血流动力学的医学应用与发展

血流动力学是指血液在血管系统中流动的力学,主要研究血流量、血流阻力、血压、切应力、扰动流等,以及它们之间的相互关系,对人类生命健康具有重要的影响。血流动力学在血管的弯曲、狭窄、堵塞、分叉以及肿瘤的治疗等方面具有重要的临床研究意义。目前,血流动力学在动脉血管搭桥、冠状动脉狭窄、腹主动脉瘤、动脉粥样硬化、脑动脉肿瘤以及旋动流等方面引起广泛研究。伴随着血流动力学的深入研究,心脑血管的手术规划、介入治疗等得到快速发展,基于血流动力学的临床检测和治疗仪器也越来越多。血流动力学因素,如血管压力、血管阻力、血流量、壁面切应力、血液黏度、流动分离、湍流、涡流等对常见血管疾病以及术后并发症的影响机理正在逐步深入探索之中,并已经取得了一定成果。     

颈内动脉虹吸部血流的数值计算和模型实验

目的研究不同几何构型颈内动脉中的血流动力学因素,分析其构型和动脉狭窄的关系,为颈内动脉狭窄的风险预测和早期诊断提供一定的血流动力学基础。方法对两种常见形状的颈内动脉——U形和V形在定常流条件下的流场分别进行数值模拟和粒子成像测速的实验研究。结果在其中较上游的弯曲处,血流动力学因素与弯曲曲率存在单调的相关关系,V形在此处的狭窄风险小于U形。但是在下游的弯曲处,由于两个弯曲的叠加效应,其血流动力学因素与此处的曲率不存在单调的相关关系。结论弯曲动脉的曲率和动脉狭窄的风险成正相关关系。但是在连续多个弯曲的动脉中,则需考虑弯曲的叠加效应。对此叠加效应的研究有助于解释多弯血管内狭窄多发的原因。     

天麻素对动脉血管顺应性以及血流动力学的影响

本文旨在研究天麻素对动脉血管顺应性和血流动力学等的作用。采用改良风箱模型来计算动脉管的顺应性和血管中血流惯性。在静脉注射天麻素前后，分别记录和计算出狗的血压，心输出量，外周阻力，血流惯性以及中央和外周动脉血管的顺应性。结果表明天麻素具有降低血压和外周务管阻力，增加动脉血管中血流惯性，以及中央和外周动脉血管的顺应性等作用。因此，天麻素是一种有效的能够改善由血管顺应性下降所致的高血压－老年性高血压的中     

锁骨下动脉、颈总动脉和椎动脉分叉处血流动力学数值模拟

目的:探讨锁骨下动脉、颈总动脉和椎动脉分叉处的血流动力学特性,分析该处发生血管狭窄引起大脑供血不足的 血流动力学原因。方法:采用内蒙古民族大学附属医院神经内科提供的CT数据,应用医学建模软件MIMICS20.0将患者 二维CT数据进行三维血管重建,经过网格划分及边界条件设置后导入计算流体力学软件FLUENT14.5中。计算和分析 不同血液入口速度的锁骨下动脉、颈总动脉和椎动脉分叉处的血流动力学特性。结果:在血液入口速度不同的情况下,锁 骨下动脉、颈总动脉和椎动脉分叉处的血液流场分布、血液压力分布和血管壁面切应力分布有显著变化。在血液入口速 度增大时,锁骨下动脉分叉处和颈总动脉分叉处的血液流速快、血管壁压力大,颈总动脉内侧血管壁面切应力大,但锁骨 下动脉分叉处和颈总动脉分叉处血管壁面切应力数值和变化幅度小,属于低切应力区。结论:通过血流动力学数值模拟 研究,分析锁骨下动脉、颈总动脉和椎动脉分叉处易发生粥样斑块病变导致大脑供血不足的血流动力学原因。     

