Flow Stagnation Research Articles

Changes in the meibomian glands in postmenopausal women with primary acquired nasolacrimal duct obstruction: a prospective study

BackgroundPrimary acquired nasolacrimal duct obstruction (PANDO) is frequently encountered in perimenopausal women, causing tear flow stagnation and resulting in a variety of ocular discomfort symptoms. However, little is known about the alterations in the meibomian gland in postmenopausal women with PANDO. Hence, this study investigated the changes in the meibomian gland and ocular surface in postmenopausal women with PANDO.MethodsThis prospective study included 60 eyes of 60 postmenopausal women with PANDO (PANDO group) and 30 eyes of 30 postmenopausal women without PANDO (control group). The PANDO group was further subdivided into incomplete and complete PANDO groups, based on the degree of nasolacrimal duct obstruction. The patients’ symptoms were evaluated using the ocular surface disease index questionnaire. The meibomian gland and ocular surface were assessed using the Keratograph 5 M. Other ophthalmologic examinations included the tear break-up time, corneal fluorescein staining, meibomian gland expression, and Schirmer I test. The correlations between the degree of nasolacrimal duct obstruction and other metrics were analyzed.ResultsThe loss ratio of the upper eyelid was greater in the incomplete PANDO group than in the control group (p = 0.023). Meibomian gland distortion of the upper eyelid was more severe in the control group than in the complete PANDO group (p = 0.022). The non-invasive tear meniscus height was greater, whereas the intensity of corneal fluorescein staining was lower in the PANDO group than in the control group (all p < 0.05). The degree of nasolacrimal duct obstruction was positively associated with the non-invasive tear meniscus height and ocular surface disease index scores (p < 0.001 and p < 0.001, respectively). Corneal fluorescein staining and meibomian gland distortion of the upper eyelid were negatively correlated with the degree of nasolacrimal duct obstruction (p = 0.01 and p = 0.007, respectively).ConclusionPostmenopausal women with PANDO exhibit significant morphological changes in the meibomian gland. More attention should be paid to meibomian gland loss in postmenopausal women with incomplete PANDO, as it is crucial for identifying meibomian gland impairments in patients with PANDO.

Structural variations of endothelial cell monolayer under startup shear conditions

We study the response of an endothelial cell monolayer lining the bottom surface of a cartesian Couette geometry in variations of critical shearing parameters that affect the fluid environment, such as the gap distance between the upper moving and the bottom stationary plates and the velocity of the moving plate. Specifically, we propose an in silico rheometric emulation based on startup shear experiments in a representative two-dimensional domain of the monolayer that accounts for the interaction of the blood plasma and the deformable multilayer poroelastic endothelial cells. We present quantitative predictions for the shear and normal stresses on each cell compartment (membrane, cytoplasm, and nucleus) and their structural changes. We show that the variation of the Wall Shear Stress (WSS) along the cell membrane is considered significant and strongly dependent on the shape of the cell, while membrane thinning is more prominent at the locus of high WSS in the range of physiological velocities. However, under extreme velocities, wall thinning prevails at the locus of flow stagnation.

A Study of the Velocity Field During Mitigation of Vortex Breakdown in Model Francis Turbine at High Load

Abstract Off-design operation leads to the development of flow instabilities like vortex breakdown phenomenon which manifests as an enlarged vortex core in the draft tube at high load operating conditions. These flow instabilities are known to potentially have detrimental effects on turbine performance necessitating investigations on their formative and mitigation mechanisms. This work clarifies the evolving velocity maps characterizing vortex breakdown seen in a model Francis turbine draft tube during the transition from high load to best efficiency point. Velocity measurements have been performed inside a draft tube cone using a 2D particle image velocimetry system. Results show a wake-like velocity profile characterizing the vortex core in the draft tube cone at high load condition. The vortex core is a centrally located flow feature embodying a quasi-stagnant flow with recirculation regions. Surrounding the core, an axial outflow is seen with shear layers arising at the interface of core and outflow due to a substantial velocity gradient. Mitigation of this vortex core through a load rejection operation was further investigated. It is seen that as the flowrate approaches the best efficiency point, the shear layers between the outflow and central stagnation region break. The breakup leads to an axially dominated and streamlined flow. This is enabled by the reduction of the swirl until no central flow separation at the stagnation point occurs. The flow at the best efficiency point is thus devoid of the vortex core due to the absence of flow stagnation, the primary instability causing the core development.

