Cerebral arteriovenous malformations, steal, and the hypertensive breakthrough threshold. An experimental study in rats.

An experiment was designed to investigate the effects of arteriovenous (AV) fistula occlusion on cerebral autoregulation. A right carotid-jugular fistula was created in 63 rats in such a way as to produce an intracranial AV fistula with a loop extension into the neck. The fistula was occluded after an 8-week interval with the rats under both normotension and metaraminol-induced hypertension, and evidence of blood-brain barrier disruption was investigated with an Evans blue dye technique. The results indicate that an intracranial AV fistula may cause cerebral steal which is responsible for a reduction in the threshold for hypertensive breakthrough following fistula occlusion.