For a stable pediatric patient with a narrow complex tachycardia (≤ 0.11 s), which treatment sequence is recommended?

• A. Vagal maneuvers only
• B. Adenosine 0.3 mg/kg IV/IO; max 12 mg; if unsuccessful
• C. Vagal maneuvers; Adenosine 0.1 mg/kg IV/IO, max 6 mg; if unsuccessful Adenosine 0.2 mg/kg IV/IO, max 12 mg
• D. Immediate synchronized cardioversion

Answer: (C)

In a stable child with a narrow-complex tachycardia, the best approach starts with noninvasive measures to interrupt the abnormal AV nodal conduction and give the heart a chance to reset. Vagal maneuvers increase parasympathetic tone and can terminate AV nodal–dependent SVT such as AVNRT or AVRT. If those maneuvers don’t restore normal rhythm, moving to adenosine is the next step. Adenosine has a very short half-life and works by transiently blocking the AV node, which can terminate the tachycardia or, at minimum, reveal the underlying rhythm.

The recommended dosing sequence is to give adenosine as a rapid IV or IO bolus with weight-based dosing: start with 0.1 mg/kg, up to a maximum of 6 mg. If there’s no response, repeat with 0.2 mg/kg, up to a maximum of 12 mg. This stepwise approach limits potential side effects while providing a high likelihood of terminating the SVT if it’s AV nodal–dependent.

If the tachycardia persists after both doses, or if the patient becomes unstable, synchronized cardioversion is indicated. In summary, vagal maneuvers first, then graded adenosine dosing (0.1 mg/kg up to 6 mg; if needed, 0.2 mg/kg up to 12 mg) aligns with the standard, safest sequence for stable pediatric narrow-complex SVT.