Sudden cardiac arrest claims 350,000“450,000 lives per year in the United States alone, and is responsible for more than half of all deaths due to cardiovascular disease. Unfortunately, it remains difficult to identify patients who are at high risk•in fact, cardiac arrest is the first œsymptom� of cardiovascular disease in 50% of patients with the disease. As a result, 90% of cardiac arrests occur without warning and outside the hospital setting; and lacking hospital care, the survival rate averages from 1% to 5%.

Cardiac arrest refers to the moment when electrical impulses in the heart are no longer capable of generating an effective heartbeat. The most common electrical disturbance is called ventricular fibrillation , which, if left untreated, will result in brain death in just 4 to 6 minutes. However, cardiac arrest can be reversed in 80-90% of cases if CPR and defibrillation therapy are administered within the first few minutes. CPR consists of mouth-to-mouth breathing and chest compressions that keep the heart pumping and lungs oxygenating; defibrillation consists of an electric shock to the heart that essentially overrides the chaotic fibrillations allowing the heart to restore its own normal heart rhythm. While CPR is only helpful in stalling for time, it is defibrillation that ultimately saves the life of a cardiac arrest victim. Each minute that defibrillation is delayed reduces chance for recovery by at least 10%.

Considering the urgent circumstances of out-of-hospital cardiac arrest, the American Heart Association set forth a four-point œchain of survival� plan to guide community response to these events. The four priorities include early access to care, early initiation of cardiopulmonary resuscitation (CPR), rapid defibrillation, and early advanced cardiac life support.

Traditionally, emergency medical personnel have delivered œrapid defibrillation.� But new, portable devices known as Automatic External Defibrillators (AEDs) have become more widely available for use by members of the general public who are on the scene. These AEDs are designed specifically for the medically uneducated and they are lightweight, relatively inexpensive, require little maintenance, and facilitate use by automatically diagnosing heart rhythms to confirm cardiac arrest. In tests, sixth graders used them expertly after minimal training.

To determine how much public access to defibrillation can improve cardiac arrest survival rates, researchers compared the outcomes of arrests responded to by community volunteers trained in either CPR alone or CPR and defibrillation. Their results, published in the August 12, 2004 issue of the New England Journal of Medicine, showed that cardiac arrests treated by volunteers trained in both CPR and defibrillation were twice as likely to recover.