How much energy (in watts) is used in a cardioversion?

100-360 J: First a couple of definitions: energy is usually expressed in joules (j). Watts are a measure of the rate of energy used, 1 watt = 1 joule/sec. Most external cardioversions use between 100 and 360 joules (or 100-360 watt-sec). Internal defibrillators deliver about 20-45 j.

Useless: Generally speaking, watts or a nonproductive measure when discussing cardioversion. The pulse delivered is generally 10 ms or less, so we speak more of the energy in joules than watts. The energy is, for most modern external defibs, around 200j. Over the 10ms, that would work out to 20, 000 watts.