Might it vary by region? The defibrillators I test for my job usually say 'ECG' for the electrocardiogram port, or sometimes they say both, ECG/EKG. The cables seem to be called ECG cables at the store.
https://shop.stryker.com/lifepak-4-wire-ecg-cable-5-ft-aha/
When I was in school, my instructor said that it was always called ECG, and you'd never hear anyone calling it EKG. That seems not to be the case. I've seen hospitals with giant signs painted on the walls pointing to the EKG department.
I can't say I've personally done any testing to see how they may be affected by moisture. I'm sure the people designing them found a way to compensate for it, though.