Finite element modeling approach for optimal electrode configuration in atrial pacing

A detailed two-dimensional finite element model of the conductive anatomy of the human thorax was designed to assess the current density distribution in atrial pacing. A genetic algorithm was developed to examine the optimal electrode configuration for tolerable esophageal pacing in three cases. According to the model, the most appropriate bipolar electrode position is to encompass the atrium-esophagus contact length, at the level of the T7 and T8 vertebrae. The interelectrode spacing was not critical - 18 to 29 mm. The active electrode length was adequate in the range of 11 to 15 mm. In unipolar eso-thoracic configuration, the position of the external chest electrode did not affect the conditions for tolerable pacing. In external anterior-posterior pacing, the front electrode should be at a level above the apex and the back one - at the level of T5-T6 vertebrae. The insertion of a metal passive electrode in the esophagus resulted in more than twofold increase of the maximum current density in the atrium.