What is the treatment for orthodromic atrioventricular (AV) reentrant tachycardia?

Treatment of Orthodromic Atrioventricular Reentrant Tachycardia (AVRT)

The treatment of orthodromic AVRT should follow a stepwise approach beginning with vagal maneuvers, followed by adenosine for acute termination, and progressing to synchronized cardioversion for hemodynamically unstable patients or when pharmacological therapy fails. 1

Acute Management Algorithm

Step 1: Assess Hemodynamic Stability

• Hemodynamically unstable patients (hypotension, altered mental status, chest pain, heart failure)

  • Proceed directly to synchronized cardioversion 1, 2

• Hemodynamically stable patients

  • Proceed with vagal maneuvers (Step 2)

Step 2: Vagal Maneuvers (First-Line)

• Valsalva maneuver (Class I, Level B-R recommendation)

  • Patient in supine position
  • Bear down against closed glottis for 10-30 seconds (30-40 mmHg pressure)
  • Modified Valsalva (with leg elevation after strain) has higher success rate (43.7%) than standard Valsalva (24.2%) 3

• Carotid sinus massage

  • Only after confirming absence of carotid bruit
  • Apply steady pressure over right or left carotid sinus for 5-10 seconds
  • Less effective than Valsalva (9.1% success rate) 3

• Other techniques

  • Cold stimulus to face (ice-cold wet towel)
  • Quickly lying backward from seated position 4

Step 3: Adenosine (If Vagal Maneuvers Fail)

• Adenosine IV (Class I, Level B-R recommendation)
  • Highly effective (90-95% success rate) 1
  • Rapid onset and short half-life
  • Have resuscitation equipment available

Caution with adenosine:

• May precipitate atrial fibrillation
• Can cause transient AV block (6% of patients) 5
• Contraindicated in patients with severe asthma or COPD 5
• Can cause hypotension 5

Step 4: Other Pharmacological Options (If Adenosine Fails)

• IV calcium channel blockers (Class IIa, Level B-R)

  • Diltiazem or verapamil for hemodynamically stable patients
  • Do not use in patients with pre-excited AF (can cause ventricular fibrillation) 1, 2

• IV beta blockers (Class IIa, Level B-R)

  • Alternative to calcium channel blockers
  • Do not use in patients with pre-excited AF 2

Step 5: Synchronized Cardioversion

• For hemodynamically unstable patients (Class I, Level B-NR)

  • When vagal maneuvers or adenosine are ineffective or not feasible 1

• For hemodynamically stable patients (Class I, Level B-NR)

  • When pharmacological therapy is ineffective or contraindicated 1
  • Requires adequate sedation or anesthesia

Special Considerations: Pre-excited AF

If orthodromic AVRT degenerates into pre-excited atrial fibrillation:

• Hemodynamically unstable: Immediate synchronized cardioversion (Class I, Level C-LD) 1

• Hemodynamically stable: Ibutilide or IV procainamide (Class I, Level B-R) 1

  • Avoid AV nodal blocking agents (beta blockers, calcium channel blockers, digoxin)
  • These can increase conduction through the accessory pathway and precipitate ventricular fibrillation

Long-term Management

• Catheter ablation

  • Definitive treatment with >95% success rate 2
  • First-line therapy for recurrent, symptomatic AVRT
  • Targets the accessory pathway
  • Special consideration for pathways near the His bundle (cryoablation may be preferred) 6

• Chronic pharmacological therapy (if ablation declined or contraindicated)

  • Beta blockers or calcium channel blockers
  • Flecainide or propafenone (in patients without structural heart disease) 2
  • Sotalol, dofetilide, or amiodarone for refractory cases 2

Common Pitfalls to Avoid

1. Misdiagnosing the arrhythmia - Ensure it's truly orthodromic AVRT before treatment
2. Using AV nodal blockers in pre-excited AF - Can accelerate ventricular rate and cause ventricular fibrillation
3. Delaying cardioversion in unstable patients - Don't waste time with medications
4. Inadequate vagal maneuver technique - Proper patient positioning and technique are crucial
5. Forgetting to have resuscitation equipment available - Especially when using adenosine