TITLE:
Dynamical modelling of cardiac electrical activity using bidomain approach: The effects of variation of ionic model parameters
AUTHORS:
Adebisi O. Ibrahim, Adejumobi I. Adediji, Dada J. Olufemi
KEYWORDS:
Dynamical Modelling; Cardiac Electrical Activity; Bidomain Model, Ionic Model Parameters; Discretization; Transmembrane Potential
JOURNAL NAME:
Journal of Biomedical Science and Engineering,
Vol.6 No.6,
June
26,
2013
ABSTRACT:
This work presents the dynamical modelling of cardiac electrical
activity using bidomain approach. It focuses on the effects of variation of the
ionic model parameters on cardiac wave propagation. Cardiac electrical
activity is governed by partial differential equations coupled to a system of
ordinary differential equations. Numerical simulation of these equations is computationally expensive due to their non-linearity and stiffness. Nevertheless, we
adopted the bidomain model due to its ability to reflect the actual cardiac
wave propagation. The derived bidomain equations coupled with FitzHugh-Nagumo’s
ionic equations were time-discretized using explicit forward Euler method and
space-discretized using 2-D network modelling to obtain linearized equations
for transmembrane potential Vm,
extracellular potential φe and gating variable w.
We implemented the discretized model and performed simulation
experiments to study the effects of variation of ionic model parameters on the
propagation of electrical wave across the cardiac tissue. Time characteristic
of transmembrane potential, Vm,
in the normal cardiac tissue was obtained by setting the values of ionic model
parameters to 0.2, 0.2, 0.7 and 0.8 for excitation rate constant ε1, recovery
rate constant ε2, recovery
decay constant γ and excitation decay
constant β respectively. Changing the
values of ε1, ε2 to 0.04
and 0.28 respectively, the obtained Vm showed a time dilation at 0.04 indicating cardiac arrhythmia but no significant
change to Vm was observed
at 0.28. Also, changing β to 0.3 and
1.1 and γ to 0.4 and 1.2
sequentially, there was no significant change to the time characteristic of Vm. The obtained results
revealed that only decrease in ε1, ε2 impacted significantly
on the cardiac wave propagation.