A reliable endocardial map is obtained by constructing a matrix relationship between a small number of endocardial points and a large number of external receiving points using a multi-electrode chest panel. Inversion of the matrix yields information allowing the endocardial map to be con-structed. Subsequent maps are obtained noninvasively using the multi-electrode chest panel, applying new electrical signals to the matrix relationship, and again inverting the matrix to generate new endocardial electrical maps.
