This is a reformatted version of a twitter thread I had put together nearly a year ago. In a former life I worked on designing the manufacturing system for cardiac pacemakers. I had done a bit of research on pacemakers at the time, but I had never come across the fact that some early pacemakers were designed and built with plutonium power sources.

Begin reformatted thread:

Fell down a history hole and came across the fact that we used to implant plutonium (!) powered cardiac pacemakers ❤️⚡️☢️


Below is a cutaway schematic - they used the heat generated from radioactive decay to generate electricity using thermocouples [1]


Why nuclear power? In the early days if you wanted to pace a patient for a long time (i.e. a pediatric patient) you would need to replace the pacing device a lot because the batteries would die 🔋😧 [2]


In order to sell these in the US you needed sign-off from both @US_FDA and the @NRCgov (nuclear regulatory commission). of course @Medtronic made one, but apparently a bunch other folks got in the game as well - including monsanto! [3]


As weird as it sounds people were 𝕚𝕟𝕥𝕠 the concept of having plutonium powered pacemakers at the time. [2]


Radiation exposure was a concern, although theoretically the devices were well shielded and risk would be minimal. theory was borne out in practice - after years of study it turned out that patients with these pacemakers did NOT have higher rates of cancer. [4]


Thousands of these pacemakers were implanted in the 70s and it turns out that they lasted for a very long time. in 2007 a case report was written about a pacemaker that was still firing since its implantation in 1973! 😧 [5]

This crazy longevity wasn’t necessarily a great thing - replacements = better features (i.e. interrogation and programming). plus end-of-life disposal issues made plutonium pacemakers a poor choice once better batteries came along.

On one hand the logic behind why you would design and implant these pacemakers makes total sense and on the other its totally wild because of the current stigma associated with everything nuclear.

Go ÖN Home


  1. Radioisotope thermoelectric generator - Wikipedia. 2022; Available from:
  2. Smyth, N.P., T. Hernandez, and A. Johnson, Clinical experience with radioisotopic powered cardiac pacemakers. Henry Ford Hospital Medical Journal, 1974. 22(3): p. 113-116.
  3. Wayback Machine - Cardiac Pacemaker. 2022; Available from:
  4. Parsonnet, V., A.D. Berstein, and G.Y. Perry, The nuclear pacemaker: Is renewed interest warranted? The American Journal of Cardiology, 1990. 66(10): p. 837-842.
  5. Parsonnet, V., A lifetime pacemaker revisited. New England Journal of Medicine, 2007. 357(25): p. 2638-2639.