What is the treatment for Supraventricular Tachycardia (SVT)?

Treatment of Supraventricular Tachycardia (SVT)

The treatment of SVT should follow a stepwise approach, starting with vagal maneuvers (particularly modified Valsalva maneuver), followed by adenosine administration, and synchronized cardioversion for hemodynamically unstable patients. 1

Acute Management Algorithm

Step 1: Assess Hemodynamic Stability

• If patient is hemodynamically unstable (hypotension, altered mental status, chest pain, heart failure):

  • Proceed directly to synchronized cardioversion 2, 1

• If patient is hemodynamically stable:

  • Proceed to vagal maneuvers

Step 2: Vagal Maneuvers

• Modified Valsalva maneuver is the most effective vagal maneuver with a 43% success rate compared to 17% with standard techniques 3, 4

  • Technique: Patient performs strain (bearing down against closed glottis for 10-30 seconds, equivalent to 30-40 mmHg) in semi-recumbent position, then immediately lies flat with legs elevated 2, 3

• Other vagal maneuvers (less effective):

  • Standard Valsalva maneuver
  • Carotid sinus massage (after confirming absence of carotid bruits)
  • Cold stimulus to face (ice-cold wet towel)

Step 3: Pharmacological Treatment

If vagal maneuvers fail:

1. Adenosine (first-line pharmacological agent):

   • Initial dose: 6 mg IV rapid bolus
   • If ineffective: Up to 2 subsequent doses of 12 mg IV
   • Success rate: approximately 91% 1, 5
   • Caution: Transient side effects include chest discomfort and flushing

2. Calcium Channel Blockers (if adenosine fails):

   • Verapamil: 2.5-5 mg IV 1, 6
     • Conversion rate: ~60% within 10 minutes 6
   • Diltiazem: 15-20 mg IV 1
   • Contraindicated in patients with suspected Wolff-Parkinson-White syndrome

3. Beta-blockers (alternative option):

   • Metoprolol, atenolol, propranolol, or esmolol 1

Step 4: Synchronized Cardioversion

• Indicated when:
  • Patient is hemodynamically unstable
  • Pharmacological therapy is ineffective or contraindicated 2

Long-term Management

Pharmacological Options

• Beta-blockers or calcium channel blockers (first-line) 1
• Flecainide or propafenone (for patients without structural heart disease) 1
• Amiodarone (for short-term use or when alternative therapy is not an option) 2
  • Caution: Risk of thyroid disorders (13-36% in ACHD patients)

Definitive Treatment

• Catheter ablation is recommended as first-line therapy for recurrent SVT 1, 5
  • Success rates: 94-98% 1, 5
  • Should be considered for patients with symptomatic episodes requiring medical intervention

Special Populations

Pregnant Patients

1. Vagal maneuvers (first-line) 2
2. Adenosine (if vagal maneuvers fail) 2
   • Safe due to short half-life, unlikely to reach fetal circulation
3. Synchronized cardioversion for hemodynamically unstable patients 2

Patients with Congenital Heart Disease

• Avoid flecainide in patients with significant ventricular dysfunction 2
• Risk of cardiac arrest is highest among patients with complex heart disease or ventricular dysfunction

Follow-up Recommendations

• Cardiology follow-up within 1-2 weeks after an SVT episode 1
• Monitor for medication side effects and efficacy
• Consider referral for catheter ablation evaluation for recurrent episodes

Pitfalls and Caveats

• Never apply pressure to the eyeball as a vagal maneuver (dangerous and abandoned) 2
• Avoid calcium channel blockers in patients with suspected Wolff-Parkinson-White syndrome 1
• Avoid flecainide in patients with ventricular dysfunction or structural heart disease 2
• When using medications during pregnancy, use the lowest recommended dose and avoid first trimester if possible 2