Hemodynamic Properties Research Articles

Hemodynamics of Capillary Networks in Sickle Cell Disease

ObjectiveSickle cell disease (SCD) is a complex hereditary blood disorder that can significantly affect the rheological properties of patients. Researches on the change of the rheological properties of blood and hemodynamics in a single capillary vessel have been carried out in recent three decades. The target of this work is to explore the hemodynamic behavior of diseased capillary networks based on anatomical data, in order to provide advice on the generation and prevention of the vaso‐occlusive crisis of patients with sickle cell disease.MethodIn this work, we use numerical simulations to calculate the sickle RBC velocity, blood hematocrit and blood viscosity in capillary bifurcations and networks based on mesenteric anatomical data. Then, the model predictions are discussed with reported clinical manifestations and compared with normal networks.ResultsThe predictions from our simulations show agreement with clinical manifestations. Compared with the properties of normal capillary networks, the blood flow in diseased micro vessel networks has 10%–25% larger hematocrit, slower RBC velocity and larger blood viscosity, which can lead to the vaso‐occlusive crisis and the pain of patients with sickle cell disease.ConclusionsThis study helps us to understand the blood flow properties of capillary networks of patients with sickle cell disease, and may help us to prevent the vaso‐occlusive crisis. To improve our study, we can use capillary networks from the diseased part of sickle cell patients instead.Support or Funding InformationThis research is supported by Shenzhen Science and Technology Innovation Institution (China) Grant JCYJ20160427170536358 (Y Huo).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Determination of an estimate point of rupture for intracranial aneurysms using mathematical models applied to fluids dynamics

BackgroundIntracranial aneurysms represent a potential risk factor for various comorbidities, mainly associated with its rupture. Available information for aneurysms intervention is changing a paradigm and now, the decision of operating or not, varies in co‐dependence with the patient. We present the preliminary results of a potential tool that shows high rupture probability areas, predicting early rupture risk, also as an alternative for surgical planning.ObjectiveTo describe the mathematical models that best characterize the blood flow in an aneurysm and implement them through computational simulations to define the hemodynamic properties in terms of pressure, velocity and shear rate in artery walls.Materials/MethodsUsing the software ITK snap, an angioscanography of a patient from the Fundación Santa Fe de Bogotá was segmented. This program implements the methodology of snake evolution to obtain a 3D model by creating an estimated anatomical form and calculating internal forces of the image gradient inside of a closed curve. This gradient is determined by the pixel intensity on every point of the closed curve, which can be enhanced by contrast made previously to the volume. Secondly, with the purpose of having a non‐restriction model, the software Meshlab was used. This software edits and processes a model that is composed of triangular meshes. For this, a three Laplacian smooth was implemented in the final model. Finally, the blood flow within an aneurysm was modeled using the Comsol Multiphysics software assuming that blood behaves like Newtonian fluid with laminar flow, density of 1000 kg/m3 and a dynamic viscosity of 0.0035 Pa * s, governed by conservation of momentum and mass equations. For the simulation, a free tetrahedral mesh was used, with refinement at the edges of the geometry, whose size was defined by the previously established fluid dynamics.ResultsFor our first model, the highest stress levels were found at two points of an aneurysm: at the entrance and at the wall, where the highest velocity of blood flow was present. As for the velocity of the blood, it was reduced in the model, meaning that recirculation was present which is to be expected when dealing with aneurysms. Lastly, the shear rate was highest at the neck of the aneurysm and its lowest degree inside the aneurysm.DiscussionThe mathematical models describe the behavior of different variables. The simulation of blood flow within an aneurysm model obtained from diagnostic images of a real patient generates a good approximation to the behavior of blood flow in real life.ConclusionPressure, speed and shear stress on the arterial wall are the main factors involved in the development and possible rupture of an aneurysm. The mathematical models of this preliminary study will be implemented on a larger database. By doing so, a method capable of predicting the point in which there is a greater probability of rupture in an aneurysm can be developed, based on its hemodynamic properties.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Central Hemodynamics in Relation to Circulating Desphospho-Uncarboxylated Matrix Gla Protein: A Population Study.

