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