人体周围血管双向血流的初步研究

双向血流,是指在心动周期中的一定时相段,同一血管腔内同时存在两种方向相反的血流成分的现象。它在人体血液循环中广泛存在,而且含有有关血液动力学状态和血管、心脏多种病变的丰富信息。因而,对双向血流的研究具有重要价值。 人体中常见的双向血流可归为三种类型:收缩期末—舒张期初的动脉双向层流、涡流与湍流、以及两血管相交通时的混合血流,本文分别讨论了它们各自的不同特点。作者应用W-1、W-2型双向定量超声血流速度仪进行实际检测,获得了与血液动力学定性分析相符的初步结果。研究表明,双向血流检测对于慢性动脉闭塞症、主动脉瓣关闭不全及颈动脉瘤的诊断、以及对于下肢深、浅静脉交通支的定位具有临床价值。相似的方法也适用于对下肢深静脉瓣膜关闭不全的研究。     

分岔动脉血管脉动血流的动力学分析

通过分析血管性肺癌介入治疗的特性，建立了分岔动脉血管二维几何模型和动脉血流平均流速脉动流模型。基于SMPLE算法对分岔动脉血管脉动血流的动力学进行了数值模拟，获得用导管注射药液时血液流场的变化情况。结果表明，建立的典型几何模型和血液平均流速脉动流模型可较好地分析临床上观察到的血流动力学现象，能反映分岔动脉血管脉动流的特点。为实施进一步数值模拟提供了可靠的前提，此项研究的计算结果也为优化血管性介入治疗等提供了血流动力学依据。     

锥度角对弯曲动脉血管的血流动力学影响

运用血流动力学的基本原理和计算流体力学方法,对具有锥度角的弯曲血管内的血液二维定常流动流场进行数值模拟和分析.计算出具有锥度角的弯曲动脉内血液流动的压力和速度的分布情况.计算结果表明由于弯曲血管的曲率和沿血管渐缩的锥度角使得血管截面血流速度分布尤其是径向速度分布发生较大畸变;锥度角对弯曲动脉血管的血流动力学影响主要体现在对血流径向速度分布的影响.     

老年大鼠模型视网膜血管改变及视网膜中央动脉血流变化的高分辨率超声图像检测

背景：视网膜对缺血非常敏感,所以眼部血流动力学的改变可直接影响眼的功能,目前评估眼部血液循环可借助多种仪器设备。 目的：应用高分辨率小动物超声影像系统检测视网膜中央动脉的血流动力学变化,结合视网膜血管消化铺片技术检测视网膜血管结构变化,以明确老年大鼠视网膜中央动脉血流动力学的变化规律。 方法：使用高分辨率小动物超声影像系统测量老年大鼠和青年大鼠及视网膜中央动脉的血流参数,包括收缩期峰值血流速度、舒张末期血流速度,计算搏动指数、阻力指数和收缩期舒张期血流速度比值。同时使用视网膜血管消化铺片技术检测视网膜血管形态学改变。 结果与结论：与青年大鼠组相比,老年组大鼠视网膜血管内皮细胞增生,排列紊乱,管径增粗,血管壁不光滑;视网膜中央动脉血流速度、舒张末期血流速度均降低(P < 0.01),计算搏动指数、阻力指数及收缩期峰值与舒张末期血流速度比值则升高(P < 0.01)。说明使用高分辨率小动物超声影像系统检测视网膜中央动脉收缩期和舒张期峰值速度及阻力指数能较敏感地反映血管的老化过程。     

颈内动脉狭窄对大脑动脉环血流动力学影响的有限元分析

目的　大脑动脉环血流变化常与颈内动脉狭窄相联系。本研究试用有限元方法来研究颈内动脉狭窄对大脑动脉环内的血流动力学影响,以此探讨动脉环内交通动脉代偿机制。 方法　采用MIMICS10.0软件及ANSYS14.5软件,建立了一个包括血管和血流在内的流固耦合的三维有限元模型,模拟了健康模型（颈内动脉无狭窄）及各种病理模型（颈内动脉狭窄率分别为15%、 30%、 45%, 60%、 70%、 80% 和90%）。通过监测前交通动脉和后交通动脉内的血流变化,掌握动脉环内血流动力学的改变。 结果　包括血管和血流的流固耦合有限元模型首次得以建立。随着狭窄率增加,前交通动脉与患侧后交通动脉内血流逐渐增多,狭窄率达到90%后,两条血管内血流减少;健侧后交通动脉内血流也全程逐渐增加,但量极小,基本无明显变化。 结论　通过以上的结果可见,随着颈内动脉狭窄程度的加重,大脑动脉环通过前交通动脉与患侧后交通动脉开放达到代偿,狭窄率达到90%后代偿失效,从机制上印证了颈内动脉狭窄与颅内缺血性病变相关。     

