Here's an article from analog devices (who make the AD620 used in the article) http://www.analog.com/library/analogdialogue/archives/37-11/ecg.html http://www.a

Here's an article from analog devices (who make the AD620 used in the article) http://www.analog.com/library/analogdialogue/archives/37-11/ecg.html http://www.analog.com/library/analogdialogue/archives/37-11/... It has some background as well as an example circuit with a discussion of safety and isolation issues which is a bit more in-depth than the posted article. For the posted schematic: at least put some current limiting resistors on the electrode leads.