Ventricular activation pattern of left ventricular septal pacing in a canine model.

Abstract

Left bundle branch pacing (LBBP) is a feasible and effective physiological pacing technique. The QRS morphology of left ventricular septal pacing (LVSP) is similar to that of LBBP. The ventricular activation pattern of LBBP is well-known, whereas the pattern of LVSP still needs further investigation. The present study aimed to determine ventricular activation pattern difference between LVSP and LBBP in a canine model. All six canines underwent successful LBBP and LVSP through trans-ventricular septum using intracardiac echocardiography and intracardiac electrogram. Their hearts were isolated and stained with Lugol's iodine to determine the position of the pacing lead. The activation sequences of the left ventricular myocardium and His-Purkinje system were recorded by placing multiple electrode catheters. First, the left His-Purkinje system in LVSP was activated simultaneously from apical and basal regions to the left ventricular middle septal region, whereas the left ventricular septal myocardium was activated from the apical to basal region. The left His-Purkinje system activation in LBBP occurred in the direction of the apex from the pacing lead, but the left ventricular septal myocardium was activated in the apical to basal direction. Furthermore, the left intraventricular electrical synchrony was similar between LVSP and LBBP as determined by mapping the left ventricular septal to free wall activation time (46.7 ± 1.8ms vs. 45.0 ± 1.4ms, p = 0.11). The ventricular activation sequence of LVSP was similar to LBBP. LVSP can capture LBB due to the wide distribution of LBB. These findings suggest a rationale for clinical application of LVSP.