Novel mapping array for transmural mapping of myocardial activation: proof of concept in electro-tomography
K De Silva, T Subha, S Masse, Y Abderrahman, J Asta, G Mokhtar-Sasani, I Ahmed, B Ebrahimi, P Van Niekerk, D Highsmith, P F H Lai, K NanthakumarAbstract
Introduction
Current electroanatomic mapping techniques lack the practical clarity to resolve three-dimensional intramural activation, which we term tomographic mapping. The capacity to assess intramural and epicardial activation from endocardial mapping has great potential in clinical electrophysiology
Objective
Using a novel electrode array with variable size, spacing, and isolation, designed to sample the electric field in planes both perpendicular and parallel to the myocardium, we aimed to validate its ability to resolve multidimensional intramural myocardial activation during endocardial mapping.
Methods
Sequential controlled experiments were performed in Langendorff beating swine hearts (n=6) modified for ex-vivo Carto3 mapping. Three investigations were conducted: (1) generating a myocardial wavefront engaging both Purkinje and epicardium to create distinct mappable fronts; (2) creating a selective epicardial lesion by radiofrequency ablation while mapping endocardially; and (3) inducing selective functional epicardial conduction slowing with lidocaine, validated by intramural needle mapping. The novel multidimensional mapping catheter (Multi-D) (1A) consisted of bipolar electrodes in-plane with the myocardium (0.1 mm "ultra-close" and 2 mm spacing) and perpendicular (0.3 mm spacing). This array was compared to a commercial multi-electrode grid catheter using a custom designed experimental catheter ("Hybrid") which consisted of 1 spline Multi-D, 1 spline current state of the art "traditional" grid array catheter.
Results
Multi-layer myocardial activation was evident on the perpendicular electrogram, showing richer Purkinje sampling than ultra-close and 2 mm bipoles (1B). In five experiments, epicardial ablation with endocardial sampling produced widening, splitting, or attenuation of the perpendicular bipole, indicating sensitivity to intramural and epicardial activity. Figure 2A shows electrogram widening and attenuation on the Hybrid catheter Multi-D spline, with relative sparing of the traditional bipole. In the needle experiment (2B), perpendicular bipoles displayed multi-component signals matching needle electrogram peaks. After epicardial lidocaine, needle bipoles near the surface showed delayed conduction, while deeper bipoles remained unchanged. Differential slowing in the Multi-D perpendicular bipoles confirmed their field of view includes sub-epicardial intramural activation.
Conclusion
A novel mapping array incorporating perpendicular electrodes can, for the first time, resolve intramyocardial activation in depth. The perpendicular bipole provides excellent spatial resolution in the X–Y plane (mapping Purkinje), while modified size, spacing, and isolation confers field of view across the myocardium. Further studies are warranted to assess its potential translation for human arrhythmia mapping.Figure 1 Multi-D mapping catheterFigure 2 Evidence of tomographic mapping