Sudden cardiac death occurs when your heart stops functioning unexpectedly and suddenly. When this happens if you experience sudden cardiac arrest and blood stops flowing to the brain and other vital organs. Sudden cardiac arrest usually results in death if it is not treated within minutes.
Occurring during a heart attack, the sudden cardiac arrest should not be mistaken for a heart attack. The immediate cause of sudden cardiac arrest is usually an abnormality in your heart rhythm, which is the result of a problem with your heart's electrical system. Your heart has its own electrical stimulator, which is a specialized group of cells called the sinus node located in the upper right chamber of your heart. The sinus node generates electrical impulses that flow in an orderly manner through your heart to synchronize heart rate and coordinate the pumping of blood from your heart to rest of your body.
If something goes wrong with the flow of these electric impulses through your heart, a condition known as arrhythmia occurs, causing your heart to beat too fast or too slow or in an irregular manner. Often these interruptions in rhythm are momentary and harmless. But if it is severe it can lead to a sudden stop in heart function.