Atrial

Atrial fibrillation happens when electrical impulses in two of the four chambers of the heart go into an irregular or chaotic pattern.

Atrial fibrillation is a major cause of stroke and heart failure and may also be related to an increased risk of death. It's an abnormal rhythm of the heart that is caused when the upper chambers of the heart beat in an uncoordinated and irregular fashion.

The most common type of irregular heartbeat is atrial fibrillation or AFib. It is estimated that between three and six million people in the United States have AFib.