Estimation of the bidomain conductivity parameters of cardiac tissue from extracellular potential distributions initiated by point stimulation.

A method for determining the bidomain conductivity values is developed. The study was generated because the different sets of measured conductivity values reported in the literature each produce significantly different bidomain simulation results. The method involves mapping the propagation of the electrical activation of cardiac tissue, initiated by point stimulation, via extracellular electrodes. A time-dependent bidomain model is used to simulate the electrical phenomena. The optimum set of conductivity values is achieved by minimizing the difference between the bidomain model output and the measured extracellular potential, by means of inverse techniques in parameter estimation least-squares and singular value decomposition. The method is validated with synthetic data with added random noise. Other parameters in the model such as membrane capacitance and fiber angle can also be estimated. The method takes a different approach to the conventional four-electrode technique, as it does not require the small electrode separation needed to separate the extracellular current from the intracellular.