A NEW 3-DIMENSIONAL FINITE-DIFFERENCE BIDOMAIN FORMULATION FOR INHOMOGENEOUS ANISOTROPIC CARDIAC TISSUES

Bidomain modelling of cardiac tissues provides important information a bout various complex cardiac activities, The cardiac tissue consists o f interconnected cells which form fiber-like structures, The fibers ar e arranged in different orientations within discrete layers or sheets in the tissue, i.e., the fibers within the tissue are rotated. From a mathematical point of view, this rotation corresponds to a general ani sotropy in the tissue's conductivity tensors, Since the rotation angle is different at each point, the anisotropic conductivities also vary spatially. Thus, the cardiac tissue should be viewed as an inhomogeneo us anisotropic structure, In most of the previous bidomain studies, th e fiber rotation has not been considered, i.e., the tissue has been mo delled as a homogeneous orthotropic medium, In this paper, we describe a new finite-difference bidomain formulation which accounts for the f iber rotation in the cardiac tissue and hence allows a more realistic modelling of the cardiac tissue, The formulation has been implemented on the data-parallel CM-5 which provides the computational power and t he memory required for solving large bidomain problems. Details of the numerical formulation are presented together with its validation by c omparing numerical and analytical results, Some computational performa nce results are also shown. In addition, an application of this new fo rmulation to provide activation patterns within a tissue slab with a r ealistic fiber rotation is demonstrated.