This year, more than 1 million Americans will have a heart attack or stroke, making heart disease the leading cause of death in this country. It affects people of all ages, races and occupations.

Many of these heart attack victims could survive this otherwise fatal event through the use of an automated external defibrillator (AED) by someone willing to use it. AEDs are designed to be used by laypersons, who ideally should have received AED training.

An automated external defibrillator or AED is a portable electronic device that automatically diagnoses the life threatening cardiac arrhythmias of ventricular fibrillation and ventricular tachycardia in a patient, and is able to treat them through defibrillation, the application of electrical therapy which stops the arrhythmia, allowing the heart to reestablish an effective rhythm. In each of these, the heart is in a life-threatening, pattern. In ventricular tachycardia, the heart beats too fast to effectively pump blood.

Ultimately, ventricular tachycardia leads to ventricular fibrillation. In ventricular fibrillation, the electrical activity of the heart becomes chaotic, preventing the ventricle from effectively pumping blood causing the victim to eventually die.

 Because these cardiac conditions rapidly lead to irreversible brain damage and death it is critical for CPR to be performed properly prior to the arrival of an AED. After approximately three to five minutes, irreversible brain/tissue damage may begin to occur. For every minute that a person in cardiac arrest goes without being successfully treated (by CPR and defibrillation), the chance of survival decreases by 10 percent. Everyone needs to learn the simple skill of CPR so they can provide their loved ones with a much greater chance of surviving a heart attack.

In many areas, emergency vehicles such as police cars and fire department vehicles carry AEDs. They are also becoming common on commercial airlines, cruise ships, and other transportation facilities such as bus and train stations. Automated external defibrillators may also be found in places like corporate and government offices, shopping centers, airports, restaurants, casinos, hotels, sports stadiums, schools and universities, community centers, fitness centers, health clubs, workplaces and any other location where people may congregate.

When turned on or opened, the AED will instruct the user to connect the electrodes (pads) to the patient. Once the pads are attached, avoid touching the patient so as to not cause false readings by the unit. The pads allow the AED to examine the electrical output from the heart and determine if the patient is in a shockable rhythm. If the device determines that a shock is warranted, it will use the battery to charge its internal capacitor in preparation to deliver the shock.

When charged, the device instructs the user to ensure no one is touching the victim and then to press a button to deliver the shock. Depending on the manufacturer and particular model, after the shock is delivered most devices will analyze the victim and either instruct that CPR be given, or administer another shock.

Bras with a metal underwire and ornamental metal piercings on the torso must be removed before using the AED on someone to avoid burns and interference.

AEDs approved for use in the United States use an electronic voice to prompt users through each step but because the user may be hearing impaired, many now include visual prompts as well. Their ease of use has given rise to the notion of public access defibrillation (PAD), which has the potential to be the single greatest advance in the treatment of out-of-hospital cardiac arrest since the invention of CPR. FSM Mike Dunn is president of Emergency Response Training, Inc., a Port Allen, La. based contract training and consulting firm. He is a member of ASTM and NFPA.