I saw this article in The New England Journal of Medicine. Here is the
URL, unfortunately behind a paywall.

http://content.nejm.org/cgi/content/short/360/13/1363

The gist is that a danish doctor had a patient who was getting
inappropriate cardiac shocks from an ICD (implantable cardioverter-
defibrillator) while in the shower, which turned out to be due to bad
house wiring causing a 50 Hz leakage current from showerhead to floor
drain.

A current of 3.5 to 4.0 milliamps is not usually felt, but can spoof the
ICD, which looks for such signals lasting about 300 milliseconds.

This would be easy to check with a voltmeter. And to prevent by
running a ground wire from showerhead to drain pipe.

Joe Gwinn