Ex vivo Validation of Noninvasive Epicardial and Endocardial Repolarization Mapping.

Charly N W Belterman,Jeanne G Van Der Waal,Thom F Oostendorp,Veronique M F Meijborg,Geert J Streekstra,Ruben Coronel

doi:10.3389/fphys.2021.737609

Abstract

Background: The detection and localization of electrophysiological substrates currently involve invasive cardiac mapping. Electrocardiographic imaging (ECGI) using the equivalent dipole layer (EDL) method allows the noninvasive estimation of endocardial and epicardial activation and repolarization times (AT and RT), but the RT validation is limited to in silico studies. We aimed to assess the temporal and spatial accuracy of the EDL method in reconstructing the RTs from the surface ECG under physiological circumstances and situations with artificially induced increased repolarization heterogeneity.Methods: In four Langendorff-perfused pig hearts, we simultaneously recorded unipolar electrograms from plunge needles and pseudo-ECGs from a volume-conducting container equipped with 61 electrodes. The RTs were computed from the ECGs during atrial and ventricular pacing and compared with those measured from the local unipolar electrograms. Regional RT prolongation (cooling) or shortening (pinacidil) was achieved by selective perfusion of the left anterior descending artery (LAD) region.Results: The differences between the computed and measured RTs were 19.0 ± 17.8 and 18.6 ± 13.7 ms for atrial and ventricular paced beats, respectively. The region of artificially delayed or shortened repolarization was correctly identified, with minimum/maximum RT roughly in the center of the region in three hearts. In one heart, the reconstructed region was shifted by ~2.5 cm. The total absolute difference between the measured and calculated RTs for all analyzed patterns in selectively perfused hearts (n = 5) was 39.6 ± 27.1 ms.Conclusion: The noninvasive ECG repolarization imaging using the EDL method of atrial and ventricular paced beats allows adequate quantitative reconstruction of regions of altered repolarization.

Highlights

Risk stratification of patients with functional arrhythmogenic substrates may help to reduce mortality caused by arrhythmias
In contrast to the epicardial potential (EP) method, the equivalent dipole layer (EDL) method allows simultaneous calculation of both the endocardial and epicardial activation and repolarization times (AT and RT), thereby identifying transmural timing differences that are potentially important for arrhythmogenesis (Antzelevitch et al, 1999; Sabir et al, 2007)
We demonstrated that the EDL-based inverse methods allow the adequate reconstruction of RTs and repolarization patterns on the endocardium and epicardium of a heart in an ex vivo setting with an accuracy of about 25 ms

Summary

Introduction

Risk stratification of patients with functional arrhythmogenic substrates may help to reduce mortality caused by arrhythmias. The detection and localization of these substrates is not easy and currently involves invasive mapping (Visser et al, 2016). A potential noninvasive tool to overcome this problem is electrocardiographic imaging (ECGI). This technique combines the recording of multiple body surface ECGs with a patient-specific heart-torso geometry to mathematically reconstruct cardiac electrical activity through the solution of the inverse problem. The detection and localization of electrophysiological substrates currently involve invasive cardiac mapping. Electrocardiographic imaging (ECGI) using the equivalent dipole layer (EDL) method allows the noninvasive estimation of endocardial and epicardial activation and repolarization times (AT and RT), but the RT validation is limited to in silico studies. We aimed to assess the temporal and spatial accuracy of the EDL method in reconstructing the RTs from the surface ECG under physiological circumstances and situations with artificially induced increased repolarization heterogeneity

Objectives

Methods

Results

Discussion

Conclusion