BackgroundStiffening and calcification of the large arteries are forerunners of cardiovascular complications. MGP (Matrix Gla protein), which requires vitamin K–dependent activation, is a potent locally acting inhibitor of arterial calcification. We hypothesized that the central hemodynamic properties might be associated with inactive desphospho‐uncarboxylated MGP (dp‐ucMGP).Methods and ResultsIn 835 randomly recruited Flemish individuals (mean age, 49.7 years; 45.6% women), we measured plasma dp‐ucMGP, using an ELISA‐based assay. We derived central pulse pressure and carotid‐femoral pulse wave velocity (PWV) from applanation tonometry and calculated forward and backward pulse waves using an automated, pressure‐based wave separation analysis algorithm. Aortic PWV (n=657), central pulse pressure, forward pulse wave, and backward pulse wave mean±SD values were 7.34±1.64 m/s, 45.2±15.3 mm Hg, 33.2±10.2 mm Hg, and 21.8±8.6 mm Hg, respectively. The geometric mean plasma concentration of dp‐ucMGP was 4.09 μg/L. All hemodynamic indexes increased across tertiles of dp‐ucMGP distribution. In multivariable‐adjusted analyses, a doubling of dp‐ucMGP was associated with higher PWV (0.15 m/s; 95% CI, 0.01–0.28 m/s), central pulse pressure (1.70 mm Hg; 95% CI, 0.49–2.91 mm Hg), forward pulse wave (0.93 mm Hg; 95% CI, 0.01–1.84 mm Hg), and backward pulse wave (0.71 mm Hg; 95% CI, 0.11–1.30 mm Hg). Categorization of aortic PWV by tertiles of its distribution highlighted a decreasing trend of PWV at low dp‐ucMGP (<3.35 μg/L) and an increasing trend at high dp‐ucMGP (≥5.31 μg/L).ConclusionsIn people representative for the general population, higher inactive dp‐ucMGP was associated with greater PWV, central pulse pressure, forward pulse wave, and backward pulse wave. These observations highlight new avenues for preserving vascular integrity and preventing cardiovascular complications (eg, by improving a person's vitamin K status).

Recurrent acute coronary syndrome in a patient with right coronary artery ectasia: a case report

BackgroundCoronary artery ectasia is characterized by an abnormal dilatation of the coronary arteries. Coronary artery ectasia is observed in 3–8% of patients undergoing coronary angiography and sometimes leads to acute coronary syndrome regardless of the presence or absence of coronary stenosis or atrial fibrillation.Case presentationA 61-year-old Indonesian man presented with typical angina that began 1 week before admission and had worsened 3 hours prior to admission. Accompanying symptoms included dyspnea, nausea, and sweating. He was hemodynamically stable and had a history of tobacco smoking and dyslipidemia. An electrocardiogram showed ST-segment depression and T inversion. Laboratory results showed an international normalized ratio of 1.28. Dual antiplatelet therapy was administered along with fondaparinux, and symptoms were alleviated. Coronary angiography showed an ectatic and turbulent mid-distal right coronary artery and slow flow at the first presentation. There was a patent stent in the proximal-mid left anterior descending coronary artery. This patient had previously presented with recurrent acute coronary syndrome and received two coronary stents for the stenotic vessels.DiscussionHe had right coronary artery ectasia and experienced recurrent acute coronary syndrome. He received dual antiplatelet therapy along with warfarin after stenting of his left anterior descending coronary artery. However, he presented with unstable angina pectoris 7 months before the latest admission and at the latest admission despite a patent stent and no other significant obstructive lesion. The unstable angina pectoris might have been caused by slow flow, microvascular angina caused by small thrombi and/or vasospasm, or epicardial thrombosis at the ectatic coronary artery that dissolved after anticoagulation therapy prior to coronary angiography. Anticoagulant therapy may have a greater benefit than antiplatelet therapy in this patient due to the turbulence and stasis of blood in the ectatic vessel, although coexisting coronary conditions mandated antiplatelet therapy. His international normalized ratio was suboptimal and needed to be improved.ConclusionCoronary ectasia may play a role in recurrent acute coronary syndrome, and administration of an anticoagulant to prevent acute coronary syndrome in this patient was in accordance with the varying hemodynamic property of coronary artery ectasia.

Clinical Cancer Nanomedicine.

Nanotechnology offers new solutions for the development of cancer therapeutics that display improved efficacy and safety. Although several nanotherapeutics have received clinical approval, the most promising nanotechnology applications for patients still lie ahead. Nanoparticles display unique transport, biological, optical, magnetic, electronic, and thermal properties that are not apparent on the molecular or macroscale, and can be utilized for therapeutic purposes. These characteristics arise because nanoparticles are in the same size range as the wavelength of light and display large surface area to volume ratios. The large size of nanoparticles compared to conventional chemotherapeutic agents or biological macromolecule drugs also enables incorporation of several supportive components in addition to active pharmaceutical ingredients. These components can facilitate solubilization, protection from degradation, sustained release, immunoevasion, tissue penetration, imaging, targeting, and triggered activation. Nanoparticles are also processed differently in the body compared to conventional drugs. Specifically, nanoparticles display unique hemodynamic properties and biodistribution profiles. Notably, the interactions that occur at the bio-nano interface can be exploited for improved drug delivery. This review discusses successful clinically approved cancer nanodrugs as well as promising candidates in the pipeline. These nanotherapeutics are categorized according to whether they predominantly exploit multifunctionality, unique electromagnetic properties, or distinct transport characteristics in the body. Moreover, future directions in nanomedicine such as companion diagnostics, strategies for modifying the microenvironment, spatiotemporal nanoparticle transitions, and the use of extracellular vesicles for drug delivery are also explored.

Abstract P014: Aortic Stiffness and Late-life Depression: the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS)

Introduction: Late-life depression, which occurs at the age of 65 years or older, is a heterogeneous syndrome associated with cognitive decline and dementia. Aortic stiffness increases pulsatility, which damages microvascular circulation, resulting in poor vasoreactivity and cerebral hypoperfusion that is related to late-life depression. However, only few studies that relate aortic stiffness to late-life depression. Hypothesis: Higher aortic stiffness is associated with greater depressive symptoms and a higher prevalence of late-life depression. Methods: A total of 4,392 ARIC-NCS participants (mean age: 75.2±5.0 years; 40% male; 21% Black) with measurements of aortic stiffness and depressive symptoms in 2011-2013 were included in this cross-sectional analysis. Aortic stiffness was assessed as carotid-femoral pulse wave velocity (cfPWV) using the VP-1000 plus system (Omron Co., Ltd., Japan). cfPWV was dichotomized based on the upper 25th percentile. The 11-item short form of the Center for Epidemiological Studies Depression Scale (CES-D) was used to assess depressive symptoms. Depressive symptoms were calculated as the sum of scores obtained from the 11 items addressing appetite, depressed feelings, sense of effort, restless sleep, feeling happy, sad, or lonely, perceiving others as unfriendly, enjoying life, feeling disliked, and not able to get going (score range:0 to 22). The CES-D score was quantified as both a binary and a continuous variable. Individuals were categorized as depressed if CES-D score≥8. The total CES-D was log-transformed due to right skewed distribution (mean: 3.1; median: 2.0). Multivariable linear regression was used to estimate the association between high cfPWV and CES-D score, and multivariable logistic regression was used to estimate the association between high cfPWV and odds of depression. All models were adjusted for age, sex, race-center, education, self-reported financial situation, smoking, alcohol use, body mass index, LDL cholesterol, prevalent hypertension, diabetes and coronary heart disease. Race and sex were tested as potential effect measure modifiers. Results: A total of 412 (9.4%) participants were depressed. Compared to participants with less stiff aortas (cfPWV&lt;13.11 m/s), those with stiffer aortas (cfPWV≥13.11m/s) had higher average CES-D scores (3.5 vs. 2.9, respectively) and a higher prevalence of depression (12.9% vs 8.2%, respectively). High cfPWV was associated with 6% higher depressive symptoms (beta (β): 0.06, 95% confidence interval (CI): 0.002, 0.13), and greater odds of depression (odds ratio (OR): 1.32, 95% CI: 1.03, 1.69). No significant interactions were found by race or sex. Conclusion: Aortic stiffness is associated with late-life depression. These results suggest a role for age-related hemodynamic properties as targets for the study of late-life depression and the mitigation of its burden.

Valves of the small coronary veins in porcine hearts.

The aim of the study was to investigate the existence of valves in small peripheral coronary veins of porcine hearts. The study was performed on 20 porcine hearts using standard histological methods. The veins in the subepicardial and intramyocardial regions of the anterior and posterior parts of the interventricular septum and in the wall of the right atrium were studied. Valves were present in intramyocardial veins (diameter of 75-180 μm), in the veins located just beneath the external surface of the myocardium (diameter 120-170 μm) and in the terminal segments of the ventricular veins (diameter 250 μm) opening into the stems of the anterior interventricular vein and middle cardiac vein. Valves were also recorded in most veins of the subepicardial space. The described rich presence of valves in the small coronary veins may contribute to a better comprehension of their hemodynamic properties. These findings may also help to improve the understanding of the efficacy of retrograde application of medications, a novel technique in cardiology and cardiac surgery.

In vitro evaluation of Capiox FX05 and RX05 oxygenators in neonatal cardiopulmonary bypass circuits with varying venous reservoir and vacuum-assisted venous drainage levels.

The purpose of this study was to evaluate the hemodynamic properties and microemboli capture associated with different vacuum-assisted venous drainage (VAVD) vacuum levels and venous reservoir levels in a neonatal cardiopulmonary bypass circuit. Trials were conducted in 2 parallel circuits to compare the performance of Capiox Baby RX05 oxygenator with separate AF02 arterial filter to Capiox FX05 oxygenator with integrated arterial filter. Arterial cannula flow rate to the patient was held at 500mL/min and temperature maintained at 32°C, while VAVD vacuum levels (0mm Hg, -15mm Hg, -30mm Hg, -45mm Hg, -60mm Hg) and venous reservoir levels (50mL, 200mL) were evaluated in both oxygenators. Hemodynamic parameters measuring flow, pressure, and total hemodynamic energy were made in real time using a custom-made data acquisition system and Labview software. Nearly 10cc bolus of air was injected into the venous line and gaseous microemboli detected using an Emboli Detection and Classification Quantifier. Diverted blood flow via the arterial filter's purge line and mean pressures increased with increasing VAVD levels (P<0.01). Mean pressures were lower with lower venous reservoir levels and were greater in RX05 groups compared to FX05 (P<0.01). Microemboli detected at the preoxygenator site increased with higher VAVD vacuum levels and lower venous reservoir levels (P<0.01). The amount of microemboli captured by the FX05 oxygenator with integrated arterial filter was greater than by the RX05 oxygenator alone, although both oxygenators were able to clear microemboli before reaching the pseudo-patient.

Hemodynamic properties and respiratory efforts: A comparative study between etomidate and propofol

Hemodynamic properties and respiratory efforts: A comparative study between etomidate and propofol

Finite Element Predictions of Sutured and Coupled Microarterial Anastomoses

Simulation using computational methods is well-established for investigating mechanical and haemodynamic properties of blood vessels, however few groups have applied this technology to microvascular anastomoses. This study, for the first time, employs analytic and numeric models of sutured and coupled mi-croarterial anastomoses to evaluate the elastic and failure properties of these techniques in realistic geometries using measured arterial waveforms. Computational geometries were created of pristine microvessels and mi-croarterial anastomoses, performed using sutures and a coupling device. Vessel wall displacement, stress, and strain distributions were predicted for each anastomotic technique using finite element analysis (FEA) software in both static and transient simulations. This study focussed on mechanical properties of the anastomosis im- mediately after surgery, as failure is most likely in the early post-operative period. Comparisons were also drawn between stress distributions seen in analogous non-compliant simulations. The maximum principal strain in a sutured anastomosis was found to be 84% greater than in a pristine vessel, whereas a mechanically coupled anastomosis reduced arterial strain predictions by approximately 55%. Stress distributions in the su-tured anastomoses simulated here differed to those in reported literature. This result is attributed to the use of bonded connections in existing studies, to represent healed surgical sites. This has been confirmed by our study using FEA, and we believe this boundary condition significantly alters the stress distribution, and is less representative of the clinical picture following surgery. We have demonstrated that the inertial effects due to motion of the vessel during pulsatile flow are minimal, since the differences between the transient and static strain cal- culations range from around 0.6–7% dependent on the geometry. This implies that static structural analyses are likely sufficient to predict anastomotic strains in these simulations. Furthermore, approximations of the shear strain rate (SSR) were calculated and compared to analogous rigid-walled simulations, revealing that wall compliance had little influence on their overall magnitude. It is important to highlight, however, that SSR variations here are taken in isolation, and that changing pressure gradients are likely to produce much greater variation in vessel wall strain values than the influence of fluid flow alone. Hence, a formal fluid-structure interaction (FSI) study would be necessary to ascertain the true relationship.

Increased expression of ryanodine receptor type-2 during atrial fibrillation by miR-106-25 cluster independent mechanism

Atrial fibrillation (AF), the most frequently encountered cardiac arrhythmia in the clinical setting and the foremost cause of stroke, results from a progressive decrease in atrial refractoriness. In addition, defective calcium signaling has been shown to play a central role in AF pathogenesis. Recently it was shown that the miR-106b-25 cluster is suppressed in patients with AF, which increased ryanodine receptor 2 (RyR2) expression. Expression of the miR-106b-25 cluster and RyR2 protein were determined in our institutional series of patients with AF. Hemodynamic properties, RyR2 binding, suppression of ATP2A2 (encoding ATPase sarcoplasmic/endoplasmic reticulum Ca2 + transporting 2) were also determined. We found that all patients had elevated RyR2 protein expression; however, a cohort of patients with AF had high miR-93, miR-106b, and miR-25 expression. There was no difference in hemodynamic properties, RyR2 binding, or suppression of ATP2A2 in either cohort of patients with AF when compared to patients with normal sinus rhythm (NSR). Immunoblot assay showed hyperactive Akt, S6K, and S6 kinases in patients with AF as compared to patients with NSR. Protein kinase C activation, as measured by PKC phosphorylation, was also hyperactive in patients with AF. Cumulatively, our findings show that RyR2 expression is regulated by multiple mechanisms including the miR-106b-25, and that PKC activation might provide novel clues to increased intracellular calcium levels during AF pathogenesis.

Comparison of Biomechanical Properties and Hemodynamics of Three Different Vena Cava Filters

The interaction mechanism of three types of vena cava filters (VCFs) with blood vessels and their influence on the bloodstream during the process of implantation are investigated by finite element method and computational fluid dynamics. The VCF models are set up with Solidworks software. Using ABAQUS software, we simulate the working conditions of the VCFs in the vessel to analyze the stress distribution and radial support stiffness of the vessel wall and the filter surface. Using FLUENT software, we simulate and analyze the velocity, pressure and shear stress distributions of blood flow when the VCFs are at their working conditions. For the retrievable VCF (R-VCF), the peak stress at the working conditions of the VCF is the highest, the peak stress toward the vessel wall is the lowest, and the support stiffness is the lowest. For the permanent VCF (P-VCF), the peak stress at the working conditions of the VCF is the highest, the peak stress toward the vessel wall is the lowest, and the support stiffness is the highest. Because of the structure of scaffolding support units and the tendency to form intimal hyperplasia on their support units, both the convertible VCF (C-VCF) and the P-VCF can embed their support units in the hyperplasia skin. This effectively prevents them from harming blood veins through filter damage at the pulse load conditions. As the biomechanical property of the C-VCF is between those of the R-VCF and the P-VCF, it has smaller obstacle to blood flow after conversion and has some fragmentation effects on the thrombus. The results show that different types of VCFs differ in their biomechanical and hemodynamic properties after implantation. Therefore, the simulative analysis can provide a reference basis for filter design and clinical decision making.

Trifecta has lower gradient and less prosthesis–patient mismatch than Mosaic Ultra in the aortic position: A prospective randomized study

ObjectiveWhen aortic valve replacement is needed, a biological valve is usually implanted in patients older than age 60 to 65 years. A large valvular opening area is important to avoid prosthesis–patient mismatch and facilitate reverse left ventricular remodeling. The Trifecta biological valve (St Jude Medical, St Paul, Minn) is, because of its design, believed to reduce transvalvular gradient compared with other biological valves, especially in smaller annuli. Several retrospective studies have compared transvalvular gradients of implanted valves prostheses using the respective manufacturers given size and not the actual annulus size measured by a metric sizer. This makes comparison of the hemodynamic properties of different valve brands and sizes difficult. We therefore performed a prospective randomized study, using the same metric sizer to measure annulus size, and compared hemodynamic profiles of the Trifecta to our standard Mosaic Ultra biological valve (Medtronic, Minneapolis, Minn). MethodsNinety elective patients with small to medium annulus diameter undergoing aortic valve replacement were randomized to either Trifecta or Mosaic Ultra. After native valve removal and decalcification, a Hegar-sizer was used to measure true annulus size. Then the largest possible valve of either brand was implanted according to the randomization protocol. Echocardiography was performed 6 months postoperatively. ResultsBaseline parameters of the 2 cohorts were comparable. There were lower transvalvular gradients in the Trifecta compared with the Mosaic Ultra group for the given annulus sizes. Severe prosthesis–patient mismatch was present in 28% of patients in the Mosaic group and 3% of patients in the Trifecta group. ConclusionsTrifecta showed lower transvalvular gradients and less severe prosthesis–patient mismatch compared with Mosaic Ultra for the given annulus sizes. ClinicalTrials.gov Protocol ID: 2011/2596/REK.

A new cerebral vessel benchmark dataset (CAPUT) for validation of image-based aneurysm deformation estimation algorithms

Hemodynamic properties and deformation of vessel structures are assumed to be correlated to the initiation, development, and rupture of cerebral aneurysms. Therefore, precise quantification of wall motion is essential. However, using standard-of-care imaging data, approaches for patient-specific estimation of pulsatile deformation are prone to uncertainties due to, e.g., contrast agent inflow-related intensity changes and small deformation compared to the image resolution. A ground truth dataset that allows evaluating and finetuning algorithms for deformation estimation is lacking. We designed a flow phantom with deformable structures that resemble cerebral vessels and exhibit physiologically plausible deformation. The deformation was simultaneously recorded using a flat panel CT and a video camera, yielding video data with higher resolution and SNR, which was used to compute ‘ground truth’ structure deformation measures. The dataset was further applied to evaluate registration-based deformation estimation. The results illustrate that registration approaches can be used to estimate deformation with adequate precision. Yet, the accuracy depended on the registration parameters, illustrating the need to evaluate and finetune deformation estimation approaches by ground truth data. To fill the existing gap, the acquired benchmark dataset is provided freely available as the CAPUT (Cerebral Aneurysm PUlsation Testing) dataset, accessible at https://www.github.com/IPMI-ICNS-UKE/CAPUT.

The brain’s hemodynamic response function rapidly changes under acute psychosocial stress in association with genetic and endocrine stress response markers

Ample evidence links dysregulation of the stress response to the risk for psychiatric disorders. However, we lack an integrated understanding of mechanisms that are adaptive during the acute stress response but potentially pathogenic when dysregulated. One mechanistic link emerging from rodent studies is the interaction between stress effectors and neurovascular coupling, a process that adjusts cerebral blood flow according to local metabolic demands. Here, using task-related fMRI, we show that acute psychosocial stress rapidly impacts the peak latency of the hemodynamic response function (HRF-PL) in temporal, insular, and prefrontal regions in two independent cohorts of healthy humans. These latency effects occurred in the absence of amplitude effects and were moderated by regulatory genetic variants of KCNJ2, a known mediator of the effect of stress on vascular responsivity. Further, hippocampal HRF-PL correlated with both cortisol response and genetic variants that influence the transcriptional response to stress hormones and are associated with risk for major depression. We conclude that acute stress modulates hemodynamic response properties as part of the physiological stress response and suggest that HRF indices could serve as endophenotype of stress-related disorders.

