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Sudden cardiac arrest

Medically reviewed by Drugs.com. Last updated on Jan 19, 2023.

Overview

Sudden cardiac arrest (SCA) is the sudden loss of all heart activity due to an irregular heart rhythm. Breathing stops. The person becomes unconscious. Without immediate treatment, sudden cardiac arrest can lead to death.

Emergency treatment for sudden cardiac arrest includes cardiopulmonary resuscitation (CPR) and shocks to the heart with a device called an automated external defibrillator (AED). Survival is possible with fast, appropriate medical care.

Sudden cardiac arrest isn't the same as a heart attack. A heart attack happens when blood flow to a part of the heart is blocked. Sudden cardiac arrest is not due to a blockage. However, a heart attack can cause a change in the heart's electrical activity that leads to sudden cardiac arrest.

Symptoms

Symptoms of sudden cardiac arrest are immediate and severe and include:

Sometimes other symptoms occur before sudden cardiac arrest. These might include:

But sudden cardiac arrest often occurs with no warning.

When to see a doctor

When the heart stops, the lack of oxygen-rich blood can quickly cause death or permanent brain damage.

Call 911 or emergency medical services for these symptoms:

If you see someone who's unconscious and not breathing, call 911 or local emergency services. Then start CPR. The American Heart Association recommends doing CPR with hard and fast chest compressions. Use an automated external defibrillator, called an AED, if one is available.

How to do CPR

Do CPR if the person isn't breathing. Push hard and fast on the person's chest — about 100 to 120 pushes a minute. If you've been trained in CPR, check the person's airway. Then deliver rescue breaths after every 30 compressions.

If you haven't been trained, just continue chest compressions. Allow the chest to rise completely between compressions. Keep doing this until an AED is available or emergency workers arrive.

Portable automated external defibrillators, called AEDs, are available in many public places, including airports and shopping malls. You can also buy one for home use. AEDs come with step-by-step voice instructions for their use. They're programmed to allow a shock only when appropriate.

Causes

A change in the heart's electrical activity causes sudden cardiac arrest. The change makes the heart stop pumping blood. No blood flow goes to the body.

How the heart beats

To understand sudden cardiac arrest, it may help to know more about the heart's signaling system.

Electric signals in the heart control the rate and rhythm of the heartbeat. Faulty or extra electrical signals can make the heart beat too fast, too slowly or in an uncoordinated way. Changes in the heartbeat are called arrhythmias. Some arrhythmias are brief and harmless. Others can lead to sudden cardiac arrest.

Heart conditions that can lead to sudden cardiac arrest

The most common cause of sudden cardiac arrest is an irregular heart rhythm called ventricular fibrillation. Rapid, erratic heart signals cause the lower heart chambers to quiver uselessly instead of pumping blood. Certain heart conditions can make you more likely to have this type of heartbeat problem.

However, sudden cardiac arrest can happen in people who have no known heart disease.

Heart conditions that can cause sudden cardiac arrest include:

Chambers and valves of the heart

A typical heart has two upper and two lower chambers. The upper chambers, the right and left atria, receive incoming blood. The lower chambers, the more muscular right and left ventricles, pump blood out of the heart. The heart valves, which keep blood flowing in the right direction, are gates at the chamber openings.

Risk factors

The same things that increase the risk of heart disease can raise the risk of sudden cardiac arrest. These include:

Other things that might increase the risk of sudden cardiac arrest include:

Complications

When sudden cardiac arrest occurs, less blood flows to the brain. If the heart rhythm isn't rapidly restored, complications may include brain damage and death.

Prevention

Keeping the heart healthy may help prevent sudden cardiac arrest. You can do this by:

Genetic tests can be done to see if you have long QT syndrome, a common cause of sudden cardiac death. Check with your insurer to see if it is covered. If you have the long QT gene, your health care provider may recommend that other family members also be tested.

If you have a known risk of cardiac arrest, your health care provider might recommend a heart device called an implantable cardioverter-defibrillator (ICD). The device is placed under your collarbone.

You also might consider purchasing an automated external defibrillator (AED) for home use. Discuss this with your health care provider. AEDs help reset the heart's rhythm when a person has sudden cardiac arrest. But they can be expensive and aren't always covered by health insurance.

Diagnosis

Sudden cardiac arrest happens suddenly and requires emergency medical care at a hospital. If the heart is quickly restored, survival is possible. When you are stable, health care providers at the hospital run tests to determine the cause.

Tests

Tests are done to help determine how well the heart pumps blood and to look for diseases that affect the heart.

Tests for sudden cardiac arrest often include:

Treatment

Treatment for sudden cardiac death includes:

At the emergency room, health care providers run tests to check for the cause, such as a possible heart attack, heart failure or changes in electrolyte levels. Treatments depend on the causes.

Medications

Medicines may be used to help restore the heart rhythm. These medicines are called anti-arrhythmic drugs.

Other medicines that might be used to treat causes of sudden cardiac death or lower the risk of it include:

Surgery or other procedures

Surgeries and other treatments may be needed to correct a heart rhythm problem, open a blockage, or place a device to help the heart work better. They may include:

Lifestyle and home remedies

Preventing sudden cardiac arrest starts with keeping the heart and blood vessels in good shape. To live a heart-healthy lifestyle:

Training

If you live with someone who is at risk of sudden cardiac arrest, it's important that you be trained in CPR. The American Red Cross and other organizations offer courses in CPR and defibrillator use.

Being trained will help not only your loved one, but your training might help others. The more people know how to respond to a heart emergency, the greater the survival rate for sudden cardiac arrest is likely to be.

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