for hemodynamically compromised polymorphic VT. 2

• For recurrent polymorphic VT with suspected ischemia: intravenous beta-blockers 2
• For recurrent polymorphic VT without QT prolongation: intravenous amiodarone loading 2
• For polymorphic VT with long QT (torsades de pointes): intravenous magnesium, overdrive pacing, and beta-blockers 2

Post-Conversion Management

After successful conversion, evaluate and correct underlying causes including ongoing myocardial ischemia, electrolyte abnormalities (especially hypokalemia), hypoxia, and acid-base disturbances. 4

• Beta-blockers are first-line therapy for preventing recurrence unless contraindicated, particularly post-MI 4
• Monitor closely for recurrence as it is common 4
• Consider urgent catheter ablation for scar-related heart disease with incessant VT or electrical storm 1, 2
• For ischemic heart disease with recurrent ICD shocks due to sustained VT, catheter ablation should be considered 1, 2

Critical Pitfalls to Avoid

Never use calcium channel blockers (verapamil, diltiazem) in patients with VT and structural heart disease - they may precipitate hemodynamic collapse. 1, 2 The only exception is fascicular VT with RBBB morphology and left axis deviation, where these agents may be considered. 4

• Do not delay cardioversion in unstable patients while attempting pharmacological conversion 4
• Electrical cardioversion is contraindicated in digitalis toxicity or hypokalemia 3
• Do not use drop counter infusion sets for amiodarone - they may underdose by up to 30% 5
• Avoid amiodarone loading infusions at concentrations and rates faster than recommended - this has resulted in hepatocellular necrosis, acute renal failure, and death 5

Special Considerations

• Acute coronary syndrome: Prompt coronary revascularization is recommended for recurrent VT or VF when myocardial ischemia is present 1
• Pregnancy: Immediate electrical cardioversion is recommended for sustained VT, especially if hemodynamically unstable 1
• Accelerated idioventricular rhythm (ventricular rate <120 bpm): Usually a harmless reperfusion rhythm requiring no treatment - distinguish this from true VT 4