This is a state, in which the pump action of the heart comes to a stop.

Cardiac action can cease due to rhythm disorder of the ventricular fibrillation type (a very rapid heart rate with complete lack of synchronization between the muscle fibers of the heart and a resulting lack of efficacious contraction) or when asystoly (total cessation of electrical and mechanical activity of the heart) is present.

Symptoms develop rapidly and include: loss of consciousness, respiratory arrest and cessation of pulse. Without treatment, irreversible brain damage ensues in a matter of minutes followed by death.

The principal mode of treatment (resuscitation) includes: external cardiac massage, mechanical ventilation, interrupting the rhythm disorder by electrical shock (defibrillation) and proper medications.