Question

A 7-year-old boy presents with palpitations, hypotension, and altered mental status. ECG confirms supraventricular tachycardia (SVT). What is the next best step?

• A. Synchronised cardioversion
• B. Beta blockers
• C. Amiodarone
• D. Adenosine

Hint:

PALS SVT Algorithm:
$\bullet$ Stable $\rightarrow$ Vagal maneuvers $\rightarrow$ IV Adenosine ($0.1\text{ mg/kg} \rightarrow 0.2\text{ mg/kg}$).
$\bullet$ Unstable (Shock/Altered mental state) $\rightarrow$ Immediate Synchronized Cardioversion ($0.5\text{--}1\text{ J/kg} \rightarrow 2\text{ J/kg}$).

Answer 1

The Correct Option is A

Concept:
Supraventricular tachycardia (SVT) is the most common symptomatic pathological tachyarrhythmia in the pediatric population.
The management algorithm depends strictly on hemodynamic stability: stable SVT is treated medically, whereas hemodynamically unstable SVT requires immediate electrical cardioversion.
Explanation:
• Hemodynamic instability is defined by signs of poor end-organ perfusion, such as hypotension, altered mental status, diaphoresis, delayed capillary refill, weak peripheral pulses, or acute pulmonary edema.

• According to Pediatric Advanced Life Support (PALS) resuscitation guidelines, an unstable patient with SVT requires immediate synchronized electrical cardioversion.

• The initial recommended energy dose is $0.5\text{ to 1.0\text{ J/kg}$}; if ineffective, the energy dose is increased to $2\text{ J/kg$}.

• Synchronizing the shock with the R wave on the ECG is critical to avoid delivering energy during the vulnerable ventricular repolarization period (the T wave), which could induce ventricular fibrillation.

• Intravenous adenosine ($0.1\text{ mg/kg}$ rapid push) or vagal maneuvers are first-line for hemodynamically stable SVT, or can be attempted while preparing the defibrillator in unstable SVT only if vascular access is immediately available without delaying cardioversion.
Final Answer:
In a child presenting with hemodynamically unstable SVT (hypotension and altered mental status), immediate synchronized cardioversion is the mandatory next step.