Atrial fibrillation is an abnormal heart rhythm. The heart's electrical system normally sends regularly spaced signals. These signals tell the heart muscle to contract or beat.
The heart has two upper chambers called atria. It also has two lower chambers called ventricles. Each signal starts in the atria and travels to the rest of the heart. In atrial fibrillation, the electrical signals from the atria are fast and irregular. The atria shake instead of contract. Some signals do not reach the ventricles and the ventricles continue pumping. This pumping is usually irregular and sometimes rapid. This rhythm can reduce the heart’s ability to pump blood out to the body. Blood left in the heart chambers can form clots. These clots may sometimes break away and travel to the brain. This can cause stroke.
Copyright © Nucleus Medical Media, Inc.
Last reviewedNovember 2012by Michael J. Fucci, DO
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