Figure 4:

Human SAN 3D model showing activation exits either via superior/inferior or both SAN conduction pathways. A-C, Left panels: The ex-vivo human SAN NIOM studies show SAN activation exiting either through superior/inferior or both SACPs rather than two different leading pacemakers. A-C, Middle panels: Human epicardial multi-electrode mapping studies show three examples of superior, inferior and both superior and inferior patterns of earliest atrial activation during sinus rhythm (SR). A-B, Right panels: Two main preferential SAN exits demonstrated with step-wise endocardial high-density catheter mapping in AF patients during stable SR. (Modified from^{2, 16,28}).