The first thing is to learn is where not to apply the pads. The usual recommendation is to not use one in the chest area, but the real concern is putting the pathway between two pads across the heart. It doesn't take much to cause fibrillation. It isn't the current, it's the voltage and frequency. It takes less than 50 volts to disrupt the sinus rhythm. Some people are sensitive to the adhesive on the pads, so watch for blisters where they have been placed. The better ones require a prescription in most states, though I have seen them on line both for therapeutic as well as recreational purposes. Practice carefully and do extensive research on applications. Many chiropractors use them (I have experienced them many times therapeutically) so that may be a direction to research. It is an interesting kink, but one must be careful.