Basic mechanisms of atrial fibrillation.

The mechanism of AF remains controversial as support still exists for multiple wavelets, "mother rotor," and focal sources. These mechanisms need not be mutually exclusive. For example, the mother rotor hypothesis may not be distinct form the focal AF, if the rotor is of small size (ie, microre-entry). With the development of several animal models to study AF, along with improving technologies and mapping techniques, a further understanding of the pathophysiology of AF is being gained. Each animal model has unique electrophysiological and structural abnormalities, and one may not be able to generalize from one model to the next. It is likely that there is not one mechanism for all AF, but that there are substrate-specific mechanisms, and that AF may be comprised of several different mechanisms.