Recent advances in the MR conditional safety assessment of active implantable medical devices (AIMDs) have begun providing guidelines in the development of transfer functions for evaluating risk to the patient due to RF-induced heating. This work introduces the complexity of the analysis of RF-induced heating and explores the impact of the computational human model (CHM) on the resulting analysis. Through historical analysis techniques, simplified structures, and real medical device geometries, the interaction of the AIMD lead with the tissue simulating medium (TSM) can be better understood. Finally, a general guiding principle for MR manufacturers is identified, whereby the thickness of the lead insulation can be used to determine the appropriate TSM for the most accurate in vivo predictions of RF-induced heating.