When the heart abruptly stops beating and halting the circulation of bloods, it is called Sudden Cardiac Arrest or SCA. People who survive previous heart attack or diagnosed with some form of heart disease are at risk of SCA. SCA symptoms include sudden collapse, loss of consciousness, abnormal breathing, inability to find pulse and loss of blood pressure.

Immediate treatment of SCA is cardiopulmonary resuscitation or CPR to help to keep the heart and blood pumping or the use of automated external defibrillator to shock the heart and restore it to normal rhythm.

People who recover from SCA or who has potential to have SCA may receive Implantable Cardioverter Defibrillator or ICD Implant. ICD is a small programmable implantable internal defibrillator device which monitor or senses the heart 24 hours a day.

If pace maker is to speed up heart rate, the ICD is working on the opposite, it slow down fast heart rate.