Characteristics of atrial re-entry and meander computed from a model of a rabbit single atrial cell

A two-dimensional excitable medium model of atrial tissue has been constructed by incorporating the Earm-Hilgemann-Noble excitation equations for membrane voltage-dependent ionic currents and pump exchanger currents, time-dependent changes in intracellular and extracellular ionic concentrations, and storage and release of Ca2+, for an atrial cell in an homogeneous partial differential equation. A diffusion coefficient of 1.25 cm2 sec-1 gives the conduction velocity of a solitary planar wave as 0.6 m sec-1. A spiral wave with a period of 78 msec develops from a broken wavefront, and initially rotates around a circular core of 2 mm diameter. After 1.5 sec of rotation, a biperiodic meander, with 6 epicycles/cycle, develops. This simple meander pattern is reflected in a period-6 modulation of the intervals between successive wavefronts.