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 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 conduction.

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
• 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

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