Filtering characteristics of the human body and reconstruction limits in the inverse problem of electrocardiography

The inverse problem of electrocardiography, consisting of the reconstruction of bioelectrical sources on the heart from measured body surface potentials, is an ill-posed problem. The human body with its tissue inbetween the heart and the body surface behaves like a filter, that damps or even eliminates higher spatial frequencies of source distributions on the heart. The source distributions leading to body surface potentials which are smaller than noise cannot be measured and belong to the "nullspace". The extent of the nullspace for a given model of the human body and for a given measurement accuracy depends strongly on the chosen electrode positions and the source locations. Without regarding any modelling error, this study investigates the limits of reconstructable source patterns for two different finite element models. To determine the reconstruction limits for these datasets, the best electrode positions and the accurate number and locations of bioelectrical sources on the heart must be found.