What is the management of supraventricular tachycardia (SVT)?

Management of Supraventricular Tachycardia (SVT)

Vagal maneuvers should be performed as first-line treatment for acute SVT in hemodynamically stable patients, followed by adenosine if vagal maneuvers fail, and synchronized cardioversion for hemodynamically unstable patients or when pharmacological therapy is ineffective. 1, 2

Acute Management Algorithm

Hemodynamically Unstable Patients

• Perform immediate synchronized cardioversion as first-line treatment 1
• For patients with pre-excited AF who are hemodynamically unstable, synchronized cardioversion should be performed immediately 1, 2

Hemodynamically Stable Patients

1. First-line: Vagal maneuvers

   • Perform in supine position 1, 2
   • Valsalva maneuver: Patient raises intrathoracic pressure by bearing down against a closed glottis for 10-30 seconds (equivalent to 30-40 mmHg) 1
   • Carotid sinus massage: After confirming absence of carotid bruits, apply steady pressure over right or left carotid sinus for 5-10 seconds 1, 2
   • Cold stimulus: Apply ice-cold wet towel to face 1
   • Success rate of switching between techniques is approximately 27.7% 1, 2
   • AVOID applying pressure to eyeball as this practice is dangerous 1, 2

2. Second-line: Adenosine

   • Highly effective (90-95% success rate) for terminating orthodromic AVRT 1, 3
   • Brief side effects (<1 minute) occur in approximately 30% of patients 1
   • Have electrical cardioversion equipment available as adenosine may precipitate AF 1

3. Third-line: Calcium channel blockers or beta-blockers

   • Intravenous diltiazem or verapamil are particularly effective for AVNRT 1, 4
   • Verapamil works by inhibiting calcium ion influx through slow channels in cardiac conduction system 4
   • Beta-blockers are less effective than calcium channel blockers but have excellent safety profile 1, 2
   • AVOID calcium channel blockers and beta-blockers in patients with:
     • Suspected pre-excited AF (may accelerate ventricular rate) 2, 4
     • Systolic heart failure 1, 2
     • Ventricular tachycardia 2

4. Fourth-line: Synchronized cardioversion

   • Highly effective when pharmacological therapy fails or is contraindicated 1
   • Success rates of 80-98% for agents such as verapamil, diltiazem, or adenosine 1

Special Considerations

Pre-excited AF Management

• For hemodynamically stable patients with pre-excited AF, ibutilide or intravenous procainamide is recommended 1, 2
• AVOID AV nodal blocking agents (verapamil, diltiazem, beta-blockers) as they may accelerate ventricular rate and lead to ventricular fibrillation 2, 5

Long-term Management

• Catheter ablation is highly effective (94-98% success rate) and recommended as first-line therapy for recurrent, symptomatic SVT 6, 3
• For pharmacological management:
  • Oral beta-blockers, diltiazem, or verapamil may be used for AVNRT 1
  • Flecainide can be used for prevention of PSVT in patients without structural heart disease 5
  • CAUTION: Flecainide can cause proarrhythmic effects, including new or worsened supraventricular or ventricular arrhythmias 5

Important Caveats and Pitfalls

• Proper ECG diagnosis is essential before treatment to distinguish SVT from ventricular tachycardia 1, 2
• Adenosine should be used with caution when diagnosis is unclear as it may produce ventricular fibrillation in patients with coronary artery disease 1
• Flecainide should not be used in patients with recent myocardial infarction or structural heart disease due to increased risk of proarrhythmic events 5
• Untreated PSVT can lead to tachycardia-mediated cardiomyopathy in approximately 1% of patients 3
• When evaluating patients with recurrent SVT, have a low threshold for referral to a cardiologist for electrophysiologic study and possible ablation 6, 7