Cerebral arterial constriction due to contrast media.

Angiography, either with Iohexol or Hexabrix, was carried out on a series of baboons, each of which had both contrast media, but on separate occasions. A double blind trial showed that in the carotid and middle cerebral arteries: Hexabrix generally caused vasoconstriction by 1.5 min, but in spite of a subsequent injection at 6 min constriction had largely disappeared by 20 minutes. Iohexol was generally followed by less severe constriction, but it may persist for longer and even show an increase at 20 min.