Definition

The ventricles are the large lower chambers of the heart. They are responsible for moving blood to the organs and tissues of the body. In ventricular fibrillation, the heart’s ventricles contract in a rapid and chaotic manner. As a result, little or no blood is pumped from the heart. Unless emergency medical help is provided immediately, ventricular fibrillation will lead to cardiovascular collapse and sudden death.

Blood Flow Through Heart Ventricles are lower area of red and blue sections Copyright © Nucleus Medical Media, Inc.

Causes

Causes of ventricular fibrillation include:

• Inadequate blood flow to the heart due to coronary artery disease (CAD)
• Scar tissue within the heart due to previous injury to the heart such as a heart attack
• Heart failure
• Infection of the heart muscle— myocarditis
• Shock
• Electrical shock
• Near-drowning
• Dangerously low body temperature— hypothermia
• Electrolyte imbalance
• Drugs that affect the electrical currents of the heart such as sodium or potassium channel blockers
• Low atmospheric oxygen

Risk Factors

Ventricular fibrillation is most commonly associated with CAD. Factors that can increase risk of CAD will also increase the risk of ventricular fibrillation. These include:

• Heart failure
• Heart arrhythmias —especially multiple premature ventricular beats
• Previous heart attack
• Previous ventricular fibrillation
• High blood pressure
• Diabetes
• Smoking
• Excessive use of alcohol
• Drug abuse
• Stress
• High cholesterol
• Obesity
• A high-fat diet
• A family history of cardiovascular disease
• Advancing age

Symptoms

Ventricular fibrillation happens without warning. When it occurs, symptoms may include:

• Loss of consciousness within seconds
• Sudden collapse
• Seizures
• Loss of color in the skin
• Dilated pupils
• No detectable pulse, heartbeat, or blood pressure

Diagnosis

Ventricular fibrillation is suspected when a person collapses suddenly and has no detectable pulse or heartbeat. The diagnosis is confirmed by ECG. An ECG records the heart’s activity by measuring electrical currents through the heart muscle.

Treatment

Ventricular fibrillation must be treated as an extreme emergency and treatment must be administered within 4-6 minutes.

Implantable Cardioverter Defibrillator

An implantable cardioverter defibrillator (ICD) can be surgically placed in the chest to help prevent ventricular fibrillation. An ICD continuously monitors the heart’s rhythm. If it detects an abnormal beat, it automatically sends electrical impulses to restore the heart’s normal rhythm.

Implanted Cardioverter Defibrillator Copyright © Nucleus Medical Media, Inc.

Prevention

To help reduce your chances of ventricular fibrillation:

• Lower your risk of CAD:
  • Eat a healthful diet, one that is low in saturated fat and rich in whole grains, fruits, and vegetables.
  • Exercise regularly.
  • If you are overweight, talk to your doctor about how to lose weight safely.
  • If you smoke, talk to your doctor about how to successfully quit.
• Avoid or limit your intake of caffeine, alcohol, and other substances that may contribute to arrhythmias or heart disease.
• Avoid unnecessary stress, and try to manage or control stressful situations that cannot be avoided.
• If you have a family history of this condition, see your doctor. A doctor can evaluate your risk.

If a person is at high risk of ventricular fibrillation, an implantable cardioverter defibrillator (ICD) can be surgically placed in the chest to help stop ventricular fibrillation. In addition, anti-arrhythmic drugs may be given to try to prevent a future episode.