Usefulness of Left Ventricular Vortex Flow Analysis for Predicting Clinical Outcomes in Patients with Chronic Heart Failure: A Quantitative Vorticity Imaging Study Using Contrast Echocardiography

The goal of the study described here was to evaluate whether left ventricular vortex flow parameters, as assessed by contrast echocardiography, enhance prediction of major adverse cardiac events (MACE) in patients with chronic heart failure and systolic dysfunction. A total of 75 patients with contrast echocardiography and systolic dysfunction (ejection fraction ≤45%) were prospectively enrolled and underwent vortex flow analysis with particle image velocimetry using contrast echocardiography. Vortex flow parameters, including kinetic energy fluctuation (KEF), were evaluated. Patients were followed up for a primary endpoint of MACE that comprised hospital admission for cardiovascular causes and cardiac deaths. Across a median 277-d follow-up, 29 patients (38.7%) experienced MACE. Among these, the incidence of diabetes and the E/e' ratio were significantly higher in patients with MACE than in those without, whereas the hemoglobin level and ejection fraction were significantly lower. KEF was significantly lower in patients with MACE. In the multivariate analysis, higher KEF was associated with a lower risk of MACE (hazard ratio?=?0.18, 95% confidence interval: 0.04–0.97, p?=?0.046). The addition of KEF to a model with conventional parameters (e.g., age, diabetes, ejection fraction and the E/e' ratio) significantly improved the model's discrimination. Elevations in the quantitative left ventricular vortex flow parameter, KEF, as determined by contrast echocardiography, are associated with a lower risk of MACE and improved functional status among patients with chronic heart failure.     

吲哚青绿血管造影联合广角接触镜观察涡状静脉

目的 应用吲哚青绿血管造影（ICGA）联合Staurenghi 230广角接触镜观察和分析人眼涡状静脉的形态及其分布特征。 方法 对28例32只眼进行广角接触镜联合ICGA检查。受检者中女性16例19只眼，男性12例13只眼；年龄28～84岁，平均年龄71岁。根据受检眼不同屈光度分为高度近视组和非高度近视组，前者15只眼，屈光度数≥－6.0 D；后者17只眼，屈光度数＜-6.0 D或正视。 结果 本组受检者中，共发现166支涡状静脉，其中，漩涡状118支，占71.1%；粗条纹状34支，占20.5%；不规则状14支，占8.4%。右眼发现涡状静脉71支，平均每一只眼有涡状静脉507支；左眼发现涡状静脉95支，平均每一只眼有涡状静脉5.28支。颞下、鼻下、颞上及鼻上象限发现的涡状静脉数分别为47、42、39、38支，平均每个象限1.34支，以颞下象限最多，每一只眼平均为1.在赤道部附近，距视盘约4~6 个视盘直径（DD），占964%；6支涡状静脉出巩膜点距离视盘较近约3～4 DD,占3.6%。123支涡状静脉可见明显壶腹，占74.1%，壶腹方向以平行或垂直于眼底水平线者多见。高度近视组和非高度近视组在涡状静脉数目、形态上差异无统计学意义。 结论 人眼涡状静脉形态呈漩涡状、粗条纹状、不规则状；高度近视眼与非高度近视眼涡状静脉分布特征基本一致，均以颞下象限最多，出巩膜点多在距视盘约4~6 DD处，多数可见明显壶腹。广角接触镜下ICGA检查视角广，能在一个视野内同时观察到几乎全部的涡状静脉。     

Formation of vortices near abrupt nano-channel height changes in electro-osmotic flow of aqueous solutions

We perform computational fluid dynamics simulations of electro-osmotic flow in nano-channels and examine the effects of sudden changes in channel cross-section area (e.g., channels with a backward-facing step) which may be a simple model of one type of fabrication flaw. When the width of the electric double layers is large enough, we observe the formation of vortices or recirculation regions near the step face. On the other hand, flows with thin electric double layers are less likely to exhibit recirculation regions. We also simulate the formation of vortices and recirculation regions for flows with asymmetrical boundary conditions for charge and concentrations.     

Characterization of the Left Atrial Vortex Flow by Two-Dimensional Transesophageal Contrast Echocardiography Using Particle Image Velocimetry

This article is the first clinical investigation of the quantitative left atrial (LA) vortex flow by two-dimensional (2-D) transesophageal contrast echocardiography (2-D-TECE) using vector particle image velocimetry (PIV). The aims of this study were to assess the feasibility of LA vortex flow analysis and to characterize and quantify the LA vortex flow in controls and in patients with atrial fibrillation (AF). Thirty-five controls and 30 patients with AF underwent transesophageal contrast echocardiography. The velocity vector was estimated by particle image velocimetry. The morphology and pulsatility of the LA vortex flow were compared between the control and AF groups. In all patients, quantitative LA vortex flow analysis was feasible. In the control group, multiple, pulsatile, compact and elliptical-shaped vortices were seen in the periphery of the LA. These vortices were persistently maintained and vectors were directed toward the atrioventricular inflow. In the AF group, a large, merged, lower pulsatile and round-shaped vortex was observed in the center of the LA. In comparisons of vortex parameters, the relative strength was significantly lower in the AF group (1.624 ± 0.501 vs. 2.105 ± 0.226, p < 0.001). It is feasible to characterize and quantify the LA vortex flow by transesophageal contrast echocardiography in patients with AF, which offers a new method to obtain additional information on LA hemodynamics. The approach has the potential for early detection of the LA dysfunction and in decisions regarding treatment strategy and guiding anticoagulation treatment in patients with AF.     

