What are the treatment options for managing Supraventricular Tachycardia (SVT)?

Treatment for SVT Management

The first-line treatment for SVT includes vagal maneuvers, followed by adenosine, with calcium channel blockers or beta blockers as third-line options, and synchronized cardioversion for hemodynamically unstable patients or when pharmacological therapy fails. 1

Acute Management Algorithm

Step 1: Assess Hemodynamic Stability

• If patient is hemodynamically unstable (hypotension, altered mental status, signs of shock, chest pain, or heart failure):
  • Immediate synchronized cardioversion (Class I, Level B-NR) 2, 1

Step 2: For Hemodynamically Stable Patients

1. Vagal Maneuvers (Class I, Level B-R)

   • Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg) in supine position 2
   • Modified Valsalva maneuver is most effective with success rates up to 43% 3, 4
   • Carotid sinus massage: Apply steady pressure over right or left carotid sinus for 5-10 seconds after confirming absence of bruits 2
   • Ice-cold wet towel to face (diving reflex) 2
   • Overall success rate of vagal maneuvers is approximately 28% 1

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

   • Terminates approximately 95% of AVNRT cases 2, 1
   • Initial dose: 6 mg rapid IV push followed by saline flush
   • If ineffective, can increase to 12 mg
   • Caution: May precipitate AF that could conduct rapidly to ventricles 2

3. IV Calcium Channel Blockers (Class IIa, Level B-R)

   • Verapamil or diltiazem for hemodynamically stable patients without heart failure 2, 1
   • Verapamil inhibits calcium ion influx through slow channels, slowing AV conduction 5
   • Contraindicated in patients with VT, pre-excited AF, or systolic heart failure 2

4. IV Beta Blockers (Class IIa, Level B-R)

   • Metoprolol or esmolol for hemodynamically stable patients 1
   • Less effective than calcium channel blockers but have excellent safety profile 2

5. Synchronized Cardioversion (Class I, Level B-NR)

   • For patients when pharmacological therapy fails or is contraindicated 2, 1
   • Highly effective in terminating SVT 2
   • Requires adequate sedation or anesthesia in stable patients 2

Long-term Management

Pharmacological Options

1. Oral Beta Blockers or Calcium Channel Blockers

   • First-line prevention for recurrent episodes 1
   • Oral beta blockers have excellent safety profile 2
   • Oral diltiazem and propranolol combination has shown success 2

2. Class IC Antiarrhythmic Agents

   • Flecainide for patients without structural heart disease 1, 6
   • Indicated for prevention of PSVT and paroxysmal atrial fibrillation/flutter 6
   • Caution: Proarrhythmic effects - can cause new or worsened arrhythmias 6

Catheter Ablation

• Recommended for recurrent, symptomatic SVT (Class I, Level B-R) 1
• Success rates >95% for most SVT mechanisms 1, 4
• Meta-analysis shows single procedure success rates of 94.3% to 98.5% 4
• Targets specific pathways depending on SVT mechanism 2

Special Considerations

• Pre-excited AF: Avoid AV nodal blockers as they can increase conduction through accessory pathway and precipitate ventricular fibrillation 1
• Wolff-Parkinson-White syndrome: Consider procainamide for hemodynamically stable patients with atrial fibrillation 7
• Tachycardia-mediated cardiomyopathy: Can occur if SVT persists for weeks to months with fast ventricular response (1% of cases) 1, 4
• Pregnancy: Vagal maneuvers and adenosine are preferred; avoid antiarrhythmic drugs if possible

Common Pitfalls to Avoid

1. Applying pressure to the eyeball is dangerous and should be abandoned 2
2. Failing to distinguish wide-complex tachycardia as VT vs. SVT with aberrancy before treatment
3. Using verapamil or diltiazem in patients with pre-excited AF or VT, which can lead to ventricular fibrillation 2, 5
4. Initiating flecainide in patients with structural heart disease or recent myocardial infarction 6
5. Delaying cardioversion in hemodynamically unstable patients

SVT is generally a benign condition but requires prompt and appropriate management to relieve symptoms and prevent complications such as tachycardia-mediated cardiomyopathy.