scholarly journals A framework for incorporating 3D hyperelastic vascular wall models in 1D blood flow simulations

2021 ◽  
Author(s):  
Alberto Coccarelli ◽  
Jason M. Carson ◽  
Ankush Aggarwal ◽  
Sanjay Pant
Keyword(s):  
Sensitivity Analysis ◽  
Blood Flow ◽  
Structural Model ◽  
Structural Parameters ◽  
Current Model ◽  
Circumferential Stress ◽  
Three Dimensional ◽  
Vascular Wall ◽  
Opening Angle ◽  
Special Focus

AbstractWe present a novel framework for investigating the role of vascular structure on arterial haemodynamics in large vessels, with a special focus on the human common carotid artery (CCA). The analysis is carried out by adopting a three-dimensional (3D) derived, fibre-reinforced, hyperelastic structural model, which is coupled with an axisymmetric, reduced order model describing blood flow. The vessel transmural pressure and lumen area are related via a Holzapfel–Ogden type of law, and the residual stresses along the thickness and length of the vessel are also accounted for. After a structural characterization of the adopted hyperelastic model, we investigate the link underlying the vascular wall response and blood-flow dynamics by comparing the proposed framework results against a popular tube law. The comparison shows that the behaviour of the model can be captured by the simpler linear surrogate only if a representative value of compliance is applied. Sobol’s multi-variable sensitivity analysis is then carried out in order to identify the extent to which the structural parameters have an impact on the CCA haemodynamics. In this case, the local pulse wave velocity (PWV) is used as index for representing the arterial transmission capacity of blood pressure waveforms. The sensitivity analysis suggests that some geometrical factors, such as the stress-free inner radius and opening angle, play a major role on the system’s haemodynamics. Subsequently, we quantified the differences in haemodynamic variables obtained from different virtual CCAs, tube laws and flow conditions. Although each artery presents a distinct vascular response, the differences obtained across different flow regimes are not significant. As expected, the linear tube law is unable to accurately capture all the haemodynamic features characterizing the current model. The findings from the sensitivity analysis are further confirmed by investigating the axial stretching effect on the CCA fluid dynamics. This factor does not seem to alter the pressure and flow waveforms. On the contrary, it is shown that, for an axially stretched vessel, the vascular wall exhibits an attenuation in absolute distension and an increase in circumferential stress, corroborating the findings of previous studies. This analysis shows that the new model offers a good balance between computational complexity and physics captured, making it an ideal framework for studies aiming to investigate the profound link between vascular mechanobiology and blood flow.

Biomechanical Mechanisms and Hemodynamics in the Case of Stenosis

2019 ◽  
Vol 9 (10) ◽  
pp. 1334-1338
Author(s):  
Yu-Chou Huang ◽  
Han-Yi Cheng
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Blood Flow ◽  
Magnetic Resonance ◽  
Blood Flow Velocity ◽  
Three Dimensional ◽  
Vascular Wall ◽  
Magnetic Resonance Images ◽  
Artery Segment

The objective of the present study is to investigate the blood flow of the artery with stenosis using finite element method. Three-dimensional 3-D artery models were reconstructed to simulate blood hemodynamic behaviors from magnetic resonance images. Many papers have studied 3-D finite element artery models, but few have examined the effects of different stenosis thicknesses in arteries. It is imperative to incorporate the mechanical properties of a diseased artery segment into treatment planning because stress is a strong biological trigger that directs atherosclerosis protection. Stress may also have predictive value to pinpoint regions at risk for restenosis. The results showed that stenosis of a 1 mm thickness decreased the blood flow velocity about 48%. This confirmed that stenosis also induces abnormal stress in the narrowest position of a vascular wall. This research provides information for arteries with stenosis in clinical treatment.

Simulation of personalised haemodynamics by various mounting positions of a prosthetic valve using computational fluid dynamics

2019 ◽  
Vol 64 (2) ◽  
pp. 147-156 ◽  
Author(s):  
Markus Bongert ◽  
Marius Geller ◽  
Werner Pennekamp ◽  
Volkmar Nicolas
Keyword(s):  
Blood Flow ◽  
Aortic Valve ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Heart Valve Disease ◽  
Patient Specific ◽  
Opening Angle ◽  
The European Union ◽  
Prosthetic Valves ◽  
Magnetic Resonance Imaging Mri

Abstract Diseases of the cardiovascular system account for nearly 42% of all deaths in the European Union. In Germany, approximately 12,000 patients receive surgical replacement of the aortic valve due to heart valve disease alone each year. A three-dimensional (3D) numerical model based on patient-specific anatomy derived from four-dimensional (4D) magnetic resonance imaging (MRI) data was developed to investigate preoperatively the flow-induced impact of mounting positions of aortic prosthetic valves to select the best orientation for individual patients. Systematic steady-state analysis of blood flow for different rotational mounting positions of the valve is only possible using a virtual patient model. A maximum velocity of 1 m/s was used as an inlet boundary condition, because the opening angle of the valve is at its largest at this velocity. For a comparative serial examination, it is important to define the standardised general requirements to avoid impacts other than the rotated implantation of the prosthetic aortic valve. In this study, a uniform velocity profile at the inlet for the inflow of the aortic valve and the real aortic anatomy were chosen for all simulations. An iterative process, with the weighted parameters flow resistance (1), shear stress (2) and velocity (3), was necessary to determine the best rotated orientation. Blood flow was optimal at a 45° rotation from the standard implantation orientation, which will offer a supply to the coronary arteries.

Static Stress Distribution in Microvessel Wall with a Layered Model

2013 ◽  
Vol 772 ◽  
pp. 258-263
Author(s):  
Fa Rong Gao ◽  
Xu Gang Xi ◽  
Yun Yuan Gao ◽  
Qi Zhong Zhang
Keyword(s):  
Stress Distribution ◽  
Outer Layer ◽  
Current Model ◽  
Circumferential Stress ◽  
Three Dimensional ◽  
Static Stress ◽  
Stress Changes ◽  
Elastic Vessel ◽  
Microvessel Wall ◽  
Initial Blood Pressure

Based on the vascular membrane stress model and the pseudo-elastic vessel model, the combination constitutive model with a layered structure in microvessel is presented in this paper. By using obtained constitutive equations of the current model, the circumferential stress of the membrane intimal (inner) layer and the three-dimensional stress distribution of the structural outer layer are analyzed. Under the initial blood pressure state, the vascular static stress changes with the inner stiffness increase are also discussed. The results show that with inner stiffness increasing, the stress of outer layer is less affected but the circumferential stress of the intimal layer is increased significantly, which may be one potential risk factor for the vascular injury. These analysis methods and its conclusions have some theoretical significance for studying the problems of arteriosclerosis and other diseases, and preventing the occurrence of related diseases.

scholarly journals Modelling the layer-specific three-dimensional residual stresses in arteries, with an application to the human aorta

2009 ◽  
Vol 7 (46) ◽  
pp. 787-799 ◽  
Author(s):  
Gerhard A. Holzapfel ◽  
Ray W. Ogden
Keyword(s):  
Residual Stress ◽  
Circumferential Stress ◽  
Three Dimensional ◽  
Residual Deformation ◽  
Cylindrical Tube ◽  
Opening Angle ◽  
Human Aorta ◽  
Geometrical Parameters ◽  
Artery Wall ◽  
The Media

This paper provides the first analysis of the three-dimensional state of residual stress and stretch in an artery wall consisting of three layers (intima, media and adventitia), modelled as a circular cylindrical tube. The analysis is based on experimental results on human aortas with non-atherosclerotic intimal thickening documented in a recent paper by Holzapfel et al. ( Holzapfel et al. 2007 Ann. Biomed. Eng. 35 , 530–545 ( doi:10.1007/s10439-006-9252-z )). The intima is included in the analysis because it has significant thickness and load-bearing capacity, unlike in a young, healthy human aorta. The mathematical model takes account of bending and stretching in both the circumferential and axial directions in each layer of the wall. Previous analysis of residual stress was essentially based on a simple application of the opening-angle method, which cannot accommodate the three-dimensional residual stretch and stress states observed in experiments. The geometry and nonlinear kinematics of the intima, media and adventitia are derived and the associated stress components determined explicitly using the nonlinear theory of elasticity. The theoretical results are then combined with the mean numerical values of the geometrical parameters and material constants from the experiments to illustrate the three-dimensional distributions of the stretches and stresses throughout the wall. The results highlight the compressive nature of the circumferential stress in the intima, which may be associated with buckling of the intima and its delamination from the media, and show that the qualitative features of the stretch and stress distributions in the media and adventitia are unaffected by the presence or absence of the intima. The circumferential residual stress in the intima increases significantly as the associated residual deformation in the intima increases while the corresponding stress in the media (which is compressive at its inner boundary and tensile at its outer boundary) is only slightly affected. The theoretical framework developed herein enables the state of residual stress to be calculated directly, serves to improve insight into the mechanical response of an unloaded artery wall and can be extended to accommodate more general geometries, kinematics and states of residual stress as well as more general constitutive models.

