Know How to Use an AED

Do you know what to do if someone is undergoing sudden cardiac arrest?

By Clarissa DePaz, OD

You have seen them in airports and restaurants, in sporting venues and malls, but are you aware of what they are there for? If the need arose, would you know what to do? Do you know what they are used for?

Surely, you have noticed those boxes on the wall in many public places labeled “AED.” You may have heard the term ventricular fibrillation. Now it is time to put it all together. Let’s talk about AEDs, SCAs, and CPR.

Automatic external defibrillators, or AEDs, are used to reset the heart’s cardiac rhythm in case of a sudden cardiac arrest, or SCA. SCA is a condition in which the heartbeat stops abruptly and unexpectedly. SCA is not a heart attack. SCA often happens when a blood clot suddenly blocks a coronary artery. In a heart attack, the individual is symptomatic, with chest pain or discomfort. More important in the differential is that the individual remains conscious.

SCA occurs when the heart muscle stops and blood flow stops to all organ systems, including the brain. The person undergoing SCA collapses immediately and is clinically dead unless the process is interrupted by a combination of cardiopulmonary resuscitation (CPR) and defibrillation, which can quickly restore life. The most common culprit is ventricular fibrillation, a common anomaly of the heart's electroneural system.

Unlike a heart attack, SCA can occur in people who have no known medical condition. It can happen in the young, the healthy, the active. SCA is often an early indication of a heart condition for youngsters and young adults. A history of a previous heart failure or heart attack, coronary disease, high blood pressure, and arrhythmia are known factors that put a person at risk for SCA.


Two common congenital conditions and one type of traumatic incident can put a young person at risk for SCA. Hypertrophic cardiomyopathy is a congenital heart disease in which the walls of the left ventricle become abnormally thickened, leading to obstruction of blood flow from the heart. It is estimated that one in 500 to 1,000 young people have this condition. Long QT syndrome is a congenital condition in the heart’s electroneural system, which compromises the repolarization of the heart beat. It is estimated to affect one in 7,000 young people.

Editor's Note

by Agustin Gonzalez, OD

My wife, Clarissa De Paz, OD, wrote the accompanying article after meeting and talking with Julie B. Walker, CMP, president of Choice Meetings, a meeting facilitation service that works with Shire. At last year’s American Academy of Optometry meeting, Julie told Clarissa about her daughter, Payton, who passed away several years ago due to sudden cardiac arrest (SCA).

Since her daughter’s death, Julie has channeled her grief by forming and leading the Payton Walker Foundation ( for the purpose of developing awareness and education regarding SCA. Since its inception, the foundation has performed screenings of hundreds of young athletes for congenital risk factors, and if you talk to Julie you will be amazed at their findings.

Clarissa felt that optometrists should be reminded of the threat of SCA, and she wrote the article. I think it is very useful information and a worthwhile cause. We encourage optometrists to arrange for cardiopulmonary resuscitation and automatic external defibrillator training in their offices for employees, and even for patients, through the American Red Cross.

The most common cause of death associated with SCA is acute coronary ischemia causing ventricular fibrillation. In the adult population, left ventricular hypertrophy associated with chronic hypertension damaging the left ventricle is the leading cause of SCA.

In young people who play contact sports, commotio cordis, or agitation of the heart, can occur due to a blunt trauma to the chest’s precordial region. This blow causes a disturbance to the cardiac muscle at a critical time and causes a form of ventricular fibrillation. The fatality rate is around 65%, but in most cases it can be reversed by defibrillation. In the United States, the Commotio Cordis Registry studied 124 cases of commotio cordis; of these, there was a 14% survival rate, with a common factor for survival being prompt CPR and defibrillation.


An AED is a device that automatically analyzes heart rhythms, and, depending on the need of the victim, advises the operator to deliver either CPR or a pulse of electricity that stimulates the heart muscle back into rhythm. This electric shock stimulates the heart of the person undergoing an SCA event.

AEDs have an internal computer that monitors the heartbeat and analyzes the individual’s heart rhythm. The AED’s internal computer then decides whether CPR or a shock is called for and tells the operator which to do. As such, AEDs are safe: They will not shock anyone who is not in a fatal heart rhythm.

It is important to understand that AEDs do not replace CPR and that CPR remains a critical and important method to improve the chances of survival of a person undergoing SCA.


It is important for health care workers to have a basic understanding of SCA and the use of AEDs. Many states require optometrists to undergo CPR training, but little is discussed about AEDs, their use, and the recognition of SCA.

Optometrists can play a role in creating and developing community awareness of AEDs and their proper use. It is possible that, at any time, we may be exposed to a situation in which we would be required to use an AED for SCA. For health professionals, having an awareness of SCA and knowledge of the use of an AED might just make the difference in saving a life. n

Clarissa De Paz, OD
• Private practice, McKinney, Texas
• (972) 562-0011