Volume imaging, defibrillation electrode models, and finite element modeling are employed in patient-specific procedural modeling in pediatric patients with cardiac arrhythmias. Due to variable size and anatomy, these patients may not be well-served by devices designed for adult defibrillation. A pipeline for rapid creation of image based models that can be interactively interrogated to determine optimal defibrillation scenarios and preliminary proof-of-concept work are presented. This approach has potential clinical applications for therapy planning and broad applications for finite element modeling in anatomical models. Clinical studies investigating the effects of body size, habitus, and anatomical variation on myocardial voltage gradients are planned.