Atrial fibrillation and flutter

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; this usually also affects contraction of the ventricles.

Causes, incidence, and risk factors:

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. This results in ineffective and uncoordinated contraction of the atria.

The impulses may be transmitted to the ventricles in an irregular fashion, or only some of the impulses may be transmitted. This causes 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. Atrial flutter is most often associated with a heart attack (myocardial infarction) or surgery on the heart.

Atrial fibrillation or flutter affects about 5 out of 1000 people. It can affect either sex. Atrial fibrillation is very common in the elderly, but it can occur in persons of any age.