Sudden Cardiac Arrest - Test Your Heart Health IQ

As the name implies, a sudden cardiac arrest (SCA) occurs when the heart suddenly stops beating. The result is blood stops pumping throughout the body, including to the brain and vital organs.

A person who has a sudden cardiac arrest can die within minutes, but immediate treatment with an automated external defibrillator (AED) can be life-saving. An AED is a portable device that sends an electric shock to the heart, stopping an irregular heart rhythm (such as ventricular fibrillation, the cause of most SCAs), and allowing a normal rhythm to resume. Even without formal training, most people can effectively follow instructions on an AED while waiting for EMS to arrive.

Sudden cardiac arrest is a life-threatening condition that results in death in 9 out of 10 cases. It is caused by an electrical malfunction in the heart, called ventricular fibrillation. This abnormality acts like a "short circuit" within the heart, causing it to suddenly stop beating.

Sudden cardiac arrest has some noticeable symptoms just immediately prior to the event. A person having an SCA will suddenly lose consciousness (faint) and will appear lifeless, except for making "gasping" sounds or movements, and the person will have no perceptible pulse or heartbeat. In some cases, victims can experience seizures (shaking of the arms and legs) for 10 to 20 seconds.

In the U.S., about 326,200 people experience out-of-hospital sudden cardiac arrest, and only about 10% survive. SCA is the leading cause of death among adults age 40 and older worldwide. The number of people who die annually from SCA is about the same as the combined total number of people who die from Alzheimer's disease, assault with firearms, breast cancer, cervical cancer, colorectal cancer, diabetes, HIV, house fires, motor vehicle accidents, prostate cancer, and suicides.

Sudden cardiac arrest (SCA) is not the same as a heart attack. A heart attack (also called myocardial infarction, or MI) occurs when the blood flow that brings oxygen to the heart is reduced or completely blocked, resulting in damage or death of part of the heart muscle. During a heart attack, a victim may be conscious and can complain about symptoms they experience. The person may be awake and the heart is still beating.

In contrast, in a sudden cardiac arrest, there is an electrical malfunction in the heart that causes it to suddenly stop beating. The victim will suddenly lose consciousness. In an SCA, the person is not awake, and the heart has stopped beating.

A heart attack may cause damage to the heart that leads to cardiac arrest, but they are not the same.

"Arrhythmia" is an irregular heartbeat. Arrhythmia describes any abnormal heart rhythm, including the heart beating too fast, too slow, or erratically. When the heart is in an arrhythmia, it is not pumping blood effectively, and this means the brain, lungs, and other organs are not receiving the blood supply and oxygen they need to function properly. Sudden cardiac arrest is a serious type of arrhythmia where an electrical malfunction "short circuits" the heart and causes it to stop beating.

Ventricular fibrillation (v-fib) is the most common reason for sudden cardiac arrest deaths. The lower chambers of the heart (ventricles) quiver which results in the heart pumping little to no blood. The person passes out, and can die within minutes if the v-fib is not treated immediately.

Other causes of sudden cardiac arrest include scarring from a previous heart attack, a thickened heart muscle (cardiomyopathy), heart medications, electrical abnormalities of the heart (such as Wolff-Parkinson-White syndrome and Long QT syndrome), blood vessel abnormalities, and recreational drug use.