Final answer:
An automated external defibrillator (AED) delivers a shock to correct abnormal heart rhythm caused by ventricular fibrillation. It terminates the arrhythmia and allows the body's pacemaker to resume its normal rhythm.
Step-by-step explanation:
In a cardiac emergency, a portable electronic device known as an automated external defibrillator (AED) can be a lifesaver. A defibrillator delivers a large charge in a short burst, or a shock, to a person's heart to correct abnormal heart rhythm (an arrhythmia).
A heart attack can arise from the onset of fast, irregular beating of the heart-called cardiac or ventricular fibrillation. Applying a large shock of electrical energy can terminate the arrhythmia and allow the body's natural pacemaker to resume its normal rhythm.
Today, it is common for ambulances to carry a defibrillator, which also uses an electrocardiogram to analyze the patient's heartbeat pattern. Automated external defibrillators (AED) are found in many public places. These are designed to be used by lay persons and can automatically diagnose the patient's heart condition and apply the shock with appropriate energy and waveform.1