What is the treatment for atrial ventricular reciprocating tachycardia (AVRT)?

Treatment of Atrioventricular Reciprocating Tachycardia (AVRT)

For AVRT, the recommended treatment follows a stepwise approach starting with vagal maneuvers, followed by adenosine, then calcium channel blockers or beta blockers, with synchronized cardioversion reserved for refractory or unstable cases. 1

Acute Management Algorithm

Step 1: Assess Hemodynamic Stability

• If unstable (hypotension, altered mental status, signs of shock, chest pain, heart failure): Proceed directly to synchronized cardioversion 2
• If stable: Proceed with pharmacological management

Step 2: First-Line Interventions for Stable Patients

1. Vagal Maneuvers (Class I, Level B-R) 1

   • Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds (30-40 mmHg pressure)
   • Carotid sinus massage: Apply steady pressure over carotid sinus for 5-10 seconds after confirming absence of bruits
   • Success rate approximately 28% 2
   • Avoid eyeball pressure (dangerous and abandoned)

2. Adenosine IV (Class I, Level B-R) 1, 3

   • Initial dose: 6 mg rapid IV push followed by saline flush
   • If ineffective: 12 mg IV push, may repeat once
   • Terminates approximately 95% of AVRT cases
   • Common side effects: flushing, chest discomfort, dyspnea (short-lived)
   • Contraindicated in patients with severe asthma or second/third-degree AV block

Step 3: Second-Line Interventions (if Step 2 fails)

1. IV Calcium Channel Blockers (Class IIa, Level B-R) 1

   • Diltiazem: 0.25 mg/kg IV over 2 minutes
   • Verapamil: 0.075-0.15 mg/kg IV over 2 minutes
   • Highly effective (90% conversion rate) 4, 5
   • Avoid in suspected heart failure, hypotension, or pre-excited AF

2. IV Beta Blockers (Class IIa, Level B-R) 1

   • Esmolol: 500 μg/kg IV over 1 minute, followed by infusion
   • Metoprolol: 5 mg IV over 2-5 minutes, may repeat twice
   • Less effective than calcium channel blockers but excellent safety profile

Step 4: Refractory Cases

• Synchronized Cardioversion (Class I, Level B-NR) 1
  • Indicated when pharmacological therapy fails or is contraindicated
  • Start with 50-100 J biphasic (or 100 J monophasic)
  • Requires sedation in conscious patients

Long-Term Management

Pharmacological Options

1. Oral Beta Blockers - First-line therapy 2

   • Metoprolol, atenolol, propranolol
   • Effective for preventing recurrences

2. Oral Calcium Channel Blockers - Alternative first-line 2

   • Diltiazem, verapamil
   • Use when beta blockers are contraindicated

3. Class IC Antiarrhythmics 6

   • Propafenone: Indicated for PSVT with disabling symptoms
   • Flecainide: Similar efficacy
   • Contraindicated in structural heart disease

Definitive Treatment

• Catheter Ablation (Class I, Level B-R) 2
  • Success rate >95% for AVRT
  • Recommended for recurrent, symptomatic episodes
  • First-line option for patients with WPW syndrome

Important Considerations and Pitfalls

• Pre-excited AF risk: Avoid AV nodal blockers (digoxin, verapamil, diltiazem) in patients with suspected WPW syndrome as they can accelerate conduction through accessory pathway, potentially causing ventricular fibrillation 2, 4

• Diagnostic value: Adenosine can help diagnose the mechanism of tachycardia by transiently blocking AV node conduction 3

• Combination therapy: Avoid simultaneous use of IV calcium channel blockers and beta blockers due to risk of profound hypotension 2

• Pregnancy: Vagal maneuvers and adenosine remain first-line treatments during pregnancy 2

• Termination mechanism: Vagal maneuvers and medications work by interrupting the reentry circuit, either in the antegrade limb (AV node) or retrograde limb (accessory pathway) 7