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 body.

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 heart 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) or sudden cardiac death (SCD). It needs immediate medical care.

What causes ventricular fibrillation?

The cause of V-fib isn't always known. But it can occur with certain medical conditions. V-fib most commonly occurs during an acute heart attack or shortly after. When the heart muscle doesn't get enough blood flow, it can become electrically unstable. This causes 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, low potassium level or other electrolyte abnormalities. Also, certain medicines, and certain genetic diseases that affect the heart's or electrical conduction.

Who is at risk for ventricular fibrillation?

The most common risk factors include:

• A weakened heart muscle (cardiomyopathy)

• An acute or previous heart attack

• Genetic diseases, such as long or short QT syndrome, Brugada disease, or hypertrophic cardiomyopathy

• 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

• Fainting

• Acute shortness of breath

• Cardiac arrest

How is ventricular fibrillation diagnosed?

Because V-fib usually elicits a loss of consciousness, it's often diagnosed in an acute emergency. To diagnose V-fib, your healthcare provider (often emergency services) will consider:

• Your vital signs, such as your blood pressure and pulse

• Heart rhythm analysis, such as an electrocardiogram (ECG), cardiac telemetry monitoring, or automatic external defibrillator (AED)

• 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 two stages of treatment for V-fib. The first tries to stop 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 (cardiopulmonary resuscitation).  The first response to V-fib may be 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's often critical to perform immediately once V-fib is diagnosed.

• Medicines. Your 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's implanted within the body to watch for V-fib. If found, 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). This 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 isn't a common procedure. It 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. There is poor blood circulation to all of your body's vital organs during an episode of V-fib. 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 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 doesn't necessarily prevent V-fib, it can rapidly and automatically diagnose and treat this potentially fatal heart rhythm.

If you're at risk for V-fib, you should wear a medical ID. Also, let friends and loved ones know what to do in an emergency. Talk with them about when to call 911. 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 advice 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's 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 these symptoms of V-fib:

• Collapsing or fainting

• 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 needs immediate medical attention.

• CPR and defibrillation can restore your heart to its normal rhythm and may be lifesaving.

• 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's 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 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 you.

• 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'll 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 don't 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 visit.

• Know how you can contact your healthcare provider if you have questions.