Challenges in Left Bundle Branch Area Pacing in Children and Congenital Heart Disease: Technical Limitations, Diagnostic Pitfalls, and Physiologic Insights
Hei-To LEUNG, Sabrina TSAO, Tsz-Kin TAM, Yuet-Wong CHENG, Sit-Yee KWOKAbstract
Introduction
Left bundle branch area pacing (LBBAP) in children is complicated by small cardiac dimensions, congenital heart disease (CHD), and the uncertain applicability of adult diagnostic criteria. This study evaluated paediatric LBBAP procedural success, technical adaptations, and diagnostic challenges.
Methods
Retrospective analysis of consecutive patients ≤18 years of age undergoing attempted LBBAP between January 2021 and June 2025.
Results
Sixteen patients (median 13.3 years) were included, three of them had CHD. Transoesophageal echocardiogram was used to guide most procedures (15 out of 16). In structurally normal hearts, LBBAP success was 61.5%, correlating with older age (P=0.048). Standard adult-configured sheaths caused oblique septal trajectories; conversely, atrial-septal-oriented sheaths (C315-S4/S5) ensured perpendicular fixation, enabling success in children weighing as little as 20.2 kg. Final V6 R-wave peak time (V6RWPT) <75ms had a poor specificity (11%) in confirming left bundle branch capture, with 53.8% of the patients met this threshold during right ventricular septal pacing. Similarly, the adult V6-V1 interpeak interval criterion (>44ms) yielded a suboptimal overall diagnostic accuracy of 37.5%. Successful LBBAP was associated with reduced left ventricular end-diastolic dimension (LVEDD) Z-scores (P=0.045) and septal-to-posterior wall motion delay (P=0.048). In CHD cases, scarring and cardiac rotation rendered standard electrical criteria non-diagnostic; however, TEE-guided left ventricular subendocardial placement maintained stable pacing and preserved synchrony.
Conclusion
Paediatric LBBAP requires adapted delivery sheaths to overcome geometric mismatches. Adult electrocardiographic criteria, including V6RWPT and V6-V1 interpeak difference, lack accuracy to define LBB capture in children. Clinically, LBBAP effectively improves left ventricular dyssynchrony.