Effects of drifts on scrape-off layer transport in W7-X

Drifts affect particle, momentum, and energy transport in the scrape-off layer (SOL) of tokamaks and stellarators, altering plasma flows and creating asymmetries between divertors. To understand how drifts affect SOL transport in the W7-X island divertor, an experiment was performed to compare plasmas with matched core parameters but opposite magnetic field directions, and therefore opposite drift transport directions. Parallel flow measurements made with coherence imaging spectroscopy are interpreted with the aid of a diagnostic forward model and a 1D simple SOL model that includes the drift. In low-density plasmas ( m−3), the poloidal drift induces a large poloidal density asymmetry within the island SOL, as measured by divertor Langmuir probes. This in turn causes the parallel flow stagnation point to shift from the position halfway between targets to the X-point in the drift direction, leading to near-unidirectional flow throughout the SOL. As density increases, the effects of the poloidal drift decrease substantially, resulting in a smaller density asymmetry and the development of a counter-streaming flow pattern. For the entire density range probed in this experiment ( m−3), the experimental observations are more consistent with the effects of the poloidal drift than the radial drift.

Effects of Escherichia coli strain Nissle 1917 on arsenic-challenged goldfish (Carassius auratus): histological evidence.

Arsenic (As) contamination in natural water resources has become a great disaster throughout the world posing serious health problems. The current study was performed to evaluate the protective effects of Escherichia coli strain Nissle 1917 (EcN) against As exposure in goldfish (Carassius auratus). Fish were fed three times a day with 4.00% of body weight of diet with different doses (0.00, 1.00 × 106, 1.00 × 107 and 1.00 × 108 CFU g-1) of EcN for 80 days and then, challenged with 20.00 mg L-1 As for 96 hr under stagnant flow. Physicochemical characteristics of the inlet water were temperature of 25.10 ± 0.70 ˚C, pH of 7.30 ± 0.20 and dissolved oxygen of 7.30 ± 0.30 mg L-1 and 50.00% of water was exchanged once a week. Afterwards, fish were euthanized with a clove oil solution (50.00 μL L-1) and tissues were dissected from each fish and immediately fixed in 10.00% buffered formalin. The histopathological results indicated that the supplemented EcN did not have any side effects on various organs. It was also observed that the damages to kidney, liver, gill and skin were pronounced in fish exposed to As. However, the histopathological damages induced by As in fish tissues were less pronounced in the EcN-treated groups compared to the fish fed with the basal diet. Lamellar blood congestion in gills and epidermal cells detachment from the skin surface as well as hepatocytes, enterocytes and tubular necrosis were reduced in treated groups. These findings indicate that EcN has the potential to ameliorate the As-induced organ toxicity.

Individualized risk assessment of recanalization of visceral aneurysms using stagnation of intra-aneurysmal flow

Individualized risk assessment of recanalization of visceral aneurysms using stagnation of intra-aneurysmal flow

Sex-Specific and Dose-Dependent Effects of Drag-Reducing Polymers on Microcirculation and Tissue Oxygenation in Rats After Traumatic Brain Injury.

