Comparative electrophysiology of aortic root pacing in humans
I Karpenko, A Ardashev, J Wasserlauf, E Zhelyakov, D Aksenov, O Yatsenko, D VolkovAbstract
Background
Millimeter-scale pacemakers integrated into transcatheter aortic valve (TAVR) platforms are emerging as a potential solution for post-valve conduction disease. Their development, however, is limited by the lack of in vivo human data defining where reliable myocardial capture can be achieved from the paravalvular aortic root and at what electrical cost.
Objective
To compare the feasibility and electrophysiologic characteristics of transaortic pacing from the right coronary cusp (RCC), left coronary cusp (LCC), non-coronary cusp (NCC), and the left-sided His bundle (LV His) region, and to translate these findings into design constraints for valve-integrated and ultra-miniaturized pacing systems.
Methods
In 25 consecutive patients undergoing clinically indicated left-sided electrophysiology procedures, sequential bipolar pacing was performed via a retrograde transaortic approach at the RCC, LCC, NCC, and LV His region following completion of the index procedure. Pacing sites were localized using 3D electroanatomic mapping, biplane fluoroscopy, and intracardiac echocardiography. Capture thresholds (1 ms pulse width), local electrogram amplitudes, and paced QRS duration and morphology were quantified.
Results
Ventricular capture was universal at the LV His region (25/25, 100%), frequent at the RCC (23/25, 92%) and LCC (19/25, 76%), and absent at the NCC (0/25, 0%), where atrial capture occurred in 8/25 (32%). LV His pacing demonstrated markedly lower capture thresholds (4.6 ± 2.1 mA) and the narrowest paced QRS duration (137.5 ± 15.6 ms), most often with an RBBB-like morphology in V1. In contrast, coronary cusp pacing required significantly higher outputs (RCC 13.3 ± 5.1 mA; LCC 14.2 ± 4.7 mA) and produced wider QRS complexes (≈165 ms).
Conclusions
Among paravalvular aortic root sites, pacing adjacent to the left-sided His bundle uniquely combined universal ventricular capture, lower capture thresholds, and narrower paced QRS duration, distinguishing it from coronary cusp pacing, which was feasible but required higher outputs and produced less synchronous ventricular activation. The non-coronary cusp demonstrated no ventricular capture but showed atrial excitability, suggesting a distinct dual-chamber electrophysiologic niche.