Numerical and Experimental Study on Mixed Use of Implantable Pulse Generator for AIMDs Under 1.5T MRI

Magnetic resonance imaging (MRI) safety for active implantable medical devices (AIMDs) can be compromised by radiofrequency-induced heating and voltage rectification, both of which are affected by the impedance of the implantable pulse generator (ZIPG). However, the influence ofZIPGon these safety mechanisms has not been systematically characterized. This article applied the transfer function (TF) approach to quantify how varyingZIPGvalues impact AIMD heating and voltage behavior. A mock implantable pulse generator (IPG) and a commercially available lead were tested across five impedance configurations using TF measurements and electromagnetic simulations with anatomically realistic human models. The results showed that voltage TFs maintained consistent shapes, but exhibited linearly increased (up to 50%) magnitudes with higherZIPG, indicating a greater risk of voltage rectification and potential device malfunction. In contrast, heating TFs remained stable when the ratio of lead characteristic impedance toZIPGwas small. These findings demonstrate that IPG impedance can significantly influence AIMD responses in MRI environments and underscore the need for individualized evaluation of IPG interchangeability to ensure safe clinical use.