Clustering of re-entry close to scar boundaries in ventricular tissue during simulated ventricular fibrillation

Scar tissue in the ventricles can act as a source of anatomical re-entry. However, the interaction of scar with complex activation during ventricular fibrillation (VF) is not well understood. In this study we investigated how simulated scars influence clustering of re-entry filaments in simplified computational models. In a slab geometry representing the ventricular wall, the number of filament voxels spiked to around 5 times the mean value in normal tissue close to the scar boundary. In a surviving epicardial layer, the number of filament voxels was around one fifth of the mean. In contrast, the number of epicardial phase singularities showed no spike close to the boundary. In an ellipsoid geometry we observed more clustering of filament voxels when the radius of the scar is increased. This study shows that the scar is able to pin re-entrant filaments, but that this effect may not be manifest as clustering of phase singularities on the tissue surface.