Sudden cardiac arrest (SCA) happens when the heart suddenly stops beating. It happens without warning. Someone may seem fine one minute and collapse the next.
Sudden cardiac arrest is a medical emergency. You should dial 911 and start CPR right away if you suspect SCA in someone.
Without quick action to revive the heart, a person can die in minutes. But delivering an electric shock to restore a normal heartbeat as soon as possible and giving CPR can be lifesaving.
If another person is available, ask him or her to look for an automated external defibrillator (AED). An AED is a portable device that can detect a harmful change in the heart’s rhythm (arrhythmia) and give an electric shock, called defibrillation. AEDs are available in many locations including shopping centers, sports venues, airports, community centers and office buildings.
Giving CPR and using an AED within the first few minutes of SCA can greatly improve the chances of survival.
SCA: What it is and isn’t
Sudden cardiac arrest is different from a heart attack.
|During a heart attack …||During sudden cardiac arrest …|
|Blood supply to the heart muscle is reduced or blocked, but the heart keeps beating; however, there may be damage to the heart muscle.||The electrical system of the heart goes wrong (think of the way the lights flash before the power goes out), and the heart stops pumping blood.|
|Usually, the person knows something is happening, and can talk about his or her symptoms.||Usually, the person is unconscious, and a pulse may not be found.|
In some cases, a heart attack might trigger the electrical issues that cause sudden cardiac arrest. But these events don’t need to happen at the same time.
Sudden cardiac arrest can happen in people without heart disease. About 80% of cases are due to existing coronary artery disease. However, in most cases SCA is the first sign of a heart problem. That is, those affected were unaware of their heart disease until they had sudden cardiac arrest.