Abstract
A computer simulation system employing the finite element method was developed to study the effects of torso inhomogeneities on the distribution of the body surface potentials. The torso model is constructed from the X-ray CT images of the patient. The torso is divided into 4992 tetrahedral elements keeping in view the fact that the potential radiates outwards from the dipole conforming to the inverse square law. The CT value is determined at the center of gravity of each of the tetrahedral elements. The CT values help us determine accurately the shape of the body and idcntify the inner organs, their shapes and relative positions. The simulation maps for homogeneous and inhomogeneous models were derived by placing a dipole at various positions in the model of the heart. The cross correlation coefficient between the two maps was found to be as low as 0.72 when the dipole was placed near the boundary of the lung. The effect of inhomogeneities due to the conductivities of inner organs on the simulated body surface potential maps was studied for various organs. The effect due to lung was most pronounced—it increased the maximum and reduced the minimum values by nearly 25%. This system will help us in better understanding of the cardiac disorders.