Beyond oxygen transport: active role of erythrocytes in the regulation of blood flow

2020 ◽  
Vol 319 (4) ◽  
pp. H866-H872 ◽  
Author(s):  
Kieran J. Richardson ◽  
Lennart Kuck ◽  
Michael J. Simmonds
Keyword(s):  
Blood Flow ◽  
Shear Flow ◽  
Intracellular Signaling ◽  
Vascular Reactivity ◽  
Three Dimensional ◽  
Tissue Perfusion ◽  
Active Role ◽  
Vascular Wall ◽  
Low Oxygen ◽  
Recent Developments

It was classically thought that the function of mammalian red blood cells (RBCs) was limited to serving as a vehicle for oxygen, given the cells’ abundance of cytosolic hemoglobin. Over the past decades, however, accumulating evidence indicates that RBCs have the capacity to sense low-oxygen tensions in hypoxic tissues, and, subsequently, release signaling molecules that influence the distribution of blood flow. The precise mechanisms that facilitate RBC modulation of blood flow are still being elucidated, although recent evidence indicates involvement of 1) adenosine triphosphate, capable of binding to purinergic receptors located on the vascular wall before initiating nitric oxide (NO; a powerful vasodilator) production in endothelial cells, and/or 2) nonvascular NO, which is now known to have several modes of production within RBCs, including an enzymatic process via a unique isoform of NO synthase (i.e., RBC-NOS), which has potential effects on the vascular smooth muscle. The physical properties of RBCs, including their tendency to form three-dimensional structures in low shear flow (i.e., aggregation) and their capacity to elongate in high shear flow (i.e., deformability), are only recently being viewed as mechanotransductive processes, with profound effects on vascular reactivity and tissue perfusion. Recent developments in intracellular signaling in RBCs, and the subsequent effects on the mechanical properties of blood, and blood flow, thus present a vivid expansion on the classic perspective of these abundant cells.

scholarly journals A functional structural model of grass development based on metabolic regulation and coordination rules

2020 ◽  
Vol 71 (18) ◽  
pp. 5454-5468 ◽  
Author(s):  
Marion Gauthier ◽  
Romain Barillot ◽  
Anne Schneider ◽  
Camille Chambon ◽  
Christian Fournier ◽  
...  
Keyword(s):  
Metabolic Regulation ◽  
Structural Model ◽  
Agronomic Traits ◽  
Current Model ◽  
Three Dimensional ◽  
Emergent Properties ◽  
Dimensional Representation ◽  
Three Dimensional Representation ◽  
C And N ◽  
Metabolic Activities

Abstract Shoot architecture is a key component of the interactions between plants and their environment. We present a novel model of grass, which fully integrates shoot morphogenesis and the metabolism of carbon (C) and nitrogen (N) at organ scale, within a three-dimensional representation of plant architecture. Plant morphogenesis is seen as a self-regulated system driven by two main mechanisms. First, the rate of organ extension and the establishment of architectural traits are regulated by concentrations of C and N metabolites in the growth zones and the temperature. Second, the timing of extension is regulated by rules coordinating successive phytomers instead of a thermal time schedule. Local concentrations are calculated from a model of C and N metabolism at organ scale. The three-dimensional representation allows the accurate calculation of light and temperature distribution within the architecture. The model was calibrated for wheat (Triticum aestivum) and evaluated for early vegetative stages. This approach allowed the simulation of realistic patterns of leaf dimensions, extension dynamics, and organ mass and composition. The model simulated, as emergent properties, plant and agronomic traits. Metabolic activities of growing leaves were investigated in relation to whole-plant functioning and environmental conditions. The current model is an important step towards a better understanding of the plasticity of plant phenotype in different environments.

