What are sudden cardiac arrest and sudden cardiac death?
Sudden cardiac death (SCD) is a sudden, unexpected death caused by loss of heart function (sudden cardiac arrest). Sudden cardiac death is the largest cause of natural death in the United States, causing about 325,000 adult deaths in the United States each year. Sudden cardiac death is responsible for half of all heart disease deaths.
Sudden cardiac death occurs most frequently in adults in their mid-30s to mid-40s, and affects men twice as often as it does women. This condition is rare in children, affecting only 1 to 2 per 100,000 children each year.
Electrical System of the Heart
How is sudden cardiac arrest (AV) Node different from a heart attack?
Sudden cardiac arrest is not a heart attack (myocardial infarction). Heart attacks occur when there is a blockage in one or more of the coronary arteries, preventing the heart from receiving enough oxygen-rich blood. If the oxygen in the blood cannot reach the heart muscle, the heart becomes damaged.
In contrast, sudden cardiac arrest occurs when the electrical system to the heart malfunctions and suddenly becomes very irregular. The heart beats dangerously fast. The ventricles may flutter or quiver (ventricular fibrillation), and blood is not delivered to the body. In the first few minutes, the greatest concern is that blood flow to the brain will be reduced so drastically that a person will lose consciousness. Death follows unless emergency treatment is begun immediately.
Emergency treatment includes cardiopulmonary resuscitation (CPR) and defibrillation. CPR keeps enough oxygen in the lungs and gets it to the brain until the normal heart rhythm is restored with an electric shock to the chest (defibrillation). Portable defibrillators used by emergency personnel, or public access defibrillators (AEDs) may help save the person’s life.
What are the symptoms of sudden cardiac arrest?
Some people may experience a racing heartbeat or they may feel dizzy, alerting them that a potentially dangerous heart rhythm problem has started. In over half of the cases, however, sudden cardiac arrest occurs without prior symptoms.
What causes sudden cardiac death?
Most sudden cardiac deaths are caused by abnormal heart rhythms called arrhythmias. The most common life-threatening arrhythmia is ventricular fibrillation, which is an erratic, disorganized firing of impulses from the ventricles (the heart’s lower chambers). When this occurs, the heart is unable to pump blood and death will occur within minutes, if left untreated.