What is the treatment for supraventricular tachycardia (SVT)?

Treatment of Supraventricular Tachycardia (SVT)

The first-line treatment for supraventricular tachycardia is vagal maneuvers, followed by adenosine if vagal maneuvers fail, and synchronized cardioversion for hemodynamically unstable patients. 1, 2

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 (Class I, Level B-NR) 1
  • Initial energy: 50-100 J (biphasic) 2

Step 2: For Hemodynamically Stable Patients

1. Vagal Maneuvers (Class I, Level B-R) 1, 2

   • Modified Valsalva maneuver (most effective vagal technique) 3
     • Patient in supine position
     • Bear down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg)
   • Carotid sinus massage (after confirming absence of carotid bruits)
     • Apply steady pressure over carotid sinus for 5-10 seconds
   • Cold stimulus to face (ice-cold wet towel)

2. If vagal maneuvers fail, administer Adenosine (Class I, Level B-R) 1, 2

   • Initial dose: 6 mg IV rapid bolus
   • If ineffective: 12 mg IV rapid bolus (can repeat once if needed)
   • Success rate: approximately 91% 4
   • Follow with saline flush and elevation of extremity

3. If adenosine fails, options include: 1, 2

   • Calcium channel blockers (Class IIa, Level B-R):
     • Diltiazem 15-20 mg IV over 2 minutes (can repeat with 20-25 mg after 15 minutes)
     • Verapamil 2.5-5 mg IV over 2 minutes (can repeat with 5-10 mg after 15-30 minutes)
   • Beta blockers (Class IIa, Level B-R):
     • Esmolol 500 μg/kg IV over 1 minute, then 50-200 μg/kg/min
     • Metoprolol 2.5-5 mg IV bolus over 2 minutes, up to 3 doses

4. If pharmacological therapy fails:

   • Synchronized cardioversion (Class I, Level B-NR) 1

Important Cautions

• Avoid verapamil/diltiazem in:

  • Suspected Wolff-Parkinson-White syndrome
  • Wide-complex tachycardias of uncertain origin
  • Systolic heart failure
  • Hypotension 1, 2

• Obtain 12-lead ECG to differentiate tachycardia mechanisms before treatment 1

Long-term Management

Pharmacological Options

1. Oral medications for chronic management: 1, 2

   • Beta blockers (metoprolol, atenolol, propranolol)
   • Calcium channel blockers (diltiazem, verapamil)
   • For patients without structural heart disease: flecainide or propafenone 5

2. Flecainide considerations: 5

   • Indicated for prevention of PSVT and paroxysmal atrial fibrillation
   • Contraindicated in patients with structural heart disease or recent myocardial infarction
   • Requires careful monitoring due to proarrhythmic effects

Definitive Treatment

• Catheter ablation is recommended as first-line therapy for recurrent SVT 2, 4
  • Success rates: 94-98% 4
  • Particularly indicated for patients with:
    • Frequent symptomatic episodes
    • Poor tolerance or response to medications
    • Preference to avoid long-term medication

Follow-up

• Cardiology referral within 1-2 weeks for patients with SVT 2
• Monitoring for medication side effects and efficacy
• Consideration of catheter ablation for definitive treatment

Special Considerations

• The 2020 ESC guidelines have downgraded recommendations for verapamil/diltiazem in acute management of narrow-QRS tachycardias compared to previous guidelines 1
• Modified Valsalva maneuver has been shown to be more effective than standard techniques, with a higher conversion rate to sinus rhythm 3