asystole

In medicine, asystole is a state of no cardiac electrical activity, hence no contractions of the myocardium and no cardiac output or blood flow. Asystole is one of the conditions required for a medical practitioner to certify death. In asystole, the heart will not respond to defibrillation because it is already depolarized, however some emergency physicians advocate a trial of defibrillation in case the rhythm is actually fine ventricular fibrillation, although little evidence exists to support the practice. Asystole is usually a confirmation of death as opposed to a heart rhythm to be treated, although a small minority of patients are successfully resuscitated, if the underlying cause is identified and treated immediately.
See more at Wikipedia.org...

Asystole /asys·to·le/ cardiac standstill or arrest; absence of heartbeat.asystol´ic a·sys·to·le n. The absence of contractions of the heart. [more]Asystole - Community and Resources

Noun
1. absence of systole; failure of the ventricles of the heart to contract (usually caused by ventricular fibrillation) with consequent absence of the heart beat leading to oxygen lack and eventually to death
(synonym) cardiac arrest, cardiopulmonary arrest
(hypernym) pathology

(n.)
A weakening or cessation of the contractile power of the heart.
  

noun
state where the heart has stopped beating