分岔动脉血管内灌注药液时的药物浓度分布

建立了分岔动脉血管二维几何模型和动脉血流平均流速脉动流模型.对分岔动脉血管脉动血流的动力学状况和匀速进行药液注射进行了数值模拟,获得用导管注射药液时的血液流场的变化情况和药液在血液流场内的周期分布.计算结果表明,所建立的几何模型和血液平均流速脉动流模型可以较好地分析解释了临床上所观察到的血流动力学现象和药液传输现象,能够反映出分岔动脉血管脉动流的传质特点.这不但为实施进一步数值模拟提供了可靠的前提,而且本文的计算结果对优化血管性介入治疗等也提供了血流动力学依据.     

Numerical study of nonlinear pulsatile flow in S-shaped curved arteries

The nonlinear pulsatile blood flow in S-shaped curved arteries was studied with finite element method. Numerical simulations for flows in two models of S-shaped curved arteries with different diameters and under the same boundary conditions were performed. The temporal and spatial distributions of hemodynamic variables during the cardiac cycle such as velocity field, secondary flow, pressure, and wall shear stresses in the arteries were analyzed. Results of numerical simulations showed that the secondary flow in the larger S-shaped curved artery is more complex than that in the smaller one; stronger eddy flow occurred in the inner bends of curved arteries; pressure and wall shear stresses changed violently in the curved arteries, especially in the larger model. These hemodynamic variables in curved arteries will cause important effects on the function of arterial endothelium in the region. For instance, they may lead to the proliferation of smooth muscle cells and the thickening of the intima, and cardiovascular diseases such as atherosclerosis may develop in such regions. Due to having the special blood flow characteristics in the S-shaped arteries, it is worthwhile to study flow in this kind of curved artery. The comprehensive theoretical foundation showed in the present study can be extended to approach problems of nonlinear pulsatile flow in curved arteries with more complex geometrical shape.     

冠状动脉血管造影图像三维分割方法

冠状动脉计算机断层扫描血管造影技术已广泛应用于心血管疾病的诊断,冠状动脉的有效分割在冠心病诊断中起着重要的作用。本文提出一种冠状动脉血管造影图像三维分割方法,首先进行数据预处理;然后,利用分水岭算法得到子区域;最后,利用区域生长方法将分水岭子区域合并,实现冠状动脉的三维分割。本文以放射科医生手动标注结果作为标准,验证提出算法的可行性和有效性。实验结果表明,本文提出的分割方法能够有效克服冠状动脉周围组织的干扰,从而取得精确的分割结果。     

A fluid?structure interaction study on the biomechanical behaviour of a curved artery with flexible wall

Research has shown that thrombus, stenosis, aneurysm, atherosclerosis and other vascular diseases are likely to occur in curved arteries such as aortic arch, coronary artery and cerebral artery. It is found that fatigue damage and failure of arteries are closely associated with the dynamic physiological environment where the arteries are situated. Based on these considerations, the behaviour of curved arteries subjected to a physiological environment is presented in this paper. The fluid-structure interaction (FSI) effect is considered. Wall stress distribution and its variation over time are investigated. Artery deformation regularity throughout the cardiac cycle has been analysed. It is believed that this study may provide insights into clinical research in the future.     

小脑皮质及髓质的微血管构筑

12例新鲜儿童尸脑,以甲醛碳素墨水灌注,光镜观察.小脑皮质及髓质的动脉来源于小脑动脉皮质支及中央支.血管多以直角及呈放射状穿小脑实质.小脑皮质及髓质的动脉分为皮质浅动脉、皮质中动脉、皮质深动脉、皮质髓质动脉及髓质动脉.动脉分支间相互吻合构成皮质浅、深层及髓质血管网.血管及血管网眼密度以皮质深层为最高.皮质的血供主要来自皮质浅、中、深动脉,髓质主要来自皮质髓质动脉及髓质动脉.髓质内的血管多呈直角分支.且血管走行与白质纤维方向一致.本文讨论了小脑皮质及髓质的血供及血管形态与小脑血管疾病的关系.     

