Pediatric Pacing from Proximal Right Ventricular Septum: Preserved Left Ventricular Systolic Function at Follow-Up

Chronic right ventricular (RV) pacing can impair left ventricular (LV) function. Non-fluoroscopic 3D-electroanatomic mapping (3D-EAM) allows targeted catheter navigation to septal sites close to the conduction system, reducing fluoroscopy exposure. This study evaluated whether 3D-EAM-guided pacing of the proximal RV septum (RVS) preserves LV contractility in pediatric patients with systemic LV and complete atrioventricular block (CAVB). We conducted a retrospective, single-center study. Electrocardiograms and echocardiograms obtained before implantation and during follow-up were analyzed for QRS duration, LV dimensions and systolic function: ejection fraction (EF), global longitudinal/circumferential strain (GLS/GCS), and rotation. Data are presented as median (25th-75th percentile). Statistical significance was set at P < 0.05. The cohort included 61 patients, aged 11.0 (8.0-14.0; full range 3-18) years: 9 of whom underwent non-selective His bundle pacing (NSHBP), 48 RVS, and 4 RV outflow septum pacing. All procedures were successful. Follow-up was 4 years (2-6), maximum 10 years. For all patients, the paced QRS duration was 118 ms (110-124) and remained stable. No significant differences in QRS duration or LV systolic function were observed between NSHBP and RVS. Echocardiographic indexes remained largely within normal limits. Patients with reduced LV systolic function at baseline improved during follow-up, while two patients demonstrated impaired function at longer follow-up. Lead dysfunction occurred more frequently with NSHBP than with RVS pacing, requiring lead repositioning or replacement. In pediatric patients with CAVB, 3D-EAM-guided pacing of the proximal RV septum near the conduction system preserved LV systolic function during follow-up.