Fluid-structure interaction of heart valve dynamics in comparison to finite-element analysis

Abstract An established therapy for aortic valve stenosis and insufficiency is the transcatheter aortic valve replacement. By means of numerical simulation the valve dynamics can be investigated to improve the valve prostheses performance. This study examines the influence of the hemodynamic properties on the valve dynamics utilizing fluidstructure interaction (FSI) compared with results of finiteelement analysis (FEA). FEA and FSI were conducted using a previously published aortic valve model combined with a new developed model of the aortic root. Boundary conditions for a physiological pressurization were based on measurements of ventricular and aortic pressure from in vitro hydrodynamic studies of a commercially available heart valve prosthesis using a pulse duplicator system. A linear elastic behavior was assumed for leaflet material properties and blood was specified as a homogeneous, Newtonian incompressible fluid. The type of fluid domain discretization can be described with an arbitrary Lagrangian-Eulerian formulation. Comparison of significant points of time and the leaflet opening area were used to investigate the valve opening behavior of both analyses. Numerical results show that total valve opening modelled by FEA is faster compared to FSI by a factor of 5. In conclusion the inertia of the fluid, which surrounds the valve leaflets, has an important influence on leaflet deformation. Therefore, fluid dynamics should not be neglected in numerical analysis of heart valve prostheses.

MULTI-BRAIN NETWORK ACROSS CONSUMERS’ RIGHT INFERIOR FRONTAL GYRUS PREDICTS THEIR ATTITUDES TOWARD ADVERTISING

Introduction How to evaluate quality of advertising? Previous behavioral studies have mainly focused on subjective reports of survey and interview containing social and cognitive bias, or objective data of sell changes suffering huge temporal and monetary cost. Recently, increasing researchers have proposed that techniques of neuro-imaging could provide an objective and effective way to examine cognitive neural mechanisms underlying consumer behavior (referred to as consumer neuroscience) (Karmarkar & Yoon, 2016), and several studies have measured consumer's brain responses to advertising and movie trailer in both single- and two-brain frames (Barnett & Cerf, 2017; Venkatraman et al., 2015). However, still little is known about cognitive neural mechanisms underlying comprehension of advertising. Functional near-infrared spectroscopy (fNIRS) is a non-invasive technique of brain-imaging measuring changes in the hemodynamic properties of human brain. Compared with fMRI and EEG, fNIRS is portable, has few physical constraints on participants with reasonable spatial and temporal resolution, and is tolerant to electromagnetic noise and motion artifact. Therefore, fNIRS is a suitable tool for research of human behavior in daily-life contexts (Liu et al., in press), which is a trends in neuroimaging (Hasson & Honey, 2012) and consumer neuroscience as weill. Methods To examine the neural responses to different quality of advertisings, in the present study we measured 14 undergraduate students' frontal activations while watching 20 advertisings in Study 1 and listening 30 music demos in Study 2 using a portable fNIRS device, and analyzed interpersonal neural network across all participants based on graph theory. Figure 1 shows positions of the fNIRS channels. Positions of the fNIRS channels were measured by a 3D magnetic digitizer. In a pilot study, another group of participants were recruited to score 30 advertisings from three dimensions: degree of liking, degree of willing to pay (WTP), and degree of understanding, and finally top-10 and bottom-10 scored adverting were remained for the final experiment in Study 1. Concerning the music demos used in Study 2, we selected the top-15 and bottow-15 ranking music in the ‘Billboard 2014 hot 100’. During the experiment, participants were asked to score their degree of liking and WTP to the advertising or the music immediately after each stimulus was displayed. After the experiment, they were also instructed to score and report their understanding on each advertising or music. Results and Discussion In Study 1, the intra-brain activations revealed higher medial prefrontal cortex (mPFC) activation when participants watched low-scored advertisings than watched high-scored ones (Fig. 2), and the mPFC activations showed a positive relationship with participants’ understanding on the meaning of the advertisings. This result only suggests that low-scored advertisings were relatively hard for participants to understand the intentions of the adverting, requiring more cognitive resources of mentalizing (Lieberman, 2007). Importantly, when we considered all participants' brains as a network, and then calculated the interpersonal neural connectivity (INS) across the network (defined as the number of participant pairs who showed significant positive inter-brain neural synchronization across them indicating shared understanding) (Hasson et al., 2012), only the network connectivity in the right inferior frontal gyrus (IFG) had significantly positive relationships with participants' scores of attitude towards the advertisings (defined as mean of the scores of liking and WTP) (Fig. 3). Study 2 confirmed the result showing significantly positive relationship between the network connectivity across all participants' brains and their scores of attitude towards the song demos. More importantly, the network connectivity in the right IFG of the small group of participants also significantly predicted the public's attitude towards the songs assessed by the rating scores on Douban website (Fig. 4). Conclusion The right IFG is a core area of mirror neuron system and is closely associated with empathy (Lamm et al., 2007). Thus, the present results suggest that high-scored advertisings may activate consumer's empathic response to simulate and experience their contents and intentions. And the network connectivity across consumers' brains in the right IFG may be a critical index evaluating quality of experiential advertisings. Practically, advertising should invite consumers to experience their products, and then could convey information and emotion more effectively.

