Electrophysiological Characteristics and Mechanism of His-Bundle Pacing Guided by Electrocardiograms in Uninterrupted Real-Time Monitoring Technique.

Background: His-bundle pacing (HBP) is a pacing mode that provides near-physiological pacing and has more advantages over standard right ventricle (RV) septum pacing in positive clinical results. However, traditional HBP cannot accurately and stably place the lead tip into the His-Purkinje system. Hence, this study aimed to establish a novel strategy for HBP to strike a balance between an excellent pacing threshold and minor injuries to the conduction system.

Methods: HBP, using continuous and real-time monitoring of unipolar His-bundle (HB) electrograms along with electrocardiograms, was performed in 29 consecutive atrial fibrillation patients. We analyzed the unipolar HB intracardiac electrogram (EGM) and electrophysiological characteristics during HBP using John Jiang's connecting cable and an electrophysiology recording system. All patients were followed up for 12 months.

Results: Of the 29 patients, 28 (96.55%) successfully received HBP. Twenty-one (75%) patients were confirmed to have the negative deflection of His potential with a negative amplitude of ≥ 0.1 mV in HB EGM. The subgroup with a deep negative deflection was recorded with an HBP threshold (0.71 ± 0.41 V), significantly lower than those thresholds with no deep negative deflection (1.83 ± 0.76 V) (p < 0.05). The selective HBP rate was significantly different between the two groups: 20 (95.24%) in the deep negative deflection group and three (42.86%) in the non-deep negative deflection group (p < 0.05); five (17.24%) patients presented right bundle branch block (RBBB) during the lead placement.

Conclusions: This study supports the safety and feasibility of using an uninterrupted real-time monitoring technique for HBP. An uninterrupted real-time monitoring technique can guide the accurate placement of the HB lead and may provide a balance between an excellent pacing threshold and minor injury to the conduction system.