MedStar Heart and Vascular Institute | Sudden Cardiac Arrest - MedStar Heart and Vascular Institute

The largest cause of natural death in the U.S.

Sudden cardiac arrest is a medical emergency triggered by an abrupt loss of heart function, known as sudden cardiac arrest. This medical emergency is triggered by an electrical disturbance in the heart that stops it from beating and pumping blood to the rest of your body.

Sudden cardiac arrest is not the same as a heart attack. Heart attacks occur when a blockage in a coronary artery prevents blood from reaching the heart. While a heart attack can trigger an electrical disturbance, most do not lead to sudden cardiac arrest.

What are the symptoms of sudden cardiac arrest?

A lack of blood flow to the brain will cause a person to lose consciousness, stop breathing, and have no pulse within minutes. Death will follow without immediate medical care. People can survive sudden cardiac arrest if bystanders take fast action to help by calling 911 immediately and starting cardiopulmonary resuscitation (CPR) or using an automated external defibrillator (AED), found in many public locations, until emergency personnel arrive.

What are the causes of sudden cardiac arrest?

The most common cause of sudden cardiac arrest is an arrhythmia, or abnormal heart rhythm, particularly ventricular fibrillation.

Other heart conditions that can disrupt the heart’s rhythm include:


Individuals who survive sudden cardiac arrest will require diagnostic and imaging procedures to prevent it from happening again.

Angiogram (Angiography)

An angiogram is a special X-ray taken as a special dye is injected through a thin, flexible tube called a catheter to detect blockages or aneurysms in blood vessels.

Chest X-ray

Chest X-rays use a small dose of radiation to create pictures of the structures inside the chest, including the lungs, heart, and chest wall.

Computerized Tomography (CT) Scan

The cardiac computed tomography scan, or cardiac CT, uses X-rays to create three-dimensional images of your heart and blood vessels.


An echocardiogram uses high-frequency sound waves to create images of your heart.

Electrocardiogram (ECG)

An electrocardiogram, also known as an ECG, measures the heart’s electrical activity.

Event Monitors

An event monitor is a small device that records the heart’s electrical activity. It’s similar to an electrocardiogram, but whereas an electrocardiogram takes place over a few minutes, an event monitor measures heart rhythms over a much longer time.

Holter Monitors

A Holter monitor is a small device that records the heart’s electrical activity. It’s similar to an electrocardiogram, but whereas an electrocardiogram records over a few minutes, a Holter monitor records over the course of a day or two.

Stress Tests

Stress tests are used to assess how your heart works during physical activity. There are several types of stress tests, including treadmill or bike stress tests, nuclear stress tests, stress echocardiograms, and chemically induced stress tests.


Sudden cardiac arrest can be counteracted with CPR or a defibrillator before leading to sudden cardiac death, but action must be taken immediately. Once you arrive at the hospital, doctors will work to stabilize your heart rhythm. They also will address any underlying heart conditions to reduce your risk of another cardiac arrest.

Implantable Cardioverter Defibrillator (ICD)

An implantable cardioverter defibrillator (ICD) is a device implanted below your collarbone that monitors your heart’s rhythm. When it detects an abnormal rhythm, it delivers an electrical impulse or shock to the heart to correct it.

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