Cellular Heterogeneity in the Atria: An In Silico Study in the Impact on Reentries

In-silico modelling is increasingly relied upon to gain new insights into the underlying mechanisms of atrial fibrillation. Due to the complex nature of the atria, insilico models typically exclude cellular heterogeneity. One question that remains unanswered is the impact of cellular heterogeneity on reentrant mechanisms and in the vulnerable window (VW). This study aims to present the impact of cellular heterogeneity on the AF mechanisms and susceptibility to re-entry behaviour. Cellular heterogeneity was introduced into the whole atrial model using the population of models approach and regionally specific node assignment. Each atrial model was stimulated from the SA node, followed by a series of rapid-paced ectopic beats at one of three locations in the left atria. Results showed a small, insignificant increase in reentrant frequency as a result of cellular heterogeneity, with only minor changes to the re-entrant circuit. However, the vulnerable window was significantly impacted through the introduction of cellular heterogeneity. The results suggest that cellular heterogeneity in the atrial model resulted in an increased VW for reentry depending on EB location. This suggests that local cellular heterogeneity plays a significant role in the susceptibility to re-entries, but does not significantly impact the path or frequency of re-entries.