Multiobjective Optimization Approach to Localization of Ectopic Beats by Single Dipole: Case Study

A novel reliability parameter was suggested for the inverse solution using a single dipole for localization of the origin of an undesired ventricular activity from clinical data.Body surface potential maps (BSPMs) were measured for several minutes on the patient with premature ventricular contractions and implanted cardiostimulator. The measured signal was segmented into ECG beats that were further clustered according to their morphology. Assuming a normal distribution of the signals within the cluster a parameter "reliability score" (RS) evaluating the distribution of the inversely computed dipole moments was suggested. Then the optimal inverse solution (dipole) was estimated in the multi-objective optimization setting through simultaneous optimization of both the relative residual error (RRE) between the input BSPM and the map computed by the inverse dipole and the RS parameter.The method was applied on BSPMs measured for 5 minutes of imposed pacing (498 beats). The inclusion of the reliability score lead to improvement of the localization error from 16 mm (RRE only) to 11 mm (RRE+RS) and from 13 to 9 mm for a homogeneous and inhomogeneous torso, respectively.