A heart attack can occur when one of the blood vessels that nourish the heart muscle is blocked. When a blocked blood vessel affects part of the heart that carries the signal for the heart to beat, the heart may beat irregularly or go into cardiac arrest and not beat at all. Blockage of a heart artery is the most common cause of cardiac arrest. Other causes of cardiac arrest include major electrical shock, drowning, and abnormal heartbeats.
Cardiac arrest can be fatal.
The person usually collapses and does not appear to be breathing and there is no pulse. Sometimes the heartbeat can be restarted by CPR, cardiopulmonary resuscitation. They know how to breathe for a person who has stopped breathing and pump the heart if there is no pulse. If CPR is started within seconds of a cardiac arrest, there is a better chance that the person will survive. CPR is often used to keep the person alive until emergency medical care arrives.