Cardiac Arrest

The National Heart Lung and Blood Institute (NHLBI) says there are over 460,000 deaths from "out-of-hospital" cardiac arrest each year in the United States, about half of which occur suddenly. Your heart is a muscle that works like a pump. It is always pumping blood throughout the body, beating an average of 100,000 times a day. (Read about "The Heart and Cardiovascular System") In cardiac arrest, the heart stops beating effectively, blood does not circulate and no pulse can be felt. The victim collapses suddenly into unconsciousness.

The American Heart Association (AHA) says that, in most sudden cardiac deaths, there is underlying coronary heart disease, which may or may not have been diagnosed. (Read about "Coronary Heart Disease") In many cases, there is a sudden disturbance in the electrical impulses in the diseased heart's ventricles or lower chambers. This is called an arrhythmia and there are two types that are most dangerous:

• ventricular tachycardia (rapid)
• ventricular fibrillation (highly irregular)

Arrhythmias (Read about "Arrhythmia") can be triggered by a heart attack or can just represent a primary catastrophic rhythm disturbance. Heart attacks alone (Read about "Heart Attack"), which are caused by a blockage of a coronary artery, can also lead to cardiac arrest.

Other factors besides heart disease and heart attack can cause cardiac arrest. They include:

• respiratory arrest
• electrocution
• drowning (Read about "Water Safety")
• choking
• trauma
• anaphylaxis (Read about "Anaphylaxis")
• sudden deprivation of oxygen
• severe electrolyte disorders
• drug overdose

Sometimes, there is no known cause for cardiac arrest.

AHA says early cardiopulmonary resuscitation (CPR) and rapid defibrillation, combined with early advanced care, can lower the risk of death from cardiac arrest. CPR keeps blood and oxygen flowing to the heart and brain until defibrillation can be started. In defibrillation, electric shock is applied to the heart to restore a normal heartbeat. Unless a victim of cardiac arrest is treated within minutes, however, they can die. If you suspect cardiac arrest, call 911 immediately.

Related Information:

    Arrhythmia

    Peripheral Arterial Disease

    Vascular System

    Cardiac Rehabilitation

    The Heart and Its Valves

    Glossary of Heart Terms