What is ventricular fibrillation?
Ventricular fibrillation (V-fib) is a dangerous type of arrhythmia, or irregular heartbeat.
It 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
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 (fibrillate) instead. The quivering means that your blood is
not pumping blood out to your body. In some people, V-fib may happen several times
a day. This is called an “electrical storm.”
Because sustained V-fib can lead to cardiac arrest and death, it requires immediate
What causes ventricular fibrillation?
The cause of ventricular fibrillation is not always known but it can occur during
certain medical conditions. V-fib most commonly occurs during an acute heart attack
or shortly thereafter. When heart muscle does not get enough blood flow, it can become
electrically unstable and cause dangerous heart rhythms. A heart that has been damaged
by a heart attack or other heart muscle damage is vulnerable to V-fib.
Other causes include electrolyte abnormalities such as low potassium, certain medicines,
and certain genetic diseases that affect the heart's ion channels or electrical conduction.
Who is at risk for ventricular fibrillation?
The most common risk factors are:
- A weakened heart muscle (cardiomyopathy)
- An acute or prior heart attack
- Genetic diseases such as Long or Short QT syndrome, Brugada disease, or hypertrophic
- Certain medicines that affect heart function
- Electrolyte abnormalities
What are the symptoms of ventricular fibrillation?
Symptoms of V-fib include:
- Near fainting or transient dizziness
- Acute shortness of breath
- Cardiac arrest
How is ventricular fibrillation diagnosed?
To diagnose V-fib, your healthcare provider will consider:
- Your vital signs, such as your blood pressure and pulse
- 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 exam
How is ventricular fibrillation treated?
There are 2 stages of treatment for V-fib. The first tries to stops your V-fib immediately
to restore a blood pressure and pulse. The second stage focuses on reducing 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 can 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. This rarely used procedure for V-fib looks to eliminate electrical triggers
- 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 and is reserved for people with uncontrolled V-fib with
a genetic predisposition.
What are the complications of ventricular fibrillation?
Complications include the possibility of repeat episodes of fainting or near fainting.
V-fib can be fatal.
Can ventricular fibrillation be prevented?
Prevention focuses on diagnosing and treating the underlying medical conditions that
cause V-fib. Certain medicines can be used to reduce the risk of recurrence.
Implantable cardiac defibrillators are devices that are implanted within the body
that can shock the heart back to normal rhythm within seconds if V-fib is present.
Although this device does not necessarily prevent V-fib, it can rapidly and automatically
diagnose and treat this potentially fatal heart rhythm.
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 are at high risk for it, follow your healthcare provider's
recommendations for taking medicine to control arrhythmia. It's also helpful to 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 healthcare 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:
- 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 and may be life
- Medications and cardiac procedures after an episode of ventricular fibrillation can
prevent or reduce the chances of another episode.
- An implantable cardiac defibrillator can promptly treat V-fib.
- It is extremely important to make sure that people around you know what to do if you
collapse because of ventricular fibrillation
Tips to help you get the most from a visit to your healthcare provider:
- Know the reason for your visit and what you want to happen.
- Before your visit, write down questions you want answered.
- Bring someone with you to help you ask questions and remember what your provider tells
- At the visit, write down the name of a new diagnosis, and any new medicines, treatments,
or tests. Also write down any new instructions your provider gives you.
- Know why a new medicine or treatment is prescribed, and how it will help you. Also
know what the side effects are.
- Ask if your condition can be treated in other ways.
- Know why a test or procedure is recommended and what the results could mean.
- Know what to expect if you do not take the medicine or have the test or procedure.
- If you have a follow-up appointment, write down the date, time, and purpose for that
- Know how you can contact your provider if you have questions.