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

Management of Supraventricular Tachycardia (SVT)

The first-line management for SVT is vagal maneuvers, particularly the modified Valsalva maneuver which has superior efficacy, followed by adenosine if vagal maneuvers fail, with catheter ablation being the definitive treatment for recurrent symptomatic SVT. 1

Initial Assessment and Management Algorithm

Step 1: Hemodynamic Assessment

• Determine if patient is hemodynamically stable or unstable
• If unstable (hypotension, altered mental status, chest pain, heart failure): proceed directly to synchronized cardioversion (Class I, Level B-NR) 1
• If stable: proceed with vagal maneuvers

Step 2: Vagal Maneuvers (Class I, Level B-R)

• Modified Valsalva maneuver is the most effective vagal maneuver with success rates of 43.7% compared to 24.2% for standard Valsalva and 9.1% for carotid sinus massage 1, 2
• Technique: Patient performs Valsalva in semi-recumbent position, then is immediately laid flat with legs raised after the strain
• Alternative vagal maneuvers:
  • Standard Valsalva maneuver
  • Carotid sinus massage (avoid in elderly or those with carotid bruits)
  • Facial application of ice-cold wet towel

CAUTION: Do not attempt vagal maneuvers in hypotensive patients as they may worsen hemodynamic status 1

Step 3: Pharmacological Management

• Adenosine (Class I, Level B-R): First-line medication if vagal maneuvers fail 1

  • Success rate approximately 91%
  • Acts as both diagnostic and therapeutic agent
  • Administer as rapid IV bolus followed by saline flush

• If adenosine fails, use (Class IIa, Level B-R) 1:

  • IV calcium channel blockers (diltiazem, verapamil)
  • IV beta blockers (metoprolol, esmolol)

CAUTION: Calcium channel blockers are contraindicated in suspected pre-excited AF or VT 1

Step 4: Synchronized Cardioversion

• Indicated when:
  • Patient is hemodynamically unstable
  • Pharmacological therapy fails or is contraindicated
  • (Class I, Level B-NR) 1

Long-term Management Options

1. Catheter Ablation (Class I, Level B-NR)

• Recommended for recurrent symptomatic SVT 1
• Success rates of 94-98%
• Provides potential cure without need for chronic medications
• Refer to cardiology/electrophysiology within 1-2 weeks after initial presentation

2. Pharmacological Prevention (Class I, Level B-R)

For patients without structural heart disease:

• Oral beta blockers
• Oral calcium channel blockers
• Class IC antiarrhythmics:
  • Flecainide: Indicated for prevention of PSVT and paroxysmal atrial fibrillation/flutter 1, 3
  • Propafenone: Effective for prevention of PSVT with 47% of patients remaining attack-free compared to 16% on placebo 1, 4
• Ivabradine (2.5-7.5 mg twice daily) is a reasonable option (Class IIa, Level B-R) 1

CRITICAL WARNING: Flecainide and propafenone are contraindicated in patients with structural heart disease due to increased risk of proarrhythmia 1, 3

Special Populations

Pregnancy

• Adenosine is safe due to short half-life
• Use lowest recommended medication doses
• Avoid medications in first trimester if possible 1

End-stage Renal Disease

• Monitor for electrolyte abnormalities
• Be aware of dialysis-related fluid shifts triggering arrhythmias 1

Patient Education

• Teach proper vagal maneuver techniques for home termination of episodes
• Explain warning signs requiring medical attention
• Discuss risks and benefits of long-term management options 1

Common Pitfalls to Avoid

1. Delaying cardioversion in hemodynamically unstable patients
2. Using calcium channel blockers in suspected pre-excited AF
3. Prescribing flecainide or propafenone to patients with structural heart disease
4. Failing to refer patients with recurrent SVT for definitive treatment with catheter ablation
5. Not monitoring patients on amiodarone for thyroid disorders (13-36% risk in ACHD patients) 1