Ventricular fibrillation (VFib) is a life-threatening heart rhythm disorder that occurs when the lower chambers of the heart (ventricles) beat in a rapid, chaotic, and disorganized manner. Instead of pumping blood effectively to the body and brain, the ventricles quiver ineffectively, causing blood circulation to stop.

Because ventricular fibrillation prevents the heart from delivering oxygen-rich blood to vital organs, it is considered a medical emergency. Without immediate treatment, ventricular fibrillation can lead to sudden cardiac arrest, loss of consciousness, and death within minutes.

VFib is often associated with underlying heart disease, including coronary artery disease, prior heart attack, cardiomyopathy, inherited heart rhythm disorders, and other structural or electrical abnormalities of the heart.

Signs & Symptoms

Ventricular fibrillation frequently causes sudden collapse and loss of consciousness. In some cases, warning signs may occur before an episode develops. Potential symptoms include:

• Sudden loss of consciousness
• Collapse
• No detectable pulse
• Sudden cardiac arrest
• Severe dizziness or lightheadedness
• Heart palpitations
• Chest pain
• Shortness of breath

Because ventricular fibrillation is a medical emergency, anyone experiencing sudden collapse, loss of consciousness, or suspected cardiac arrest should receive immediate emergency medical attention.

Diagnosis

Ventricular fibrillation is typically diagnosed during an emergency using an electrocardiogram (EKG) or heart rhythm monitoring that shows the characteristic chaotic electrical activity of the ventricles. After emergency treatment, additional testing is often performed to identify the underlying cause of the arrhythmia and determine the most appropriate long-term treatment plan. Diagnostic testing may include:

• Electrocardiogram (EKG)
• Echocardiogram
• Cardiac catheterization
• Cardiac CT or MRI
• Stress testing
• Electrophysiology (EP) study
• Genetic testing for inherited heart rhythm disorders

Identifying the cause of ventricular fibrillation is an important step in reducing the risk of future episodes and guiding treatment. Depending on the underlying condition, treatment may include medications, catheter ablation, an implantable cardioverter defibrillator (ICD), coronary intervention, or other advanced cardiac therapies.