{HEAD ~ a second electrode} having {TAIL ~ a second pair} of bipolar contacts attached to the expandable balloon, 
{ HEAD ~ a second electrode } having { TAIL ~ a second pair } of bipolar contacts attached to the expandable balloon ,
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH