Final answer:
Ventricular fibrillation is the most common presenting initial rhythm for children in cardiac arrest and requires immediate life support. Defibrillation is the most common treatment for restoring a normal heart rhythm.
Step-by-step explanation:
Ventricular fibrillation is the most common presenting initial rhythm for children in cardiac arrest. This occurs when the ventricles of the heart quiver instead of pumping blood effectively. Ventricular fibrillation is a medical emergency and requires immediate life support, often referred to as 'code blue'. The most common treatment for ventricular fibrillation is defibrillation, which uses electrical shocks to restore a normal heart rh