What is the treatment for Supraventricular Tachycardia (SVT)?

Treatment of Supraventricular Tachycardia (SVT)

The first-line treatment for SVT is vagal maneuvers, particularly the modified Valsalva maneuver, followed by adenosine administration if vagal maneuvers fail, and synchronized cardioversion for hemodynamically unstable patients. 1, 2

Acute Management Algorithm

For Hemodynamically Stable Patients:

1. Vagal Maneuvers (First-Line)

   • Modified Valsalva maneuver is the most effective vagal maneuver with a 43% success rate 3, 4, 5
   • Technique: Patient performs Valsalva in supine position by bearing down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg pressure) 1, 2
   • Alternative vagal maneuvers include:
     • Carotid sinus massage (only after confirming absence of carotid bruits) 1, 2
     • Cold stimulus (applying ice-cold wet towel to face) 1, 2
   • Switching between techniques can increase overall success rate to 27.7% 1, 2
   • Important caveat: Never apply pressure to the eyeball as this is dangerous 2

2. Pharmacological Treatment (If Vagal Maneuvers Fail)

   • Adenosine (First-line drug)

     • Highly effective (90-95% success rate) 1, 2
     • Acts as both diagnostic and therapeutic agent 1
     • Side effects are minor and brief (<1 minute) 1
     • Caution: May precipitate atrial fibrillation; have electrical cardioversion equipment available 1

   • Calcium Channel Blockers (Alternative)

     • Intravenous diltiazem or verapamil are reasonable alternatives (Class IIa recommendation) 1, 2
     • Particularly effective for AVNRT 1
     • Contraindication: Avoid in suspected pre-excitation, ventricular tachycardia, or heart failure 2

   • Beta-Blockers (Alternative)

     • Class IIa recommendation for hemodynamically stable patients 1, 2
     • Less effective than calcium channel blockers 2
     • Contraindication: Avoid in suspected pre-excitation 2

3. Synchronized Cardioversion

   • Indicated when pharmacological therapy is ineffective or contraindicated 1
   • Highly effective in terminating SVT 1

For Hemodynamically Unstable Patients:

1. Immediate Synchronized Cardioversion
   • First-line treatment for hemodynamically unstable patients 1, 2
   • Indicated when adenosine and vagal maneuvers don't terminate the tachycardia or aren't feasible 1

Special Considerations

Pre-excited AF (Wolff-Parkinson-White Syndrome)

• Synchronized cardioversion is recommended for hemodynamically unstable patients 1, 2
• Ibutilide or intravenous procainamide for hemodynamically stable patients 1, 2
• Avoid AV nodal blocking agents (verapamil, diltiazem, beta-blockers) as they may accelerate ventricular rate and lead to ventricular fibrillation 2

Long-term Management

• Catheter ablation is highly effective (94-98% success rate) and recommended as first-line therapy to prevent recurrence 4
• Flecainide can be used for prevention of paroxysmal SVT in patients without structural heart disease 6
  • Warning: Can cause proarrhythmic effects, especially in patients with coronary artery disease or sustained ventricular tachycardia 6

Common Pitfalls to Avoid

• Failing to distinguish SVT from ventricular tachycardia before treatment 2
• Using AV nodal blocking agents in patients with suspected pre-excitation 2
• Applying pressure to the eyeball (dangerous and abandoned practice) 1, 2
• Using flecainide in patients with recent myocardial infarction or structural heart disease 6