What are the two rhythms an AED can shock in over 80% of sudden cardiac arrests?

The two rhythms that an Automated External Defibrillator (AED) can shock during sudden cardiac arrest are Ventricular Fibrillation (VF) and Ventricular Tachycardia (VT).

Ventricular Fibrillation is a chaotic heart rhythm where the heart muscles quiver instead of contracting in a coordinated manner, preventing effective blood circulation. This highly disorganized electrical activity in the heart makes it crucial to deliver a shock to restore a normal rhythm.

Ventricular Tachycardia, on the other hand, is characterized by a rapid succession of heartbeats originating from the ventricles. If it is sustained and the heart cannot effectively pump blood, it can lead to a similar state of cardiac arrest as VF. Shocking VT can also restore a normal rhythm.

Both of these rhythms are shockable and represent the most common conditions encountered in patients suffering from sudden cardiac arrest, which is why AEDs are designed to recognize and deliver shocks for them. Other options, such as Asystole or Ventricular Dyspnea, are not shockable rhythms and contribute differently to outcomes in cardiac emergencies.