Heart stops. Cardiac arrest is when the heart stops beating effectively. The heart actually ceases to beat or the heart has other electrical rhythm disturbances in which the heat no longer can work as a pump. Because of the lack of blood flow to the brain, patients become comatose, and stop breathing. Unless the condition is reversed quickly, death follows. CPR can provide some protection until help arrives.
Heart stops beating. Cardiac arrest is synonymous to sudden death and is most commonly caused by ventricular fibrillation - rapid irregular heart beats coming from the bottom heart chambers (over 250 beats per minute) - that lead to inefficient cardiac contractions with resultant circulatory collapse. If CPR is not administered promptly, the person dies. Main reasons for it are heart attacks and cardiomyopathy.