What is the treatment for Supraventricular Tachycardia (SVT)?

Treatment of Supraventricular Tachycardia (SVT)

The treatment of SVT should follow a stepwise approach based on hemodynamic stability, with vagal maneuvers as first-line treatment for stable patients, followed by adenosine, calcium channel blockers or beta blockers, and synchronized cardioversion for refractory cases or unstable patients. 1

Initial Assessment

1. Assess hemodynamic stability:
   • Look for signs of instability: altered mental status, ischemic chest pain, acute heart failure, hypotension, or shock 1
   • Determine QRS duration, regularity, and heart rate (heart rate in the 170s likely indicates pathologic tachyarrhythmia) 1

Treatment Algorithm

For Hemodynamically Unstable Patients

• Immediate synchronized cardioversion (Class I, Level B-NR recommendation) 1
  • Energy settings: 120-200 J for biphasic defibrillators, 200 J for monophasic defibrillators 1

For Hemodynamically Stable Patients

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

   • Valsalva maneuver is most common (success rate ~27.7% when techniques are combined) 1
   • Modified Valsalva maneuver has shown improved efficacy (43% effective) 2

2. Adenosine IV if vagal maneuvers fail (Class I, Level B-R recommendation) 1

   • First dose: 6 mg rapid IV push followed by saline flush
   • Second dose: 12 mg if required
   • Highly effective (terminates AVNRT in ~95% of patients) 1
   • Also serves as a diagnostic agent 1

3. IV calcium channel blockers or beta blockers if adenosine fails (Class IIa, Level B-R recommendation) 1

   • Calcium channel blockers (verapamil, diltiazem) are particularly effective for converting AVNRT to sinus rhythm 1
   • Beta blockers are less effective than calcium channel blockers but may be used as an alternative 1

4. Synchronized cardioversion if pharmacological therapy fails 1

Special Considerations

Wolff-Parkinson-White Syndrome

• Avoid AV nodal blocking agents (calcium channel blockers, beta blockers, digoxin) 1
• Consider procainamide for wide-complex tachycardias (20-50 mg/min until arrhythmia suppressed, hypotension occurs, QRS duration increases >50%, or maximum dose 17 mg/kg given) 1

Pregnancy

• Follow the same management algorithm, with vagal maneuvers as first-line treatment 1
• Adenosine is a safe second-line option 1
• For cardioversion, place electrode pads to direct energy away from the uterus 1

Pediatric Patients

• Avoid verapamil in infants and children <1 year (risk of cardiovascular collapse) 1
• Avoid digoxin if pre-excitation is suspected 1
• Beta-blockers are generally safe but require monitoring for bradycardia and hypotension 1

Long-term Management

• Catheter ablation is highly effective (94.3-98.5% success rate) and recommended as first-line therapy to prevent recurrence of PSVT 2

• Pharmacological options for long-term prevention:

  • Flecainide is FDA-approved for prevention of paroxysmal SVT and paroxysmal atrial fibrillation/flutter associated with disabling symptoms in patients without structural heart disease 3
  • Caution: Flecainide has proarrhythmic effects and should not be used in patients with recent myocardial infarction or structural heart disease 3
  • Other options include calcium channel blockers and beta-blockers 2

Common Pitfalls and Caveats

• Avoid calcium channel blockers in patients with ventricular dysfunction, suspected ventricular tachycardia, or pre-excited atrial fibrillation 1

• Flecainide risks: Can cause new or worsened arrhythmias, including potentially fatal ventricular tachyarrhythmias. In SVT patients, proarrhythmic events occurred in 4% of cases 3

• Recognize wide complex tachycardia: Distinguish SVT with aberrancy from ventricular tachycardia before treatment, as misdiagnosis can lead to inappropriate therapy 1

• Monitor for tachycardia-mediated cardiomyopathy: Though rare (1%), this can develop in untreated or poorly controlled SVT 2

• Refer all patients treated for SVT for heart rhythm specialist evaluation for definitive management 4