real life heart anisotropy might have a rather anti-arrhythmic function as it facilitates fast self-termination of cardiac re-entry. ]{}

\[Methods\]Methods
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\[DT-MRI\]DT-MRI based anatomy model
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![\[HF\_slice\_x\_63\] [[**The 143 DGA human foetal heart [@Pervolaraki-etal-2013]**]{}. [BeatBox]{} [@bbx-2017-PONE] geometry [`.bbg`]{} format visualisation[: shown here are projections of the unit vectors of the local fibre orientation onto the cross-section plane. Laminar fibres are well formed except near the surfaces of the outer walls, where chaotic structure from earlier developmental stages is still present. This is seen even better in the colour-coded Figure 4 in Pervolaraki et al [@Pervolaraki-etal-2013 p. 5]. ]{}]{}](Fig1-eps-converted-to.pdf)

The DT-MRI data sets of the $128\times128\times128$ voxels size, with voxel resolution of $\sim100\mu m$, of ethically obtained 143 days of gestational age (DGA) human foetal heart [@Pervolaraki-etal-2013], were converted into the [BeatBox]{} [@bbx-2017-PONE] regular Cartesian mesh [`.bbg`]{} geometry format, containing the DT-MRI cartesian coordinates of the heart tissue points together with the corresponding components of the diffusion tensor primary eigenvectors [@bbx-2017-PONE]. The [[`.bbg`]{}]{} file is an ASCII text file, each line in which describes a point in a regular mesh in the following format: $${\texttt{ x,y,z,status,fibre\_x,fibre\_y,fibre\_z}}$$ Here [`x, y, z`]{} are integer Cartesian coordinates of a DT-MRI voxel, [`status`]{} is a 