Two Approaches for Inverse PVC Localization from Clinical ECG Data Using Heart Surface Potentials

The standard approach for the inverse problem of ECG computes the potentials on the epicardial or endo-epicardial surface. For localization of premature ventricular contractions (PVC), the point with the earliest activation time is considered the PVC origin. A point potential approach assumes that at the beginning of the PVC signal, only a small area of the ventricles is activated. The inverse localization of the PVC origin using a homogeneous and inhomogeneous torso and two methods (standard and point) for epicardial potentials was performed on the measured body surface potential maps of ten patients. The true PVC location and the patient-specific torso geometry from the CT scan were known. The localization error (LE) between estimated and true PVC origins for both methods was evaluated and compared. For the homogeneous torso and the standard method, the mean LE was 3$7.2\pm 15.9$ mm and $37.6\pm 17.\delta$ mm for epicardial and endo-epicardial surfaces, respectively. The corresponding values for the point method were $25.6\pm 10.5$ mm and $31.2\pm 16.5$ mm. For the inhomogeneous torso and the standard method, the mean LE was $38.6\pm 18.9$ mm and $31.3\pm 11.1$ mm. The mean LE improved to 2 $7.6\pm 7.2mm$ and $29.5\pm 9.6$ mm, respectively, for the point method. The assumption of a single-point equivalent electrical generator improved the LE for PVC origin localization.