What is Atrial Fibrillation (AFib)?

Atrial fibrillation, or "AFib," is the most common type of serious arrhythmia - it affects about 2.2 million Americans, with 160,000 new cases diagnosed annually.

AFib is a very fast and irregular rhythm originating in the atria. AFib occurs when the heart’s electrical signal begins in a different part of the atrium other than where it is supposed to begin, the sinoatrial (SA) node, which is known as the pacemaker of the heart.

When this happens, the electrical signal does not travel through the normal pathways in the atria, but instead may spread throughout the atria in a fast and disorganized manner. This causes the walls of the atria to quiver very fast (fibrillate) instead of beating normally. As a result, the atria are not able to adequately fill with blood or pump blood in sufficient amounts.

The two most serious complications of chronic (long-term) AF are stroke and heart failure. Stroke can happen when a blood clot travels to an artery in the brain, blocking off blood flow. In AFib, blood clots can form in the atria because some of the blood “pools” in the fibrillating atria instead of flowing into the ventricles. If a piece of a blood clot in the left atrium breaks off, it can travel to the brain, causing a stroke. People with AFib are often treated with blood-thinning medicines to reduce the chances of developing blood clots.

Heart failure occurs when the heart cannot pump enough blood to meet the needs of the body. AFib can cause heart failure when the ventricles beat too fast and do not have enough time to fill with blood to pump out to the body. Heart failure causes tiredness, leg swelling and shortness of breath.

AFib and other supraventricular (originating above the ventricles) arrhythmias can occur for no apparent reason. Most of the time, however, supraventricular arrhythmias are caused by an underlying condition that interferes with the heart’s ability to conduct electrical impulses. These conditions include high blood pressure (hypertension), coronary artery disease, heart failure or rheumatic heart disease.

Other conditions also can lead to AFib, including overactive thyroid gland (too much thyroid hormone produced) and heavy alcohol use. AF also becomes more common as people get older.

Causes and Risk Factors of AFib

Causes and risk factors of heart arrhythmia include:

Symptoms of AFib

Atrial Fibrillation can be "silent" and not show any symptoms, but among individuals who do experience atrial fibrillation symptoms, common complaints include:

  • Rapid or slow heartbeat (palpitations)
  • Skipping beats - changes in the pattern of the pulse
  • Chest pain
  • Dizziness, light-headedness
  • Shortness of breath
  • Sweating
  • Fainting

Diagnosing AFib

Tests to find underlying heart diseases, like atrial fibrillation, may include:

Finding Treatment

The innovative team at Memorial Hermann is here to help you find the treatment you need. For more information on diagnostic procedures to minimally invasive treatments for your thoracic condition, fill out the form below or call to schedule an evaluation.

Contact Us

If you have questions regarding the Memorial Hermann Heart & Vascular Institute, our cardiologists, or treatment facilities, please use our contact form below or call (713) 222-2273 for more information.


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