How ischaemic region shape affects ST potentials in models of cardiac tissue

This numerical study uses a simple bidomain model of cardiac tissue to compare the effect of three different ischaemic region geometries (rectangular, cylindrical and semi-ellipsoidal) on the extracellular epicardial potentials during the ST segment. Results are obtained using anisotropic conductivities based on experimentally derived data. The model is then altered, to include heterogeneous conductivities in the ischaemic region and larger border zone widths, in order to better reproduce realistic scenarios. Initial results for the rectangular and cylindrical ischaemic shapes show a central depression over the ischaemic region, for low ischaemic thicknesses, which separates into three depressions as the ischaemic thickness increases. For ischaemic thicknesses above 70% an elevation appears over the ischaemic region and this increases in magnitude as the ischaemia becomes transmural. Results for the semi-ellipsoidal shape, however, differ, with the central depression separating into only two depressions as the thickness increases. Changing the conductivity inside the ischaemic region significantly affects results for each geometry, with depression staying over the ischaemic region for much higher levels of ischaemia (up to 90% thickness). Increasing the intramural border zone thickness did not significantly affect the epicardial potential distributions.

► Anisotropic bidomain model is used to represent slab of cardiac tissue.
► Rectangular, cylindrical and semi-ellipsoidal ischaemic regions are examined.
► Realistic conductivities and border zones are incorporated to study their affects.
► The relationship between current loops and ischaemic geometry is studied.