Towards the cardiac equivalent source models in electrocardiography and magnetocardiography: A simulation study

The cardiac equivalent source model is very crucial in the electrocardiogram (ECG) and magnetocardiography (MCG) problems. In this study, we presented a thoroughly investigation of the three models: the dipole, equivalent double layer (EDL) and epicardial potential (EP) models in terms of the ECG/MCG forward problem within a unified framework. The cardiac electromagnetic field is calculated using boundary element method (BEM). The numerical performance and the properties of the three source models are studied in detail. Three different resolutions of dipole and two of EP and EDL models are studied. Besides, the effect of the volume conductor model is studied. The simulation results demonstrated that the resolution of the source models shouldn´t be too small, otherwise some information about the cardiac activities will be lost as shown in the single dipole model situation. The effect of the resolution on the MCG is larger than that on BSP. The higher resolutions of the source, the larger effect of the volume conductor happened for each source. While for the EDL source, the lung has little effect on the MCG. The EDL source can generate the similar performance compared to the dipole source, and the largest difference happened at the time when the ventricle start or finish the activation. The presented study suggests that the EDL source is a good choice as source model for ECG/MCG problem.