Cardiac arrest occurs when the heart suddenly stops functioning. With no effective heartbeat, the brain and other vital organs are deprived of blood, leading to death within minutes.
Cardiac arrest is not a heart attack. The heart usually continues beating during a heart attack. But cardiac arrest may occur as a result of a heart attack.
An estimated 250,000 to 450,000 Americans suffer cardiac arrest each year. Ninety-five percent die, often before receiving advanced medical attention.
What causes cardiac arrest?
Electrical signals in the heart synchronize heart function so that the heart beats properly and pumps blood through the body. Abnormal heart rhythms, called arrhythmias, can interfere with normal heart function.
Ventricular fibrillation is a dangerous type of arrhythmia and the most common cause of cardiac arrest. It makes the lower chambers of the heart beat rapidly or chaotically. Other types of electrical problems that can lead to cardiac arrest include electrical signals that slow and stop, or the heart muscle's inability to respond to electrical signals.
Who is at risk?
Men are twice as likely as women are to experience cardiac arrest. This condition is rare in children.
Parents may be concerned about reports of young athletes who die of cardiac arrest. Underlying heart problems and trauma that damages the heart can cause cardiac arrest in young athletes, although the risk is very low.
What are the risk factors?
Several factors can increase the risk for developing the electrical problems that can trigger cardiac arrest. These factors include:
Coronary artery disease
Abnormal heart rhythms
A personal or family history of cardiac arrest or other genetic conditions that increase the risk for arrhythmias
Changes in the heart structure
Excessive alcohol consumption
Cardiac arrest can also occur for no known reason.
What are the symptoms of cardiac arrest?
People who suffer cardiac arrest lose consciousness and stop breathing. They have no pulse or blood pressure. An electrocardiogram shows either no electrical activity in the heart or a rhythm that is inadequate for heart function.
How is cardiac arrest treated?
Immediate treatment with a defibrillator--a device that delivers an electrical shock to the heart--can help restore the heart's normal rhythm when victims experience cardiac arrest. Cardiopulmonary resuscitation (CPR), when performed properly, can help provide adequate blood circulation until defibrillation and/or other emergency care is available.
How is cardiac arrested prevented?
Different strategies are available for preventing cardiac arrest, depending on a person's risk. Doctors may recommend that patients who survive or who are at very high risk for cardiac arrest undergo surgery to place an implantable cardioverter defibrillator under the skin of their abdomen or chest. These devices have tiny wires that connect to the heart and constantly monitor heart rhythms. When they detect dangerous arrhythmias, they deliver electrical shocks that help reestablish normal heart rhythm.
Doctors may also prescribe beta-blocker medications or perform procedures to address underlying coronary artery disease and other problems that can cause cardiac arrest.
Those who have no known risk can take these steps to help prevent cardiac arrest:
Get regular medical care
Follow a healthy diet, be physically active, lose extra pounds, and quit smoking
Work with their doctor to control chronic conditions, such as diabetes, high blood pressure, and high cholesterol
What can bystanders do?
The odds of surviving cardiac arrest decline dramatically during every minute that defibrillation and/or CPR is not provided.
A bystander who sees someone who may be suffering cardiac arrest should call 911 immediately and, if possible, use an automated external defibrillator (AED). AEDs are portable defibrillator devices posted in many public areas. If an AED is not readily available, the bystander should perform CPR until the victim has access to defibrillation.
Trained or untrained bystanders may perform "hands-only" CPR without giving mouth-to-mouth breaths. To perform hands-only CPR, follow these steps: