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Atrial fibrillation/flutter    See images

Overview | Symptoms | Treatment | Prevention

Alternative names:

Auricular fibrillation

Definition:

A disorder of heart rate and rhythm in which the upper heart chambers (atria) are stimulated to contract in a very rapid and/or disorganized manner, rather than in an organized manner from the sino-atrial node.

Causes and Risks

Arrhythmias are caused by a disruption of the normal functioning of the electrical conduction system of the heart. Normally, the atria and ventricles contract in a coordinated manner. In atrial fibrillation and flutter, the atria are stimulated to contract very quickly and differently from the normal activity originating from the sino-atrial node. This results in ineffective and uncoordinated contraction of the atria.

The impulses may be transmitted to the ventricles in an irregular fashion, or some of the impulses may fail to be transmitted. This can cause the ventricles to beat more rapidly than normal, resulting in a rapid or irregular pulse. The ventricles may fail to pump enough blood to meet the needs of the body.

Causes of atrial fibrillation and flutter include dysfunction of the sinus node (the "natural pacemaker" of the heart) and a number of heart and lung disorders, including coronary artery disease, rheumatic heart disease, mitral valve disorders, pericarditis, and others. Hyperthyroidism, hypertension, and other diseases can cause arrhythmias, as can recent heavy alcohol use (binge drinking). Some cases have no identifiable cause. These irregular rhythms can occur in the setting of a heart attack (myocardial infarction) or surgery on the heart.

Atrial fibrillation or flutter affects about 5 out of 1000 people and can affect both men and women. Atrial fibrillation becomes more common as one gets older, but it can occur in persons of any age.

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