Regarding the use of AC or DC current, are there specific instances where the 
use of either is not recommended? Or could produce problems?  If the left 
side of my body has zero resistance to electrical stimulation, would there be 
any health risk in using AC or DC on the right side?  (The zero resistance 
situation was discovered through nerve conduction tests by a Neurologist.)  
Used a tens unit once, and it caused a major heart problem, and provided a 
weeks vacation at the cardiac unit.  Is there a VERY LOW level of AC or DC to 
start with, and then work up from there? Even toughing both sides of a small 
9 V battery causes a tingle with the right hand. Or is this a normal 
situation with most everyone?   Thank you.  suzy