When Does Fibrillation Occur?

Atrial fibrillation (A-fib or AF) is the most common type of sustained cardiac arrhythmia. It occurs when there are too many electrical signals that normally control the heartbeat, causing the upper chambers of the heart (the atria) to beat extremely rapidly (more than 400 beats per minute) and quiver (fibrillate).

What is the most common cause of ventricular fibrillation?

The cause of ventricular fibrillation is not always known but it can occur during 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.

What causes AFib to occur?

Abnormalities or damage to the heart's structure are the most common cause of atrial fibrillation. Possible causes of atrial fibrillation include: High blood pressure.