Cardiac Arrest

Medically Reviewed By William C. Lloyd III, MD, FACS

What is cardiac arrest?

Cardiac arrest is when your heart stops beating suddenly—with no warning—because of a problem with the electrical system that regulates your heart. Sudden cardiac arrest is a life-threatening medical emergency and treatment within a few minutes is essential to save the life of someone experiencing it.

Many people confuse cardiac arrest with a heart attack but they are different. In a heart attack, the heart continues to beat but there is a block in blood flow to the heart muscle itself. Left untreated, heart attack can also lead to cardiac arrest. Cardiac arrest is due to an arrhythmia, which is when your heart’s rhythm is not functioning correctly. However, not all arrhythmias cause cardiac arrest.

There are many possible causes of cardiac arrest, including heart disease, extreme physical stress, drug or alcohol abuse, and some inherited conditions. Sometimes doctors don’t know the underlying cause of cardiac arrest.

If you have high blood pressure or heart disease, you are at increased risk for cardiac arrest. Medical treatment for these conditions will help reduce your risk of cardiac arrest. Smoking, obesity, drug abuse, and a family history of cardiac disease can also increase your risk. Cardiac arrest is more common in men and in people who have suffered a heart attack in the past. In the United States, more than 400,000 people a year will have cardiac arrest.

When a person experiences cardiac arrest, they will collapse suddenly, losing consciousness. They will not breathe and do not have a pulse. If you are with someone you think may be experiencing cardiac arrest, call 911 and perform CPR to try and restore a heartbeat until help arrives. If you do not know how to perform CPR, find someone who does, but call 911 first. Look for a portable defibrillator (automated external defibrillator, or AED) which restarts the heart with an electric shock. If one is available, a 911 operator may be able to guide you on how to use it. Restoring a normal heartbeat can prevent sudden cardiac death and save a life.

What are the symptoms of a cardiac arrest?

Cardiac arrest is a life-threatening emergency that occurs with no warning.

Common symptoms of cardiac arrest

The most common cardiac arrest symptoms are:

  • Sudden collapse
  • Loss of consciousness, which you can determine by shaking the person and speaking loudly
  • Cessation of breathing, which you can determine by chest movement, hearing the sound of breathing, and feeling air on your cheek
  • Lack of pulse, which can be felt at the wrist or neck
  • Heart not beating

Call 911 for signs and symptoms of cardiac arrest. CPR and defibrillation can help save the person’s life. Even if you have no CPR training, begin chest compressions—100 to 120 hard compressions per minute—until emergency personnel arrive.

What causes cardiac arrest?

The immediate cause of cardiac arrest is when the heart’s electrical conduction system fails and doesn’t send signals to the heart to keep it beating in a way that allows the heart to pump blood effectively. This is ventricular fibrillation, which is characterized by random and rapid electrical impulses that make your heart quiver rather than beat. When the heart does not beat properly, it does not send oxygenated blood to the rest of the body. That can lead to cardiac arrest, in which the heart stops beating.

Various types of heart disease and structural problems in the heart can trigger ventricular fibrillation and other arrhythmias leading to cardiac arrest.

What are the risk factors for cardiac arrest?

A number of factors increase the risk of developing cardiac arrest. Not all people with risk factors will have cardiac arrest, which is most common in older males and those with a family history of heart disease.

Risk factors for cardiac arrest include:

 If you have a healthy heart with no heart disease or other heart condition, you are unlikely to have a serious arrhythmia leading to cardiac arrest without a direct cause, such as a large electric shock or overdose.  

Reducing your risk of cardiac arrest

You may be able to lower your risk of cardiac arrest by:

  • Getting regular physical exercise
  • Staying at a healthy weight
  • Not smoking
  • Controlling diabetes, high cholesterol, and high blood pressure

How do medical professionals treat cardiac arrest?

Cardiac arrest is a serious medical emergency that can be fatal if not treated immediately. CPR and heart defibrillation must be administered within minutes of cardiac arrest. Call 911 if you suspect someone has had cardiac arrest. Perform CPR or use a portable defibrillator. AEDs come with simple instructions.

If a normal rhythm can be established, the person will stay in a hospital for cardiac monitoring and care. A cardiologist will likely order cardiac diagnostic and imaging tests to help determine the underlying cause of cardiac arrest, if possible. Cardiac arrest treatment may include medicine to reduce the risk of another episode. People at high risk for sudden cardiac arrest may be candidates for a heart defibrillator implant, which involves minor chest surgery. 

What are the potential complications of cardiac arrest?

Emergency medical treatment is necessary to prevent death from cardiac arrest. After resuscitation, complications of cardiac arrest can include neurological and other types of organ damage from lack of freshly oxygenated blood flow. There are also potential complications of resuscitation and restoring blood flow throughout the body, including postcardiac arrest shock. Reduced heart function with postcardiac arrest shock is often temporary.

Patients should be evaluated, treated and monitored for heart disease and other conditions to prevent a second event and to the reduce the risk of complications of cardiac arrest and its treatment.

Was this helpful?
  1. Cardiac Arrest. MedlinePlus, U.S. National Library of Medicine.
  2. About Cardiac Arrest. American Heart Association.
  3. Sudden cardiac arrest. Mayo Clinic.
  4. Ventricular fibrillation. American Heart Association.
  5. How Can Death Due to Sudden Cardiac Arrest Be Prevented? National Heart, Lung, and Blood Institute.
  6. Mongardon N, Dumas F, Ricome S, et al. Postcardiac Arrest Syndrome: From Immediate Resuscitation to Long-term Outcome. Ann Intensive Care. 2011;1:45-56.
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Jan 23
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