Propagation of electrical activity in the SA node

Computational models of the sinoatrial node and atrium are used to investigate the functional role of fine strands of atrial tissue which interdigitate with and penetrate into the center of the SA node. Model results indicate that by localizing gap junction channels at the strand tips, interdigitations form a near uni-directional conduction pathway, facilitating conduction of the pacemaker potential from the SA node into the atrium, but limiting the ability of depolarizing atrial waves to perturb pacemaking behavior of central SA node cells.