Active Implantable Medical Devices generate heat as a result of resistive losses in their circuitry, exothermic reaction in their batteries, eddy-current heating due to inductive recharge, friction between mechanical components, etc. The European Standard which regulates AIMDs limits the heating of the outer surface of an AIMD to 2ºC above normal body temperature. Despite the rapid growth in the use of AIMDs, the relationship between AIMD endogenous heat generation and tissue temperature has not been quantified. In the attached paper we aimed at determining the limit of endogenous heat that can be dissipated in-vivo by the surface area of an AIMD to remain compliant with the 2ºC temperature increase limit. In our study, four Sinclair mini-pigs underwent implantation of AIMD simulants instrumented to dissipate heat and measure temperature internally, as well as the device/tissue interface temperature.
We found that for a device with the surface area and geometry that we used, approximately 1W can be dissipated before reaching the 2ºC temperature increase limit.
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