What are the clinical treatment guidelines for supraventricular tachycardia?

Clinical Treatment Guidelines for Supraventricular Tachycardia

The first-line treatment for supraventricular tachycardia (SVT) is vagal maneuvers, followed by adenosine for acute conversion, with synchronized cardioversion reserved for hemodynamically unstable patients or when pharmacological therapy fails. 1

Acute Management of SVT

Step 1: Initial Assessment and Vagal Maneuvers

• Modified Valsalva maneuver is the most effective vagal maneuver with higher conversion rates than standard techniques 2
  • Performed with patient supine, bearing down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg)
  • After strain, immediately position patient in supine position with legs elevated
• Carotid sinus massage is an alternative after confirming absence of carotid bruit
  • Apply steady pressure over right or left carotid sinus for 5-10 seconds
• Ice to face technique (based on diving reflex) can also be effective
  • Apply ice-cold wet towel to face

Step 2: Pharmacological Management (if vagal maneuvers fail)

1. Adenosine IV (Class I, Level B-R) 1

   • First-line drug therapy
   • Terminates approximately 95% of AVNRT cases
   • Short half-life makes it ideal for diagnostic and therapeutic purposes
   • Common side effects include chest discomfort, dyspnea, and flushing but are short-lived

2. IV beta blockers, diltiazem, or verapamil (Class IIa, Level B-R) 1

   • For hemodynamically stable patients
   • Particularly effective for AVNRT
   • Avoid in patients with heart failure, severe pulmonary disease, or pre-excited AF

3. IV amiodarone (Class IIb) 1

   • Consider when other agents are ineffective or contraindicated

Step 3: Synchronized Cardioversion

• Immediate synchronized cardioversion (Class I, Level B-NR) 1
  • For hemodynamically unstable patients
  • When pharmacological therapy fails or is contraindicated
  • Not appropriate for rhythms that break or recur spontaneously

Long-Term Management

Pharmacological Options

• Oral beta blockers, diltiazem, or verapamil for chronic management 1
• Flecainide for prevention of PSVT in patients without structural heart disease 3, 4
  • Clinical trials show 79% of PSVT patients remained attack-free on flecainide vs. 15% on placebo
  • Contraindicated in patients with structural heart disease or recent MI
• Propafenone for paroxysmal SVT 3
  • Clinical trials demonstrate 47-67% of patients remained attack-free vs. 7-22% on placebo

Definitive Treatment

• Catheter ablation (Class I, Level B-R) 1
  • Recommended for recurrent, symptomatic SVT
  • Success rates are high for most forms of SVT
  • Consider as first-line therapy for patients with WPW syndrome

Special Considerations

SVT in Structural Heart Disease

• Avoid calcium channel blockers in patients with heart failure
• Metoprolol can be used cautiously in patients with pulmonary disease after correction of hypoxia
• Avoid beta blockers in patients with severe conduction abnormalities or sinus node dysfunction

Common Pitfalls

1. Misdiagnosis of wide-complex tachycardia

   • Always rule out ventricular tachycardia before treating presumed SVT
   • Avoid verapamil in wide-complex tachycardias of uncertain origin

2. Pre-excited atrial fibrillation

   • Avoid AV nodal blocking agents (adenosine, beta blockers, calcium channel blockers) in patients with WPW syndrome and atrial fibrillation
   • These can accelerate conduction through accessory pathway and precipitate ventricular fibrillation

3. Medication interactions

   • Flecainide elimination is slower in patients with renal impairment and CHF
   • Small increases in plasma levels occur when flecainide is co-administered with propranolol or digoxin

4. Inadequate dosing of adenosine

   • Initial dose may be ineffective; be prepared to increase dose if needed
   • Administer via large proximal vein followed by saline flush for rapid delivery

By following this stepwise approach to SVT management, clinicians can effectively treat both acute episodes and provide long-term management strategies to reduce recurrence and improve quality of life.