Cardiac arrest, otherwise known as Asystole, is a medical condition where the heart does not have any electrical activity nor pumps blood.
Certain forms of cardiac arrest may be treated using a defibrillator.
In medical parlance, cardiac arrest is referred to as a "code" or a "crash". This typically refers to "code blue" on the hospital emergency codes. A dramatic drop in vital sign measurements is referred to as "coding" or "crashing", though coding is usually used when it results in cardiac arrest, while crashing might not. Treatment for cardiac arrest is sometimes referred to as "calling a code".
Also see Cardiac arrest at Wikipedia