An Automated External Defibrillator (AED) is used to diagnose and treat which arrhythmias through defibrillation?

• A. Atrial fibrillation and flutter
• B. Asystole and pulseless electrical activity
• C. Ventricular fibrillation and ventricular tachycardia
• D. Sinus tachycardia

Answer: (C)

The important idea is that an AED is used to shock the heart only when the rhythm is one that can be reset by a defibrillating shock. The rhythms that respond to defibrillation are ventricular fibrillation, where the ventricles quiver and stop pumping effectively, and pulseless ventricular tachycardia, a very fast rhythm that blocks adequate blood flow. A shock can interrupt the chaotic electrical activity and allow the heart to restart a coordinated rhythm, improving the chance of return of spontaneous circulation.

Other listed rhythms aren’t treated with defibrillation by an AED. Atrial fibrillation or flutter originate in the atria and are typically managed with medications or, if needed, electrical cardioversion under appropriate conditions—not the immediate shock used for ventricular rhythms. Asystole and pulseless electrical activity show little to no effective heart activity, so the approach is CPR and treatments to address reversible causes rather than defibrillation. Sinus tachycardia is a fast but regular rhythm and is not a shockable rhythm.