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

Management of Supraventricular Tachycardia (SVT)

For patients with SVT, a stepwise approach is recommended with vagal maneuvers and adenosine as first-line interventions for hemodynamically stable patients, while synchronized cardioversion is the first-line treatment for hemodynamically unstable patients. 1, 2

Acute Management Algorithm

Hemodynamically Unstable Patients

1. Immediate synchronized cardioversion (Class I, Level B-NR)
   • Perform without delay when patient shows signs of hemodynamic instability
   • Signs include hypotension, altered mental status, shock, or acute heart failure

Hemodynamically Stable Patients

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

   • Modified Valsalva maneuver (most effective at 43% success rate)
   • Carotid sinus massage (in appropriate patients without carotid disease)
   • Ice-cold wet towel to face (diving reflex)
   • Quick lying backward from seated position 3

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

   • Initial dose: 6 mg rapid IV push
   • If ineffective: 12 mg IV push (may repeat once if needed)
   • Acts as both diagnostic and therapeutic agent
   • Contraindicated in patients with severe asthma or known hypersensitivity

3. Third-line: IV calcium channel blockers (Class IIa, Level B-R)

   • Diltiazem or verapamil
   • Contraindicated in patients with heart failure, hypotension, or pre-excitation syndromes

4. Fourth-line: IV beta blockers (Class IIa, Level B-R)

   • Metoprolol or esmolol
   • Use with caution in patients with bronchospastic disease or decompensated heart failure

5. Fifth-line: Synchronized cardioversion (Class I, Level B-NR)

   • For stable patients when medications fail or are contraindicated

Long-term Management Options

Pharmacological Management

1. First-line: Beta blockers or calcium channel blockers (Class I, Level B-R)

   • Oral metoprolol, propranolol, diltiazem, or verapamil
   • Well-tolerated with excellent safety profile
   • Effective for prevention of recurrent episodes

2. Second-line: Flecainide or propafenone (Class IIa, Level B-R)

   • For patients without structural heart disease or ischemic heart disease
   • Flecainide starting dose: 50 mg every 12 hours, may increase to 100 mg bid
   • Maximum dose: 300 mg/day for PSVT 4
   • Contraindicated in patients with recent myocardial infarction or structural heart disease 4

3. Third-line: Sotalol (Class IIb, Level B-R)

   • May be reasonable when first and second-line agents are ineffective or contraindicated

4. Fourth-line: Dofetilide (Class IIb, Level B-R)

   • May be reasonable when first, second, and third-line agents are ineffective or contraindicated

5. Fifth-line: Amiodarone (Class IIb, Level C-LD)

   • Reserved for patients who cannot take other antiarrhythmics
   • Significant long-term side effects limit use

Catheter Ablation

• Recommended as first-line therapy for recurrent, symptomatic SVT (Class I, Level B-NR)
• High success rates (94-98.5%) with low complication rates 5
• Particularly effective for AVNRT, AVRT, and focal atrial tachycardia
• Should be considered early in management rather than after failed drug therapy

Special Considerations

Patient Education

• Teach patients how to perform vagal maneuvers for self-management (Class I, Level C-LD)
• Educate about medication side effects and when to seek emergency care

Common Pitfalls to Avoid

1. Delaying cardioversion in unstable patients

   • Hemodynamic instability requires immediate electrical cardioversion

2. Using verapamil or diltiazem in patients with pre-excitation

   • Can accelerate conduction through accessory pathway and worsen arrhythmia

3. Inadequate dosing of adenosine

   • Ensure rapid push followed by saline flush for maximum effectiveness

4. Failure to identify underlying structural heart disease

   • Comprehensive cardiac evaluation needed before starting certain antiarrhythmics

5. Overlooking Wolff-Parkinson-White syndrome

   • Pre-excitation on ECG requires special management considerations

By following this evidence-based approach to SVT management, clinicians can effectively treat both acute episodes and prevent recurrences while minimizing risks to patients.