Novel reconstruction technique of omnipolar signals in high density electrode arrays
Authors: Ruiperez-Campillo S , Castells F , Segarra I , Merino J L , Casado-Arroyo R , Milltet J 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: Public grant(s) – EU funding. Main funding source(s): National Research Program, Ministerio de Ciencia e Innovación, Spanish Government; Instituto de Salud Carlos III.

Background
Novel multi-electrode array catheters with equidistant spacing between the electrodes, have emerged in recent years - e.g. Advisor™ HD Grid Mapping Catheter, Sensor Enabled™ (SE). These systems typically use unipolar signals, sensitive to low-frequency noise, and bipolar signals - highly dependent on the direction of propagation. Thus, the full potential of these new devices is not yet fully exploited. We hypothesise that, a new clique (4-electrode in a squared 2x2 matrix) configuration for the computation of omnipolar signals allows to take full advantage of novel multi-electrode catheters, more robust to the direction of propagation of the wavefront against the one currently proposed in literature – thus helpful in the clinic given the challenging positioning of the catheter in the heart cavity during electrophysiologic studies.

Methods
In the current 3-electrode clique, the centre of the signal obtained does not correspond to the centre of the area of the clique, being less robust to wavefront propagation direction (see fig. 1A). A new configuration, the cross clique, is proposed for calculating the electrogram to improve the robustness and reduce the errors in the estimation local activation time (LAT) and others – see figure 1. One thousand simulated signals with stratified propagation angles and variable parameters were implemented to emulate flat waves and homogeneous propagation over cardiac tissue. The methods used to calculate the signal with the proposed shape are: obtaining the bipoles, 45 degree correction of the signal, detection of the propagation angle, rotation of the detected angle and estimation of the LAT.

Results
The average amplitude of the bipolar loop increased from the old triangular clique configuration: 600.36 ± 116.40 mV; to the novel one cross-clique: 840.47 ± 160.09 mV. Regarding the local activation time estimation, a decrease in the error is observed from the current omnipolar reconstruction: 207.50 ± 256.91 μs, to the one proposed 22.75 ± 29.426 μs. When the bEGM propagation angle estimation is activated, the angle estimation error is 2.77 ± 25.26o for the current reconstruction method, in contrast to 1.09 ± 11.35o in the proposed one – see figure 1B.

Conclusion
Our novel configuration considerably reduces the LAT estimation error and, on average, captures a larger signal amplitude than the classic triangular clique method. Thus, it allows using the full potential of new catheters, improving the omnipolar analysis. hen applying automatic angle detection to the methods, in the case of the traditional method, it is influenced by the desynchronisation of the components of the traditional model as it widens the bipolar EGM loop – see figure 1.B. Thus, a novel omnipolar reconstruction method is proposed to better estimate intracardiac EGMs, more robustly against the direction of the wavefront propagation. Further studies are under consideration with clinical signals.