What is the initial management for a patient presenting with Supraventricular Tachycardia (SVT)?

Initial Management of Supraventricular Tachycardia (SVT)

For patients presenting with SVT, vagal maneuvers should be performed as first-line treatment, followed by adenosine if unsuccessful, and synchronized cardioversion for hemodynamically unstable patients. 1

Step-by-Step Management Algorithm

1. Assess Hemodynamic Stability

• If patient is hemodynamically unstable (hypotension, altered mental status, signs of shock, severe chest pain), proceed directly to synchronized cardioversion 1
• If patient is hemodynamically stable, proceed with vagal maneuvers 1, 2

2. Vagal Maneuvers (First-Line for Stable Patients)

• Position patient supine for all vagal maneuvers 1
• Valsalva maneuver: Have patient bear down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg pressure) 1
• Carotid sinus massage: After confirming absence of carotid bruits, apply steady pressure over right or left carotid sinus for 5-10 seconds 1
• Cold stimulus: Apply ice-cold wet towel to face to trigger diving reflex 3
• Success rate of vagal maneuvers is approximately 28% 1
• Note: Eyeball pressure is dangerous and should not be performed 1

3. Pharmacological Management (If Vagal Maneuvers Fail)

• Adenosine: First-line medication for stable patients 1

  • Dosing: 6 mg rapid IV push through a large vein, followed by saline flush 3
  • If unsuccessful, can repeat with 12 mg dose
  • Success rate: 91-95% for terminating SVT 1, 2
  • Monitor for transient side effects (flushing, chest discomfort, brief asystole) 2

• For stable patients who don't respond to adenosine:

  • IV beta blockers (e.g., esmolol) 1
  • IV calcium channel blockers (diltiazem or verapamil) 1
  • Note: Avoid verapamil/diltiazem if suspected pre-excited AF or VT as they may cause hemodynamic collapse 1

4. Synchronized Cardioversion

• Indicated for:
  • Hemodynamically unstable patients 1
  • Stable patients who fail pharmacological therapy 1
• Initial energy: 50-100J for SVT 3
• Ensure proper sedation for stable patients undergoing elective cardioversion 1

Special Considerations

• Pre-excited AF: Avoid AV nodal blocking agents (adenosine, beta blockers, calcium channel blockers); use procainamide or immediate cardioversion 1, 3
• Suspected Wolff-Parkinson-White syndrome: Avoid verapamil and diltiazem as they can accelerate conduction through accessory pathway 3
• Patients with heart failure: Avoid calcium channel blockers; prefer beta blockers or cardioversion 1
• Pregnancy: Vagal maneuvers are first-line; medications should be used with caution 2

Long-term Management

• Refer all patients to a cardiologist/electrophysiologist after acute management 2, 4
• Catheter ablation is highly effective (94-98% success rate) and recommended as first-line therapy for recurrent, symptomatic SVT 5, 2
• Oral medications (beta blockers, calcium channel blockers) may be used for long-term management in patients who are not candidates for ablation 1

Common Pitfalls to Avoid

• Failing to recognize hemodynamic instability requiring immediate cardioversion 1
• Using verapamil/diltiazem in patients with pre-excited AF or VT 1, 3
• Inadequate adenosine administration technique (needs rapid push followed by saline flush) 2
• Not having cardioversion equipment ready when administering adenosine, as it may precipitate atrial fibrillation 1, 3
• Delaying referral for definitive management with catheter ablation in appropriate candidates 5, 2