A fluid—structure interaction study on the biomechanical behaviour of a curved artery with flexible wall

Research has shown that thrombus, stenosis, aneurysm, atherosclerosis and other vascular diseases are likely to occur in curved arteries such as aortic arch, coronary artery and cerebral artery. It is found that fatigue damage and failure of arteries are closely associated with the dynamic physiological environment where the arteries are situated. Based on these considerations, the behaviour of curved arteries subjected to a physiological environment is presented in this paper. The fluid–structure interaction (FSI) effect is considered. Wall stress distribution and its variation over time are investigated. Artery deformation regularity throughout the cardiac cycle has been analysed. It is believed that this study may provide insights into clinical research in the future.     

Changes in the lesser circulation vessels in chronic nonspecific lung diseases

Clinicomorphological study of the pulmonary circulation vessels was performed in 20 patients with bronchiectatic disease without right ventricle hypertrophy and in 14 patients with chronic bronchitis complicated with pulmonary heart. Pathology data of persons dying from diseases other than vitium cordis and lung diseases were used as control. Morphological signs of pulmonary hypertension are found in all cases of chronic nonspecific lung diseases. The most pronounced changes develop in the vascular segment starting from arterioles and up to the arteries of muscle type with the diameter of 400 microns. The dependence of the pulmonary arteries changes on the type of lung disease is established. Pathological changes in the walls of the pulmonary circulation vessels, in parallel with pronounced compensatory alterations, are found in cases complicated with pulmonary heart.     

The role of the system of bronchial arteries in pathology

The evidence accumulates that bronchial circulation provides important adaptive functions besides serving as "vasa nutritia" of the lungs. One can suppose pathomorphological changes of the bronchial arteries to follow any pulmonary pathology. No doubt that, bronchial arteries in some diseases undergo secondary pathological changes while in others they are of an initiative role. The literature data on bronchial artery structure in normal and pathological conditions are controversial. The present study is likely to generate new information in this area.     

Animal Models of Vasculitides

The vasculitides are a group of diseases in which the common denominator is the immune attack to components of the vascular wall. Vasculitides may attack large vessels like the aorta, medium-sized vessels like the coronary arteries or small vessels like the glomeruli. We review in this paper the animal models that have been developed to study these diseases.     

动脉粥样硬化血栓形成疾病的发病机制进展

动脉粥样硬化是血管系统疾病的主要病理基础，动脉粥样硬化斑块破裂和继发的血栓形成是大多数急性血管事件发生的主要原因。动脉粥样硬化血栓形成，可引起动脉局部闭塞或远端栓塞，从而导致相应动脉部位的疾病，称作动脉粥样硬化血栓形成性疾病。近年来动脉粥样硬化血栓形成的发病机制的研究有了较大进展，从以前的脂质沉积假说演变成多种因素包括内皮功能障碍、炎症发应、细胞凋亡、组织因子等共同参与的病因理论。     

Penetration of an artificial arterial thromboembolism in a live animal using an intravascular therapeutic microrobot system

The biomedical applications of wireless robots are an active area of study. In addition to moving to a target lesion, wireless locomotive robots can deliver a therapeutic drug for a specific disease. Thus, they hold great potential as therapeutic devices in blood vessel diseases, such as thrombi and occlusions, and in other diseases, such as cancer and inflammation. During a percutaneous coronary intervention (PCI), surgeons wear a heavy shielding cloth. However, they cannot escape severe radiation exposure owing to unstable shielding. They may also suffer from joint pains because of the weight of the shielding cloth. In addition, the catheters in PCIs are controlled by the surgeon's hand. Thus, they lack steering ability. A new intravascular therapeutic system is needed to address these problems in conventional PCIs. We developed an intravascular therapeutic microrobot system (ITMS) using an electromagnetic actuation (EMA) system with bi-plane X-ray devices that can remotely control a robot in blood vessels. Using this proposed ITMS, we demonstrated the locomotion of the robot in abdominal and iliac arteries of a live pig by the master-slave method. After producing an arterial thromboembolism in a live pig in a partial iliac artery, the robot moved to the target lesion and penetrated by specific motions (twisting and hammering) of the robot using the proposed ITMS. The results reveal that the proposed ITMS can realize stable locomotion (alignment and propulsion) of a robot in abdominal and iliac arteries of a live pig. This can be considered the first preclinical trial of the treatment of an artificial arterial thromboembolism by penetration of a blood clot.