Atrial fibrillation (AFib) is the most common abnormal heart rhythm. In a normal heart, the four chambers of the heart beat in a steady, rhythmic pattern. With AFib, the atria (upper chambers of the heart) fibrillate (quiver or twitch quickly) and create an irregular rhythm.

Click the image to view an animation on Atrial Fibrillation 

This irregular heart rhythm can lead to symptoms that negatively impact the quality of life in some people. Others experience nosymptoms at all. AFib itself is not life threatening. If left untreated, however, the side effects of AFib can be life threatening, leading to stroke or heart failure. This makes identifying and treating AFib so important.

What is Atrial Fibrillation?

A normal heartbeat begins as a single electrical impulse that comes from the atria. The impulse sends out an electrical pulse that causes the atria to contract (squeeze) and move blood into the lower ventricles. The electrical current then passes through the AV node (the electrical bridge between the upper and lower chambers of the heart), causing the ventricles to contract and relax in a steady, rhythmic sequence. This results in blood being drawn into the heart and pushed back out to the rest of the body.

When AFib occurs, the electrical impulse does not follow this order. Instead of one impulse moving through the heart, many impulses begin in the atria and fight to get through the AV node. This happens for two reasons:

• First, the structure of the heart and its electrical pathway may change over time. This happens more often as we get older.
• Second, as the electrical pathway changes, one or more “triggers” may develop. “Triggers” are electrical circuits that send extra impulses at a faster than usual rate.

These extra impulses are all trying to get through the AV node and the atria begin to fibrillate, quiver or twitch, in a fast and disorganized way.