Ventricular Fibrillation

What is ventricular fibrillation?

Ventricular fibrillation (V-fib) is a type of arrhythmia, or irregular heartbeat, that affects your heart’s ventricles. Your heart is a muscle system that contains 4 chambers; the 2 bottom chambers are the ventricles. In a healthy heart, your blood pumps evenly in and out of these chambers. This keeps blood flowing throughout your body.

An arrhythmia that starts in your ventricle is called ventricular fibrillation. This occurs when the electrical signals that tell your heart muscle to pump cause your ventricles to quiver instead. The quivering means that your blood is not pumping blood throughout your body. In some people, V-fib may happen several times a day. This is called an “electrical storm.”

Because V-fib can lead to cardiac arrest and death, it requires immediate medical attention.

A defibrillator is an electronic device used to treat V-fib. It produces an electric shock that can restore a normal heartbeat. Many public places, such as malls, movie theaters, and restaurants, now have defibrillators on-site. CPR training often includes instruction on their use. If you find and use a defibrillator promptly when someone collapses, you can save a life.

What causes ventricular fibrillation?

The cause of ventricular fibrillation is not always known. The most common cause, however, is a myocardial infarction (MI), or heart attack. Ventricular fibrillation can occur soon after an MI, due to its effect on the electrical system of the heart. It can also occur or much later after an MI due to scar tissue in the heart.

Who is at risk for ventricular fibrillation?

Anyone can develop V-fib, but the most common risk factors are:

  • A weakened heart muscle from an infection or illness
  • A heart attack
  • Recovery from a recent heart attack
  • A heart condition called long QT syndrome, which increases your risk for a specific type of V-fib. This type is called torsades de pointes (torsades)
  • Certain medications that affect heart function

What are the symptoms of ventricular fibrillation?

Symptoms of V-fib include:

  • Collapsing
  • Loss of responsiveness
  • Inability to breathe

How is ventricular fibrillation diagnosed?

To diagnose V-fib, your health care provider will consider:

  • Your vital signs, such as your blood pressure
  • Tests of heart function, such as an electrocardiogram
  • Your overall health and medical history
  • A description of your symptoms that you, a loved one, or a bystander provides
  • A physical examination


There are 2 stages of treatment for V-fib. The first stops your V-fib and saves your life. The second reduces your chances of developing V-fib in the future. Treatment includes:

  • CPR. The first response to V-fib may be cardiopulmonary resuscitation (CPR). This will keep your blood moving.
  • Defibrillation. You will need this during or immediately after the V-fib. Electric shock will correct the signals that are telling your heart muscles to quiver instead of pump.
  • Medication. Your health care provider may give you drugs immediately after V-fib to help you control and prevent another episode. He or she may prescribe additional medications to control arrhythmia and reduce your risk over time.
  • Catheter ablation. This procedure uses energy to destroy small areas of your heart affected by the irregular heartbeat.
  • Left cardiac sympathetic denervation. This is a surgical procedure that might help you if you have  frequent V-fib events. It is not yet commonly used.

What are the complications of ventricular fibrillation?

Complications are problems that your condition can cause. With V-fib, complications include the possibility of a repeat episode and cardiac arrest. V-fib can be fatal.

Can ventricular fibrillation be prevented?

You can help prevent V-fib by taking any medications that your health care provider has prescribed to manage your arrhythmia. Follow your health care provider’s instructions exactly. If you are at high risk for V-fib, your health care provider can implant a tiny defibrillator in your body. Talk with him or her about whether this is an appropriate option for you.

If you are at risk for V-fib, you should wear a medical ID and let friends and loved ones know what to do in an emergency. Talk with them about when to call 911, and encourage them to learn how to use a defibrillator.

How can I manage ventricular fibrillation?

If you have had V-fib, or who are at high risk for it, follow their health care provider's recommendations for taking medication to control arrhythmia. It's also helpful to research and discuss other more invasive options, such as an implantable defibrillator, or surgery, to prevent V-fib. Educate your friends and family about how to respond if you collapse and stop breathing.

When should I call my health care provider?

It is extremely important to make sure that people around you know what to do in an emergency. Someone should call 911 immediately if you experience any of the following symptoms of V-fib:

  • Collapsing
  • Unresponsiveness
  • Loss of consciousness
  • Inability to breathe

Key points about ventricular fibrillation

  • Ventricular fibrillation is a type of arrhythmia, or irregular heartbeat, that affects your heart’s ventricles
  • Ventricular fibrillation is life-threatening and requires immediate medical attention
  • CPR and defibrillation can restore your heart to its normal rhythm
  • Medications and cardiac procedures after an episode of ventricular fibrillation can prevent or reduce the chances of another episode
  • It is extremely important to make sure that people around you know what to do if you collapse because of ventricular fibrillation

Next steps

Tips to help you get the most from a visit to your health care provider:

  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the names of new medicines, treatments, or tests, and any new instructions your provider gives you.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions
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Treatments for Ventricular Fibrillation

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Symptoms and Screenings for Ventricular Fibrillation

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Causes and Preventions for Ventricular Fibrillation

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Education and Resources for Ventricular Fibrillation

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