症状性大脑中动脉粥样硬化性狭窄的血流动力学数值模拟研究

Computational Fluid Dynamic Study of Symptomatic Middle Cerebral Artery Atherosclerotic Stenosis

目的探讨血流动力学因素在大脑中动脉粥样硬化性狭窄患者急性脑缺血事件中的作用。方法收集10例第二军医大学附属长海医院脑血管病中心收治的症状性单侧大脑中动脉(middle cerebral artery,MCA)M1段局限狭窄的患者,依据脑血管造影建立病例特异三维数值模型,测量M1段狭窄程度,并应用计算机流体力学方法测算血流动力学参数,分析动脉不同部位及不同狭窄程度血流动力学参数的变化。狭窄段至远端正常血管段壁面剪切力(wall shear stress,WSS)变化用标准化WSS表示,为狭窄段WSS(WSS_s)与远端正常血管段WSS(WSS_p)的比值,记为WSS_(S/P);血流速度(velocity)及震荡剪切指数(oscillatory shear index,OSI)的变化用标准化的velocity_(S/P)、OSI_(S/P)表示。结果 MCA狭窄段WSS明显高于远端正常段(中位数81.85 vs 18.81,P=-0.000);狭窄段流速快于远端正常段(中位数2.26 vs 0.33,P=-0.000);而MCA最狭窄处OSI低于远端正常血管段(中位数0.00039vs 0.015 70,P=0.000);不同狭窄程度间,标准化血流动力学参数不同;狭窄程度增大,WSS_(S/P)、velocity_(S/P)增加(r_s=0.828,P=-0.003;r_s=0.79,P=-0.007),OSI_(S/P)逐渐下降(r_s=-0.822,P=-0.004)。结论大脑中动脉狭窄病变伴有血流动力学改变,血流动力学因素可能参与了颅内动脉粥样硬化形成和发展。

Objective To explore the role of hemodynamic risk factors in patients with intracranial artery stenosis in acute ischemic events.Methods A total of 10 patients of symptomatic unilateral middle cerebral artery（Ml） stenosis treated in Stroke Center of Changhai Hospital Affiliated to the Second Military Medical University were analyzed.Patient-specific three-dimensional numerical models were reconstructed,the Ml segment stenosis degrees were measured and the values of hemodynamic parameters were calculated based on the cerebral angiography image to analyze the value of hemodynamic parameters between different parts and degrees of stenosis.Change of wall shear stress（WSS）across a lesion was represented by the ratio of WSS,standardized WSS,at the stenotic throat and proximal normal vessel segment,named as WSS_（s/p）,similar for the change of flow velocity and oscillatory shear index（OSI）,denoted as velocity_（S/P）,OSI_（S/P）.Results WSS_s and velocity_s at the stenotic throat was significantly higher than those in proximal normal vessel segment（median level of WSS 81.85 vs 18.81,P=0.000;median level of velocity 2.26 vs 0.33,P=0.000）.While OSI at the stenotic throat was lower than that in proximal normal vessel segment（median level of OSI 0.33 vs 2.26,P=0.000）.Standardized hemodynamic parameters were different between different degrees of stenosis.Standardized hemodynamic parameters,such as WSS_（S/P）,velocity_（S/P） increased apparently（r_S=0.828,P=0.003;r_S=0.79,P=0.007）,while OSI_（S/P）declined gradually as the degrees of stenosis increasing（r_S=- 0.822,P=0.004）.Conclusion Our study reveals that hemodynamic factors might be involved in the forming and development of intracranial atherosclerosis,because of obvious change of hemodynamic parametersin patients with intracranial artery stenosis.