下肢动脉疾病(LEAD)具有发病率高危害大的特点,如何有效改善下肢血流动力学其治疗的关键环节之一。源自本课题组实验室的现代体外反搏(EECP)是一种高效的无创辅助循环技术,获国际临床指南推荐用于缺血性心脑血管疾病治疗。最近临床观察...下肢动脉疾病(LEAD)具有发病率高危害大的特点,如何有效改善下肢血流动力学其治疗的关键环节之一。源自本课题组实验室的现代体外反搏(EECP)是一种高效的无创辅助循环技术,获国际临床指南推荐用于缺血性心脑血管疾病治疗。最近临床观察显示EECP在LEAD疾病的管理中具有巨大潜力,但相关机制尚不清晰。目的开展首个前瞻性研究,深入探索EECP及不同作用模式所诱导的下肢股动脉血流及WSS相关应力因子的变化机制。方法入组12名健康志愿者,采用基于超声多普勒的非介入技术测量EECP干预中下肢股总动脉(CFA)及股浅动脉(SFA)的血流变化。通过磁共振技术获得股动脉分叉的血管影像并进行几何重构。进而建立三维个体特异性的流体动力学(CFD)模型进行WSS相关的血流动力学因子求解。通过网格独立性分析得到最优求解网格方案。结果EECP显著促进了CFA及SFA的顺行与逆行血流,但心率保持不变。相对于基线状态,反搏压为10、20、30、40 k Pa的EECP作用分别增加32.41%、121.30%、178.24%、214.81%的周期平均切应力(TAWSS),而粒子相对滞留时间(RRT)分别下降24.53%、61.01%、69.81%、77.99%。当反搏压不低于30k Pa时,低WSS水平区域比例接近于0。结论EECP是一种高效、无创及安全的下肢血流及WSS调控方法。展开更多
目的计算老年血管性认知障碍患者的颈内动脉壁面切应力,研究其与简易智力状态检查量表(mini-mental state examination,MMSE)评分及腔隙性脑梗死、皮质下脑白质病变的关系。方法纳入神经科住院的老年血管性认知障碍患者,行颈动脉彩色多...目的计算老年血管性认知障碍患者的颈内动脉壁面切应力,研究其与简易智力状态检查量表(mini-mental state examination,MMSE)评分及腔隙性脑梗死、皮质下脑白质病变的关系。方法纳入神经科住院的老年血管性认知障碍患者,行颈动脉彩色多普勒超声检查,测量双侧颈内动脉内中膜厚度(intima media thickness,IMT)、内径、收缩期血流速度(peak systolic velocity,Vps)、舒张期血流速度(end diastolic velocity,Ved),计算得到壁面切应力(wall shear stress,WSS)值,再根据WSS结果,分为低切组、正常组和高切组。同时评定各患者MMSE分数,收集MRI检查提示的腔隙性脑梗死和脑白质病变情况。结果空腹血糖(FPG)、低密度脂蛋白(LDL-c)水平低切组最高,高切组最低。低切组MMSE评分最低。低切组内膜中膜最厚而Vps最低,高切组内膜中膜最薄而Vps最高。低切组腔梗的数量最多,正常组最低。多元线性回归分析提示WSS(t=4.364,P<0.01)、LDL-c(t=12.793,P<0.01)和颈内动脉IMT(t=-2.891,P<0.01)是MMSE分数的主要影响因素。结论颈动脉血流动力学在脑小血管病变和认知障碍的发生发展中起重要作用,临床上可以干预血流动力学因素来影响认知障碍的形成和发展。展开更多
Based on the VOF model,CFD simulations were carried out for wall shear stress in gas-liquid vertical and inclined upward slug flow.The simulation results showed that the thickness of the falling film in the vertical u...Based on the VOF model,CFD simulations were carried out for wall shear stress in gas-liquid vertical and inclined upward slug flow.The simulation results showed that the thickness of the falling film in the vertical upward slug flow was always smaller than that in the inclined upward slug flow.In the vertical tubes,wall shear stress increased gradually from Taylor bubble nose to the falling liquid film until it became stable in the developed falling liquid film,but in the wake zone the wall shear stress appeared irregular.In the inclined tubes,the tip of the Taylor bubble nose was above the centerline of the tube and the smaller the angle,the greater the thickness of the falling liquid film.Meanwhile,for the wall shear stress of slug flow in an inclined tube,when FrTB was small,the shear stress profile of falling liquid film on the top wall fluctuated significantly,but it was smooth on the bottom wall.With increasing FrTB, the difference between the shear stress profile on the top wall and the shear stress profile on the bottom wall gradually disappeared.展开更多
文摘下肢动脉疾病(LEAD)具有发病率高危害大的特点,如何有效改善下肢血流动力学其治疗的关键环节之一。源自本课题组实验室的现代体外反搏(EECP)是一种高效的无创辅助循环技术,获国际临床指南推荐用于缺血性心脑血管疾病治疗。最近临床观察显示EECP在LEAD疾病的管理中具有巨大潜力,但相关机制尚不清晰。目的开展首个前瞻性研究,深入探索EECP及不同作用模式所诱导的下肢股动脉血流及WSS相关应力因子的变化机制。方法入组12名健康志愿者,采用基于超声多普勒的非介入技术测量EECP干预中下肢股总动脉(CFA)及股浅动脉(SFA)的血流变化。通过磁共振技术获得股动脉分叉的血管影像并进行几何重构。进而建立三维个体特异性的流体动力学(CFD)模型进行WSS相关的血流动力学因子求解。通过网格独立性分析得到最优求解网格方案。结果EECP显著促进了CFA及SFA的顺行与逆行血流,但心率保持不变。相对于基线状态,反搏压为10、20、30、40 k Pa的EECP作用分别增加32.41%、121.30%、178.24%、214.81%的周期平均切应力(TAWSS),而粒子相对滞留时间(RRT)分别下降24.53%、61.01%、69.81%、77.99%。当反搏压不低于30k Pa时,低WSS水平区域比例接近于0。结论EECP是一种高效、无创及安全的下肢血流及WSS调控方法。
文摘Based on the VOF model,CFD simulations were carried out for wall shear stress in gas-liquid vertical and inclined upward slug flow.The simulation results showed that the thickness of the falling film in the vertical upward slug flow was always smaller than that in the inclined upward slug flow.In the vertical tubes,wall shear stress increased gradually from Taylor bubble nose to the falling liquid film until it became stable in the developed falling liquid film,but in the wake zone the wall shear stress appeared irregular.In the inclined tubes,the tip of the Taylor bubble nose was above the centerline of the tube and the smaller the angle,the greater the thickness of the falling liquid film.Meanwhile,for the wall shear stress of slug flow in an inclined tube,when FrTB was small,the shear stress profile of falling liquid film on the top wall fluctuated significantly,but it was smooth on the bottom wall.With increasing FrTB, the difference between the shear stress profile on the top wall and the shear stress profile on the bottom wall gradually disappeared.
