angle in ventricular wall, although varied between species[@Hunter-etal-CompBiolOfHeart p. 173], was consistent within a species. So that the question was that, if the pro-arrhythmic mechanism of cardiac re-entry initiation by the anisotropic discontinuities in a heart[@Fenton-Karma-1998; @Spach-CircRes-2001; @Smaill-etal-2004] was correct, what would then have been a reason for the consistent structure [@Hunter-etal-CompBiolOfHeart p. 173] of the anisotropic discontinuities in healthy mammalian hearts.]{} The]{} combination of the High Performance Computing with the high-resolution DT-MRI based anatomy models of the heart allows anatomically realistic *in-silico* testing of the effects of individual heart anatomy and anisotropy on the cardiac re-entry dynamics [@Kharche-etal-2015-BMRI; @Kharche-etal-2015-LNCS; @bbx-2017-PONE]. In this paper, for the first time, we present the anatomy and myofiber structure realistic computer simulation study of the cardiac re-entry dynamics in the DT-MRI based model of the human foetal heart [@Pervolaraki-etal-2013].

The comparative isotropic *vs* anisotropic simulation of the otherwise homogeneous foetal heart shows that, in the 2D slice of the heart, the realistic fiber anisotropy might change the re-entry dynamics from pinning to the sharp end of the septum cuneiform opening, Fig. \[slice\_fig\](a), into a fast anatomical re-entry around the opening, Fig. \[slice\_fig\](b). [Because of the 2D re-entry pinning to either the sharp end of 