The effect of skeletal muscle layer modeling on cardiac damage estimates during transthoracic defibrillation

The objective of this study is to examine how modeling the skeletal muscle layer affects computed estimates of cardiac damage during transthoracic defibrillation. The study is implemented with a physiologically realistic 3-D volume conductor model of the human thorax. The model computes current density distributions within the heart from a knowledge of defibrillation shock strength, defibrillation electrode location, and the relative conductivities of the interior thorax. Cardiac damage estimates are based on achieving 95% critical mass during a defibrillation shock. Solutions have been constructed for three sets of skeletal muscle conductivities that are widely used in the literature. The results for anterior-posterior, precordial, and right-left defibrillation electrode configurations indicate that computed estimates of cardiac damage vary by as much as 85%, 23%, and 18%, respectively. These results strongly suggest that computed estimates for cardiac damage during a defibrillation shock are dependent on the conductivity values chosen for the skeletal muscle layer, and therefore estimates of cardiac damage at present are limited to realistic ranges rather than precise determination