Traumatic brain injury (TBI) ultimately leads to a reduction in the cerebral metabolic rate for oxygen due to ischemia. Previously, we showed that 2ppm i.v. of drag-reducing polymers (DRP) improve hemodynamic and oxygen delivery to tissue in a rat model of mild-to-moderate TBI. Here we evaluated sex-specific and dose-dependent effects of DRP on microvascular CBF (mvCBF) and tissue oxygenation in rats after moderate TBI. In vivo two-photon laser scanning microscopy over the rat parietal cortex was used to monitor the effects of DRP on microvascular perfusion, tissue oxygenation, and blood-brain barrier (BBB) permeability. Lateral fluid-percussion TBI (1.5 ATA, 100ms) was induced after baseline imaging and followed by 4h of monitoring. DRP was injected at 1, 2, or 4ppm within 30 min after TBI. Differences between groups were determined using a two-way ANOVA analysis for multiple comparisons and post hoc testing using the Mann-Whitney U test. Moderate TBI progressively decreased mvCBF, leading to tissue hypoxia and BBB degradation in the pericontusion zone (p<0.05). The i.v. injection of DRP increased near-wall flow velocity and flow rate in arterioles, leading to an increase in the number of erythrocytes entering capillaries, enhancing capillary perfusion and tissue oxygenation while protecting BBB in a dose-dependent manner without significant difference between males and females (p<0.01). TBI resulted in an increase in intracranial pressure (20.1±3.2mmHg, p<0.05), microcirculatory redistribution to non-nutritive microvascular shunt flow, and stagnation of capillary flow, all of which were dose-dependently mitigated by DRP. DRP at 4ppm was most effective, with a non-significant trend to better outcomes in female rats.

Modern concepts and biomarkers of blood stasis in cardio- and cerebrovascular diseases from the perspectives of Eastern and Western medicine: a scoping review protocol.

The objective of this review is to provide a modern definition and identify potential biomarkers of blood stasis in cardio- and cerebrovascular diseases by mapping, comparing, and combining Eastern and Western concepts. Blood stasis is a pathological concept found in both Eastern and Western medical literature. In traditional East Asian medicine, blood stasis is a differential syndrome characterized by stagnant blood flow in various parts of the body. Similarly, in Western medicine, various diseases, especially cardio- and cerebrovascular diseases, are known to be accompanied by blood stasis. Numerous scientific studies on blood stasis have been conducted over the last decade, and there is a need to synthesize those results. We will use the keywords "blood stasis," "blood stagnation," "blood stagnant," and "blood congestion" in 3 electronic databases: PubMed, Cochrane CENTRAL, and Google Scholar. In addition, we will use the keywords "어혈" and "혈어" in 4 Korean electronic databases (ie, NDSL, OASIS, KISS, and DBpia). Peer-reviewed articles published from 2010 to the present that focus on blood stasis in cardio- and cerebrovascular diseases in human subjects according to the International Classification of Diseases 11 th revision categories BA00-BE2Z, 8B00-8B2Z, 8E64, and 8E65 will be included. Reviews, opinion articles, in vivo, in vitro, and in silico preclinical studies will be excluded. We will follow the frameworks by Arksey and O'Malley and Levac et al. as well as JBI guidelines and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis extension for Scoping Reviews. Two reviewers will independently search and screen titles and abstracts followed by full-text screening of eligible studies. If there are discrepancies between the 2 reviewers, a third reviewer will be consulted to make the final decision. We will use descriptive narrative, tabular, and graphical displays, and content analysis to present the results. Open Science Framework https://osf.io/gv4ym.

Mhd Stagnation Point Flow and Heat Transfer of Cu –Water Nanofluid over A Stretching Sheet

A comprehensive study of Magnetohydrodynamics flow (stagnation Point) with heat transferal properties of Cu–Water nanofluid along a stretched sheet in the existence of a transverse magnetic field is analyzed. The governing equalities along with their conditions on boundary points are firstly converted to ordinary differential equations of non-linear category by similarity transformations. Lastly finite difference discretization is utilized. The flow and heat transfer parameters, namely: stretching parameter, magnetic parameter, the Prandtl number and solid volume fraction are investigated by tablular and graphical representation.

The Effect of Gap Reduction on Fluid Dynamics and Mass Transfer in Membrane Narrow Channels Filled with Novel Spacers-A Detailed Computational Study.

