Final answer:
An automated external defibrillator (AED) is used in emergencies to reestablish normal heart rhythm by delivering a controlled shock to the heart, helping to correct arrhythmias and allowing the heart to resume its natural pacing.
Step-by-step explanation:
A piece of emergency equipment used to reestablish normal heart rhythm is an automated external defibrillator (AED). This portable device is crucial in cardiac emergencies, delivering a controlled electrical shock to correct arrhythmias such as ventricular fibrillation, which can lead to a heart attack. The shock provided by a defibrillator essentially 'reboots' the heart to allow the body's natural pacemaker to regain control and reestablish a normal sinus rhythm.
Defibrillators can be found in ambulances and many public places. Simplified external automatic defibrillators are often available in areas with high foot traffic, like airports and schools, allowing even nonmedical personnel to render aid. Devices can automatically diagnose the heart condition and apply the necessary shock, while verbal instructions guide the user through the process. For chronic arrhythmias, a cardiologist may implant an artificial pacemaker with a built-in defibrillator to maintain a regular heartbeat.