  The effect of heart geometry and anisotropy on cardiac re-entry dynamics and
self-termination is studied here in anatomically realistic computer simulations
of human foetal heart. 20 weeks of gestational age human foetal heart isotropic
and anisotropic anatomy models from diffusion tensor MRI data sets are used in
the computer simulations. The fibre orientation angles of the heart were
obtained from the DT-MRI primary eigenvalues. In a spatially homogeneous
electrophysiological mono domain model with the DT-MRI based heart geometries,
we initiate simplified Fitz-Hugh-Nagumo kinetics cardiac re-entry at a
prescribed location in a 2D slice, and in the full 3D anatomy model. In a slice
of the heart, the MRI based fibre anisotropy changes the re-entry dynamics from
pinned to anatomical re-entry. In the full 3D MRI based model, the foetal heart
fibre anisotropy changes the re-entry dynamics from a persistent re-entry to
the re-entry self-termination.
