Atrial Fibrillation Overview

Atrial fibrillation is a problem with the rate and rhythm of the heartbeat. The heart’s electrical signals become rapid and disorganized, causing the two upper chambers of the heart (called the atria) to contract very fast and irregularly. This rapid and irregular rhythm is called fibrillation. Atrial fibrillation is caused by damage to the heart’s electrical system, most often from conditions that impair heart health.

When the atria fibrillate, they do not pump all of the blood out and into the two lower chambers of the heart (called the ventricles). In addition, the atria and ventricles do not beat in a coordinated manner. As a result, the amount of blood pumped out of the ventricles to the body is inconsistent. It may be rapid, small amounts of blood or sporadic large amounts of blood. Atrial fibrillation may be temporary, in which it occurs briefly and stops on its own. Or it may be ongoing and require medications or other treatments to restore a normal heart rhythm.

Symptoms of atrial fibrillation are listed below. However, many people have no symptoms at all. Regardless of whether a person has symptoms, atrial fibrillation increases the risk of having a stroke or heart failure.

  • Irregular or rapid heartbeat
  • Heart palpitations
  • Lightheadedness or fainting
  • Confusion
  • Extreme fatigue
  • Shortness of breath
  • Chest pain
  • Difficulty exercising

Atrial fibrillation is the most common type of irregular heart rate or rhythm (called an arrhythmia). More than 2.5 million Americans have atrial fibrillation. The condition is more common in men than in women and in white Americans than in African Americans.

Risk factors for atrial fibrillation include:

  • High blood pressure
  • Heart failure
  • Diabetes
  • Advanced age
  • Hyperthyroidism
  • Heart disease
  • Structural heart defects
  • Pericarditis (inflamed tissues around the heart)


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