Analysis of atrial defibrillation thresholds in two finite element torso models based on anatomical differences

Due to geometrical and structural differences between the ventricles and the atria, the field distribution created by a shock in ventricular myocardium and atrial myocardium is quite different. The resulting difference in field distribution greatly influences the atrial defibrillation thresholds (ADFTs). Finite Element Analysis (FEA) modeling of atrial defibrillation electrode configurations in human torso models has not been reported even though finite element models have been increasingly used to study ventricular defibrillation field. In atrial fibrillation, an arrhythmia that is not immediately life threatening, optimization of the electrode system is hypothesized to reduce the discomfort associated with atrial defibrillation shocks. To have effective defibrillation, two Finite Element Thorax models were built from MRI and fast CT images of two patients. One patient had a dilated left atrium and ventricular abnormalities and the other patient had no heart disease. Various atrial defibrillation electrode configurations were analyzed and compared in the two models. The calculated atrial DFTs were also compared with those measured clinically for both patients with a history of atrial fibrillation. The FEA results indicate that anatomical variations such as the LA dimensions affect atrial DFTs.