What does an AED do?

An AED, or Automated External Defibrillator, is a medical device specifically designed to diagnose life-threatening cardiac arrhythmias, particularly ventricular fibrillation and pulseless ventricular tachycardia. When it detects these abnormal heart rhythms, which can lead to cardiac arrest, the AED prompts the user with voice instructions and visual prompts to deliver an electric shock to the heart. This shock can restore a normal rhythm, thereby increasing the chances of survival for someone experiencing a cardiac emergency.

The other options describe functions that are not related to the primary purpose of an AED. For instance, exercising the heart refers to physical activity which is separate from the AED's function. Providing external breathing assistance, like with a bag-valve mask, is a different aspect of emergency care that AEDs do not perform. Similarly, while first aid kits contain various supplies for treating a range of medical emergencies, they do not have the diagnostic and therapeutic functions of an AED. Thus, diagnosing and addressing life-threatening arrhythmias is the essential and defining role of an AED in emergency medical situations.