What are the management options for Supraventricular Tachycardia (SVT)?

Management of Supraventricular Tachycardia (SVT)

The management of SVT should follow a stepwise approach, with vagal maneuvers as first-line treatment, followed by adenosine for hemodynamically stable patients, and synchronized cardioversion for unstable patients or when pharmacological therapy fails. 1, 2

Acute Management

First-Line Approaches

• Vagal maneuvers should be performed as initial treatment for all hemodynamically stable patients with SVT 1, 2
  • Perform in supine position to maximize effectiveness 1, 2
  • Valsalva maneuver: patient bears down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg pressure) 1, 2
  • Modified Valsalva maneuver (MVM) is more effective than standard techniques with higher conversion rates 3
  • Carotid sinus massage: apply steady pressure over right or left carotid sinus for 5-10 seconds (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 approximately 27.7% 1, 2
  • AVOID applying pressure to eyeballs (dangerous and abandoned practice) 1, 2

Second-Line Approaches (Pharmacological)

• Adenosine is recommended when vagal maneuvers fail 1, 2

  • Highly effective (91-95% success rate) for acute termination 1, 4
  • Initial dose: 6 mg rapid IV bolus, followed by up to two 12 mg doses if needed 1
  • Brief side effects (chest discomfort, flushing) typically resolve within 1 minute 1
  • Also serves diagnostic purpose by unmasking atrial activity in arrhythmias like atrial flutter 1

• Calcium channel blockers (for hemodynamically stable patients) 1, 2

  • Intravenous diltiazem or verapamil are particularly effective for AVNRT 1, 2
  • AVOID in patients with suspected pre-excitation, ventricular tachycardia, or systolic heart failure 1, 2

• Beta blockers (for hemodynamically stable patients) 1, 2

  • Less effective than calcium channel blockers but have excellent safety profile 1
  • Reasonable alternative when calcium channel blockers are contraindicated 1, 2

For Hemodynamically Unstable Patients

• Synchronized cardioversion is indicated when: 1, 2
  • Patient is hemodynamically unstable 1
  • Adenosine and vagal maneuvers fail to terminate the tachycardia 1
  • Pharmacological therapy is contraindicated 1

Special Considerations

Pre-excited AF (in WPW Syndrome)

• Synchronized cardioversion is first-line 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

Pregnancy

• Vagal maneuvers remain first-line treatment 1
• Adenosine is safe during pregnancy due to its short half-life 1
• Maternal side effects (chest discomfort, flushing) are usually transient 1

Long-Term Management

• Catheter ablation is highly effective (94-98% success rate) and recommended as first-line therapy to prevent recurrence of PSVT 4

• Pharmacological options include: 2, 5, 4

  • Oral beta-blockers 1
  • Calcium channel blockers 1
  • Class IC antiarrhythmics (flecainide, propafenone) in selected patients without structural heart disease 6, 5
    • Flecainide is indicated for prevention of PSVT but should NOT be used in patients with structural heart disease or ventricular dysfunction 1, 6
    • Propafenone has demonstrated efficacy in clinical trials for PSVT management 5

Important Caveats and Pitfalls

• Proper ECG diagnosis is essential before treatment to distinguish SVT from ventricular tachycardia 2
• Flecainide should be avoided in patients with structural heart disease, recent myocardial infarction, or ventricular dysfunction due to proarrhythmic effects 6
• AV nodal blocking agents must be avoided in patients with suspected pre-excitation as they may accelerate ventricular rate 2
• Carotid sinus massage should only be performed after confirming absence of carotid bruits 1, 2
• Adenosine may precipitate atrial fibrillation that could conduct rapidly to ventricles; have electrical cardioversion equipment available 1