三、脑血管痉挛后的病理生理学改变 根据血液动力学特性脑动脉可分为两种类型:一种是位于脑表面的较粗大导动脉,主要指Willis环及其一、二级动脉分支,能为血管造影所见;另一种是位于远端的小穿通动脉,其作用是,正常情况下机体的血压和血容量在一定范围变动时,通过这些小穿通动脉的舒缩使脑血流维持在一定水平。SAH发生后,导动脉发生痉挛,使血流阻力增加,当痉挛发展到一定程度时可导致脑血流降低。这一异常变化影响了小穿通动脉的自动调节作用,使脑血流易受全身血压和血容量的影响。CVS后血液动力学机制十分复杂。SAH后脑血流改变受多种机制影响,诸如脑血管痉挛、颅内压增高、平均动脉压降低、小阻力血管功能障碍、脑代谢 Third, the pathophysiology of cerebral vasospasm changes According to hemodynamic characteristics of cerebral arteries can be divided into two types: one is located in the brain surface of the larger leading artery, mainly refers to the Willis ring and its primary and secondary branches, can For the angiography seen; the other is located in the distal small through the arteries, its role is under normal circumstances, the body’s blood pressure and blood volume changes in a certain range, the small perforating artery contraction and contraction to maintain cerebral blood flow At a certain level. SAH occurs, the spasm of the guide artery, so that increased blood flow resistance, when the spasms to a certain extent, can lead to decreased cerebral blood flow. This abnormal change affects the auto-regulation of small penetrating arteries and makes the cerebral blood flow susceptible to systemic blood pressure and blood volume. The hemodynamic mechanism after CVS is very complicated. Cerebral blood flow changes after SAH are affected by several mechanisms such as cerebral vasospasm, increased intracranial pressure, decreased mean arterial pressure, small resistance vascular dysfunction, brain metabolism