What is the treatment for Supraventricular Tachycardia (SVT)?

Treatment for Supraventricular Tachycardia (SVT)

The definitive treatment algorithm for SVT begins with vagal maneuvers (particularly modified Valsalva maneuver) followed by adenosine, with catheter ablation being the most effective long-term solution for recurrent SVT with success rates of approximately 95%. 1, 2

Acute Management of SVT

First-line Treatments

1. For hemodynamically stable patients:

   • Modified Valsalva maneuver - Most effective vagal maneuver with 43% conversion rate 1, 3, 2
   • Standard vagal maneuvers - Including standard Valsalva or carotid sinus massage (less effective than modified Valsalva) 3

2. If vagal maneuvers fail:

   • Adenosine - Administered as 6 mg IV rapid bolus via proximal IV access
     • Success rate: 90-95% 1
     • May require second dose of 12 mg if first dose fails
     • Caution: Avoid or use with extreme caution in patients with asthma or COPD 1
     • Dose adjustment: Reduce dose in heart transplant recipients 1

3. If adenosine fails:

   • Calcium channel blockers (IV) - Diltiazem or verapamil

     • Effectiveness: 64-98% termination rate 1
     • Contraindications: Avoid in patients with systolic heart failure, hypotension, pre-excited atrial fibrillation, or ventricular tachycardia 1

   • Beta blockers (IV) - Esmolol, metoprolol, or propranolol

     • Caution: Use carefully in patients with conduction abnormalities, sinus node dysfunction, or bronchospastic disease 1

4. For hemodynamically unstable patients:

   • Immediate synchronized cardioversion - Starting energy 50-100 J
     • Requires appropriate sedation for conscious patients 1

Long-term Management

Definitive Treatment

• Catheter ablation - Recommended as first-line therapy for recurrent SVT 1, 2
  • Success rates: 94-98.5% 2
  • Low complication rates
  • Provides potential cure without need for chronic medication 1

Pharmacological Options

• For ongoing management if ablation is not performed:
  • Beta blockers - First-line oral medication 1
  • Calcium channel blockers - Diltiazem or verapamil 1
  • Flecainide - For patients without structural heart disease 1, 4
    • Indicated specifically for paroxysmal SVT including AVNRT and AVRT 4
    • Important safety warning: Should not be used in patients with recent myocardial infarction or structural heart disease due to proarrhythmic effects 4

Special Considerations

Pregnancy

• Vagal maneuvers are preferred first-line treatment
• Low-dose adenosine if vagal maneuvers fail
• Avoid antiarrhythmic drugs if possible 1

Heart Failure

• Avoid verapamil and diltiazem
• Use beta-blockers cautiously 1

End-Stage Renal Disease

• Monitor for electrolyte abnormalities that can exacerbate arrhythmias
• Digoxin may be reasonable but must be used with extreme caution 1

Common Pitfalls to Avoid

1. Misdiagnosis of wide-complex tachycardia as SVT when it's actually ventricular tachycardia
2. Administering calcium channel blockers to patients with pre-excited atrial fibrillation (can accelerate ventricular rate)
3. Using flecainide in patients with structural heart disease or recent MI (can cause life-threatening proarrhythmia) 4
4. Delaying cardioversion in unstable patients while attempting pharmacological conversion
5. Failure to refer for electrophysiology evaluation after successful acute termination

Monitoring After Treatment

• Monitor for recurrence of SVT
• Assess vital sign stability
• Evaluate resolution of symptoms 1