In infants, SVT often exceeds 220 bpm, while in older children, it is typically >180 bpm.

Epinephrine (0.01 mg/kg IV/IO) is the first-line drug for bradycardia unless it is caused by increased vagal tone or AV block, in which case atropine is used.

While wide QRS tachycardia suggests VT, SVT with aberrant conduction can also present with a wide QRS.

PEA and asystole are the most common arrest rhythms in children due to respiratory failure or shock, while VF is rare.

Epinephrine (0.01 mg/kg IV/IO) should be given every 3-5 minutes during cardiac arrest to improve coronary and cerebral perfusion.

Mobitz II can progress to complete heart block, so it often requires pacing if symptomatic.

Atrial fibrillation is rare in children unless they have an underlying cardiac condition (e.g., congenital heart disease, cardiomyopathy).

Severe hyperkalemia widening the QRS complex can evolve into a sine wave pattern, leading to asystole.

PEA is a non-shockable rhythm and requires CPR, epinephrine, and treatment of reversible causes (H’s & T’s).

Peaked T waves are one of the first ECG signs of hyperkalemia, which can progress to widened QRS and cardiac arrest if untreated.

Hypoxia leads to bradycardia due to inadequate oxygenation, making oxygenation and ventilation the first priorities in treatment.

QT prolongation predisposes to Torsades de Pointes, a form of polymorphic VT that may require IV magnesium sulfate.

The initial pediatric defibrillation dose is 2 J/kg, increasing to 4 J/kg if needed.

Adenosine (0.1 mg/kg IV push, max 6 mg first dose) is the preferred initial treatment for stable SVT.

If SVT is unstable (poor perfusion, hypotension, altered mental status), synchronized cardioversion (0.5-1 J/kg) is required.