Which energy setting should be used first for synchronized cardioversion of stable, monomorphic ventricular tachycardia with a biphasic defibrillator?

• A. 200 joules
• B. 50 joules
• C. 100 joules
• D. 150 joules

Answer: (C)

Start with a moderate but effective energy because this is synchronized cardioversion for a stable VT with a pulse. Using a biphasic defibrillator, lower energies are typically enough to terminate the rhythm while minimizing myocardial injury. The first shock should be delivered in synchronization with the R wave to avoid delivering on the T wave, which could precipitate degeneration into VF. Therefore, 100 joules is the best initial setting because it has a high likelihood of terminating the monomorphic VT efficiently and safely with a biphasic waveform. If the VT persists, you would escalate to higher energies (for example, 150–200 joules) on subsequent shocks according to device guidelines.