Which deadly arrhythmia requires an automated external defibrillator (AED)?

• A. Ventricular fibrillation
• B. Atrial fibrillation
• C. Sinus tachycardia
• D. Premature ventricular contractions

Answer: (A)

The main idea is that an AED is used only for heart rhythms that are life-threatening and respond to a shock. Ventricular fibrillation is exactly that kind of rhythm: the ventricles twitch in a chaotic, uncoordinated way so the heart isn’t pumping effectively and there’s no usable pulse. The rapid, unsynchronized electrical activity stops when a delivery of energy is applied, allowing the heart’s normal rhythm to take over again.

Atrial fibrillation, while irregular, usually still has a pulse and is managed with medications or procedures to control rate and rhythm, not with an AED shock. Sinus tachycardia is a fast but organized rhythm with a pulse, so it’s not a target for defibrillation. Premature ventricular contractions are extra beats that can be harmless; they’re not the life-threatening rhythm that requires an AED unless they escalate into a dangerous ventricular rhythm.