A patient with a shockable initial rhythm is more likely to survive if quickly defibrillated ("shocked"). This is an important predictor of survival following a cardiac arrest.

Shockable rhythms include:

(1) ventricular tachycardia

(2) ventricular fibrillation

(3) shock by an AED


Nonshockable rhythm:

(1) asystole

(2) pulseless electrical activity


Supraventricular tachycardia (SVT) may be treated with synchronized cardioversion rather than defibrillation.


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