Longitudinal Dissociation of the conduction system during His/LBBP Bundle Pacing: A Case Report

Abstract Background Evidence of the conduction system longitudinal dissociation was rare. Case presentation We report a case of a third-degree atrioventricular block. During HB pacing (HBP) lead deployment, widening and splitting of HB potential and intrahisian Wenckebach phenomenon were recorded in intracardiac electrogram. Then, we began unipolar HBP at 2 V/0.5 ms.The paced QRS exhibited morphology identical to that during intrinsic rhythm, indicating selective capture of the HB. After stopping screw; three different QRS patterns were recorded at unipolar 1.3mv/0.5ms pacing. During His injury repairment, the H1-H2 interval was gradually shortened, the H1 potential was seems invisible and integrated into H potential. When LBB electrode was screwed in at 2V/0.5ms continuous pacing condition, the His lead showed obvious double potential reverse transmission (H2-H1) at the presence of S-LBBP. Conclusion The interesting finding in this case provided further electrophysiological evidences for longitudinal dissociation of the conduction system.