Clinical Scenario:
A 2-month-old previously healthy infant is brought to the emergency department with poor feeding and irritability for 6 hours. On examination: the infant is pale, HR 280/min and regular, RR 60/min, capillary refill time 3 seconds, and BP is difficult to record. Peripheral pulses are weak. ECG shows a narrow QRS complex tachycardia with no visible P waves. The infant is alert but lethargic, with no IV access established yet.
What is the most appropriate immediate management?
A. Adenosine
B. Amiodarone
C. Cardioversion
D. Ice application
E. Vagal maneuvers
Correct answer & Explanation:
Correct Answer: C — Cardioversion
Explanation:
Why C is correct: This infant shows signs of hemodynamic compromise (poor perfusion, weak pulses, difficult-to-record BP, lethargy) from SVT. In an unstable infant with SVT, synchronized DC cardioversion (0.5–1 J/kg) is the immediate treatment of choice, regardless of IV access status — it should not be delayed for vagal maneuvers or drug administration.
Why others are wrong:
- A — Adenosine is first-line only in a stable patient with IV access; here the child is unstable, so cardioversion takes priority.
- B — Amiodarone is used for refractory/recurrent SVT or when cardioversion/adenosine fails, not as immediate first-line therapy.
- D — Ice application (vagal maneuver) is appropriate only in a stable infant; too slow and unreliable in a compromised child.
- E — Vagal maneuvers are first-line in stable SVT, but this infant’s poor perfusion and lethargy indicate instability, mandating immediate cardioversion.
