They evidently used to use radiothermal generators (RTGs) as the power source for some pacemakers. https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge

They evidently used to use radiothermal generators (RTGs) as the power source for some pacemakers. https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator#History https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge... Plutonium is nasty & expensive stuff, however. That puts some pretty severe limitations on its usefulness for domestic purposes.