What is the initial management for Supraventricular Tachycardia (SVT)?

Initial Management of Supraventricular Tachycardia (SVT)

For patients with SVT, the initial management should follow a stepwise approach starting with vagal maneuvers, followed by adenosine, then calcium channel blockers or beta blockers, and finally synchronized cardioversion if other methods fail. 1

Acute Management Algorithm for SVT

Step 1: Assess Hemodynamic Stability

• Hemodynamically Unstable Patients (hypotension, altered mental status, chest pain, heart failure)
  • Proceed directly to synchronized cardioversion (Class I, Level B-NR) 1

Step 2: For Hemodynamically Stable Patients

1. First-line: Vagal Maneuvers (Class I, Level B-R) 1

   • Modified Valsalva maneuver (43% effective) 2
   • Carotid sinus massage (in appropriate patients)
   • Techniques include:
     • Lying backward quickly from a seated position 3
     • Head-down tilt position
     • Facial immersion in cold water (diving reflex)

2. Second-line: Adenosine IV (Class I, Level B-R) 1

   • Highly effective (91% success rate) 2
   • Rapid onset and short half-life
   • Start with 6 mg IV bolus, followed by rapid saline flush
   • If unsuccessful, give 12 mg IV bolus (may repeat once if needed)
   • Monitor for transient side effects: flushing, chest discomfort, brief asystole

3. Third-line: IV Calcium Channel Blockers or Beta Blockers (Class IIa, Level B-R) 1, 4

   • Diltiazem or verapamil IV for patients without heart failure
   • Beta blockers IV (metoprolol, propranolol) for patients without contraindications

4. Fourth-line: Synchronized Cardioversion (Class I, Level B-NR) 1

   • Indicated when pharmacological therapy is ineffective or contraindicated
   • Requires sedation in conscious patients

Special Considerations

Pre-excitation Syndromes (e.g., Wolff-Parkinson-White)

• Avoid AV nodal blocking agents (calcium channel blockers, beta blockers, digoxin)
• These may accelerate conduction through accessory pathway during atrial fibrillation
• Use procainamide IV instead for hemodynamically stable patients 5
• Multiple accessory pathways are present in nearly 50% of patients with Ebstein's anomaly 4

Common Pitfalls to Avoid

• Failure to record 12-lead ECG during tachycardia
• Misdiagnosis of SVT mechanism leading to inappropriate treatment
• Inadequate adenosine administration (requires rapid push followed by saline flush)
• Delayed cardioversion in unstable patients
• Underestimating the need for specialist referral after initial management

Long-term Management Options

• Catheter ablation is highly effective (94-98% success rate) and recommended as first-line therapy for recurrent, symptomatic SVT 2
• Pharmacological options include:
  • Beta blockers or calcium channel blockers (diltiazem, verapamil) (Class I, Level B-R) 1
  • Flecainide or propafenone in patients without structural heart disease (Class IIa, Level B-R) 1, 6
  • Sotalol, dofetilide, or amiodarone as alternatives when other options fail 1

All patients with SVT should be referred to a cardiologist or electrophysiologist for evaluation and consideration of definitive treatment with catheter ablation 7, 8.