Defibrillation is indicated for which of the following situations?

Defibrillation is indicated for pulseless ventricular tachycardia because this condition involves a rapid heart rhythm that prevents the heart from effectively pumping blood, potentially leading to cardiac arrest. When the heart is in this state, it requires a jolt of electricity to reset its rhythm and allow it to regain normal function. Defibrillation delivers that electrical shock, which can restore a viable rhythm, thereby increasing the chances of survival if performed promptly.

In contrast, the other conditions listed do not typically warrant immediate defibrillation. Fainting spells might require evaluation for underlying causes, but they do not usually involve the life-threatening heart rhythm associated with defibrillation needs. Severe chest pain can indicate a heart problem but does not necessarily mean that defibrillation is required unless there are more acute signs of cardiac arrest. Bradycardia, which is characterized by a slow heart rate, may require other interventions based on the patient's symptoms and vital signs, rather than defibrillation.