Figure 1.

The leading circle, “wave length,” of re-entry in atrial fibrillation (AF). The size of a functional re-entry circuit [(A), right], depends on the wavelength (WL) which is a product of conduction velocity (CV) and refractory period (RP; WL = CV × RP). Short wavelengths allow multiple circuits [(B), left], favoring AF. The wave rotating around a fixed point, rotor [(C), lower; Jalife, 2003]. Factors such which slow conduction enhance the potential for multiple smaller waves. Enhanced cholinergics decrease conduction velocity and/or reduce effective refractoriness. Modified connexins also slow conduction. Either, or a combination of both could promote the initiation and sustaining of AF.