Sudden Cardiac Death is NOT a heart attack
Sudden cardiac death, also called cardiac arrest, is not the same as a heart attack. A heart attack as it is commonly used, means there is death of some of the muscle cells of the heart as a result of a lack of supply of oxygen and other nutrients. This lack of supply is caused by closure of the artery that supplies that particular part of the heart muscle with blood. Sudden cardiac death happens when the heart abruptly and without warning starts beating very rapidly and erratically.
An analogy would be if the heart were compared to a house, sudden cardiac death occurs when there is an electrical problem and a heart attack happens when the problem is the plumbing.
Sudden cardiac death is a leading cause of death in the United States, responsible for half of all heart disease deaths.
Sudden cardiac death occurs when the heart’s electrical system malfunctions. It is not a heart attack, but can occur in association with a heart attack.
What causes sudden cardiac death?
The most common cause of cardiac arrest is a heart rhythm disorder, also known as arrhythmia, called ventricular fibrillation. The heart has a built-in electrical system and in a healthy heart, electrical impulses run along pathways in the heart causing it to contract in a regular, rhythmic way. When a contraction happens, blood is pumped.
When ventricular fibrillation occurs, the electrical signals that control the pumping of the heart suddenly become rapid and chaotic, causing the lower chambers of the heart (the ventricles) to “quiver” or “fibrillate” instead of contract. This means the heart no longer effectively pumps blood to the rest of the body. Without blood, the brain becomes starved of oxygen and the person loses consciousness.
If ventricular fibrillation is severe enough, it can cause death.
Who Is At Risk?
Sudden cardiac death can occur in people with no known heart disease or other problems that appear outwardly healthy, but it is not a random event. Most people at risk of sudden cardiac arrest do have heart diseases or other health problems, although they may not know it.
A number of problems increase the risk of having a cardiac arrest, including:
- having suffered a previous heart attack — Seventy-five percent of people who die of Sudden Cardiac Death show signs of a previous heart attack;
- coronary artery disease — Eighty percent of Sudden Cardiac Death victims have signs of coronary artery disease, a condition in which the arteries that supply blood to the heart are narrowed or blocked; or,
- heart failure from other causes.
To identify people at high risk for Sudden Cardiac Death, an electrophysiologist will perform any of a number of special tests, including echocardiograms, electrocardiogram, holter monitoring, event recorders, and electrophysiology studies.
Signs and symptoms that may indicate a person is at increased risk for Sudden Cardiac Death include:
- an abnormal heart rate or rhythm (arrhythmia) of unknown cause;
- episodes of fainting (called syncope) of unknown cause; and
- a low ejection fraction — The ejection fraction is a measurement of how much blood is pumped by the ventricles with each heart beat. A healthy heart pumps 55 percent or more of its blood with each beat. People at highest risk for Sudden Cardiac Death have ejection fractions of less than 40 percent, combined with ventricular tachycardia, an abnormally fast heart rate in the lower chambers of the heart.
Since a heart attack can damage the heart’s electrical system, decreasing the risk of heart attacks also decreases the risk of Sudden Cardiac Death. So, living a “heart healthy” life can help reduce the chances of dying of cardiac arrest or other heart conditions. This includes exercising regularly, eating healthful foods, maintaining a reasonable weight and avoiding smoking.
Treating and monitoring diseases and conditions that can contribute to heart problems, including high blood pressure, high cholesterol and diabetes, is also important.
Finally, for some patients, preventing Sudden Cardiac Death means controlling or stopping the abnormal heart rhythms that may trigger ventricular fibrillation. Treatment
After testing, an electrophysiologist may recommend one of three options:
Implantable Cardioverter Defibrillators (ICDs) An Implantable Cardioverter Defibrillator is a small device about the size of a pager that is implanted under the skin in the chest. It monitors the heart and if it detects abnormal beating it delivers a small shock that restores the normal rhythm.
Medications Once the main treatment for the control of abnormal heart rhythms, medications like ACE inhibitors, beta blockers and calcium channel blockers are now used more to augment other treatments. Taking medications alone has not proven to be very effective in preventing Sudden Cardiac Death caused by abnormal hearhythmstms, and are more commonly used to reduce how often implantable cardioverter defibrillators are activated.
Catheter Ablation Following tests, an electrophysiologist may be able to determine if a certain part of the heart is the cause of the quivers that lead to sudden cardiac death. If so, the electrophysiologist may decide that the best option is to use heat or cold to destroy the small areas of heart muscle that cause the abnormal electrical signals that cause rapid or irregular heart rhythms. The heat or cold is delivered through catheters that are snaked through the veins or arteries to the heart. Ablation can decrease the frequency of abnormal heart rhythms, and as with medications, may reduce how often the device fires.