A 6-week-old infant presents with poor feeding and pallor. Heart rate is 290/min, regular, with a narrow QRS complex on ECG and absent visible P waves. Pulses are palpable and perfusion is adequate. After an attempted vagal maneuver fails, which drug should be given next?

• A Digoxin loading dose
• B Amiodarone 5 mg/kg loading infusion
• C Synchronized cardioversion at 2 J/kg
• D Adenosine 0.1 mg/kg rapid intravenous push ✓

Explanation

This is supraventricular tachycardia, the commonest sustained arrhythmia of infancy: rate typically above 220/min, narrow QRS, absent or abnormal P waves, and little beat-to-beat variability. In a hemodynamically stable infant, after failed vagal maneuvers the next step is adenosine 0.1 mg/kg by rapid push with a flush, doubling to 0.2 mg/kg if needed. Cardioversion is reserved for instability, and amiodarone or digoxin are later-line options.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.