Sudden Cardiac Death

What is a sudden cardiac death?

Every year in the United States, at least 300,000 people die suddenly of heart problems. That is, they die within 1 to 6 hours of getting symptoms. Doctors are just now beginning to understand why sudden cardiac death occurs.

How does it occur?

Sudden cardiac death occurs because the heart stops working. The usual cause is an abnormal heart rhythm called ventricular fibrillation (VF). In VF, the heart muscle suddenly loses its ability to squeeze in a coordinated way and stops pumping. Lack of blood flow to the brain and other body tissues results in death.

Most cases of sudden cardiac death occur in the morning within the first 3 hours after waking. Only about 12% happen during sleep. Most cases of sudden cardiac death occur during everyday activities. People who don’t exercise regular and then engage in heavy physical activity are most at risk. There may be some connection between mental and emotional stress and increased risk of sudden death.

Sudden death can occur in children and young adults. In the United States, the three most common causes of sudden cardiac death in people under age 35 are:

Hypertrophic cardiomyopathy (HCM)
Coronary artery narrowing
Failure of the right ventricle to develop properly

Most cases of VF are caused by coronary artery disease. The arteries to the heart muscle become blocked by deposits called plaque and the blockage reduces blood flow to the heart muscle. Lack of enough blood to the heart muscle leads to the abnormal heart rhythm.

Disease of the heart muscle itself may cause VF. People with a thick left ventricle muscle are more likely to have VF. Heart muscle scars from prior disease, heart attacks, or infections may also trigger VF.

During times of stress, a hormone called adrenaline pours into the body to help meet physical and emotional crises. The release of adrenaline makes the heart muscle more likely to go into VF. It also increases blood pressure and heart rate and may trigger blood clot development in a coronary artery.

Can it be prevented?

Preventing sudden cardiac death depends on finding the conditions that could cause it early. Preventing coronary artery disease, treating any existing heart disease, maintaining physical fitness, and management of stress are all important.

Beta-adrenergic blockers, drugs that help prevent abnormal heart rhythms, are medicines known to reduce the risk of sudden cardiac death.

Some people at high risk for sudden death may be treated with implantable cardioverter-defibrillators (ICDs). These devices detect the onset of abnormal heart rhythms and shock the heart back to a normal rhythm before death can occur.

Information obtained from GE Medical Systems; authorization given to reproduce on HCNW web site 9/02.
Written by Donald L. Warkentin, MD
Published by McKesson Clinical Reference Systems.
Copyright © 1997-2002 McKesson Health Solutions LLC. All rights reserved.

This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.