Distance Between the Electrode Tip and the Left Ventricular Conduction System During Left Bundle Branch Area Pacing

Left bundle branch area pacing (LBBAP) represents an essential physiological pacing technique, and conduction system (CS) capture can be achieved even in the absence of detectable CS potential. We aimed to measure the distance between the electrode tip and the left ventricular conduction system (LVCS) during LBBAP.

Sixteen canines are evenly divided into two groups: (1) conduction system pacing (CSP) group, including left bundle branch pacing (LBBP) and left fascicular pacing (LFP); (2) left ventricular septal pacing (LVSP) group. A three-dimensional electroanatomical mapping (EAM) system used to visualize the LVCS and guide electrode implantation. Pathological specimens are used to measure the distances between the electrode tip and LVCS, as well as the depth and angle of electrode implantation. Group 1 showed electrode tip-to-LVCS distance ≤ 2 mm versus > 2 mm in Group 2. Significant differences existed in pacing and pathological parameters between groups: stimulus to left ventricular activation time (Stim-LVAT) (48.75 ± 2.38 ms vs. 59.75 ± 2.05 ms, p < 0.01), Stim-Retro-His interval (21.00 ± 2.27 ms vs. 44.50 ± 2.83 ms, p < 0.01), QRS duration (89.50 ± 4.34 ms vs. 109.88 ± 5.96 ms, p < 0.01), the depth of electrode implantation (10.38 ± 0.53 mm vs. 9.35 ± 0.76 mm, p < 0.01), the angle of electrode implantation (76.88° ± 11.32° vs. 55.63° ± 12.66°, p < 0.01), and the distance between the electrode tip and the LVCS (0.69 ± 0.66 mm vs. 3.06 ± 0.28 mm, p < 0.01).

When the distance between the electrode tip and LVCS is ≤ 2 mm, the CS could be captured at outputs of ≤ 1.5 V/0.5 ms.