  Computer-based simulations of non-invasive cardiac electrical outputs, such
as electrocardiograms and body surface potential maps, usually entail severe
computational costs due to the need of capturing fine-scale processes and to
the complexity of the heart-torso morphology. In this work, we model cardiac
electrical outputs by employing a coupled model consisting of a
reaction-diffusion model - either the bidomain model or the most efficient
pseudo-bidomain model - on the heart, and an elliptic model in the torso. We
then solve the coupled problem with a segregated and staggered in-time
numerical scheme, that allows for independent and infrequent solution in the
torso region. To further reduce the computational load, main novelty of this
work is in introduction of an interpolation method at the interface between the
heart and torso domains, enabling the use of non-conforming meshes, and the
numerical framework application to realistic cardiac and torso geometries. The
reliability and efficiency of the proposed scheme is tested against the
corresponding state-of-the-art bidomain-torso model. Furthermore, we explore
the impact of torso spatial discretization and geometrical non-conformity on
the model solution and the corresponding clinical outputs. The investigation of
the interface interpolation method provides insights into the influence of
torso spatial discretization and of the geometrical non-conformity on the
simulation results and their clinical relevance.
