A primary mechanism for spiral wave meandering

The stability and dynamics of spiral wave meandering were studied by examining the behavior of small perturbations to a steadily rotating action potential wave. The disturbances responsible for meandering were found to be generated through an interaction between the unstable local linear dynamics characteristic of the action potential trailing edge near the core and perturbations existing in the region immediately behind this edge. Significantly, for the cases studied, neither wavefront curvature nor head-tail interactions were involved in this process. Study of the generation mechanism using a series of representative mathematical models and computer experiments led to the prediction that the following features of rotating action potentials render them more susceptible to meandering: (1) proximity of the wave tip to the center of rotation, (2) wider action potential leading and trailing edges, and (3) slower wave rotation speeds. Variation of basic tissue properties, including firing threshold potentials and excitability above threshold, affected these properties, and those of the perturbation dynamics, in several ways, producing both stabilizing and destabilizing effects. The nature of the involvement of various tissue and membrane electrical properties is therefore complex, affecting several factors relevant to meandering at once.