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.
Some cases have no identifiable cause.
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. Please read it.