What is the initial treatment for neonatal supraventricular tachycardia (SVT)?

Initial Treatment for Neonatal Supraventricular Tachycardia (SVT)

Vagal maneuvers should be considered the first-line treatment for neonatal SVT with a palpable pulse, followed by adenosine if vagal maneuvers are unsuccessful. 1

First-Line Approach: Vagal Maneuvers

• Vagal maneuvers are recommended as the initial intervention for SVT episodes as they are safe, quick to perform, and can be effective in terminating SVT 1
• For neonates, stimulation of the diving reflex (applying an ice-cold wet towel to the face) is particularly effective 1, 2
• Other vagal maneuvers that can be used include:
  • Valsalva maneuver (for older infants/children) 1
  • Carotid sinus massage (after confirming absence of bruits) 1

Second-Line Approach: Adenosine

• If vagal maneuvers fail to terminate SVT, adenosine is the preferred medication for neonates and infants with SVT 1
• Adenosine has a short half-life, making it unlikely to reach fetal circulation in significant amounts if the mother is pregnant 1
• The initial dose for adenosine is 6 mg rapid IV bolus, followed by a saline flush 1, 3
• If the initial dose is ineffective, up to 2 subsequent doses of 12 mg may be administered 1
• Recent studies confirm adenosine's safety profile in pediatric patients with typical SVT 3

Third-Line Approaches for Refractory SVT

• For refractory SVT, procainamide or amiodarone given by slow IV infusion with careful hemodynamic monitoring may be considered 1
• One pediatric comparison study showed procainamide had a significantly higher success rate with equal incidence of adverse effects compared to amiodarone for treating refractory SVT 1
• Beta-blockers (metoprolol, propranolol) can be considered when adenosine is ineffective or contraindicated 1

For Hemodynamically Unstable Patients

• Synchronized cardioversion is recommended for neonates with hemodynamically unstable SVT when pharmacological therapy is ineffective or contraindicated 1, 4
• The electrode pads should be applied such that the energy source and trajectory are directed away from vital organs 1
• Energy dosing should be 50-100J for SVT 2, 4

Important Considerations and Pitfalls

• Verapamil should NOT be used in neonates and infants due to documented severe hypotension, bradycardia, and heart block causing hemodynamic collapse and death 1
• Careful monitoring is essential when administering any rate-controlling medication to neonates 2
• For neonates with Wolff-Parkinson-White syndrome (which represents 70% of all SVT in neonates <3 months), preventive treatment with digoxin (10 μg/kg/day divided in three doses) may be required after conversion 5
• Amiodarone can cause rare but significant side effects including bradycardia, hypotension, and cardiovascular collapse with rapid administration 1

By following this algorithmic approach, starting with vagal maneuvers and progressing to adenosine and other interventions as needed, most cases of neonatal SVT can be effectively managed while minimizing risks to the patient.