What is the treatment for Supraventricular Tachycardia (SVT)?

Treatment of Supraventricular Tachycardia (SVT)

The treatment of SVT follows a stepwise approach, beginning with vagal maneuvers and progressing to medications or cardioversion based on hemodynamic stability, with catheter ablation being the definitive treatment for recurrent cases.

Acute Management of SVT

Hemodynamically Unstable Patients

• Immediate synchronized cardioversion is recommended for patients with hemodynamic instability (hypotension, altered mental status, signs of shock, or ischemic chest pain) 1
• Cardioversion should be performed when vagal maneuvers and adenosine fail or are not feasible in unstable patients 1

Hemodynamically Stable Patients

1. First-line: Vagal Maneuvers

   • Valsalva maneuver (bearing down against closed glottis for 10-30 seconds) 1
   • Modified Valsalva maneuver (standard Valsalva followed by supine positioning with passive leg raise) is more effective with conversion rates of 43% vs 17% for standard technique 2, 3
   • Carotid sinus massage (after confirming absence of carotid bruits) 1
   • Overall success rate of vagal maneuvers is approximately 28% 1

2. Second-line: Adenosine

   • Recommended if vagal maneuvers fail 1
   • Highly effective with 95% termination rate for AVNRT 1, 4
   • Administer as rapid IV bolus followed by saline flush 5
   • Short half-life makes it safer even in patients with cardiac dysfunction 4

3. Third-line: Other Pharmacological Options

   • IV calcium channel blockers (diltiazem or verapamil) are reasonable for hemodynamically stable patients 1
     • Contraindicated in patients with hypotension, heart failure, or pre-excited AF 1, 6, 7
   • IV beta-blockers are reasonable alternatives 1
     • Less effective than calcium channel blockers but have excellent safety profile 1
   • IV amiodarone may be considered when other therapies are ineffective or contraindicated 1

4. Fourth-line: Synchronized Cardioversion

   • Recommended when pharmacological therapy fails or is contraindicated 1
   • Highly effective for terminating SVT 1

Long-term Management

Pharmacological Options

1. First-line: Oral Medications

   • Beta-blockers, diltiazem, or verapamil are recommended for ongoing management 1
   • Use with caution in patients with heart failure (especially verapamil/diltiazem) 6, 7
   • Monitor for side effects:
     • Verapamil: hypotension, heart failure exacerbation, AV block 7
     • Diltiazem: hepatic dysfunction, hypotension 6

2. Second-line: Antiarrhythmic Medications

   • Flecainide or propafenone for patients without structural heart disease 1
   • Sotalol may be reasonable for symptomatic SVT 1
   • Dofetilide may be considered when first-line agents are ineffective or contraindicated 1
   • Amiodarone may be considered as a last resort when other options fail 1, 5

Definitive Treatment

• Catheter ablation is recommended as the definitive treatment for recurrent SVT 1, 5
• Success rates of approximately 95% for AVNRT with low complication rates 5
• Should be considered first-line for patients with frequent episodes or those who prefer not to take long-term medications 1

Special Considerations

• Pre-excited AF: Avoid AV nodal blocking agents (verapamil, diltiazem, beta-blockers, digoxin) as they may accelerate ventricular response 1, 7
• Heart failure: Avoid verapamil and diltiazem; use beta-blockers cautiously 6, 7
• Renal impairment: Adjust medication doses and monitor for toxicity, especially with amiodarone 5
• Pregnancy: Vagal maneuvers and adenosine are preferred; avoid antiarrhythmic drugs if possible

Common Pitfalls to Avoid

• Failing to differentiate SVT from ventricular tachycardia before treatment
• Using verapamil or diltiazem in patients with pre-excited AF (can precipitate ventricular fibrillation)
• Neglecting to offer catheter ablation to patients with recurrent episodes
• Applying eyeball pressure as a vagal maneuver (dangerous and abandoned) 1
• Underutilizing modified Valsalva technique, which has higher success rates than standard Valsalva or carotid sinus massage 2, 8