Zusammenfassung
Atrial fibrillation (AF) is believed to be perpetuated by recirculating
spiral waves. Atrial structures are often characterized with action
potentials of varying morphologies; however, the role of the structure-dependent
atrial electrophysiological heterogeneity in spiral wave behaviour
is not well understood. The purpose of this study is to determine
the effect of action potential morphology heterogeneity associated
with the major atrial structures in spiral wave maintenance. The
present study also focuses on how this effect is further modulated
by the presence of the inherent periodicity in atrial structure.
The goals of the study are achieved through the simulation of electrical
behaviour in a two-dimensional atrial tissue model that incorporates
the representation of action potentials in various structurally distinct
regions in the right atrium. Periodic boundary conditions are then
imposed to form a cylinder (quasi three-dimensional), thus allowing
exploration of the additional effect of structure periodicity on
spiral wave behaviour. Transmembrane potential maps and phase singularity
traces are analysed to determine effects on spiral wave behaviour.
Results demonstrate that the prolonged refractoriness of the crista
terminalis (CT) affects the pattern of spiral wave reentry, while
the variation in action potential morphology of the other structures
does not. The CT anchors the spiral waves, preventing them from drifting
away. Spiral wave dynamics is altered when the ends of the sheet
are spliced together to form a cylinder. The main effect of the continuous
surface is the generation of secondary spiral waves which influences
the primary rotors. The interaction of the primary and secondary
spiral waves decreased as cylinder diameter increased.
Nutzer