The effect of gap thickness reduction 2h (i.e., the reduction h at each membrane surface) is studied on the flow field and mass transfer, in membrane channels filled with novel spacers, under conditions representative of those prevailing in RO desalination modules. The patented novel net-type spacers are comprised of regularly-spaced spherical nodes (in contact with the membranes) and interconnecting cylindrical filaments at the midplane of the channel. Advanced 3D flow simulations, performed at "unit cell" level, show the strong effect of a modest gap reduction on the flow field. Analysis of the computational results leads to new insights regarding flow development as well as to useful correlations of key process parameters (i.e., for friction losses, mass-transfer rates, wall shear stresses) accounting for the effect of gap reduction. Contrary to conventional spacers, the novel spacer geometry, under conditions of usual/modest channel-gap reduction, exhibits no stagnant flow zones and relatively high shear stresses on both the membranes and the filaments, which leads to desirable mitigation of fouling and a reduction in concentration polarization. The developed correlations can be adapted to existing advanced simulators of RO module performance for improved process design and optimization.

Numerical evaluation of a new impingement cooling scheme with a separate return-channel applied to turbine blade leading edge

The turbine blade leading edge is imposed with large heat load due to the flow stagnation effect. Jet impingement cooling is widely used to keep blade leading edge below critical metal temperature. However, accumulated crossflow deteriorates jet-flow penetration and subsequently reduces impingement effectiveness. This study introduces a novel impingement-jet cooling scheme with a separate return-channel to reduce the effect of crossflow by extracting the spent flow upwards. In addition, the swirling flow generated inside the return-channel further augments heat transfer. The effects of different return hole patterns and outflow paths are investigated through Computational Fluid Dynamics (CFD) method based on the BSL turbulence model. The effects of return hole pattern and coolant outflow path are investigated and evaluated. The numerical results prove that introduction of the return-channel has improved area-averaged Nu on the target surface significantly compared to the baseline value. The inline pattern performs better than the staggered pattern within the channels with single outlet in the return-channel. However, with outlets in both the impingement channel and the return-channel, the heat-transfer effects of different return patterns are insignificant.

Mixing dynamics at river confluences governed by intermodal behaviour

The extent to which flows mix at confluences is pivotal for determining spatial patterns of water quality and biodiversity. Because mixing processes are complex, predicting rates and characteristic scales of mixing is difficult. Here we introduce a theory for confluence mixing dynamics of shallow flows in which the mixing process is controlled by the switching between two modes of behaviour—one similar to a wake behind an obstacle and the other similar to a mixing layer between two parallel flows. Dye visualizations of mixing in field-based controlled experiments agree with theoretical predictions and support transitional behaviour between the two mixing modes. According to our theoretical framework, the mixing interface can grow rapidly in wake mode, when large vortices are shed from a zone of stagnant flow within the confluence, but lateral shear between incoming flows is negligible. This rapid growth occurs even though flow curvature and shallowness inhibit growth through advective and turbulent lateral exchange of momentum and through bed friction. Our findings provide insight into the importance of different modalities of flow structure in controlling mixing at river confluences, thereby contributing to practical knowledge on the role of confluences in dispersal of contaminants in river systems.

Analysis of nanobiofilm flow of Carreau fluid with the effect of buoyancy forces and activation energy: A numerical approach

In the past few years, many technical strategies, such as molding, condenser heat exchanger, liquefied metal filtration, fusion control and nuclear reactor coolant, that involve hydromagnetic fluxes and thermal intensification in porous media have been observed. This study investigates the Carreau nanofluid of nanobiofilm through stretching/shrinking sheet with a stagnant point flow, nanoparticles and convecting microbes. The orthogonal ([Formula: see text] impinge) coating stagnant point circulation of a medium is considered, although the sheet may be stretched/shrinked as the procedure utilized in industry. The variations in the fluid (dynamic viscosity, thermal conductivity, mass permeability) and microbes are utilized. The similarity transformation factors are used to transform the system of partial differential equations into a nonlinear system of ordinary differential equations. To find the solution of a system of equations, the Runge–Kutta method with shooting technique has been used. The flow rate, temperature and concentration, as well as the heat transfer rate, and the physical quantities have been discussed. The nanoparticle volume fraction increases with the increasing effect of activating energy as well as thermophoresis parameter, but it decreases with the enhancing effect of Lewis number (Le) and Brownian motion parameter (Nb). The graphs and tables display the illustration of the influence of different parameters.

