The Significance of the Torso Electrodes for Selected Cardiac Regions

The significance of the torso electrodes for the solution of the inverse problem of electrocardiography using a single dipole depends on the position of the true origin of the cardiac activity, i.e., ground truth. However, the ground truth is not known in clinical practice. Therefore, we studied whether similar electrode significances would be computed for the dipole corresponding to the ground truth, the computed inverse solution, and dipoles within the 30 mm radius around the inverse solution. The significance of torso electrodes was computed for 8 datasets of patients with a known position of the ground truth. The significance assessment of torso electrodes was performed using algebraic properties of the transfer matrix computed for the given dipole position. We studied three variants of the significance assessment of torso electrodes and for two of them similar electrode significances were obtained for all positions of dipoles within 30 mm of the inverse solution. For those two variants, the most significant electrodes created a subset of 47 ± 6% and 40 ± 4% from the full set of electrodes. The results suggest that the electrode significances for a given patient can be established from the inverse solution if the inverse solution lies within 30 mm of the ground truth.