Heat Flow from Rechargeable Neuromodulation Systems into Surrounding Media

A synergistic investigation involving both experiment and numerical simulation was performed in vitro to determine the heat flow from rechargeable neuromodulation systems into surrounding media. Each system consists of an implant and an external recharging antenna, and the heat flows of each of these components were determined separately. Three systems, each produced by a different medical device firm, were evaluated. The evaluated products included those from Medtronic Inc. (MDT), ANS (a St. Jude Company), and the Boston Scientific Company (BSC, formerly Advanced Bionics). To ensure statistical significance, three nominally identical samples of each of the three systems were included in the study. Furthermore, for each sample of each system, replicate evaluations were performed for both the implant and the antenna. It was found that for both components of MDT, substantially lower rates of heat flow were produced compared with those for ANS and BSC. With regard to the latter systems, the higher rates of heat flow were not consistently ordered for the implant and for the antenna. In general, replicate data runs for each system and each component were in satisfactory agreement. The different samples of the MDT system showed only minor deviations with regard to heat flow. The deviations among the different samples of both ANS and BSC were larger than those evidenced for MDT.