1. A sudden cessation of the pumping function of the heart with the disappearance of arterial blood pressure, connoting either ventricular fibrillation or ventricular standstill.
2. The sudden stopping of the heartbeat and therefore of the pumping action of the heart.

Cardiac arrest requires immediate treatment to prevent brain damage and death.

Sudden death due to cardiac causes rather than to trauma.

The event begins with an abrupt loss of consciousness within one hour of the onset of acute symptoms.

Sudden cardiac arrest occurs most commonly in individuals with known preexisting heart disease, but in whom the time and mode of death were unexpected.