Hypertension and cerebral ischemia with special reference of cerebral hemodynamics.

DOI Web Site

Bibliographic Information

Other Title
  • 高血圧と脳虚血　　脳循環動態よりみた検討
  • シン ベンマクショウ ニ オケル ノウ ジュンカン ドウタイ
  • 脳循環動態よりみた検討

Search this article

Description

It has been known that hypertension is a major risk factor for cerebral infarction. Its relation has been discussed mainly on a static or morphological aspect, based on the epidemiological and clinicopathological studies, but rarely from a hemodynamic standpoint. In this paper, mechanism of development of cerebral ischemia in hypertension is discussed on cerebral hemodynamic aspect.<BR>Regional cerebral blood flows in the cortex and deep structures are reduced in hypertensive humans (measured by PET) as well as animals (measured by H2 technique), its reduction being related with the severity and duration of hypertension. In similar to normotensives, however, cerebral autoregulation is preserved in hypertensives, although its upper and lower limits are shifted to higher levels in hypertension. The lower limit shift is more rapid and great during development of hypertension in spontaneously hypertensive rats (SHR), followed by a gradual but progressive upward shift even in the established state of hypertension. Therefore, in aged and long-lasting hypertensives the autoregulatory range from blood pressure at rest to the lower limit level becomes narrower, indicating that cerebral blood flow easily reduces when blood pressure falls.<BR>Observing the blood pressure changes in patients who newly or recurrently develop non-embolic cerebral infarction during hospitalization, a greater reduction of blood pressure prior to attacks by antihypertensive treatment seems to play some role in the occurrance of cerebral infarction. In such cases, infarct is relatively large and sited mainly in the watershed area or in the cortical artery territory.<BR>These experimental and clinical data strongly suggest that a blood pressure lowering by treatment of hypertension beyond the lower limit of autoregulation, which significantly shifts upwards, appears to cause cerebral ischemia or infarction. Careful treatment, namely a more slow and less extensive reduction of blood pressure is recommended, and also choice of antihypertensive agents is important, vasodilating drugs being less harmful.

Journal

Keywords

Details 詳細情報について

Report a problem

Back to top