Ventricular fibrillation is a cardiac disturbance that causes abnormal heart rhythms and can be fatal.

For many people with this condition, irregular heart rhythms are the first and only sign of coronary artery disease.

People sometimes confuse ventricular fibrillation (VF or VFib) with atrial fibrillation (AF or AFib). Both involve irregular heart rhythms, but they affect different parts of the heart.

VF can lead to cardiac arrest within minutes if a person does not receive immediate help.

AF can also signal a serious heart condition, but it usually indicates a chronic problem that may become life threatening. VF is life threatening without treatment.

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Ventricular fibrillation (VF) is the most serious abnormal heart rhythm, according to the American Heart Association (AHA). It can lead to sudden cardiac death within minutes if a person does not receive treatment.

In VF, changes in electrical activity cause the ventricles, the lower heart chambers, to quiver rather than beat as they should.

The heart cannot pump blood, and the cardiovascular system will collapse unless a person receives immediate help. Cardiac arrest is next, which can result in death.

Almost 70% of people who experience cardiac arrest have VF.

The most common signs of VF are sudden collapse or fainting because the muscles and brain have stopped receiving blood from the heart.

Symptoms include:

Without urgent help, a person is unlikely to survive.

What is the difference between cardiac arrest and a heart attack?

Is it a heart attack?

Heart attacks occur when there is a lack of blood supply to the heart. Symptoms include:

  • chest pain, pressure, or tightness
  • pain that may spread to arms, neck, jaw, or back
  • nausea and vomiting
  • sweaty or clammy skin
  • heartburn or indigestion
  • shortness of breath
  • coughing or wheezing
  • lightheadedness or dizziness
  • anxiety that can feel similar to a panic attack

If someone has these symptoms:

  1. Dial 911 or the number of the nearest emergency department.
  2. Stay with them until the emergency services arrive.

If a person stops breathing before emergency services arrive, perform manual chest compressions:

  1. Lock fingers together and place the base of hands in the center of the chest.
  2. Position shoulders over hands and lock elbows.
  3. Press hard and fast, at a rate of 100–120 compressions per minute, to a depth of 2 inches.
  4. Continue these movements until the person starts to breathe or move.
  5. If needed, swap over with someone else without pausing compressions.

Use an automated external defibrillator (AED) available in many public places:

  1. An AED provides a shock that may restart the heart.
  2. Follow the instructions on the defibrillator or listen to the guided instructions.
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Emergency treatment focuses on restoring blood flow as quickly as possible to the organs, including the brain. The person may also receive treatment to reduce the risk of a recurrence.

Emergency treatment

Immediate emergency treatment includes CPR and the use of an automated external defibrillator (AED).

A healthcare professional will also give the emergency use drugs, amiodarone and epinephrine, and take other measures, such as maintaining an open airway and correcting a person’s electrolyte levels.

Using CPR

CPR aims to restore blood flow throughout the body. Anyone with basic life support training can do it.

The AHA recommends the following steps for hands-only CPR:

  1. Call 911 or ask someone else to do so.
  2. Lay the person on their back and look, listen, and feel for breathing.
  3. If the person is not breathing or has no pulse, start CPR.
  4. Push hard and fast at the midway point of their chest to the beat of the song “Staying Alive.”
  5. Allow the chest to rise back up between compressions.
  6. Continue until emergency help arrives or you are exhausted.

Early CPR and the use of an AED can significantly increase a person’s chance of survival.

See a visual guide on how to do CPR.

Using a defibrillator

Using an AED alongside CPR can increase a person’s chance of surviving a cardiac arrest.

An AED sends electric shocks across a person’s chest. It aims to shock the heart back to regular activity. The shock may initially stop the heartbeat but can also stop chaotic rhythms and restore regular function.

Public-use AEDs are available in many shopping malls, parks, and other public places. Anyone can use one by switching it on and following the voice instructions.

Hospital treatment

If a person has VF, a doctor will provide advanced cardiac life support (ACLS).

ACLS aims to stabilize the condition immediately and save the person’s life.

It involves:

  • CPR
  • the use of an AED
  • drug therapy

For people who recover from VF, a doctor may recommend the following to prevent a recurrence:

They may prescribe medications, such as:

They may also use:

  • An implantable cardioverter-defibrillator (ICD): An ICD recognizes faulty heart rhythms and sends a shock to correct them.
  • Coronary angioplasty: Angioplasty aims to open up an artery and keep it open by inserting a balloon or stent.
  • Coronary artery bypass graft (CABG): CABG surgery allows the blood to pass around a blockage and into the heart.
  • Catheter ablation: In catheter ablation surgery, a cardiologist inserts catheters and uses radiofrequency or freezing to destroy, or scar, the tissue that is blocking electrical signals.
  • Genetic testing and counseling: This is relevant for people with dilated cardiomyopathy who have or may have a family history of heart disease.

When the heart beats, electrical impulses that trigger a contraction need to follow a specific route to the heart. If a problem occurs with the path of these impulses, an arrhythmia, or irregular heartbeat, may occur.

When the muscles in the four chambers of the heart tighten, a heartbeat occurs. During a heartbeat, a chamber closes and pushes blood out. Also, the muscular atria, or smaller upper chambers, contract and fill the relaxed ventricles with blood.

The contraction begins when the sinus node, a small group of cells in the right atrium, emits an electrical impulse. This makes the right and left atria contract.

The impulse continues to the center of the heart, to the atrioventricular (AV) node, between the atria and the ventricles.

From the AV node, the impulse travels through the ventricles, making them contract.

As a result, blood is pumped out of the heart and into the body.

VF happens when defective electrical impulses cause the ventricles to quiver instead of pumping. When this happens, they cannot supply the body with blood. Vital organs, including the brain, lose their blood supply and stop working.

Various health conditions can cause this to happen.

Medical conditions that can lead to VF include:

What is heart disease, and how can people reduce their risk?

The left and right atria form the heart’s upper chambers, and the left and right ventricles form the two lower chambers. Together, all four chambers pump blood to and from the body.

AF happens when the atria beat irregularly and quiver. They are unable to move the blood into the ventricles.

VF is when the two lower chambers beat irregularly and flutter. VF is immediately life threatening as the heart can no longer pump blood to the rest of the body.

VF is more serious than AF. AF affects the blood supply to the body and increases the risk of severe and life threatening complications, but a person with VF is at immediate risk of losing all heart function.

Ventricular tachycardia and VF

Ventricular fibrillation usually begins with ventricular tachycardia (VT).

VT is an unusually fast heart rhythm that originates from a ventricle. It affects people with an existing heart problem. For instance, it can happen when unusual electrical impulses travel around a scar from a previous heart attack.

A sustained VT is when a VT lasts longer than 30 seconds. It can increase the risk of VF in some people.

Diagnosis of VF usually happens in emergency circumstances, and medical professionals will immediately begin ACLS.

Health professionals will use an electrocardiogram (ECG or EKG) to assess the person’s heart rhythms.

When the person’s condition is stable, a doctor will:

  • consider the person’s individual and family medical history
  • review any medications they use
  • carry out an emergency ECG and angiogram to look for underlying heart problems
  • do blood tests to look for signs of an underlying condition

Various tests can help identify the cause of VF.

Most times, VF stems from a heart condition. Some heart conditions are unavoidable, such as structural problems a person is born with.

However, a person can take measures to keep their heart as healthy as possible, including:

If a person has a heart arrhythmia, a doctor will prescribe a treatment to prevent it from progressing to VF.

Here are some questions people often ask about VF.

What usually causes ventricular fibrillation?

VF affects 3–12% of people who are experiencing a heart attack. It can result from various conditions that affect the heart, including a blockage, cardiomyopathy, exposure to toxins, sepsis, and an electrical injury.

Can you survive VF?

VF is the most serious heart rhythm problem, but people can survive if they receive emergency medical treatment. With early treatment, around half of all people with VF will likely survive. Outside of the hospital, the survival rate is around 30–40%, but people often have long-term neurological damage.

What is the treatment for VF?

A bystander can perform CPR and use an AED. When emergency healthcare professionals arrive, they will take over the use of CPR and AED and will also administer emergency medication. In the hospital, a doctor will likely give medication and may perform surgery, if necessary.

Ventricular fibrillation, also known as VF or VFib, is when the lower chambers of the heart quiver instead of pumping blood to the body. This can soon prevent blood from reaching vital organs, including the brain.

A person with VF is at risk of cardiac arrest or sudden death and needs immediate medical attention. Signs of VF include an increase in breathing problems, swelling in the feet, chest pain, and nausea and vomiting. This may progress to a loss of consciousness and sudden collapse.

Immediate emergency medical treatment can enable the person to survive in many cases.