The state of cardiac arrest has the nickname, flatline because on an electrocardiogram (EKG), the lack of electrical activity in the heart is indicated by a flat horizontal line. (A normal EKG would show three peaks in the line corresponding with electrical activity associated with each heartbeat.)
Cardiac arrest can sometimes be reversed by defibrillation. In some cases where there is no nearby defibrillation machine nearby, the victim can be sustained through cardiopulmonary resuscitation (or "CPR") until emergency personnel arrive. Conversely, in cases of terminal illness, measures may be taken in order to obtain a do not resuscitate (DNR) order which prevents these measures from being taken if the patient goes into cardiac arrest. This advance denial of consent to initiate resuscitation, called in some jurisdications an "advance directive", is usually initiated by the person with the terminal illness when resuscitation will not alter the outcome of the disease.
Television dramas depict an unrealistically high rate of short-term and long-term success of CPR. While in actuality, about 40% short-term survival can be expected, short-term success rates in American medical dramas approach 75%, with more than 60% appearing to survive to leave the hospital. (Only about 15% of patients resuscitated in a hospital are discharged alive.)
About one fifth of the people who undergo cardiac arrest and survive report a near-death experience.