Abstract:

The sinus node (SN), which is the primary pacemaker of the heart, is a heterogeneous structure, i.e. there is a difference between center and periphery regarding morphology, electrophysiology and electrical coupling. The behavior of the whole SN in detail is difficult to investigate experimentally. Therefore, realistic computer models are helpful to understand the electrophysiological mechanisms quantitatively. In this work, different models of the SN including heterogeneity are benchmarked.Several approaches considering SN heterogeneity exist. One possible description of the electrical conduction is the mosaic model, in which the density of two discrete cell types, central and peripheral cells, is varied from the center to the periphery of the SN. The gradient model is another approach for this task. As the name implies, there is a gradual transition in cell morphology and electrophysiology between the center and periphery.The behavior of single nodal cells were described best by the rabbit SN model of Zhang et al. [1], offering explicit formulations for central and peripheral cells. A one-dimensional model of the SN and surrounding atrial tissue and a two-dimensional slice of the SN and adjoining crista terminalis (CT) were applied. Both approaches describing electrical conduction were compared using these different geometric models, in order to find the most exact model in relation to measured data describing activation patterns and action potential durations.