The role of distributed conduction velocities in simulated epicardial activation maps

Abstract

The effects of the spatial arrangement of myocardial fibers and of the inferred 3-dimensional distribution of conduction velocities on epicardial activation patterns are described. A simplified geometry is considered, that of an ellipsoidally shaped left ventricle (LV), attached to a sectioned ellipsoidal right ventricle. The modeled myocardial volume is sectioned into different layers and areas. each filled with different ‘cells’, thus allowing to describe the distribution of velocities and orientation similar to physiological and anatomical data. The propagation velocity along the myocardial fiber is assumed to be 3 times the transverse velocity. Once simulation starts, a stimulated ‘cell’ activates all its neighbors, thus generating patterns of activation within and on the surfaces of the myocardium. The simulated activation maps from the myocardial surfaces are found to be sensitive to the underlying distribution of conduction velocities, specifically when abnormal velocities are introduced at certain ‘infarcted’ areas. The existence of ectopic foci is readily identified by the distortion of the normal patterns. The maps, however, are much less sensitive to minute changes in the location of the foci of activation within the normal conduction system. While the simulated epicardial and endocardial maps are affected by the spatial distribution of the conduction velocities, the surface maps are specifically sensitive in displaying the existence of abnormally propagating myocardial activity.