人体上呼吸道中气流涡结构特征数值仿真研究

目的研究上呼吸道内涡结构特征及其演化形式,深入认识上呼吸道内气流运动特性,对于分析气溶胶在人体上呼吸道内的扩散、转捩以及沉积模式具有重要作用。方法应用大涡模拟的方法,对人体在低强度呼吸条件下上呼吸道内的气流涡结构及其运动特性进行了数值仿真研究,讨论了人体口喉模型以及气管支气管内的涡结构演化过程和涡结构特征。结果气流在咽部、喉部形成两次射流,导致气流在咽部和喉部出现两个主要的涡量增长区,咽喉部位形成扁平涡,在靠近气管中心偏向前壁的位置出现一个"类壁弯涡",气管内出现了以接近对称的反向旋转涡对;G0气管末端的涡量由壁面向中心处扩展,并随着流动向G1支气管内延伸,各级支气管中涡量并不是对称分布的。结论涡结构特征及其演化形式是上呼吸道内气流运动的显著特点,气道结构特点是引起不同尺度涡结构演化的主导因素。     

血流向量成像评价心肌梗死患者收缩期左心室涡流状态

目的 探讨血流向量成像(VFM)技术评价心肌梗死患者心腔内血液流场和流体力学状态的应用价值.方法 15例心肌梗死患者和20名正常人分别接受常规超声心动图检查,采集连续四个心动周期的标准心尖三腔心切面彩色血流动态图像.应用VFM技术进行脱机分析,测量收缩期左心室内涡流纵径、横径、涡流于左心室内纵向、横向位置、涡流最大向量速度,观察收缩期涡流演变过程,比较心肌梗死患者与正常人之间的差异.结果 收缩早期心肌梗死患者涡流纵径大于正常人(0.49±0.21 vs 0.21±0.12,P＜0.05),纵向位置高于正常人(0.60±0.08 vs 0.85±0.05,P＜0.05),最大向量速度减低[(31.10±8.54)cm/s vs (44.58±16.39)cm/s,P＜0.05],心肌梗死患者收缩期涡流持续时间较长.结论 心肌梗死患者收缩期左心室腔内涡流长径、纵向位置及涡流最大向量速度与正常人之间存在差异.VFM为心腔内血流结构及心脏整体功能的研究提供了一种新的方法.     

BPH微创术后前列腺段尿道形态对排尿力学的影响

目前众多的经尿道微创术式治疗良性前列腺增生(BPH)均通过扩大或再造前列腺段尿道(PU)的腔内空间发挥作用,因此,探讨BPH微创术后PU形态对排尿的力学影响,具有重要的指导意义。本研究采用计算流体力学(CFD)技术探讨PU/膀胱颈横径比(RPU-1)对尿流的影响。结果表明,在RPU-1>0.79时,PU两侧出现涡流;且...     

Factors Influencing Vortex Development in a Model of a Skeletal Muscle Ventricle

Abstract A video technique was used to visualize flow patterns in a pulsatile model of a skeletal muscle ventricle (SMV). The shape and duration of SMV filling/emptying curves were determined by the stroke action of a computer-controlled piston pump. In this way we examined the effect of filling duration and injection volume on the flow structures. To simulate the interaction between the left ventricle and the SMV in the proposed clinical application, two filling/emptying regimes were employed with the period of each SMV cycle being either equal to or twice that of a typical cardiac cycle. Vortex formation at the inlet to the ventricle was a feature of both flow cycles during filling for all the combinations of injection volume and filling duration considered. When a pacing ratio of 1:1 was simulated, SMV filling was immediately followed by ejection, and the formed vortex was expelled. Under this flow regime, fluid in the apical end of the ventricle remained undisturbed. When the pacing ratio was 2:1, however, the quiescent period that followed filling allowed time for the formed vortex to travel a significant distance toward the apical end of the ventricle. Under certain conditions of injection volume and flow rate, the vortex reached the apex by the end of the quiescent period. We suggest that a ventricle connected to the aorta by a single, valveless conduit would require a flow regime that included a significant period of quiescence after filling. This would allow the vortex to reach and displace blood that would otherwise stagnate in the apex, thereby reducing the risk of thrombus formation.     

免疫突触形成过程中T细胞受体的重定向运动:涡旋驱动模型

目的：建立T细胞受体（TCR）在免疫突触形成过程中作重定向（reorientation）运动的机制模型.方法：基于经典流体力学环境中的双分子反应传能原理,提出了T细胞受体的涡旋驱动模型,利用免疫突触内耦合的受体或配体分子作为涡源驱动T细胞受体分子的募集.结果：模型计算的结果表明,在强度及作用频率同时具备一定范围的涡旋连续驱动下,TCR重定向运动速度可达到实验测定的范围（0.04～0.1 μm/s）.结论：本模型证明突触内受体/配体对耦合时通过将其结合自由能转化为细胞内外流体涡旋运动的机械能可能直接提供了TCR重定向运动的驱动力.