tissue. A low electrical conductivity of 0.18 S/m was assigned to this region and the tissue was
assumed isotropic.13 Simulations where a potential difference input was applied were done in
order to compare to the healthy heart tissue model.
IN
Figure 3-9. Transverse slice images of anisotropic electrical heart model in FEM software with
infarct region (dark blue), from apex=l to base=5 of the heart. (red=parallel to xy-
plane, blue=perpendicular)
Time-Dependent Model
A time-dependent model was implemented using a modified version of the FitzHug-
Nagumo equations for excitable media, Equation 3-7.28 A fully anisotropic electrical
conductivity tensor G' was implemented which has not been previously analyzes.
The electrical conductivity tensor affects the speed at which the tissue is excited as well
as the speed at which the tissue depolarizes. Non-linear membrane kinetics were implemented by
using modified FitzHugh-Nagumo equations for excitable media
-ul = V. G'Vu, + cu1 (u1 a)(1 u)- c2u2
at (3-7)
=su
at
G'is the electrical conductivity tensor and as well as in the general form of the equations, u, is
an activation variable, u2 is an inhibitor, a sets the excitation threshold, P the excitability, and 3,y,
and 6 are the parameters that describe the resting state and dynamics of the system.28