I mean, with that level of heart failure that an artificial heart is required, there are a bunch of other medical concerns that should be reliably transmitted.

I mean, with that level of heart failure that an artificial heart is required, there are a bunch of other medical concerns that should be reliably transmitted. As an example, people with diabetes might have tattoos. Also, CPR is administered primarily when breathing is not sensed. If the patient is already in the hospital, they will surely check basic stuff, like a huge scar on the chest. Though it would be very interesting if the machine would artificially output a potential vector that makes it very apparent to EKG and similar devices that it is operating, but it is not an ordinary heart (e.g. doing a square wave). It would require minuscule energy.