Pulmonary vascular pathophysiology

Knowledge of pulmonary vascular pathophysiology is crucial to understand the various disease processes and their medical management. Pulmonary vascular system constitutes the right sided circulation which is distinct from the left side circulation and facilitates unique hemodynamic properties to adapt to a multitude of external demands and circumstances. With growing prevalence and increasing ability to diagnose and treat pulmonary diseases, this review becomes more relevant.

Reduced embryonic blood flow impacts extracellular matrix deposition in the maturing aorta.

Perturbations to embryonic hemodynamics are known to adversely affect cardiovascular development. Vitelline vein ligation (VVL) is a model of reduced placental blood flow used to induce cardiac defects in early chick embryo development. The effect of these hemodynamic interventions on maturing elastic arteries is largely unknown. We hypothesize that hemodynamic changes impact maturation of the dorsal aorta (DA). We examined the effects of VVL on hemodynamic properties well into the maturation process and the corresponding changes in aortic dimensions, wall composition, and gene expression. In chick embryos, we found that DA blood velocity was reduced immediately postsurgery at Hamburger-Hamilton (HH) stage 18 and later at HH36, but not in the interim. Throughout this period, DA diameter adapted to maintain a constant shear stress. At HH36, we found that VVL DAs showed a substantial decrease in elastin and a modest increase in collagen protein content. In VVL DAs, up-regulation of elastic fiber-related genes followed the down-regulation of flow-dependent genes. Together, these suggest the existence of a compensatory mechanism in response to shear-induced delays in maturation. The DA's response to hemodynamic perturbations invokes coupled mechanisms for shear regulation and matrix maturation, potentially impacting the course of vascular development. Developmental Dynamics 247:914-923, 2018. © 2018 Wiley Periodicals, Inc.

Assessment of structural and hemodynamic performance of vascular stents modelled as periodic lattices

This work considers vascular stents with tubular geometry assumed to follow a periodic arrangement of repeating unit cells. Structural and hemodynamic metrics are presented to assess alternative stent geometries, each defined by the topology of the unit cell. Structural metrics include foreshortening, elastic recoil and radial stiffness, whereas hemodynamic performance is described by a wall shear stress index quantifying the impact of in-stent restenosis. A representative volume element (RVE) modelling approach is used, and results are compared to those obtained from full simulations of entire stents. We demonstrate that the RVE approach can be used to quantify the impact of the topology of the repeating unit on the structural and hemodynamic properties of a stent, and thus support clinicians in making proper choices among alternative stent geometries.