OPTIMIZATION OF TRANSCUTANEOUS CARDIAC PACING BY 3-DIMENSIONAL FINITE-ELEMENT MODELING OF THE HUMAN THORAX

The goal of the study is to determine by finite element analysis (FE) the optimal electrode placement, size and electrolyte resistivity that minimise the pain experienced by patients during successful transcuta neous cardiac pacing (TCP), The three-dimensional FE model generated f or this purpose has 55 388 nodes, 50 913 hexahedral elements and simul ated 16 different organs and tissues, as well as the properties of the electrolyte. The model uses a non-uniform mesh with an average spatia l resolution of 0.8 cm in all three dimensions. To validate this model , the voltage across 3 cm(2) Ag-AgCl electrodes is measured when curre nts of 5 mA at 50 kHz are injected into a subject's thorax through the same electrodes. For the same electrode placements and sizes and the same injected current, the FE analysis produced results in good agreem ent with the experimental data. The optimisation analysis tested seven different electrode placements, five different electrode sizes and si x different electrolyte resistivities. The analysis indicates that the anterior-posterior electrode placement, electrode sizes of about 90 c m(2) and electrolytes with resistivity of about 800 Omega . cm yield t he most uniform current distribution through the skin, thus having the best chances to minimise the pain delivered to the patient during suc cessful TCP. The anterior-anterior electrode placement is the second m ost efficient.