The funnel shaped occlusion balloon seals the walls of the vessel to establish {HEAD ~ retrograde flow} of {TAIL ~ blood} 
of
The funnel shaped occlusion balloon seals the walls of the vessel to establish { HEAD ~ retrograde flow } of { TAIL ~ blood }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL