Electrophysiological demonstration of nonselective His-Purkinje system capture with para-Hisian pacing.

Abstract

The adverse effects of conventional right ventricular (RV) apical pacing prompted the search for more physiological pacing sites, such as selective and nonselective His bundle pacing (HBP), a variant of nonselective HBP (para-Hisian pacing), and mid-septal pacing. However, knowledge of their true benefit on the physiology of ventricular activation, lead stability, and pacing thresholds is limited. We included 152 consecutive patients (mean age 61±24, 63% men) in this retrospective study. Of these, 137 patients with different bradyarrhythmias underwent active fixation lead implantation at the RV apex (n=54), para-Hisian region (n=66), or mid interventricular septum (n=17). Fifteen patients with ventricular preexcitation due to an accessory pathway not undergoing pacing were included as controls. A 12‑lead ECG was recorded in all patients, and cardiac electrical synchrony was assessed using the Synchromax® cross-correlation cardiac synchrony index (CSI). QRS duration was prolonged in all pacing sites: from 114±28 to 160±29 (RV apex), from 110±28 to 122±29 (para-Hisian), and from 121±24 to 154±30 (mid interventricular septum). The CSI was significantly improved only in patients undergoing para-Hisian pacing, despite a slight widening of the QRS interval. There was no difference in pacing thresholds and sensed R-wave voltage between pacing sites. Only 1 lead, implanted at the para-Hisian region (1.5%), was dislodged towards the mid septum 48h after implantation but did not require repositioning. QRS duration was not associated with changes in CSI, meaning that QRS width does not significantly affect electrical synchrony.