What is the treatment for Atrioventricular Nodal Reentrant Tachycardia (AVNRT)?

Treatment of Atrioventricular Nodal Reentrant Tachycardia (AVNRT)

The first-line treatment for AVNRT is vagal maneuvers, followed by adenosine if vagal maneuvers fail, with catheter ablation being the definitive treatment for recurrent symptomatic cases. 1

Acute Management Algorithm

Hemodynamically Stable Patients

1. First-line: Vagal maneuvers

   • Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds (30-40 mmHg pressure) 1
   • Carotid sinus massage: Apply steady pressure over carotid sinus for 5-10 seconds (after confirming absence of bruits) 1
   • Ice-cold wet towel application to face 1, 2
   • Success rate approximately 27.7% when switching between techniques 1, 3
   • Perform in supine position for best results 1

2. Second-line: Adenosine

   • Terminates AVNRT in approximately 95% of cases 1, 2
   • Acts as both diagnostic and therapeutic agent 1
   • Brief side effects (<1 minute) may occur in about 30% of patients 1
   • Have equipment for cardioversion available as adenosine may precipitate atrial fibrillation 1

3. Third-line: IV calcium channel blockers or beta blockers

   • IV diltiazem or verapamil particularly effective for AVNRT 1
   • IV beta blockers (e.g., metoprolol, esmolol) are reasonable alternatives 1
   • Avoid in patients with suspected pre-excitation, severe heart failure, or significant conduction abnormalities 1

4. Fourth-line: Synchronized cardioversion

   • Indicated when pharmacological therapy fails or is contraindicated 1
   • Highly effective in terminating AVNRT 1
   • Perform after adequate sedation in stable patients 1

Hemodynamically Unstable Patients

1. Immediate synchronized cardioversion if vagal maneuvers and adenosine fail or aren't feasible 1
2. Prepare for post-cardioversion arrhythmias as patients may have premature complexes that could reinitiate AVNRT 1

Long-term Management Options

1. Catheter ablation

   • First-line therapy for recurrent symptomatic AVNRT 4, 5
   • High success rate (>95%) with low complication rate 4
   • Targets slow pathway in AV node 6
   • Curative approach that eliminates need for long-term medication 5

2. Pharmacological therapy

   • Oral calcium channel blockers (verapamil, diltiazem) 2
   • Beta blockers 5
   • Class I and III antiarrhythmic agents for refractory cases 5

Special Considerations

• Anatomical variations: In approximately 1.2% of cases, AVNRT may involve an inferolateral left atrial slow pathway requiring specialized ablation techniques 7
• Diagnostic challenges: P waves may be obscured by QRS complex or appear in terminal portion of QRS in common AVNRT 5
• Avoid eyeball pressure as a vagal maneuver as it is potentially dangerous 1
• Monitor for AV block as a potential complication of ablation, particularly with fast pathway ablation 5

Pitfalls to Avoid

• Misdiagnosis: Ensure AVNRT is distinguished from other SVTs before treatment 5
• Inappropriate medication use: Avoid calcium channel blockers and beta blockers in patients with pre-excited AF as they may enhance conduction over accessory pathway 2
• Inadequate follow-up: Even after successful ablation, echo beats may remain inducible in approximately 40% of patients 6
• Delayed definitive treatment: Consider early referral for catheter ablation in symptomatic patients rather than prolonged trials of pharmacological therapy 4, 5