Final answer:
Defibrillation can effectively treat ventricular fibrillation and ventricular tachycardia, both of which are life-threatening ventricular arrhythmias. Automated External Defibrillators (AEDs) are crucial in diagnosing these conditions and delivering the shock needed to restore a normal heart rhythm, often after performing CPR.
Step-by-step explanation:
The most common abnormal heart rhythms that can be treated by defibrillation in cardiac arrest victims are ventricular fibrillation and ventricular tachycardia. These are types of ventricular arrhythmias which occur when the lower chambers of the heart (the ventricles) beat in a fast and chaotic manner, preventing the heart from pumping effectively. During a cardiac arrest, this can lead to a cessation of effective blood flow and can be fatal if not treated promptly. An Automated External Defibrillator (AED) is a life-saving device that can diagnose these arrhythmias and deliver the necessary electrical shock to restore a normal heart rhythm, often preceded by CPR to ensure oxygenated blood continues to flow to vital organs until the normal heart rhythm is reestablished.