When should you suggest using a bi-phasic 2 shock waveform?

When should you suggest using a bi-phasic 2 shock waveform?

• A. When patients are taking a class 3 antiarrhythmic drug
• B. When patients have bradycardia
• C. After a long QT interval
• D. When there is ventricular pacing

Answer: (A)

Biphasic two-shock defibrillation is more effective at terminating ventricular fibrillation with less energy and less myocardial injury than older single-phase or monophasic shocks. This increased efficiency is particularly helpful in patients whose heart tissue properties are altered by antiarrhythmic drugs, especially class III agents like amiodarone or sotalol, which prolong repolarization and can make defibrillation less straightforward. The two-phase waveform delivers a more reliable depolarizing effect across these altered tissues, improving the chance of successful rhythm conversion at lower energy. The other scenarios aren’t about choosing the waveform for defibrillation: bradycardia isn’t a shockable rhythm issue, a long QT interval is a risk factor for torsades de pointes but not a specific trigger to switch to a biphasic two-shock approach, and ventricular pacing relates to pacing rather than defibrillation strategy.

Biphasic two-shock defibrillation is more effective at terminating ventricular fibrillation with less energy and less myocardial injury than older single-phase or monophasic shocks. This increased efficiency is particularly helpful in patients whose heart tissue properties are altered by antiarrhythmic drugs, especially class III agents like amiodarone or sotalol, which prolong repolarization and can make defibrillation less straightforward. The two-phase waveform delivers a more reliable depolarizing effect across these altered tissues, improving the chance of successful rhythm conversion at lower energy.

The other scenarios aren’t about choosing the waveform for defibrillation: bradycardia isn’t a shockable rhythm issue, a long QT interval is a risk factor for torsades de pointes but not a specific trigger to switch to a biphasic two-shock approach, and ventricular pacing relates to pacing rather than defibrillation strategy.