Cerebral vascular changes during chronic hypertension: good guys and bad guys.

AIM: To examine new concepts concerning structural changes in cerebral blood vessels during chronic hypertension, and to examine mechanisms that lead to cerebral vascular complications, in light of the hypothesis that hypertensive vascular hypertrophy may be harmful.
METHOD: Literature review.
RESULTS: The evidence suggests that the current view is not correct in relation to the cerebral circulation. Vascular hypertrophy and remodeling appear to protect cerebral vessels during hypertension, instead of being harmful. Major cerebral vascular complications during hypertension may be largely due to endothelial dysfunction. One function of the cerebral endothelium is to serve as the blood-brain barrier. Disruption of the blood-brain barrier appears to mediate hypertensive encephalopathy. A second endothelial function is to modulate vascular tone. Abnormalities in vasoactive factors that are released by the endothelium (impaired vasodilator mechanisms and augmented vasoconstrictor mechanisms) may make an important contribution to the pathophysiology of transient ischemic episodes, and perhaps stroke, in chronic hypertension.