a first electrode having {HEAD ~ a first pair} of {TAIL ~ bipolar contacts} attached to the expandable balloon; and 
of
a first electrode having { HEAD ~ a first pair } of { TAIL ~ bipolar contacts } attached to the expandable balloon ; and
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH