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

First-Line Treatment: Vagal Maneuvers

• Perform vagal maneuvers with the patient in a supine position 1
  • Valsalva maneuver: Have patient bear down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg) 1
  • Carotid sinus massage: After confirming absence of carotid bruit, apply steady pressure over right or left carotid sinus for 5-10 seconds 1
  • Application of ice-cold wet towel to face (diving reflex) 1
• Success rate of vagal maneuvers is approximately 27.7% when switching between techniques 2

Second-Line Treatment: Adenosine

• If vagal maneuvers fail, administer adenosine IV 1
• Adenosine terminates AVNRT in approximately 95% of patients 1
• Adenosine serves both therapeutic and diagnostic purposes by unmasking atrial activity 1, 2
• Monitor for brief side effects (<1 minute) which may occur in approximately 30% of patients 3

Third-Line Treatment: Calcium Channel Blockers or Beta Blockers

• For hemodynamically stable patients when adenosine fails, consider IV diltiazem, verapamil, or beta blockers 1
• Diltiazem and verapamil are particularly effective in converting AVNRT to sinus rhythm 1
• Beta blockers have an excellent safety profile but limited evidence for effectiveness in terminating AVNRT 1

For Hemodynamically Unstable Patients

• Perform synchronized cardioversion when adenosine and vagal maneuvers do not terminate the tachycardia or are not feasible 1
• Synchronized cardioversion is highly effective in terminating SVT including AVNRT 1

Long-Term Management

Pharmacological Management

• Oral beta blockers, diltiazem, or verapamil may be used for ongoing management in patients with recurrent symptomatic AVNRT 1
• These medications are effective for prevention of recurrences but do not provide curative therapy 4, 5

Definitive Treatment

• Catheter ablation using radiofrequency energy is the definitive treatment for AVNRT 4, 6
• Targets the slow pathway in the AV node region 6
• High success rate (>95%) and low complication rate 4, 5
• Considered first-choice therapy for symptomatic AVNRT requiring treatment 5

Important Considerations and Precautions

• Ensure absence of pre-excited AF before administering calcium channel blockers or beta blockers, as these can enhance conduction over accessory pathways and potentially lead to ventricular fibrillation 2
• Adenosine is contraindicated in patients with:
  • Second or third-degree AV block (except with functioning pacemaker) 3
  • Sick sinus syndrome or symptomatic bradycardia 3
  • Bronchospastic lung disease 3
  • Known hypersensitivity to adenosine 3
• Monitor for potential adenosine side effects including:
  • Transient AV block (occurs in approximately 6% of patients) 3
  • Hypotension 3
  • Dyspnea and bronchoconstriction 3
  • Rarely: seizures, cerebrovascular accidents 3

Special Situations

• In patients with unusual variants of AVNRT using inferolateral left atrial slow pathway (approximately 1.2% of cases), specialized mapping techniques may be required for successful ablation 7
• For patients with frequent recurrences despite medical therapy, early referral for catheter ablation is recommended 4, 5