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The patho-physiology of chronic arterial hypertension: a hypothesis
Insights
Hypertension can become self-sustaining due to arteriolar narrowing. This study proposes endothelial damage, not structural adaptation, causes narrowing by increasing shear stress on vessel walls.
Area of Science:
- Cardiovascular physiology
- Pathology of hypertension
Background:
- Hypertension's self-sustaining nature is a key unresolved problem.
- Previous theories suggest "structural adaptation" causes arteriolar narrowing.
Purpose of the Study:
- To propose an alternative mechanism for arteriolar narrowing in chronic hypertension.
- To investigate the role of endothelial damage in sustained hypertension.
Main Methods:
- Histological examination of arterioles in chronic hypertension.
- Comparison with intimal damage in experimental atherosclerosis.
Main Results:
- Histological findings suggest arteriolar changes are pathological, not adaptive.
- Arteriolar narrowing is proposed to result from endothelial damage.
Conclusions:
- Endothelial damage, caused by increased shear stress, is a likely cause of arteriolar narrowing in hypertension.
- This pathological process may explain hypertension's self-sustaining nature.
Abstract:
An important unresolved problem in hypertension is how an elevated blood pressure from any cause may eventually become self-sustaining and apparently independent of the initiating event. Folkow has suggested that this results from arteriolar narrowing due to a physiological response or " structural adaptation" to the higher pressure, but it is suggested here that the histological appearances within arterioles in chronic hypertension are much more in keeping with a pathological process, and not vastly different from those observed after intimal damage to larger arteries in experimental atherosclerosis. From this, it is proposed that the arteriolar narrowing is secondary to the endothelial damage which arises when a maintained cardiac output is forced through a constricted arteriolar bed, so increasing substantially the shearing stress on their walls.