Sudden cardiac arrest (SCA) is a condition in which the heartbeat stops abruptly and unexpectedly. This usually is caused by ventricular fibrillation (VF), an abnormality in the heart's electrical system. When this happens, blood stops flowing to the brain the heart and the rest of the body, and the person collapses. In fact, the victim is clinically dead and will remain so unless someone helps immediately. A quick combination of CPR and defibrillation can restore life.

Most heart attacks involve discomfort in the center of the chest that lasts more than a few minutes or that goes away and comes back.
Some heart attack victims experience mild intermittent chest discomfort that comes and goes over a period of days. These are early “warning signs” that may precede a heart attack. (Some victims, however, do not experience any warning signs.)
Chest discomfort can feel like uncomfortable pressure, squeezing or fullness. It can evolve into crushing pain if nothing is done.

Other symptoms of heart attack include:

• Pain or discomfort in one or both arms, spreading to the shoulder, upper back, neck or jaw
• Shortness of breath
• Nausea, sweating, lightheadedness
• A general sense of anxiety
• A tendency to deny that anything serious is happening.

It’s important to act right away if these symptoms occur to maximize the odds of survival and minimize potential permanent damage to the heart.

The risk factors for heart attack include:

• A family history of heart disease
• Smoking
• High blood pressure
• High cholesterol
• Obesity
• Diabetes
• A sedentary lifestyle
• Stress.
  

How do you know whether you are at risk for SCA? Here are some risk factors:

• A previous heart attack
• A previous episode of cardiac arrest
• A low (<35%) ejection fraction or EF (the heart’s ability to pump blood)
• Underlying heart conditions such as coronary artery disease, congenital heart disease (e.g., hypertrophic cardiomyopathy), electrophysiological abnormalities (e.g., Long QT syndrome, Wolff-Parkinson-White disease, Brugada syndrome)
• Severe heart failure
• Marked changes in electrolytes in the blood
• A tendency to faint
• Hyperthyroidism
• Electrocution
• Drug abuse
• A family history of heart disease or stroke.

If you have one or more of these risk factors, you may be a candidate for SCA. If you think may be at risk, you should see a cardiologist or heart rhythm specialist (e.g., electrophysiologist, or EP) for an evaluation. The specialist may recommend implantable cardioverter defibrillator (ICD) therapy, medications, or other measures to prevent sudden death.

There are three common causes. Long QT syndrome is an often unrecognized congenital condition that predisposes the child to an abnormality in the heart's electrical system, which can lead to SCA. This is a genetic disease that affects 1 in 7,000 young people. Episodes are most commonly triggered by physical exertion or emotional stress. Commotio cordis is an electrical disturbance cases by a blow to the chest. It occurs most often in baseball, but has been reported in other sports and situations in which there is a blow to the chest. Researchers at the U.S. Commotio Cordis Registry studied 124 cases and found the average age is 14. Only 18 victims (14%) survived; most who survived received prompt CPR and defibrillation. Hypertropic cardiomyopathy is a congenital heart muscle disease. The walls of the heart's left ventrical become abnormally thickened (hypertrophy). The structural abnormality can lead to obstruction of blood flow from the heart, causing loss of consciousness and irregular heartbeat, leading to SCA. About 1 in 500 to 1000 young people have this condition.

An AED, or automated external defibrillator, is a device that automatically analyzes heart rhythms and advises the operator to deliver a shock if the heart is in a fatal heart rhythm. AEDs are safe and will not shock anyone who is not in a fatal heart rhythm. Non-medical personnel can use AEDs safely and effectively with minimal training.

SCA is treatable most of the time, especially when it is due to an electrical abnormality called ventricular fibrillation (VF). Immediate treatment includes cardiopulmonary resuscitation (CPR) and use of defibrillators. This treatment must be provided within moments of collapse to be effective, preferably within three to five minutes. Even the fastest emergency medical services may not be able to reach a victim this quickly. That is why prompt action by bystanders is so critical and why it is so important that more laypersons learn CPR and how to use an automated external defibrillator (AED).

Subsequent care includes administration of medications and other advanced cardiac life support (ACLS) techniques by emergency medical personnel. In patients who have been successfully resuscitated but remain in a coma after cardiac arrest due to VF, mild hypothermia can improve the chances of survival with good brain function. SCA survivors should see heart specialists (cardiologists and electrophysiologists) for follow-up care.

The ejection fraction (EF) is a measurement of how much blood is pumped by the verntricles with each heart beat. A healthy heart pumps 55 percent or more of its blood with each beat.

Everyone is at risk for developing heart disease. The American Heart Association has identified several risk factors. Some can be modified, treated or controlled — and some cannot.
Children of parents with heart disease, African Americans, Mexican Americans, American Indians, native Hawaiians, and some Asian Americans are at higher risk for developing heart disease. Smoking, smoke exposure, high cholesterol, high blood pressure, physical inactivity, obesity, and diabetes also contribute.
According to the American Heart Association, most people with a strong family history of heart disease have one or more other risk factors. Yet a fair amount of people affected by cardiac problems have no risk factors or are not aware that they have risk factors.
Everyone should talk to their doctor about ways to preserve cardiac health.