In Adult Unstable VT, what energy levels are used for synchronized cardioversion?

• A. 200 J, then 150 J
• B. 100 J
• C. 300 J
• D. 150 J, then 200 J

Answer: (D)

When an adult is unstable with ventricular tachycardia that has a pulse, the goal is to terminate the tachycardia quickly with a synchronized shock that’s strong enough to convert but as gentle as possible to the heart. Synchronized cardioversion means the shock is timed with the R wave so you don’t hit during the vulnerable moment that could trigger ventricular fibrillation.

The best sequence is to deliver a first synchronized shock at 150 joules, and if conversion doesn’t occur, deliver a second shock at 200 joules. This escalating approach uses moderate energies that are typically effective with modern biphasic defibrillators and minimizes myocardial injury, while still being strong enough to interrupt the VT when synchronized.

Starting at 100 joules or jumping straight to much higher energies isn’t aligned with this common protocol for unstable VT with a pulse. A single 150 joule shock followed by 200 joules if needed provides a practical, effective progression.