cardiac arrest

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Sudden cessation of heartbeat and cardiac function, resulting in the loss of effective circulation.
• noun An instance of this.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun cardiology, pathology Sudden and complete cessation of the heartbeat resulting in the loss of effective circulation of the blood.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun 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