What is sudden cardiac arrest?
Sudden cardiac arrest (SCA) is a condition in which the heart suddenly and unexpectedly stops beating. Blood stops flowing to the brain and other vital organs.
SCA occurs because of problems with the heart's electrical system, which signals the heart to contract and pump blood. When this system misfires, abnormal heart rhythms result. The heart simply twitches and can't pump blood.
Cardiac arrest is not the same as a heart attack, which is caused by a sudden blockage to a small artery that supplies blood to the heart muscle. (In some cases, the death of heart muscle caused by the blockage can result in someone experiencing cardiac arrest.)
Cardiac arrest usually causes death if it's not treated within minutes. Each minute the heart is stopped reduces the chance of survival by 10 percent.
Who is most at risk for sudden cardiac arrest?
It can strike people at virtually any age, although the majority of victims are in their 60s and older. People with some congenital heart defects or a history of heart attack may face greater risks, but cardiologists are divided on what types of screening might help prevent incidents even among younger people.
What are the signs of sudden cardiac arrest?
The victim may suddenly collapse or pass out or be found unresponsive. He or she may not be breathing, or have an abnormal, gasping breathing pattern. There is no pulse. Skin color may become blue or dark from lack of oxygen.
What should be done first?
Call 911, check for breathing and a pulse, begin cardiopulmonary resuscitation (CPR) and ask where the nearest automated external defibrillator, or AED, is located. If an AED is available, use it immediately. If someone has to retrieve it, start CPR until the AED arrives.
Why is an AED so important?
The only way to save a person in cardiac arrest is to shock their heart with an AED. The machine -- which is neither heavy nor hard for a layman to operate -- delivers an electric current through the chest wall to the heart muscle, momentarily stunning the heart and stopping all activity.
This "resets" the heart and allows it to resume a normal rhythm. Giving CPR before and after the shock is delivered may improve survival odds.
How does an AED work?
An AED is a small, portable device that analyzes the heart's rhythm and determines if an electric shock is needed to restore heartbeat through hand-sized adhesive electrode patches attached to the victim's chest.
AEDs come equipped with simple-to-follow instructions, which are clearly displayed on the machine's control panel. Some AEDs also give audio step-by-step instructions. The patches are simple to attach to the person's chest, and the machine is turned on by pushing a button or simply opening its case.
Public-use defibrillators bear little resemblance to the paddles and crash carts long featured in television medical dramas. The shock is mild and no one is jolted off a gurney.
It's important to remember: Do not be afraid that you will hurt the person by using the AED. The heart is already stopped.
The battery-powered device will not deliver a shock unless it determines that the heart has one of two types of rhythm problems that may respond to the jolt.
What steps do I follow?
Turn the machine on. This may happen automatically when you open the case, or there may be a power switch to press on front/top of the device.
On most AEDs, the pads are already connected by cables to the machine. Some will require the cables to be plugged into ports marked on the machine. The instructions will guide you.
Next, following instructions, place the electrodes firmly on the chest, which should be dry. The adhesive will keep them in place.
Once the pads are placed, the device should automatically start analyzing the person's heart rhythm. Stop CPR and do not touch the patient while the machine is doing this. This takes five to 10 seconds. If it determines a shock is needed, it takes a few seconds more to charge up.
If the device determines a shock is needed, it will again warn bystanders not to touch the patient. Then the AED will either automatically send the electrical current, or it will instruct you to push a flashing button on the control panel to deliver the shock.
The AED will indicate that the shock has been delivered, and there will be a slight twitch in the patient's chest muscles as it happens.
After the shock is delivered, resume CPR for two minutes unless the patient shows signs of life – normal breathing, normal pulse, moving, trying to talk. In that case, roll them on their side and wait for paramedics. If the patient is still unresponsive, leave the device in place and resume CPR. The AED will signal to start another cycle of analysis and shock after two minutes. This cycle will continue while the device is turned on and attached to the patient.
Remember: By deploying the AED, you will not hurt the person. You're
giving him or her a fighting chance at life.
(Sources: American Heart Association, American Red Cross, National Heart Lung and Blood Institute and cardiologists. Scripps health and science writer Lee Bowman can be reached at email@example.com . Distributed by Scripps Howard News Service, www.shns.com.)