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Cerebral vascular changes during chronic hypertension: good guys and bad guys
1Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
Insights
Vascular hypertrophy protects cerebral blood vessels in chronic hypertension, contrary to previous beliefs. Endothelial dysfunction, not hypertrophy, drives major vascular complications like stroke.
Area of Science:
- Neuroscience
- Cardiovascular Science
- Pathophysiology
Background:
- Chronic hypertension leads to structural changes in cerebral blood vessels.
- The prevailing hypothesis suggested hypertensive vascular hypertrophy is detrimental.
Purpose of the Study:
- To review new concepts on cerebral vascular structural changes in hypertension.
- To investigate mechanisms of cerebral vascular complications.
- To test the hypothesis that hypertensive vascular hypertrophy is harmful.
Main Methods:
- Comprehensive literature review of existing studies.
Main Results:
- Evidence contradicts the notion that vascular hypertrophy is harmful in cerebral circulation.
- Vascular hypertrophy and remodeling appear protective against hypertension's effects on cerebral vessels.
- Endothelial dysfunction is identified as a primary cause of major cerebral vascular complications in hypertension.
- Disruption of the blood-brain barrier by endothelial dysfunction mediates hypertensive encephalopathy.
- Impaired endothelial modulation of vascular tone contributes to transient ischemic episodes and stroke.
Conclusions:
- Hypertensive vascular hypertrophy is protective, not harmful, to cerebral vessels.
- Endothelial dysfunction is the key mechanism underlying major cerebral vascular complications in chronic hypertension.
- Targeting endothelial dysfunction is crucial for managing hypertensive cerebrovascular diseases.
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.