Local-scale feedbacks influencing cold-water coral growth and subsequent reef formation

Despite cold-water coral (CWC) reefs being considered biodiversity hotspots, very little is known about the main processes driving their morphological development. Indeed, there is a considerable knowledge gap in quantitative experimental studies that help understand the interaction between reef morphology, near-bed hydrodynamics, coral growth, and (food) particle transport processes. In the present study, we performed a 2-month long flume experiment in which living coral nubbins were placed on a reef patch to determine the effect of a unidirectional flow on the growth and physiological condition of Lophelia pertusa. Measurements revealed how the presence of coral framework increased current speed and turbulence above the frontal part of the reef patch, while conditions immediately behind it were characterised by an almost stagnant flow and reduced turbulence. Owing to the higher current speeds that likely promoted a higher food encounter rate and intake of ions involved in the calcification process, the coral nubbins located on the upstream part of the reef presented a significantly enhanced average growth and a lower expression of stress-related enzymes than the downstream ones. Yet, further experiments would be needed to fully quantify how the variations in water hydrodynamics modify particle encounter and ion intake rates by coral nubbins located in different parts of a reef, and how such discrepancies may ultimately affect coral growth. Nonetheless, the results acquired here denote that a reef influenced by a unidirectional water flow would grow into the current: a pattern of reef development that coincides with that of actual coral reefs located in similar water flow settings. Ultimately, the results of this study suggest that at the local scale coral reef morphology has a direct effect on coral growth thus, indicating that the spatial patterns of living CWC colonies in reef patches are the result of spatial self-organisation.

Modeling of liquid film thickness around Taylor bubbles rising in vertical stagnant and co-current slug flowing liquids

The hydrodynamic study of the liquid film around Taylor bubbles in slug flow has great significance for understanding parallel flow and interaction between Taylor bubbles. The prediction models for liquid film thickness mainly focus on stagnant flow, and some of them remain inaccurate performance. However, in the industrial process, the slug flow essentially is co-current flow. Therefore, in this paper, the liquid film thickness is studied by theoretical analysis and experimental methods under two conditions of stagnant and co-current flow. Firstly, under the condition of stagnant flow, the present work is based on Batchelor's theory, and modifies Batchelor’s liquid film thickness model, which effectively improves its prediction accuracy. Under the condition of co-current flow, the prediction model of average liquid film thickness in slug flow is established by force and motion analysis. Taylor bubble length is introduced into the model as an important parameter. Dynamic experiments were carried out in the pipe with an inner diameter of 20 mm. The liquid film thickness, Taylor bubble velocity and length were measured by distributed ultrasonic sensor and intrusive cross-correlation conductivity sensor. Comparing the predicted value of the model with the measured results, the relative error is controlled within 10%.

Influence of cardiac function on intermittent hypoxia in rats fed with high-fat diet

A high-fat diet (HFD) accumulates fat in the cardiovascular system, alters the metabolism, and affects cardiac function. Dyslipidemia is associated with the development of sleep apnea syndrome (SAS), which is associated with intermittent hypoxia (IH); however, it is unclear whether SAS affects cardiac function in patients with dyslipidemia. The purpose of this study was to evaluate how IH affects cardiac function in rats fed with a HFD. Male 5-week-old Sprague-Dawley rats of two groups (normal diet (SD) and HFD) were divided into IH-exposed and unexposed groups. Zinc protoporphyrin-9 (ZnPPIX) was administered as a heme oxygenase-1 (HO-1) inhibitor to the SD and IH + HFD groups, and cardiac function and blood viscosity were examined. In the IH + HFD group, echocardiography showed an increased fractional shortening (FS), which peaked on day 4. Western blot analysis revealed an increase in HO-1 after 2 weeks. This peak continued even after the HO-1 inhibitor and ZnPPIX were administered. One cause of increased FS is the stagnation of blood flow due to an increased blood viscosity. To be able to send highly viscous blood to every corner of the body, the heart must contract strongly. Therefore, HO-1 is released by the body as a biological defense reaction. HO-1 has a vasodilatory effect and suppresses hyper constriction. Thus, IH exposure to HFD causes and drives transient hyper constriction, releasing HO-1 as a biological response. This led to dilated blood vessels, after which the FS returned to normal.

