The Effect of Modeling Assumptions on the ECG in Monodomain and Bidomain Simulations

Abstract

Computing a physiologically accurate electrocardiogram (ECG) is one of the key outcomes of cardiac electrophysiology (EP) simulations. Indeed, the simulated ECG serves as a validation, may be the target for optimization in inverse EP problems, and in general allows to link simulation results to clinical ECG data. Several approaches are available to compute the ECG corresponding to an EP simulation. Lead field approaches are commonly used to compute ECGs from cardiac EP simulations using the Monodomain or Eikonal models. A coupled passive conductor model is instead common when the full Bidomain model is adopted. An approach based on solving an auxiliary Poisson problem propagating the activation field from the heart surface to the torso surface is also possible, although not commonly described in the literature. In this work, through a series of numerical experiments, we investigate the limits of validity of the different approaches to compute the ECG from simulations based on the Monodomain and Bidomain models. Significant discrepancies are observed between the common lead field and direct ECG approaches in most realistic cases – e.g., when conduction anisotropy is included – while the ECG computed via solution of an auxiliary Poisson problem is similar to the direct ECG approach. We conclude that either the direct ECG or Poisson approach should be adopted to improve the accuracy of the computed ECG.KeywordsElectrocardiogramCardiac electrophysiologyValidation criteriaMonodomain modelBidomain model