It might be cheap to make, but its absolutely not a cheap procedure for any of the medical applications I know of. The drug itself is around 1k for the low end of the typical therapeutic dose, and a lot of insurances (if you’re in the US) want you to jump through hoops to pay for it.

Specifically it’s very possible to stimulate the vagus nerve, which helps regulate heart rhythm, with an exam like this. This is a known effect, but typically in the context of a possible adverse effect of some procedures (e.g. enema).