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Atrial Fibrillation
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Atrial Fibrillation
Related terms:  afib, a-Fib, arrhythmia

Fibrillation, the most serious form of arrhythmia (heart rhythm disorder), is fast, uncoordinated beats, which are contractions of individual heart-muscle fibers. Atrial fibrillation (also called AFib or AF) is the most common type of supraventricular arrhythmia with irregular beats that are too fast (tachycardia).

Anatomy of the conduction system

See also on this site: Arrhythmia 

In the news . . . 
The Heart Problem You're Not Worried About
Atrial fibrillation is a growing epidemic . . . awareness and early diagnosis can save lives. Age is the biggest risk factor for afib (an irregular and often rapid heartbeat that causes poor blood flow). A person's chances of developing the irregular heartbeat increase after age 60 . . . "Many people develop afib in their later years," says Mohammad Saeed, MD, a cardiac electrophysiologist at THI. Full article and associated videos from

Supraventricular Arrhythmias and Atrial Fibrillation

Supraventricular arrhythmias begin in the areas above the heart’s lower chambers, such as the upper chambers (the atria) or the atrial conduction pathways. Generally, supraventricular or "atrial arrhythmias" are not as serious as ventricular arrhythmias. Sometimes, they do not even require treatment. Like PVCs, atrial arrhythmias can happen in response to a number of things, including tobacco, alcohol, caffeine, and cough and cold medicines. The disorder also may result from rheumatic heart disease or an overactive thyroid gland (hyperthyroidism). Supraventricular arrhythmias can cause shortness of breath, heart palpitations, chest tightness, and a very fast pulse. 

Atrial fibrillation is a fast, irregular rhythm where single muscle fibers in your heart twitch or contract. According to the Centers for Disease Control and Prevention (CDC), between 2.7 and 6.1 million Americans have atrial fibrillation. It is a main cause of stroke, especially among elderly people. Atrial fibrillation may cause blood to pool in the heart's upper chambers. The pooled blood can lead to the formation of clumps of blood called blood clots. A stroke can occur if a blood clot travels from the heart and blocks a smaller artery in the brain (a cerebral artery). About 15-20% of strokes happen in people with atrial fibrillation.

For this reason, many patients with atrial fibrillation need antiplatelet therapy. These medicines can prevent blood clots from forming and causing a stroke.

What are the symptoms?

If you have AFib, you may 

  • Feel a strong pulse in your neck, or a fluttering, racing heartbeat in your chest.
  • Feel chest discomfort, weak, short of breath, faint, sweaty, or dizzy.

See the discussion of diagnosing and treating arrhythmias in the topics listed below.

See also on this site:

Ask a Texas Heart Institute Doctor



See on other sites:

Atrial Fibrillation (AFib)  

National Heart, Lung and  Blood Institute
What Is Atrial Fibrillation?

Updated August 2016
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