Atrial fibrillation occurs when the heart’s two upper chambers (the atria) beat chaotically and irregularly. This can cause blood to pool in the atria because it isn’t pumped regularly into the heart’s two lower chambers (ventricles). As a result, the upper and lower chambers don’t work in sync.
Atrial fibrillation is an arrhythmia—a problem with the electrical signals that cause the heart to beat.
Normally, the electrical impulse that acts as the heart’s “natural pacemaker” begins in the heart’s right atrium and spreads throughout the atria. From there, the impulses travel to the left and right ventricles of the heart.
In atrial fibrillation, the signals don’t start in the right atrium like they should. Instead, they start in another part of the atria or in the pulmonary veins, which makes the signals disorganized. This can cause problems between the upper and lower chambers of the heart.
Atrial fibrillation can happen every once in a while or become a long-term heart condition that lasts many years. Possible causes of atrial fibrillation include:
The lower chambers of the heart, the ventricles, are responsible for pumping blood to the lungs and body. Atrial fibrillation can disrupt their normal rhythm and lead to the following:
Sometimes atrial fibrillation doesn’t cause any symptoms and is caught when your doctor does a test for another condition.
Your doctor can diagnose atrial fibrillation using a combination of your medical history, a physical exam (pulse check and listening to heart sounds), and the results of the following tests:
If atrial fibrillation isn’t caused by an underlying heart condition, it may not need any treatment and could go away on its own. However, repeat episodes can permanently damage the heart and increase your risk of a stroke, so your doctor may treat it in one of several ways: