Blood Flow Patterns Research Articles

Calculation of intraprocedural hemodynamics with computational functional dynamic in mitral valve edge-to-edge repair

Abstract Background Hemodynamic outcomes in patients undergoing transcatheter edge-to-edge-repair of the mitral valve (M-TEER) are difficult to predict. Computational functional dynamic (CFD) is frequently used in biomedical engineering to simulate blood flow patterns under various conditions. The authors developed a standardized workflow for individualized analyses and investigated the hemodynamic of mitral regurgitation volumes and gradients by using CFD. Methods 20 patients from two high volume centers who suffered from severe mitral regurgitation (MR) and underwent full cycle cardiac computed tomography (CT) prior procedure were enrolled. Baseline computed tomography and intraprocedural data were analyzed. Based on the specific valve morphology, individualized CFD-simulations were performed to calculate MR volumes prior to intervention and estimate hemodynamics after M-TEER. Results CFD-analyses of 20 patients (mean age 80±4 years, 60% male) showed excellent correlation between baseline PISA method-based MR volumes (45±23ml) measured in transesophageal echocardiography (TEE) and CFD-based calculation (45±26ml; R=0.917; P<0.001) as well as between TEE-measured mean baseline effective regurgitant orifice area (EROA; 27±16mm²) and CFD-measured EROA (24±18mm²; R=0.869; P<0.001)). After device implantation, correlation between intraprocedural TEE-measured and CFD-estimated correlation for residual MR volumes (R=0.949; P<0.001) and EROA (R=0.841; P<0.001) remained robust. Post-interventional mean diastolic pressure gradient (TEE) was 3.6±2.8mmHg which was in close correlation with the CFD estimated gradient (3.0±1.8mmHg, R=0.905; P<0.001). Conclusions This is the first study to use a CFD-standardized workflow for predicting hemodynamic changes in patients undergoing M-TEER using data from two different centers. In the future, CFD-based analyses might serve as a key-diagnostic tool for predicting residual MR volumes and gradients for M-TEER-procedures.Comparison of TEE and CFD flow patternBland-Altman-Blots

Ultrasonographic and functional evaluation of forearm circulation with occluded radial artery

Abstract Introduction The transradial approach (TRA) has gained popularity in cardiology procedures. This study aims to evaluate forearm and hand arterial circulation in radial artery (RA) occlusion (RAO) patients after coronary angiography (CAG) and percutaneous coronary interventions (PCI). The ulnar (UA) and anterior interosseous artery (AIA) can compensate for RAO. Methods A prospective, observational study was conducted on 40 RAO patients after CAG/PCI. Ultrasonographic and functional evaluation (Barbeau test) of collateral circulation through AIA or UA were performed. Statistical analyses were applied to evaluate various Doppler ultrasound parameters and the anatomical characteristics of the RAO. Results The RAO group mean age was 71.22 ± 9.99 years, and 45% were male. RA, UA, and AIA showed significant differences in peak systolic velocity, end-diastolic velocity, arterial diameter, total flow volume, and stroke volume (p < 0.01). Pulse quality over RA and UA also differed significantly (p < 0.0001). Blood flow direction in the distal RA segment divided patients into an antegrade flow group (50%) from AIA and a retrograde flow group (50%) from UA. The Barbeau test results varied among RAO patients, with type D being the most common. Anatomical locations of RAO included the anatomical snuffbox (10%), wrist (60%), and forearm (30%). The logistic regression model revealed that the Barbeau test results on Finger 2 (p=0.0006, OR=0.1398) and Finger 4 (p=0.004, OR 0.2843) were significant predictors for the occurrence of antegrade or retrograde blood flow in the distal RA when RAO occurred. Furthermore, when the RA was occluded, the study revealed that a palpable pulse over the RA was still possible in 15% of cases. Conclusion Ultrasonographic evaluation and the Barbeau test can assess collateral circulation and predict blood flow patterns in RAO patients. Further research is needed to validate these findings, explore additional factors influencing collateral circulation and access route selection, and investigate the clinical implications of different RAO anatomical locations in cardiology procedures.Radial Artery OcclusionThe pulse quality over RA/UA with RAO

Optimizing Lower Extremity Local Flap Reconstruction in Peripheral Vascular Disease.

Local flaps remain a valuable reconstructive tool as a means for limb salvage for patients with advanced arterial disease. Our single-center, retrospective cohort study aims to compare the outcomes of different patterns of blood flow affected by vascular disease to pedicles in local flap reconstruction of the foot and ankle. A retrospective review of 92 patients and 103 flaps was performed. On angiograms, pattern of blood flow to the flap pedicle was determined to be direct inline flow (DF) or indirect flow (IF). Patterns of IF were either by arterial-arterial connections (AC) or unnamed randomized collaterals (RC). Primary outcomes were immediate flap success and limb salvage. Comparative analyses were performed using the χ2 and Fisher tests for categorical variables. Among all flaps, 73.8% (n = 76/103) had DF and 26.2% (n = 27/103) had IF. Both groups experienced similar rates of immediate flap success (DF = 97.3% vs IF = 92.6%, P = 0.281) and limb salvage (DF = 75.% vs IF = 66.7%, P = 0.403). However, the rate of contralateral amputation was significantly higher in the IF group (26.9% vs 5.3%, P = 0.006). When comparing the 3 distinct patterns of blood flow (DF vs AC vs RC), pedicled flaps were more commonly supplied by DF and AC, while random pattern flaps were more commonly supplied by RC (P = 0.042). Alternative routes of revascularization can maintain local flap viability and achieve similar rates of limb salvage but risks contralateral amputation. We found that pedicled and local muscle flaps require inline blood flow or blood supply by ACs. Meanwhile, random pattern flap can be supported by random collaterals.

Computational Evaluating on the Role of Sac Centerline Length on hemorrhage Risk of Anterior Cerebral Artery with saccular aneurysm

The present article investigates geometrical features of an aneurysm, particularly the sac centreline length (SCL), in determining the hemodynamic environment within the aneurysm for evaluation of the haemorrhage risk. Indeed, understanding how these geometric characteristics influence blood flow patterns is essential for assessing rupture risk and optimizing treatment strategies. Computational fluid dynamic is used to perform computational modelling of the blood hemodynamic in ACA cases. Wall shear stress (WSS), OSI and pressure over sac surface are investigated and compared for selected saccular aneurysm to evaluate risk of aneurysm rupture when sac centreline length is varied. Comparison of the results show that the inverse relationship between sac centerline length and these key hemodynamic parameters (OSI, velocity, WSS) underscores the importance of geometrical factors in assessing aneurysm rupture risk. Longer sac centerline lengths appear to be associated with more stable flow dynamics and reduced mechanical stress, while shorter sac lengths correlate with more disturbed and high-stress conditions.

Numerical Study of the Effect of the Port Angle of the Superior Vena Cava Supplying Cannula on Hemodynamics in the Right Atrium in VV-ECMO.

Objective: To elucidate the pattern of the influence of the port angle of the superior vena cava supplying cannula (SVCS) on hemodynamics within the right atrium in VV-ECMO. Methods: A three-dimensional model of the right atrium was established based on CT images of a real patient. The 3D models of the SVCS and inferior vena cava draining cannula (IVCD) were established based on the Edwards 18Fr and Medos 22Fr real intubation models, respectively. Based on these models, three-dimensional models of the SVCS ports with bending angles of -90°, -60°, -30°, 0°, 30°, 60°, and 90° in the plane formed by the centerline of the SVCS and the center point of the tricuspid valve (TV) were established. Transient-state computational fluid dynamics (CFD) was performed to clarify the right atrium blood flow pattern and hemodynamic states at different SVCS port orientation angles. The velocity clouds, wall pressure, wall shear stress (WSS), relative residence time (RRT), and recirculation fraction (RF) were calculated to assess hemodynamic changes in the right atrium at different angles of the port of the SVCS. Results: As the angle of the port of the superior chamber cannula changed, the location of the high-velocity blood impingement from the SVCS changed, and the pattern of blood flow within the right atrium was dramatically altered. The results for the maximum right atrial wall pressure were 13,472 pa, 13,424 pa, 10,915 pa, 7680.2 pa, 5890.3 pa, 5597.6 pa, and 7883.5 pa (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), and the results for the mean right atrial wall pressure were 6788.9 pa, 8615.1 pa, 8684.9 pa, 6717.2 pa, 5429.2 pa, 5455.6 pa, and 7117.8 pa ( -90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°). The results of the maximum right atrial wall WSS in the seven cases were 63.572 pa, 55.839 pa, 31.705 pa, 39.531 pa, 40.11 pa, 28.474 pa, and 35.424 (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), respectively, and the results of the mean right atrial wall WSS results were 3.8589 pa, 3.6706 pa, 3.3013 pa, 3.2487 pa, 2.3995 pa, 1.3304 pa, and 2.0747 pa (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), respectively. The results for the area percentage of high RRT in the seven cases were 3.44%, 2.23%, 4.24%, 1.83%, 3.69%, 7.73%, and 3.68% (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), and the results for the RF were 21.57%, 23.24%, 19.78%, 12.57%, 10.24%, 5.07%, and 8.05% (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°). Conclusions: The more the port of the SVCS is oriented toward the TV, the more favorable it is for reducing RF and the impingement of blood flow in the right atrial wall, but there may be an increased risk of RRT. The opposite orientation of the SVCS port to the TV is not conducive to reducing flow impingement on the right atrial wall and RF.

Effects of Different Eccentric Cycling Intensities on Brachial Artery Endothelial Shear Stress and Blood Flow Patterns

ABSTRACT Eccentric exercise has gained attention as a novel exercise modality that increases muscle performance at a lower metabolic demand. However, vascular responses to eccentric cycling (ECC) are unknown, thus gaining knowledge regarding endothelial shear stress (ESS) during ECC may be crucial for its application in patients. The purpose of this study was to explore ECC-induced blood flow patterns and ESS across three different intensities in ECC. Eighteen young, apparently healthy subjects were recruited for two laboratory visits. Maximum oxygen consumption, power output, and blood lactate (BLa) threshold were measured to determine workload intensities. Blood flow patterns in the brachial artery were measured via ultrasound imaging and Doppler on an eccentric ergometer during a 5 min workload steady exercise test at low (BLa of 0–2 mmol/L), moderate (BLa 2–4 mmol/L), and high intensity (BLa levels > 4 mmol/L). There was a significant increase in the antegrade ESS in an intensity-dependent manner (baseline: 44.2 ± 8.97; low: 55.6 ± 15.2; moderate: 56.0 ± 10.5; high: 70.7 ± 14.9, all dynes/cm2, all p values < 0.0002) with the exception between low and moderate and Re (AU) showed turbulent flow at all intensities. Regarding retrograde flow, ESS also increased in an intensity-dependent manner (baseline 9.72 ± 4.38; low: 12.5 ± 3.93; moderate: 15.8 ± 5.45; high: 15.7 ± 6.55, all dynes/cm2, all p values < 0.015) with the exception between high and moderate and Re (AU) showed laminar flow in all intensities. ECC produced exercise-induced blood flow patterns that are intensity-dependent. This suggests that ECC could be beneficial as a modulator of endothelial homeostasis.

Low or oscillatory shear stress and endothelial permeability in atherosclerosis.

Endothelial shear stress is a tangential stress derived from the friction of the flowing blood on the endothelial surface of the arterial wall and is expressed in units of force/unit area (dyne/cm2). Branches and bends of arteries are exposed to complex blood flow patterns that generate low or oscillatory endothelial shear stress, which impairs glycocalyx integrity, cytoskeleton arrangement and endothelial junctions (adherens junctions, tight junctions, gap junctions), thus increasing endothelial permeability. The lipoproteins and inflammatory cells penetrating intima due to the increased endothelial permeability characterizes the pathological changes in early stage of atherosclerosis. Endothelial cells are critical sensors of shear stress, however, the mechanisms by which the complex shear stress regulate endothelial permeability in atherosclerosis remain unclear. In this review, we focus on the molecular mechanisms of the endothelial permeability induced by low or oscillatory shear stress, which will shed a novel sight in early stage of atherosclerosis.

Two-phase magnetohydrodynamic blood flow through curved porous artery

Blood arteries are important part of our cardiovascular system. A comprehensive study of shape and anatomy of blood arteries allows to elucidate the dynamics of blood flow in these arteries. Typically, the arteries are a curved-tube like structure, with arterial walls exhibiting a composition of various porous layers. The current study embarks on a theoretical exploration of a two-fluid model of blood flow and heat transfer through the curved artery under an influence of a magnetic field. The artery walls are composed of Brinkman and Darcy layers. The blood flows through a curved artery exerts centrifugal forces on the arterial walls that leads to change the blood flow patterns. The significant effects of curvature along with the intensity of an applied magnetic field on the blood flow patterns, heat transfer, and resistance impedance in curved artery have been investigated in the present work. The mathematical model of the proposed work is tackled by the homotopy analysis method using physically relevant boundary and interface conditions. The significant outcome of the present work is that the heat transfer rate increases with the increase in the curvature parameter, and it reduces on raising the couple stress parameter and Hartmann number. The novelty of this work lies in the consideration blood flow and heat transfer in inner endothelial layers of curved porous artery. The result presented in this work is vital to assess the condition of atherosclerosis, aneurysms, vasculties, blood clot, etc.; beyond this, the present model can be extended for medical diagnostics, treatment planning, medical device design, drug delivery optimization, and biomedical engineering research. This study can ultimately contribute for improved patient care and outcomes in cardiovascular medicine.

Laser ablation for preventing coronary obstruction and maintaining coronary access in redo-TAVR: A proof of concept.

Redo-transcatheter aortic valve replacement (TAVR) is a promising treatment for transcatheter aortic valve degeneration, becoming increasingly relevant with an aging population. In redo-TAVR, the leaflets of the initial (index) transcatheter aortic valve (TAV) are displaced vertically when the second TAV is implanted, creating a cylindrical cage that can impair coronary cannulation and flow. Preventing coronary obstruction and maintaining coronary access is essential, especially in young and low-risk patients undergoing TAVR. This study aimed to develop a new leaflet modification strategy using laser ablation to prevent coronary obstruction and facilitate coronary access after repeat TAVR. To evaluate the feasibility of the leaflet modification technique using laser ablation, the initial phase of this study involved applying a medical-grade ultraviolet laser for ablation through pericardial tissue. Following this intervention, computational fluid dynamics simulations were utilized to assess the efficacy of the resulting perforations in promoting coronary flow. These simulations played a crucial role in understanding the impact of the modifications on blood flow patterns, ensuring these changes would facilitate the restoration of coronary circulation. Laser ablation of pericardium leaflets was successful, demonstrating the feasibility of creating openings in the TAV leaflets. Flow simulation results show that ablation of index valve leaflets can effectively mitigate the flow obstruction caused by sinus sequestration in redo-TAVR, with the extent of restoration dependent on the number and location of the ablated openings. Laser ablation could be a viable method for leaflet modification in redo-TAVR, serving as a new tool in interventional procedures.

Associations of Cerebral Blood Flow Patterns With Gray and White Matter Structure in Patients With Temporal Lobe Epilepsy.

Neuroimaging studies in patients with temporal lobe epilepsy (TLE) show widespread brain network alterations beyond the mesiotemporal lobe. Despite the critical role of the cerebrovascular system in maintaining whole-brain structure and function, changes in cerebral blood flow (CBF) remain incompletely understood in the disease. Here, we studied whole-brain perfusion and vascular network alterations in TLE and assessed its associations with gray and white matter compromises and various clinical variables. We included individuals with and without pharmaco-resistant TLE who underwent multimodal 3T MRI, including arterial spin labelling, structural, and diffusion-weighted imaging. Using surface-based MRI mapping, we generated individualized cortico-subcortical profiles of perfusion, morphology, and microstructure. Linear models compared regional CBF in patients with controls and related alterations to morphological and microstructural metrics. We further probed interregional vascular networks in TLE, using graph theoretical CBF covariance analysis. The effects of disease duration were explored to better understand the progressive changes in perfusion. We assessed the utility of perfusion in separating patients with TLE from controls using supervised machine learning. Compared with control participants (n = 38; mean ± SD age 34.8 ± 9.3 years; 20 females), patients with TLE (n = 24; mean ± SD age 35.8 ± 10.6 years; 12 females) showed widespread CBF reductions predominantly in fronto-temporal regions (Cohen d -0.69, 95% CI -1.21 to -0.16), consistent in a subgroup of patients who remained seizure-free after surgical resection of the seizure focus. Parallel structural profiling and network-based models showed that cerebral hypoperfusion may be partially constrained by gray and white matter changes (8.11% reduction in Cohen d) and topologically segregated from whole-brain perfusion networks (area under the curve -0.17, p < 0.05). Negative effects of progressive disease duration further targeted regional CBF profiles in patients (r = -0.54, 95% CI -0.77 to -0.16). Perfusion-derived classifiers discriminated patients from controls with high accuracy (71% [70%-82%]). Findings were robust when controlling for several methodological confounds. Our multimodal findings provide insights into vascular contributions to TLE pathophysiology affecting and extending beyond mesiotemporal structures and highlight their clinical potential in epilepsy diagnosis. As our work was cross-sectional and based on a single site, it motivates future longitudinal studies to confirm progressive effects, ideally in a multicentric setting.

Differentiating optic neuropathies using laser speckle flowgraphy: Evaluating blood flow patterns in the optic nerve head and peripapillary choroid.

To compare blood flow (BF) impairment patterns in different optic neuropathies using laser speckle flowgraphy (LSFG). This retrospective study enrolled 24 eyes of 24 patients with non-arteritic anterior ischemic optic neuropathy (NAAION), 59 eyes of 59 patients with optic neuritis (ON), 677 eyes of 677 patients with open-angle glaucoma (OAG), and 110 eyes of 110 controls. The patient backgrounds of all groups were compared. Ophthalmologic findings were evaluated, adjusting for age, sex, blood pressure, pulse rate, and underlying systemic diseases with 1:1 optimal propensity score matching. We used LSFG to obtain optic nerve head (ONH) vessel-area mean blur rate (MBR; ONH-MV), ONH tissue-area MBR (ONH-MT), and choroidal MBR. The NAAION and ON groups were compared with the control and OAG groups. Best-corrected visual acuity was worse in the NAAION, ON, and OAG groups than in controls (p < 0.001). Circumpapillary retinal nerve fibre layer thickness was higher in the NAAION and ON groups and lower in the OAG group than in controls (p < 0.001). Compared to controls, the NAAION and OAG groups had significantly lower ONH-MV, ONH-MT, and choroidal MBR (p < 0.05). Additionally, the NAAION group had lower ONH-MV and choroidal MBR than the OAG group (p = 0.003 and p < 0.001, respectively) but no difference in ONH-MT (p = 0.857). The ON group had significantly lower ONH-MV and choroidal MBR compared to the controls (p < 0.001 and p = 0.022, respectively) but no difference in ONH-MT (p = 0.773). Optic neuropathies showed different patterns of ocular BF impairment. Therefore, LSFG can be a useful tool for differentiating optic neuropathies.

The New Frontiers of Fetal Imaging: MRI Insights into Cardiovascular and Thoracic Structures.

Fetal magnetic resonance imaging (fMRI) represents a second-line imaging modality that provides multiparametric and multiplanar views that are crucial for confirming diagnoses, detecting associated pathologies, and resolving inconclusive ultrasound findings. The introduction of high-field magnets and new imaging sequences has expanded MRI's role in pregnancy management. Recent innovations in ECG-gating techniques have revolutionized the prenatal evaluation of congenital heart disease by synchronizing imaging with the fetal heartbeat, thus addressing traditional challenges in cardiac imaging. Fetal cardiac MRI (fCMR) is particularly valuable for assessing congenital heart diseases, especially when ultrasound is limited by poor imaging conditions. fCMR allows for detailed anatomical and functional evaluation of the heart and great vessels and is also useful for diagnosing additional anomalies and analyzing blood flow patterns, which can aid in understanding abnormal fetal brain growth and placental perfusion. This review emphasizes fMRI's potential in evaluating cardiac and thoracic structures, including various gating techniques like metric optimized gating, self-gating, and Doppler ultrasound gating. The review also covers the use of static and cine images for structural and functional assessments and discusses advanced techniques like 4D-flow MRI and T1 or T2 mapping for comprehensive flow quantification and tissue characterization.

Numerical simulation and in vitro experimental study of the hemodynamic performance of vena cava filters with helical forms

Inferior vena cava filter (IVCF) implantation is a common method of thrombus capture. By implanting a filter in the inferior vena cava (IVC), microemboli can be effectively blocked from entering the pulmonary circulation, thereby avoiding acute pulmonary embolism (PE). Inspired by the helical flow effect in the human arterial system, we propose a helical retrievable IVCF, which, due to the presence of a helical structure inducing a helical flow pattern of blood in the region near the IVCF, can effectively avoid the deposition of microemboli in the vicinity of the IVCF while promoting the cleavage of the captured thrombus clot. It also reduces the risk of IVCF dislodging and slipping in the vessel because its shape expands in the radial direction, allowing its distal end to fit closely to the IVC wall, and because its contact structure with the inner IVC wall is curved, increasing the contact area and reducing the risk of the vessel wall being punctured by the IVCF support structure. We used ANSYS 2023 software to conduct unidirectional fluid–structure coupling simulation of four different forms of IVCF, combined with microthrombus capture experiments in vitro, to explore the impact of these four forms of IVCF on blood flow patterns and to evaluate the risk of IVCF perforation and IVCF dislocation. It can be seen from the numerical simulation results that the helical structure does have the function of inducing blood flow to undergo helical flow dynamics, and the increase in wall shear stress (WSS) brought about by this function can improve the situation of thrombosis accumulation to a certain extent. Meanwhile, the placement of IVCF will change the flow state of blood flow and lead to the deformation of blood vessels. In in vitro experiments, we found that the density of the helical support rod is a key factor affecting the thrombus trapping efficiency, and in addition, the contact area between the IVCF and the vessel wall has a major influence on the risk of IVCF displacement.

Abstract Tu017: MerTK inhibition aggravates partial carotid ligation-induced atherosclerosis

Introduction: Partial carotid ligation (PCL) is a widely used model to generate acute disturbed flow (d-flow) in left carotid artery (LCA), leading to rapid endothelial dysfunction and atherosclerosis formation. While the right carotid artery (RCA) without PCL is a built-in control characterized by steady flow (s-flow). Endothelial cells (ECs) form a single cell layer that is constantly exposed to blood flow patterns and play important roles in atherosclerosis. MER proto-oncogene tyrosine kinase (MerTK) is the major receptor for efferocytosis, a process of the efficient clearance of apoptotic cells. MerTK is mainly expressed in macrophages and there are very limited reports focusing on MerTK function in ECs. This study was designed to investigate the role of blood flow patterns in regulating MerTK expression in aortic ECs and its contributions to the development of atherosclerosis. Methods: Partial carotid artery ligation combined with AAV-PCSK9 and high fat diet (HFD) were used to set up acute atherosclerosis within 4 weeks with WT and MerTK -/- mice. Proteomics and molecular experiments were applied to reveal the potential mechanism pathways. Results: Our proteomics data showed that, compared with WT group, MerTK -/- aggravates atherosclerosis in LCA through upregulation of endothelial dysfunction markers (e.g. IL-1β, NF-κB, TLR4, MAPK signaling) and mitochondrial dysfunction. Our immunostaining data further validates the proteomics data, showing that MerTK -/- induces impaired endothelial efferocytosis and expression of endothelial dysfunction markers (e.g., Caspase-3, NF-κB, TLR4, vWF, VCAM-1, and P22 phox ) and promotes the development of atherosclerosis. Conclusion: Our data suggests that endothelial MerTK is sensitive to d-flow and determines endothelial efferocytosis in vivo. MerTK inhibition promotes endothelial dysfunction and atherosclerosis. Our data may provide novel evidence and reference opinions for the application of endothelial MerTK- targeted therapeutics to treat atherosclerosis.

Effects of high-frequency mechanical stimuli on flow related vascular cell biology.

Mechanical forces related to blood pressure and flow patterns play a crucial role in vascular homeostasis. Perturbations in vascular stresses and strain resulting from changes in hemodynamic may occur in pathological conditions, leading to vascular dysfunction as well as in vascular prosthesis, arteriovenous shunt for hemodialysis and in mechanical circulation support. Turbulent-like blood flows can induce high-frequency vibrations of the vessel wall, and this stimulus has recently gained attention as potential contributors to vascular pathologies, such as development of intimal hyperplasia in arteriovenous fistula for hemodialysis. However, the biological response of vascular cells to this stimulus remains incompletely understood. This review provides an analysis of the existing literature concerning the impact of high-frequency stimuli on vascular cell morphology, function, and gene expression. Morphological and functional investigations reveal that vascular cells stimulated at frequencies higher than the normal heart rate exhibit alterations in cell shape, alignment, and proliferation, potentially leading to vessel remodeling. Furthermore, vibrations modulate endothelial and smooth muscle cells gene expression, affecting pathways related to inflammation, oxidative stress, and muscle hypertrophy. Understanding the effects of high-frequency vibrations on vascular cells is essential for unraveling the mechanisms underlying vascular diseases and identifying potential therapeutic targets. Nevertheless, there are still gaps in our understanding of the molecular pathways governing these cellular responses. Further research is necessary to elucidate these mechanisms and their therapeutic implications for vascular diseases.

Neural networks-based framework for recognizing streaming patterns in magnetized Maxwell–Oldroyd-B blood blended with tetra-hybrid nanoparticles and microbes over stenosis in an elastic artery

The proposed study delves into investigating blood flow patterns and thermal and solutal transport in an artery affected by stenosis. Specifically, it explores the behavior of blood ingrained with tetra-hybrid nanoparticles and gyrotactic microbes under magnetic effects. To capture the non-Newtonian nature of blood in such complex scenarios, the Maxwell-Oldroyd-B (MO) fluid model is employed. The pertinent nonlinear partial differential equations system accounts for similarity transformations and boundary layer assertions. Numerical results are assessed using a potent shooting approach with a fourth-order Runge–Kutta (RK4) method implemented through MATLAB’s bvp4c commands. The computational outcomes are visualized via graphical representation and tabulated data for in-depth analysis and illustration. The research yields significant insights into various model parameters. For instance, the Lorentz force is observed to exert a drag effect, hindering blood flow velocity, while the opposite trend is observed for blood temperature. Additionally, higher Peclet numbers correlate with reduced mass concentration levels, while gyrotactic microbes’ density profile exhibits an upsurge with elevated Lewis numbers. Notably, the Nusselt number for Newtonian blood is lower than MO blood, shedding light on the impact of blood properties on heat transport. Furthermore, this study proposes a technique based on artificial neural networks (ANNs) for accurately predicting skin friction coefficient, Nusselt number, Sherwood number, and microbes’ density number. The proposed algorithm achieves remarkable accuracy rates of 99.65% on the testing dataset and 99.99% during cross-validation for predicting the skin friction coefficient. The novel findings generated by this model hold promising implications for the treatment and monitoring of arterial diseases, as well as the development of cutting-edge medical devices and technologies.

Flow-mediated modulation of the endothelial cell lipidome.

The luminal surface of the endothelium is exposed to dynamic blood flow patterns that are known to affect endothelial cell phenotype. While many studies have documented the phenotypic changes by gene or protein expression, less is known about the role of blood flow pattern on the endothelial cell (EC) lipidome. In this study, shotgun lipidomics was conducted on human aortic ECs (HAECs) exposed to unidirectional laminar flow (UF), disturbed flow (DF), or static conditions for 48h. A total of 520 individual lipid species from 17 lipid subclasses were detected. Total lipid abundance was significantly increased for HAECs exposed to DF compared to UF conditions. Despite the increase in the total lipid abundance, HAECs maintained equivalent composition of each lipid subclass (% of total lipid) under DF and UF. However, by lipid composition (% of total subclass), 28 lipid species were significantly altered between DF and UF. Complimentary RNA sequencing of HAECs exposed to UF or DF revealed changes in transcripts involved in lipid metabolism. Shotgun lipidomics was also performed on HAECs exposed to pro-inflammatory agonists lipopolysaccharide (LPS) or Pam3CSK4 (Pam3) for 48h. Exposure to LPS or Pam3 reshaped the EC lipidome in both unique and overlapping ways. In conclusion, exposure to flow alters the EC lipidome and ECs undergo stimulus-specific lipid reprogramming in response to pro-inflammatory agonist exposure. Ultimately, this work provides a resource to profile the transcriptional and lipidomic changes that occur in response to applied flow that can be accessed by the vascular biology community to further dissect and extend our understanding of endothelial lipid biology.

