Forward problem of electrocardiography: construction of human torso models and field calculations using finite element method.

Finite element models of the human torso were constructed using anatomical data measured by serial computerised tomography scans in a subject. A first set of three models with a mesh resolution of 5517 nodes and 29810 elements included an homogeneous conductivity, lungs inhomogeneity, and heart, lungs and spinal region inhomogeneities. A second set comprised similar models with a mesh resolution of 12084 nodes and 67045 elements. A cylindrically shaped volume conductor was also constructed to evaluate the convergency and accuracy of the finite element solutions by comparison with the analytical solution. Forward simulations were performed using different excitation sites on the cardiac surface. The inclusion of conductivity inhomogeneities altered the maximum and minimum values of the body surface potentials, but did not substantially modify the pattern of the potential distributions. The greatest effect was due to the inclusion of the lungs. Increasing the mesh resolution from 5517 to 12084 nodes did not change noticeably the shape or amplitude of the simulated body surface potential maps. These models can readily be used for other bioelectromagnetic problems.