Any change in the normal sequencing upon the electrical impulses is termed to be “Arrhythmia” The electrical impulses may happen either faster or slower and sometimes erratically too that can cause heart beats with improper heart rates counts, where the heart cannot pump blood effectively causing improper functioning of Pulmonary system, Nervous system to shut down or to get completely damaged. The term Cardiac arrest is a condition where there is an abrupt loss of functioning process of heart in a person which may or may not been diagnosed for heart disease. Here the time and mode of death are unexpected. It occurs instantly or shortly after symptoms appear. The term Heart Attack and Cardiac arrest differs from one another. A common arrhythmia in cardiac arrest is ventricular fibrillation where the heart's lower chambers initiates’ heart beating chaotically and don't pump blood. Death occurs within minutes after the heart stops. The reverse will be the Cardiac arrest if CPR i.e. cardiopulmonary resuscitation is performed and a defibrillator is used to shock the heart and restore a normal heart rhythm within a few minutes.