An unstable patient with polymorphic ventricular tachycardia requires which electrical treatment with a biphasic defibrillator?

• A. Synchronized cardioversion at 50 joules
• B. Defibrillation at 200 joules
• C. Pacing at 80 bpm
• D. Defibrillation at 360 joules

Answer: (B)

Unstable polymorphic VT is treated as a cardiac arrest rhythm that should be terminated with an unsynchronized defibrillation shock. The goal is to quickly stop disorganized electrical activity and restore a perfusing rhythm, rather than delivering a synchronized shock to a rhythm that is already unstable. With biphasic defibrillators, the recommended initial energy is around 200 joules, which provides effective defibrillation with less myocardial injury than higher energies. Synchronized cardioversion is reserved for stable VT with a pulse, but instability makes synchronization inappropriate because the priority is to terminate the arrhythmia immediately with a non-synchronized shock. Pacing does not terminate VT, and using a higher energy like 360 joules isn’t the standard first choice for biphasic devices.