Numerical investigation on fully-developed heat transfer augmentation and friction factor with dimple shaped intrusion and different radius of curvatures on triangular ducts

The heat transfer phenomenon is moderate in the case of triangular ducts due to the presence of sharp corners, which causes stagnant flow in the corners. Thus, this study focuses on improving heat transfer by converting one of the corners of the duct to a rounded structure having a variable curvature radius value (Rc). Rc varies from 0.67 h (maximum value) to 0.33 h (minimum value), where h is the height of the duct. Heat transfer and airflow have also been tested with dimple-shaped intrusion and rounded corners under varying ranges of relative length in the longitudinal direction (Z/e = 10–18) and relative length in the transverse direction (X/e = 10–18). Application of thermal-based boundary conditions on the turbulent flow for Re = 5600–21,000 facilitates the heat transfer analysis in a duct under steady-state. The commercial software tool, ANSYS Fluent 18.1, is used to simplify-three dimensional Reynolds averaged Navier Stokes equation with the compressible fluid flow by considering the pressure-based solver with the standard K- ε turbulence model. Compared to a typical duct, the rounded corner area shows higher velocity because of the dimple intrusions and rounded corners. Introduction of curvature to the corner opposite to the heat-conducting surface in simple triangular duct results in the increment of heat transfer by 5.71–44.37 %, 3.172–23.76 %, and 1.16–8.27 % for the values of Rc = 0.33 h, 0.49 h, and 0.56 h, respectively. Further the addition of dimple-shaped intrusion in the triangular duct with rounded corner, increases the heat transfer for Z/e = X/e = 18 as visible from the increment in average Nusselt Number by 22.9–91.52 %, 49.41–129.82 %, 31.96–89.26 % and 14.36–85 % for Rc = 0.333 h, 0.49 h, 0.56 h & 0.67 h respectively for Re spanning from 5600 to 21000.

Effect of Native Aortic Leaflet Geometry Modification on Transcatheter Aortic Valve Neo-sinus and Aortic Sinus Flow: An In-vitro Study.

Leaflet thrombosis is a potentially fatal complication after transcatheter aortic valve replacement (TAVR). Blood flow stagnation in the neo-sinus and aortic sinuses are associated with increased thrombus severity. Native aortic leaflet modification may be a potential strategy to improve the neo-sinus and aortic sinus fluid dynamics. However, limited data exist on the effect of leaflet geometry modification on the flow within the neo-sinus and aortic sinus regions. We evaluate the effect of aortic leaflet modification on the neo-sinus and aortic sinus flow stagnation after simulated TAVR. Particle image velocimetry measurements were performed under nominal (5 LPM) and low (2.5 LPM) cardiac output conditions for an intact leaflet (control) case, and 3 modified leaflet geometries. Aortic leaflet geometry modification via leaflet splay was simulated with increasing splay geometry (leaflet splay distance: 5mm-narrow, 10mm-medium, and 20mm-wide). Leaflet geometry modification influenced flow features throughout the cardiac cycle, at both cardiac outputs, and allowed for flow communication between the neo-sinus and aortic sinus regions compared to the control. In the aortic sinus, flow stagnation reduced by over 64% at 5LPM, and over 36% at 2.5LPM for all simulated modified leaflet geometries compared to the control. However, only the medium and wide splay geometries enabled a reduction in neo-sinus flow stagnation compared to the control case. These findings suggest that aortic leaflet geometry modification (of at least 10mm leaflet splay distance) may reduce flow stasis and potentially decrease valve thrombosis risk.

