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
Ventricular fibrillation is an arrhythmia that starts in your ventricle. 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 the rest of your body. In some people, V-fib may happen several times
a day. This is called an “electrical storm.”
Sustained V-fib can lead to sudden cardiac arrest (SCA) and/or sudden cardiac death
(SCD). It needs immediate medical attention.
What causes ventricular fibrillation?
The cause of ventricular fibrillation is not always known but it can occur with 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 heart
failure, heart valve disease, electrolyte abnormalities such as low potassium, certain
medicines, and certain genetic diseases that affect the heart's ion channels or electrical
Who is at risk for ventricular fibrillation?
The most common risk factors include:
A weakened heart muscle (cardiomyopathy)
An acute or prior heart attack
Genetic diseases such as long or short QT syndrome, Brugada disease, or cardiomyopathy
Certain medicines that affect heart function
What are the symptoms of ventricular fibrillation?
Symptoms of V-fib include:
How is ventricular fibrillation diagnosed?
Because V-fib usually elicits a loss of consciousness, it is often diagnosed in an
acute emergency. To diagnose V-fib, your healthcare provider (often emergency services)
Your vital signs, such as your blood pressure and pulse
Heart rhythm analysis, such as an electrocardiogram (ECG) or cardiac telemetry monitoring
or AED (automatic external defibrillator)
Your overall health and medical history
A description of your symptoms that you, a loved one, or a bystander provide
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 to important organs.
Defibrillation. This is an electrical shock that is delivered to your chest wall to restore normal
rhythm. It is often critical to perform immediately once V-fib is diagnosed.
MedicinesYour healthcare provider may give you medicines immediately after V-fib to help control
and prevent another episode. They may prescribe additional medicines to control the
arrhythmia and reduce your risk over time.
Implantable cardioverter defibrillator (ICD). This is a device that is implanted within the body to monitor for V-fib. If detected,
it can automatically deliver an energy shock to restore normal heart rhythm.
Catheter ablation. This procedure uses energy to destroy small areas of your heart affected by the irregular
heartbeat. This procedure is a treatment for ventricular tachycardia (V-tach) which
often can trigger V-fib. Most people who undergo this procedure already have an ICD
Left cardiac sympathetic denervation. This is a surgical procedure that might help you if you have frequent V-fib events.
It is not a common procedure and is usually reserved for people with uncontrolled
V-fib with a genetic predisposition.
What are possible complications of ventricular fibrillation?
Complications include the possibility of repeat episodes of fainting or near fainting.
During an episode of V-fib, there is poor blood circulation to all of your body's
vital organs. After a prolonged V-fib episode or cardiac arrest, damage involving
your neurological system, kidneys and liver may occur. This damage may be permanent
or reversible. V-fib can also be fatal.
What can I do to prevent ventricular fibrillation?
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
cardioverter defibrillators (ICDs) may also be used. An ICD is a device 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 the arrhythmia. It's also helpful to
discuss other more invasive options, such as an ICD, or surgery, to prevent V-fib.
Teach your friends and family about how to respond if you collapse and stop breathing.
When should I call my healthcare provider?
It is very important to make sure that people around you know what to do in an emergency.
Someone should call 911 right away if you have any of the following symptoms of V-fib:
Collapsing or fainting
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
Medicines and certain procedures after an episode of ventricular fibrillation can
prevent or reduce the chances of another episode.
An ICD 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