Atrial fibrillation (AF) is the most common cardiac arrhythmia.
The mechanisms of AF remain unclear, but reentry has been implicated
in its initiation and maintenance. In this computational study, we analyzed
spiral wave (SW) behavior in a 2D isotropic finite difference grid that
represented a square sheet of atrial tissue. Simulations were performed
that examined the effects action potential (AP) morphology heterogeneity
and surface continuity on reentrant activity for different tissue sizes and
SW initiation sites. Phase singularity (PS) motion was tracked over time using
PS traces. Our results demonstrate that the prolonged refractoriness of the Crista
Terminalis (CT) clearly affects the pattern of reentry, while the variation in AP
morphology of the other structures does not. The CT anchored the SWs to the sheet,
preventing them from terminating at the boundary. The SW dynamics changed when the
ends of the sheet were spliced together to form into a cylinder. The main effect
of the continuous surface was the generation of secondary SWs which influenced
the primary SWs. The interaction of the primary and secondary SWs decreased as
tissue (cylinder) size increased.
Two SWs are initiated to the right of the CT in a heterogeneous
cylinder (shown here flattened). The SWs propagate through the tissue, breaking
up into multiple daughter waves, and eventually all SWs are extinguished.
