What is the treatment for Supraventricular Tachycardia (SVT)?

Treatment of Supraventricular Tachycardia (SVT)

The treatment of SVT follows a stepwise approach based on hemodynamic stability, with vagal maneuvers as first-line treatment for stable patients, followed by adenosine, calcium channel blockers or beta blockers, and synchronized cardioversion for refractory cases or unstable patients. 1

Acute Management Algorithm

Hemodynamically Stable Patients

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

   • Modified Valsalva maneuver is most effective with success rates of approximately 43% 2
   • Standard Valsalva maneuver: bearing down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg) 3
   • Carotid sinus massage: applying steady pressure over carotid sinus for 5-10 seconds (after confirming absence of bruits) 3
   • Overall success rate of combined vagal maneuvers is about 27.7% 3
   • Modified Valsalva is superior to standard Valsalva and carotid sinus massage for both initial termination and sustained response 4, 5

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

   • Initial dose: 6 mg rapid IV push 1
   • If unsuccessful, can increase to 12 mg IV push
   • Terminates AVNRT in approximately 95% of patients 3
   • Also has diagnostic value by unmasking atrial activity in other arrhythmias 3

3. Third-line: IV Calcium Channel Blockers or Beta Blockers (Class IIa, Level B-R)

   • Options include diltiazem, verapamil, or beta blockers (esmolol, metoprolol) 3, 1
   • Only use in hemodynamically stable patients
   • Contraindicated in suspected ventricular tachycardia or pre-excited atrial fibrillation 1
   • Verapamil should be avoided in infants and children <1 year due to risk of cardiovascular collapse 1

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

   • Indicated when pharmacological therapy fails or is contraindicated 3
   • Initial energy: 0.5-1 J/kg, increasing to 2 J/kg if unsuccessful 1

Hemodynamically Unstable Patients

• Immediate synchronized cardioversion (Class I, Level B-NR) 3, 1
• Do not delay with vagal maneuvers or medications

Long-Term Management

1. Catheter Ablation

   • First-line therapy for prevention of recurrent SVT 2
   • Success rates of 94.3-98.5% with single procedure 2
   • Safe and highly effective for most SVT mechanisms

2. Pharmacological Prevention

   • Beta blockers, calcium channel blockers, or antiarrhythmic agents 2, 6
   • Flecainide is indicated for prevention of paroxysmal SVT in patients without structural heart disease 7
   • Propranolol is recommended as first-line for prevention of recurrent SVT in infants 1

Special Considerations

• Pregnancy: Follow same algorithm starting with vagal maneuvers, then adenosine (safe second-line option), and synchronized cardioversion with careful electrode pad placement away from uterus if needed 1

• Pediatric Patients: Higher initial doses of adenosine may be needed (150-250 mcg/kg) 1

• Common Pitfalls:

  • Misdiagnosing ventricular tachycardia as SVT with aberrancy - when uncertain, treat as ventricular tachycardia 1
  • Administering verapamil or diltiazem in patients with pre-excited atrial fibrillation (can accelerate ventricular rate) 1
  • Using flecainide in patients with structural heart disease or recent myocardial infarction (contraindicated) 7

• Monitoring: Regular assessment with ECG and Holter monitoring is necessary for all SVT patients 1

• Evaluation: All patients should be evaluated for accessory pathways, especially Wolff-Parkinson-White syndrome 1