狭窄程度对锥缩血管中脉动流的影响

建立了一个轴对称的狭窄锥缩刚性动脉模型.利用不可压缩的N-S方程作为计算的理论基础,采用有限差分方案进行数值分析.提供了3种狭窄程度下的管壁切应力分布曲线并进行了分析和比较,同时给出了模型M3(h/R₀=1/3)在一个流动周期内的流线图.结果显示狭窄附近的流场受到了干扰,特别是狭窄的喉部及其下游区域的流场,并且狭窄程度越严重,狭窄对流场的影响就越大.     

Simulation of Variable Viscosity and Jeffrey Fluid Model for Blood Flow Through a Tapered Artery with a Stenosis

Non-Newtonian fluid model for blood flow through a tapered artery with a stenosis and variable viscosity by modeling blood as Jeffrey fluid has been studied in this paper.The Jeffrey fluid has two parameters,the relaxation time λ1 and retardation time λ2.The governing equations are simplified using the case of mild stenosis.Perturbation method is used to solve the resulting equations.The effects of non-Newtonian nature of blood on velocity profile,temperature profile,wall shear stress,shearing stress at the stenotsis throat and impedance of the artery are discussed.The results for Newtonian fluid are obtained as special case from this model.     

心血管内流场的高质量模拟实验研究（Ⅲ）：动态流体双折射法典型应用分析

用动态流体双折射法对三种有代表性的心血管模型（模拟大血管、动脉狭窄和人造心脏瓣膜）中的脉动血流间隙测试，得出速度剖面，剪应力分布，压力和流量之间的相位关系。结果说明本文所描述的双折射液和模拟血管是适用于心血管内流场的高质量模拟实验的，动态流体双折射方法及简化的光－力学关系是适用于低频脉动模拟血流的定量分析的。     

Preliminary results of intraoperative mitomycin-C in the treatment and prevention of glottic and subglottic stenosis

Mitomycin-C is an antineoplastic antibiotic that acts as an alkylating agent by inhibiting DNA and protein synthesis. It can inhibit cell division, protein synthesis, and fibroblast proliferation. The purpose of this pilot study is to investigate intraoperative applications of topical mitomycin-C in treatment and prevention of glottic and subglottic stenosis. Eight patients with posterior glottic and/or subglottic stenosis were treated with endoscopic CO2 laser excision followed by topical application of 0.5 cc of 0.4 mg mitomycin-C per milliliter of saline for 4 minutes at the surgical site. After mean follow-up of 15 months (10-20) all patients had clinical improvement of their airway and resolution of their preoperative symptoms. No complications were noted in this study. Although a longer follow-up and further controlled studies are needed, the use of topical mitomycin-C may prove useful in the treatment and prevention of subsequent restenosis and scar formation in the larynx and trachea.     

肾动脉变窄和流-固结构相互作用对非Newton脉动流的影响——一个真实的腹部主动脉和肾动脉模型

研究肾动脉狭窄(RAS)对血液流动和血管壁的影响.根据CT扫描图像,重建腹部主动脉和肾动脉的解剖模型,通过模型的脉动流进行了仿真计算,计算中考虑了流体-固体结构的相互作用(FSI).研究RAS对血管壁剪切应力和位移的影响,RAS使得肾动脉中流量减少,肾素-血管紧缩素系统可能被激活,从而导致严重的高血压.     

Waves in fluid-filled elastic tubes with a stenosis: Variable coefficients KdV equations

In the present work, by treating the arteries as thin-walled prestressed elastic tubes with a stenosis and the blood as an inviscid fluid we have studied the propagation of weakly nonlinear waves in such a medium, in the longwave approximation, by employing the reductive perturbation method. The variable coefficients KdV and modified KdV equations are obtained depending on the balance between the nonlinearity and the dispersion. By seeking a localized progressive wave type of solution to these evolution equations, we observed that the wave speeds takes their maximum values at the center of stenosis and gets smaller and smaller as one goes away from the stenosis. Such a result seems to reasonable from the physical point of view.     

