  We prove the existence and the uniqueness of a solution for a modified
bidomain model, describing the electrical behaviour of the cardiac tissue in
pathological situations. The leading idea is to reduce the problem to an
abstract parabolic setting, which requires to introduce several auxiliary
differential systems and a non-standard bilinear form. The main difficulties
are due to the degeneracy of the bidomain system and to its non-standard
coupling with a diffusion equation, accounting for the presence of the
pathological zone in the heart tissue.