A comprehensive MRI-based computational model of blood flow in compliant aorta using radial basis function interpolation

BackgroundProperly understanding the origin and progression of the thoracic aortic aneurysm (TAA) can help prevent its growth and rupture. For a better understanding of this pathogenesis, the aortic blood flow has to be studied and interpreted in great detail. We can obtain detailed aortic blood flow information using magnetic resonance imaging (MRI) based computational fluid dynamics (CFD) with a prescribed motion of the aortic wall.MethodsWe performed two different types of simulations—static (rigid wall) and dynamic (moving wall) for healthy control and a patient with a TAA. For the latter, we have developed a novel morphing approach based on the radial basis function (RBF) interpolation of the segmented 4D-flow MRI geometries at different time instants. Additionally, we have applied reconstructed 4D-flow MRI velocity profiles at the inlet with an automatic registration protocol.ResultsThe simulated RBF-based movement of the aorta matched well with the original 4D-flow MRI geometries. The wall movement was most dominant in the ascending aorta, accompanied by the highest variation of the blood flow patterns. The resulting data indicated significant differences between the dynamic and static simulations, with a relative difference for the patient of 7.47±14.18% in time-averaged wall shear stress and 15.97±43.32% in the oscillatory shear index (for the whole domain).ConclusionsIn conclusion, the RBF-based morphing approach proved to be numerically accurate and computationally efficient in capturing complex kinematics of the aorta, as validated by 4D-flow MRI. We recommend this approach for future use in MRI-based CFD simulations in broad population studies. Performing these would bring a better understanding of the onset and growth of TAA.

Identification of cortical arteries and veins in awake mice using two-photon microscopy.

Distinguishing arteries from veins in the cerebral cortex is critical for studying hemodynamics under pathophysiological conditions, which plays an important role in the diagnosis and treatment of various vessel-related diseases. However, due to the complexity of the cerebral vascular network, it is challenging to identify arteries and veins invivo. Here, we demonstrate an artery-vein separation method that employs a combination of multiple scanning modes of two-photon microscopy and a custom-designed stereoscopic fixation device for mice. In this process, we propose a novel method for determining the line scanning direction, which allows us to determine the blood flow directions. The vasculature branches have been identified using an optimized z-stack scanning mode, followed by the separation of blood vessel types according to the directions of blood flow and branching patterns. Using this strategy, the penetrating arterioles and penetrating venules in awake mice could be accurately identified and the type of cerebral thrombus has been also successfully isolated without any empirical knowledge or algorithms. Our research presents a new, more accurate, and efficient method for cortical artery-vein separation in awake mice, providing a useful strategy for the application of two-photon microscopy in the study of cerebrovascular pathophysiology.

Numerical simulation of endovascular treatment options for cerebral aneurysms

AbstractPredicting the long‐term success of endovascular interventions in the clinical management of cerebral aneurysms requires detailed insight into the patient‐specific physiological conditions. In this work, we not only propose numerical representations of endovascular medical devices such as coils, flow diverters or Woven EndoBridge but also outline numerical models for the prediction of blood flow patterns in the aneurysm cavity right after a surgical intervention. Detailed knowledge about the postsurgical state then lays the basis to assess the chances of a stable occlusion of the aneurysm required for a long‐term treatment success. To this end, we propose mathematical and mechanical models of endovascular medical devices made out of thin metal wires. These can then be used for fully resolved flow simulations of the postsurgical blood flow, which in this work will be performed by means of a Lattice Boltzmann method applied to the incompressible Navier–Stokes equations and patient‐specific geometries. To probe the suitability of homogenized models, we also investigate poro‐elastic models to represent such medical devices. In particular, we examine the validity of this modeling approach for flow diverter placement across the opening of the aneurysm cavity. For both approaches, physiologically meaningful boundary conditions are provided from reduced‐order models of the vascular system. The present study demonstrates our capabilities to predict the postsurgical state and lays a solid foundation to tackle the prediction of thrombus formation and, thus, the aneurysm occlusion in a next step.