Some imaging parameters of the oblique dipole layer cardiac generator derivable from body surface electrical potentials.

Abstract

The goal of noninvasively imaging the cardiac electrical generator is considerably complicated by the conductive anistropy of the cardiac muscle which, as featured in the oblique dipole layer model of ventricular depolarization, introduces muscle fiber geometry and a conductivity tensor as additional unknowns. The ventricular surface activation map has been previously presented as a description of the cardiac generator in image form, but the integral equation defining its relationship to the body surface potentials is valid only under the less accurate uniform dipole layer hypothesis. Using an argument from differential geometry, which allows the integral equation approach to be bypassed, we show that the critical points of this map can still be localized on the heart surface from the body surface potentials in a manner fully consistent with the oblique dipole layer model. Thus, in principle, a realistic and useful "image-like" output is possible in a limited way even without explicit information regarding conductivity anisotropy. The realization of this output will require improvements in the temporal resolution presently available from existing body surface potential mapping systems.