What is the management of Supraventricular Tachycardia (SVT) with aberrancy?

Management of SVT with Aberrancy

For SVT with aberrancy, the management approach should follow standard SVT treatment protocols, beginning with vagal maneuvers in hemodynamically stable patients, followed by adenosine, and proceeding to synchronized cardioversion if necessary. 1, 2

Initial Assessment and Approach

• Hemodynamic stability assessment: Determine if the patient is stable or unstable
  • Unstable: Hypotension, altered mental status, chest pain, heart failure, shock
  • Stable: Normal blood pressure, alert, no signs of end-organ hypoperfusion

Treatment Algorithm

For Hemodynamically Unstable Patients:

1. Immediate synchronized cardioversion (Class I, Level B-NR)
   • Initial energy: 0.5-1 J/kg
   • If unsuccessful, increase to 2 J/kg
   • Ensure proper electrode pad placement 2

For Hemodynamically Stable Patients:

1. First-line: Vagal maneuvers (Class I, Level B-R)

   • Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg)
   • Modified Valsalva: Perform Valsalva in semi-recumbent position, then immediately lay flat and elevate legs
   • Carotid sinus massage: Apply steady pressure over carotid sinus for 5-10 seconds (after confirming absence of bruit)
   • Success rate of vagal maneuvers: approximately 27.7% 1

2. Second-line: Adenosine (Class I, Level B-R)

   • Initial dose: 6 mg rapid IV push, followed by saline flush
   • If ineffective, administer 12 mg IV push after 1-2 minutes
   • Can repeat 12 mg dose once more if necessary
   • Success rate: approximately 91% 3
   • Diagnostic value: Will terminate AVNRT in ~95% of cases and unmask underlying atrial activity 1

3. Third-line: IV calcium channel blockers or beta blockers (Class IIa, Level B-R)

   • Diltiazem or verapamil (avoid in suspected heart failure or pre-excited AF)
   • Beta blockers (e.g., esmolol, metoprolol) have excellent safety profile 1, 2
   • Caution: Calcium channel blockers and beta blockers should be avoided if there's suspicion of VT or pre-excited AF, as they may cause hemodynamic deterioration 1

4. Fourth-line: Synchronized cardioversion (Class I, Level B-NR)

   • Indicated when pharmacological therapy fails or is contraindicated 1

Important Considerations for SVT with Aberrancy

• Differential diagnosis: Critical to distinguish SVT with aberrancy from ventricular tachycardia

  • When in doubt, treat as ventricular tachycardia 2
  • Look for typical SVT features: regular rhythm, narrow QRS in previous ECGs, abrupt onset/termination

• Avoid verapamil/diltiazem if:

  • Ventricular tachycardia is suspected
  • Pre-excited atrial fibrillation is suspected
  • Patient has heart failure or hypotension 1, 2

• Flecainide consideration: May be used for prevention of recurrent episodes in patients without structural heart disease (not for acute termination) 4

  • Starting dose: 50 mg every 12 hours
  • Maximum dose: 300 mg/day
  • Warning: Proarrhythmic effects possible, especially in patients with structural heart disease 4

Long-term Management

• Catheter ablation: First-line therapy for recurrent, symptomatic SVT (success rates 94-98%) 3
• Pharmacological options:
  • Beta blockers or calcium channel blockers for prevention
  • Flecainide for prevention in patients without structural heart disease 4

Pitfalls and Caveats

• Misdiagnosis risk: SVT with aberrancy can be mistaken for VT; when in doubt, treat as VT
• Medication contraindications: Avoid AV nodal blocking agents in suspected pre-excitation syndromes
• Proarrhythmic potential: Antiarrhythmic drugs can worsen arrhythmias, particularly in patients with structural heart disease 4
• Monitoring requirement: Patients receiving antiarrhythmic medications require careful monitoring for proarrhythmic effects

By following this algorithm, clinicians can effectively manage SVT with aberrancy while minimizing risks and complications.