Estimation of ECG signal of closely separated bipolar electrodes using thorax models

New miniaturized portable ECG measuring devices may require reduced electrode size and distance. Modeling tools can be useful in predicting the behavior of electric field between electrodes. This work introduces a project where the effect of interelectrode distance (IED) of ECG precordial electrodes was studied with a model of the thorax as a volume conductor and with body surface potential map (BSPM) data. The objective was to study how the IED affects the signal strength and how well the modeling data corresponds to the clinical data. 2D and 3D finite difference method (FDM) torso models based on visible human man data were used. On these FDM models, the electrodes9 sensitivity to measure the electric field of the heart was derived. The results were compared to clinical 120 channel BSPM data. It was found out that reducing the IED obviously decreases the signal strength. According to the clinical data, the magnitude of this effect depends on the electrode location. This study indicates that modeling the volume conductor can predict the signal strength obtained with given electrode configurations. 3D modeling is more accurate in predicting the signal strength from clinical recordings; however, also simple and fast 2D modeling results show comparable values.