Which rhythms are considered shockable in pulseless cardiac arrest?

• A. Pulseless VTach and VFib
• B. Atrial Fibrillation
• C. PEA
• D. Asystole

Answer: (A)

When a heart is in pulseless cardiac arrest, only certain electrical patterns can be interrupted and reset by a shock. The ones that are shockable are ventricular fibrillation and pulseless ventricular tachycardia. In ventricular fibrillation the ventricles quiver in a chaotic, uncoordinated way, so no effective blood is pumped. In pulseless ventricular tachycardia the rhythm is too fast and disorganized to produce meaningful output. A brief defibrillation shock can depolarize the heart, giving the normal pacemaker cells a chance to reestablish a coordinated, perfusing heartbeat.

Non-shockable rhythms, such as asystole and pulseless electrical activity, reflect little to no effective electrical activity or mechanical contraction, so delivering a shock won’t help. The focus with these rhythms is high-quality CPR and addressing reversible causes, along with appropriate meds. Atrial fibrillation isn’t a typical shockable rhythm in this arrest scenario; it represents an atrial rhythm and, if a palpable pulse is absent, it’s not one you shock to terminate in the same way VF or VT are.