In adult unstable WPW, what is the energy sequence for synchronized cardioversion?

• A. 150J followed by 200J
• B. 100J followed by 200J
• C. 200J followed by 300J
• D. 50J followed by 100J

Answer: (A)

When a patient with WPW is unstable, the goal of synchronized cardioversion is to rapidly restore a stable rhythm while safely delivering the shock on the QRS complex. For this scenario, you start with a moderate energy and only increase if needed. The recommended sequence is to deliver the first synchronized shock at 150 joules, and if the rhythm persists, follow with a second synchronized shock at 200 joules. This approach provides a reliable chance of cardioverting with a balance between effectiveness and minimizing excessive energy exposure. Using much lower energies can fail to cardiovert, while much higher initial energies aren’t necessary and carry more risk; the step-up strategy optimizes safety and efficacy. Always ensure the shock is synchronized to the R wave to prevent R-on-T injury.