Hemodynamics and bio-mechanics of morphologically distinct saccular intracranial aneurysms at bifurcations: Idealised vs Patient-specific geometries

Background and Objective.Understanding the factors that influence the rupture of aneurysms is of primary concern to the clinicians, who are grappled with patient management. It is important to know how the relation between morphological features of the cerebral aneurysm, and the mechanical stresses on the containing arterial walls are influenced by the hemodynamic forces. Present study investigates three different shapes, which have been identified correspondingly in patient-specific scenarios as well. The primary objective is to categorize the bifurcation aneurysms into standard shapes such as, spherical, beehive and pear-shaped, based on patient-specific clinical studies and further compare and contrast the model aneurysms with the patient specific configurations, for their hemodynamic factors as well as the attendant stresses on the wall.MethodsComputational fluid dynamic simulations are performed accounting for the fluid-structure interaction (FSI) effects between the flowing fluid and the containing vessel wall. Blood is assumed to be Newtonian, while the arterial walls are assumed to be linearly elastic. A commercial solver is used for performing detailed calculations. Hemodynamic and bio-mechanical rupture predictions are carried out for the three different shapes. Observations derived from the idealised simulations are compared and contrasted against their patient-specific counterparts.ResultsFrom detailed numerical simulations, it was observed that pear-shaped aneurysms exhibit large re-circulation bubble and flow stagnation zone, with higher residence time for the particles, which may lead to atherosclerotic lesions. Beehive shape allows for maximum flow into the aneurysmal sac with concentrated jet impinging on the dome, leading to high values of maximum WSS (MWSS) resulting in great propensity to form a secondary bleb. However, flow field inside a spherical aneurysm is found to be stable with fewer vortices, and nearly uniform distribution of wall stresses are observed though-out the sac, which perhaps signifies hemodynamically and bio-mechanically stable condition.ConclusionCategorizing patient-specific intracranial aneurysms into standard shapes viz, spherical, beehive and pear could generalize the process of prediction of hemodynamic and bio-mechanical rupture indicators. Comparative assessment of the flow field and stresses reported from the simulations on idealised models, with corresponding patient-specific simulations reveal that, these studies could aid in understanding the generalised shape dependence of hemodynamic and bio-mechanical behaviour of aneurysms.

Abstract 13352: Differential Response of Healthy Endocardial Cells versus Endocardial Fibroelastosis-Derived Cells to Flow Alterations and Statins

Introduction: Endocardial Fibroelastosis (EFE) is a subendocardial thickening of organized collagen and elastin layers restricting the ventricle. It has been linked to flow disturbances in congenital heart defects. Endothelial-to-mesenchymal transition (EndMT) has been identified as the underlying mechanism for EFE and also plays a central role in other diseases such as atherosclerosis where statins (e. g. atorvastatin) have been successfully used as EndMT-inhibitors. This study sought to establish a causal relationship between flow and EndMT, and to determine the protective effects of atorvastatin. Methods: Healthy endocardial endothelial cells (EECs) and EFE-derived EECs were exposed to either flow stagnation (≤5dynes/cm 2 ) with and without atorvastatin (0.5μmol/l) or physiological flow (~10dynes/cm 2 ) using a flow pump system (ibidi). Active EndMT (double staining with αSMA and CD31/VE-Cadherin) and collagen production was determined by immunohistochemical staining. Results: In healthy EECs (n=4), flow stagnation induced EndMT and collagen production which was significantly ameliorated by physiological flow (n=3, p&lt;0.001, Fig. 1A+C). In contrast, physiological flow resulted in an increase in collagen production by 89% (n=8, p&lt;0.001, Fig. 1D) in EFE-derived EECs. Under flow stagnation, atorvastatin inhibited EndMT (reduction by 39%, p&lt;0.001, Fig. 1A) and collagen production in healthy EECs (reduction by 9%, p&lt;0.001, Fig. 1C). This effect was blunted in EFE-derived EECs regarding EndMT reduction (17%, p&lt;0.001, Fig. 1B), with no effect on collagen. Conclusion: Physiological flow and atorvastatin protect healthy EECs from EndMT but only the latter is beneficial for EFE-derived EECs. Thus, statins potentially offer a preventative treatment for EFE patients with flow stagnation. This study revealed a profound difference in the response to flow of healthy and EFE-derived EECs, indicating an intrinsic predisposition to EndMT in these patients.