What is the American Heart Association (AHA) algorithm for treating a patient in ventricular tachycardia (Vtach)?

AHA Algorithm for Ventricular Tachycardia Management

For patients with ventricular tachycardia (VT), immediate assessment of hemodynamic stability should guide treatment, with synchronized cardioversion being the first-line intervention for unstable patients and medication therapy for stable patients with preserved cardiac output.

Initial Assessment

• Determine if the patient has a pulse and assess hemodynamic stability 1
• Check vital signs, level of consciousness, and signs of shock or heart failure 1
• Obtain 12-lead ECG if available (but do not delay treatment in unstable patients) 1
• Provide supplemental oxygen and establish IV access 1

Treatment Algorithm for VT

Unstable VT (with pulse but hemodynamically unstable)

• Signs of instability include: hypotension, altered mental status, signs of shock, chest pain, acute heart failure 1
• Immediate synchronized cardioversion is recommended 1
  • Premedicate with sedation if patient is conscious and time permits 1
  • Initial energy: 100-200 J (biphasic) or 200 J (monophasic) 1
  • Increase energy if first shock is unsuccessful 1

Stable VT (with pulse and hemodynamically stable)

1. Pharmacological therapy options:

   • Amiodarone: 150 mg IV over 10 minutes, followed by maintenance infusion of 1 mg/min for first 6 hours 1, 2
   • Procainamide: 20-50 mg/min until arrhythmia suppressed, hypotension occurs, QRS widens >50%, or maximum dose of 17 mg/kg given 1
   • Maintenance infusion: 1-4 mg/min (avoid if prolonged QT or CHF) 1

2. If medications fail:

   • Synchronized cardioversion (after adequate sedation) 1
   • Consider EP study and catheter ablation for recurrent episodes 1

Pulseless VT (treated same as VF)

• Immediate CPR and defibrillation (unsynchronized shock) 1
• Follow ACLS Cardiac Arrest Algorithm 1

Special Considerations

• For VT with pre-excitation (WPW syndrome), avoid AV nodal blocking agents like diltiazem, verapamil, and beta blockers as they may accelerate conduction through accessory pathway 1
• For polymorphic VT or torsades de pointes:
  • Correct electrolyte abnormalities (especially potassium and magnesium) 1
  • Discontinue QT-prolonging medications 1
  • Consider beta blockers for catecholaminergic polymorphic VT 1

Medication Dosing for VT

• Amiodarone IV:

  • Initial: 150 mg over 10 minutes 1, 2
  • Maintenance: 1 mg/min for 6 hours, then 0.5 mg/min 2
  • For breakthrough VT: Additional 150 mg boluses as needed 2
  • Maximum first 24-hour dose: 2100 mg (higher doses increase hypotension risk) 2

• Procainamide IV:

  • Loading: 20-50 mg/min until arrhythmia suppressed or maximum 17 mg/kg 1
  • Maintenance: 1-4 mg/min 1
  • Avoid if QT prolongation or heart failure 1

Pitfalls and Caveats

• Misdiagnosis of wide-complex tachycardias can be dangerous - when in doubt, treat as VT 1
• Timing of shock delivery is critical - synchronization reduces risk of inducing VF 3
• Amiodarone concentrations >2 mg/mL require central venous access to avoid phlebitis 2
• Monitor for hypotension during antiarrhythmic administration 2
• For patients with ICD, magnet application may prevent inappropriate shocks during treatment 1
• Avoid AV nodal blocking agents in pre-excited tachycardias as they may accelerate conduction through accessory pathway and worsen the arrhythmia 1

The AHA algorithm emphasizes rapid assessment and prompt intervention based on hemodynamic stability, with synchronized cardioversion being the cornerstone of treatment for unstable VT and pharmacological therapy for stable patients 1.