MRI检查神经根沉降征诊断LSS患者的价值及其危险因素分析

本研究探讨磁共振成像(MRI)检查神经根沉降征(NRS)在腰椎管狭窄症(LSS)患者发生中的相关因素及其诊断学价值。选取接受腰椎MRI检查的262例(511个腰椎节段)患者进行研究,根据MRI结果患者腰椎节段分为狭窄组(172例患者,348个腰椎节段)和非狭窄组(90例患者,163个腰椎节段)。狭窄组硬膜囊面积(CSA)<100 mm²患者占比、椎管正中矢状径(PDA)≤15 mm患者占比、侧隐窝矢状径≤5 mm患者占比、神经根沉降征(NRS)阳性率均显著高于非狭窄组(P<0.05);NRS诊断LSS的曲线下面积(AUC)值为0.714;172例LSS患者,NRS阳性患者108例、NRS阴性患者64例,NRS阳性组的糖尿病率、硬膜囊CSA<100 mm²患者占比、椎管PDA≤15 mm患者占比、侧隐窝矢状径≤5 mm患者占比均高于阴性组患者,差异均具有统计学意义(P<0.05);硬膜囊CSA<100 mm²、椎管PDA≤15 mm、侧隐窝矢状径≤5 mm是LSS患者发生NRS的独立危险因素(P<0.05)。NRS对于诊断LSS具有较高的特异度,但是灵敏度一般,患者椎管狭窄越严重,其NRS发生的风险越高。     

颈动脉超声联合CT和血清miR-124、miR-155对颈动脉狭窄患者继发性脑梗的风险预测价值

本文探讨了颈动脉超声检查联合CT和血清微小RNA-124(miR-124)、微小RNA-155(miR-155)对颈动脉狭窄患者继发性脑梗的风险预测价值。以43例颈动脉狭窄患者为颈动脉狭窄组,正常志愿者43例为正常组,用RT-PCR法检测miR-124、miR-155表达,采用颈动脉超声检查颈动脉狭窄,采用CT检查颈部血管。结果显示,与正常组相比,颈动脉狭窄组miR-124、miR-155表达升高(P<0.05)。与超声、CT检查相比,超声检查联合CT检查颈动脉狭窄准确率、诊断价值较高(P<0.05)。本研究认为,颈动脉超声、CT、miR-124、miR-155对颈动脉狭窄的诊断价值较高,且可用于预测继发性脑梗的风险,预测价值较为理想。     

窦部对称狭窄对颈动脉内流场影响的数值研究

以颈动脉分岔血管为例，采用数值方法研究了窦部环缩狭窄之后的流场分布情况，并和正 常血管情况下的流场分布进行了比较. 结果表明，采用环缩方式给颈动脉分岔血管施加对称 的狭窄改变了颈动脉窦内流场，特别是壁面剪应力的分布规律. 低剪应力区出现在狭窄段之 后的窦内，并且沿整个周向均匀分布. 根据低剪应力和动脉粥样硬化的关系，指出： 若人为地给颈动脉窦内施加对称狭窄，则脂质沉积将在狭窄下游的窦内沿周向轴对称 发展. 为了更真实地反映颈动脉窦内的狭窄，建议根据动脉血管中的实际狭窄情况，采用非 对称的狭窄分布模式.     

Flow effects of blood constitutive equations in 3D models of vascular anomalies

The effects of different blood rheological models are investigated numerically utilizing two three‐ dimensional (3D) models of vascular anomalies, namely a stenosis and an abdominal aortic aneurysm model. The employed CFD code incorporates the SIMPLE scheme in conjunction with the finite‐volume method with collocated arrangement of variables. The approximation of the convection terms is carried out using the QUICK differencing scheme, whereas the code enables also multi‐block computations, which are useful in order to cope with the two‐block grid structure of the current computational domain. Three non‐Newtonian models are employed, namely the Casson, Power‐Law and Quemada models, which have been introduced in the past for modelling the rheological behaviour of blood and cover both the viscous as well as the two‐phase character of blood. In view of the haemodynamical mechanisms related to abnormalities in the vascular network and the role of the wall shear stress in initiating and further developing of arterial diseases, the present study focuses on the 3D flow field and in particular on the distribution as well as on both low and high values of the wall shear stress in the vicinity of the anomaly. Finally, a comparison is made between the effects of each rheological model on the aforementioned parameters. Results show marked differences between simulating blood as Newtonian and non‐Newtonian fluid and furthermore the Power‐Law model exhibits different behaviour in all cases compared to the other models whereas Quemada and Casson models exhibit similar behaviour in the case of the stenosis but different behaviour in the case of the aneurysm. Copyright © 2005 John Wiley & Sons, Ltd.