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, synchronized cardioversion remains first-line, but procainamide (10 mg/kg IV at 50-100 mg/min) is the most efficacious pharmacologic option if medical management is chosen. 1, 2, 3, 4

Initial Assessment: Determine Hemodynamic Stability

Your first critical decision point is assessing whether the patient is stable or unstable. Look specifically for: 1, 2

• Hypotension (systolic BP ≤90 mmHg) 3
• Altered mental status or syncope 5, 1
• Acute chest pain or signs of ongoing ischemia 1, 3
• Signs of acute heart failure (pulmonary edema, severe dyspnea) 5, 3
• Signs of shock (cool extremities, poor perfusion) 5, 1

Critical caveat: With heart rates <150 bpm in the absence of ventricular dysfunction, the tachycardia is more likely secondary to an underlying condition rather than the primary cause of instability. 5

Hemodynamically Unstable VT: Immediate Electrical Therapy

Do not delay cardioversion in unstable patients. 1, 3

Monomorphic VT (Regular Rhythm)

• Start with 100 J synchronized cardioversion using a biphasic defibrillator 5, 2, 3
• If unsuccessful, escalate to 200 J, then 360 J 3
• Provide immediate sedation if the patient is conscious but do not delay cardioversion if extremely unstable 5, 2
• If no defibrillator is immediately available, attempt a precordial thump 5

Polymorphic VT (Irregular Rhythm)

• Use unsynchronized high-energy shocks (defibrillation doses of 200 J) as you would for ventricular fibrillation 5, 2
• Synchronized cardioversion cannot be used for polymorphic VT because the device may not sense a consistent QRS wave 5

Pulseless VT

• Treat as ventricular fibrillation with immediate unsynchronized defibrillation 5, 3
• Follow standard cardiac arrest protocols 5

Hemodynamically Stable Monomorphic VT: Treatment Options

While electrical cardioversion remains first-line even for stable patients, pharmacologic therapy is a reasonable alternative. 1, 2

First-Line Pharmacologic Agent: Procainamide

Procainamide demonstrates the greatest efficacy among antiarrhythmic drugs for stable monomorphic VT. 3, 4

• Dosing: 10 mg/kg IV at 50-100 mg/min over 10-20 minutes (maximum dose 10-20 mg/kg) 3, 4
• Monitor continuously for hypotension and QRS widening during administration 3
• Contraindications: Avoid in patients with severe heart failure or acute myocardial infarction 3, 4

Alternative Agent: Amiodarone

Use amiodarone when procainamide is contraindicated, particularly in patients with heart failure or suspected ischemia. 5, 3, 6

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

Less Effective Options

• Lidocaine: Only moderately effective; initial loading dose of 1 mg/kg IV, followed by half this dose every 8-10 minutes to maximum 4 mg/kg, or continuous infusion (1-3 mg/min) 5, 1
• Sotalol: May be considered but exercise caution due to significant beta-blocking properties 3

Beta-Blockers

Beta-blockers are first-line therapy unless contraindicated, particularly for preventing recurrent episodes. 5

Special Considerations for Polymorphic VT in Stable Patients

Normal QT Interval (Likely Ischemia-Related)

• Consider IV beta-blockers 3
• Treat underlying ischemia aggressively 3

Prolonged QT Interval (Torsades de Pointes)

• Administer IV magnesium sulfate: 8 mmol bolus followed by 2.5 mmol/h infusion 3
• Correct electrolyte abnormalities (potassium, magnesium) 3

Post-Conversion Management

After successful cardioversion or pharmacologic conversion: 1, 2

• Continuous cardiac monitoring for VT recurrence 1, 3
• Obtain 12-lead ECG to assess for ST-segment elevation or ischemic changes 2
• Correct electrolyte abnormalities immediately (potassium, magnesium) 5, 2, 3
• Start IV beta-blockers to prevent recurrent arrhythmias 2
• Address underlying causes: continuing ischemia, pump failure, hypoxia, acid-base disturbances 5

Critical Pitfalls to Avoid

• Never delay cardioversion in unstable patients while attempting pharmacologic conversion 1, 3
• Never use calcium channel blockers (verapamil, diltiazem) in VT with structural heart disease—they may precipitate hemodynamic collapse 1, 3
• Never assume wide-complex tachycardia is supraventricular—when in doubt, treat as VT 3
• Do not use synchronized cardioversion for pulseless VT or polymorphic VT 5
• Avoid inadequate monitoring after successful conversion, as recurrence is common 1

Advanced Therapies for Refractory Cases

• Urgent catheter ablation is indicated for scar-related heart disease with incessant VT or electrical storm despite optimal medical therapy 1, 2, 3
• Consider transvenous overdrive pacing if VT is frequently recurrent and catheter ablation is not immediately available 2
• ICD implantation for secondary prevention in structural heart disease 3

Important Distinction: Accelerated Idioventricular Rhythm

Differentiate true VT from accelerated idioventricular rhythm (ventricular rate <120 bpm), which is usually a harmless consequence of reperfusion and requires no specific therapy. 5