Ex vivo Validation of Noninvasive Epicardial and Endocardial Repolarization Mapping

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.

Basis and applicability of noninvasive inverse electrocardiography: a comparison between cardiac source models

“…In such cases the amount of regularization required to suppress the effect of noise may obscure the presence heterogeneities in the EDL based inverse. It has been shown that a large area of repolarization heterogeneity is accurately inversely reconstructed ( Van der Waal et al, 2021 ), but for smaller areas of heterogeneity this is unknown.…”

“…Similar to the EP-based method, finding the optimal and regularization parameters is not straightforward. Approaches involve choosing an empirically determined fixed value ( Van Dam et al, 2009 ) or varying the parameter to aim for an empirically defined value for the Laplacian operator, indicating a certain spatial smoothness ( Van der Waal et al, 2021 ).…”

Unlocking cardiac motion: assessing software and machine learning for single-cell and cardioid kinematic insights

“…Due to the high interconnection between electrical and mechanical activities, researchers developed multiple types of models trying to unveil and quantify both from cellular to whole organ levels 1 – 5 . Extensive and exhaustive studies have been performed on the electrical counterpart in both physiological and pathological conditions, starting from single cells and organ slices 6 – 8 , and broadening to ex-vivo 9 and in-vivo models 10 , 11 . Thanks to the recently improved computation ability, both heart functions were studied with in-silico simulations, as an alternative to animal experimentation 12 – 14 .…”

Ventricular fibrillation: combined myocardial substrate and Purkinje ablation

“…However, in vivo validation of these techniques has faced many challenges [16], and studies comparing ECGI predictions against directly measured cardiac electrograms have yielded mixed results. Sophisticated ECGI validation work has been performed using carefully controlled isolated perfused hearts in torso tanks [17,18], and while some in-situ validation studies have demonstrated good reproducibility (e.g. [19]), others have shown variable correlation (e.g.…”