Conduction system pacing (CSP) is a new modality of pacing the heart by stimulating (“pacing”) directly the cardiac conduction system (“nerves”) of the heart. This approach of cardiac pacing offers physiologic pacing and avoids the detrimental effects of current pacing strategies (mainly right ventricular apical pacing). Currently two strategies are available for conduction system pacing: His bundle pacing (HBP) and Left bundle branch area pacing (LBBAP). Both pacing strategies result in nearly physiologic activation of the left ventricle, although different parts of the conduction system are targeted. The true potential of these innovative pacing modalities to resynchronize diseased hearts remains largely unknown and unexplored. Moreover, both targeted structures, His and left bundle conduction tissue, have a course within the interventricular septum and therefore require the pacing lead to be screwed either superficial or deep in the interventricular septum. The safety, direct and indirect effects on septal and cardiac contractility with chronic septal pacing have been poorly investigated.

The electrophysiological department of Ghent University hospital (UZ Ghent) is one of the largest centers in Europe in the field of conduction system pacing, currently performing 150 new implants a year, and with > 600 patients in active follow up. This large population of patients with CSP (both HBP and LBBAP) will be used to assess the direct and indirect effects of both HBP and LBBAP on septal and cardiac contractility patterns.