Definition of Ventricular fibrillation:

Ventricular fibrillation (VF) is a severely abnormal heart rhythm (arrhythmia) that can be life-threatening.

Causes, incidence, and risk factors:

The heart pumps blood to the lungs, brain, and other organs. Interruption of the heartbeat for only a few seconds can lead to fainting (syncope) or cardiac arrest.

Fibrillation is an uncontrolled twitching or quivering of muscle fibers (fibrils). When it occurs in the lower chambers of the heart, it is called ventricular fibrillation. During ventricular fibrillation, blood is not removed from the heart. Sudden cardiac death results.

The most common cause of VF is a heart attack. However, VF can occur whenever the heart does not get enough oxygen or if a person has other heart disorders.

Conditions that can lead to VF include:

• Congenital heart disease
• Electrocution accidents or injury to the heart
• Heart attack
• Heart muscle disease, including cardiomyopathies
• Heart surgery
• Ischemia (lack of oxygen to the heart muscle because of narrowed coronary arteries or shock)
• Sudden cardiac death (commotio cordis), typically occurring in athletes after a trauma over the surface of the heart

Most people with VF have no history of heart disease. However, many have risk factors for cardiovascular disease, such as smoking, high blood pressure, and diabetes.