Revisiting Para‐Septal Accessory Pathways: A Unified Anatomic, Electrocardiographic, and Electrophysiologic Framework for Typical and Variant Subtypes

Accessory pathways (APs) are classified as typical or variant according to their atrial and ventricular insertions. Typical APs connect atrial and ventricular working myocardium directly across the annulus, whereas variant APs-including the atrio-Hisian pathway (AHP), fasciculoventricular pathway (FVP), nodofascicular pathway (NFP), and nodoventricular pathway (NVP) pathways-partially or fully engage the atrioventricular node-His (AVN-His) axis. Focusing on trans-annular APs in the right para-septal region, this review emphasizes how their anatomic course and spatial relationship to the AVN-His axis determine their electrocardiographic (ECG) and electrophysiologic (EP) manifestations. Accurate interpretation of these features requires detailed understanding of para-septal anatomy. By integrating anatomic, ECG, and EP correlations, a unified schematic model is proposed to describe the relative positions, insertion sites, and conduction relationships of typical and variant APs within the right para-septal region. This framework clarifies how subtle anatomic variations along the AVN-His axis account for the distinct yet overlapping ECG and EP features of these pathways.