Use of electric and magnetic data to obtain a multiple dipole inverse cardiac generator: A spherical model study

Abstract

Cardiac electrical activity was modelled by two realistic generators in a spherical conductor with a centric inhomogeneity. The “Selvester” generator consisted of a 19-dipole array; the “Coriolis” generator was a 76-dipole array. Time varying electric and magnetic potentials at the surface of the sphere were calculated for each array. The inverse cardiac generator was a fixed-location, fixed-orientation, nonnegatively constrained multiple dipole array. Inverse dipole moments were calculated using electric data alone, magnetic data alone, and a combination of electric and magnetic data. The inverse solutions were examined in the presence of additive noise and modelling noise. Modelling noise involved translocating or misorienting the inverse dipoles, or assuming an incorrect conductivity for the inhomogeneity. Results for the Selvester and Coriolis simulations were similar. The mixed data solution using electric and magnetic data gave better results for additive (potential) noise but did not improve the solution in the presence of modelling noise. Septal dipoles showed the greatest errors. In the absence of modelling noise, the mixed data solution for the Coriolis array reproduced the surface magnetic and electric fields very well, but deviated from the ideal solution.