MESSINE, a Parametric Three-Dimensional Eddy Current Model

2000 ◽  
Vol 12 (1) ◽  
pp. 65-86 ◽  
Author(s):  
R. La ◽  
B. Benoist ◽  
B. de Barmon ◽  
M. Talvard ◽  
R. Lengelle ◽  
...  
Keyword(s):  
Eddy Current ◽  
Current Model ◽  
Three Dimensional

Wound With Diabetes: Present Scenario And Future

2020 ◽  
Vol 16 ◽  
Author(s):  
Kuldeep B. Pawar ◽  
Shivani Desai ◽  
Ramesh R. Bhonde ◽  
Ritesh P. Bhole ◽  
Atul A. Deshmukh
Keyword(s):  
Wound Healing ◽  
Blood Flow ◽  
Healing Process ◽  
Endocrine System ◽  
Healing Time ◽  
Special Focus ◽  
Diabetic Wound ◽  
Management Options ◽  
And Migration ◽  
Proliferation And Migration

: Diabetes is a chronic metabolic disorder of endocrine system characterized by increase in blood glucose level. Several factors such as pancreatic damage, oxidative stress, infection, genetic factor, obesity, liver dysfunction play a vital role in pathogenesis of diabetes which further lead to serious diabetic complications. Diabetic wound is one such complication where the wound formation occurs, especially due to pressure and its healing process is disrupted due to factors such as hyperglycemia, neuropathy, nephropathy, peripheral vascular disease, reduction of blood flow, atherosclerosis, impaired fibroblast. Process of wound healing is delayed due to different abnormalities like alteration in nitric oxide level, increase in aldose reductase, sorbitol and fructose. Therefore, diabetic wound requires more time to heal as compare to normal wound. Healing time is delayed in diabetic wound due to many factors such as stress, decreased oxygenation supply, infection, decreased blood flow, impaired proliferation and migration rate, impaired growth factor production, impaired keratinocytes proliferation and migration, and altered vascular endothelial mediators. The current treatment for diabetic wound includes wound patches, oxygenation therapy, hydrogel patches, gene therapy, laser therapy, and stem cell therapy. Medications with phytoconstituents is also one way to manage diabetic wound, but it is not more effective for quick healing. The objective of this review is to understand the potential of various management options which are available for diabetic wound, with a special focus on biological cells.

scholarly journals High-speed volumetric two-photon fluorescence imaging of neurovascular dynamics

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiang Lan Fan ◽  
Jose A. Rivera ◽  
Wei Sun ◽  
John Peterson ◽  
Henry Haeberle ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Speed ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Fluorescence Signal ◽  
Imaging Method ◽  
Spatiotemporal Resolution ◽  
Two Photon

AbstractUnderstanding the structure and function of vasculature in the brain requires us to monitor distributed hemodynamics at high spatial and temporal resolution in three-dimensional (3D) volumes in vivo. Currently, a volumetric vasculature imaging method with sub-capillary spatial resolution and blood flow-resolving speed is lacking. Here, using two-photon laser scanning microscopy (TPLSM) with an axially extended Bessel focus, we capture volumetric hemodynamics in the awake mouse brain at a spatiotemporal resolution sufficient for measuring capillary size and blood flow. With Bessel TPLSM, the fluorescence signal of a vessel becomes proportional to its size, which enables convenient intensity-based analysis of vessel dilation and constriction dynamics in large volumes. We observe entrainment of vasodilation and vasoconstriction with pupil diameter and measure 3D blood flow at 99 volumes/second. Demonstrating high-throughput monitoring of hemodynamics in the awake brain, we expect Bessel TPLSM to make broad impacts on neurovasculature research.

Modeling of aortic valve stenosis using fluid-structure interaction method

Perfusion ◽  
2021 ◽  
pp. 026765912199854
Author(s):  
Mohammad Javad Ghasemi Pour ◽  
Kamran Hassani ◽  
Morteza Khayat ◽  
Shahram Etemadi Haghighi
Keyword(s):  
Blood Flow ◽  
Aortic Valve ◽  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Relaxation Phase ◽  
Exercise Condition ◽  
Time Dependent Domain ◽  
Comparison Of The Results

Background and objectives: Fluid structure interaction (FSI) is defined as interaction of the structures with contacting fluids. The aortic valve experiences the interaction with blood flow in systolic phase. In this study, we have tried to predict the hemodynamics of blood flow through a normal and stenotic aortic valve in two relaxation and exercise conditions using a three-dimensional FSI method. Methods: The aorta valve was modeled as a three-dimensional geometry including a normal model and two others with 25% and 50% stenosis. The geometry of the aortic valve was extracted from CT images and the models were generated by MMIMCS software and then they were implemented in ANSYS software. The pulsatile flow rate was used for all cases and the numerical simulations were conducted based on a time-dependent domain. Results: The obtained results including the velocity, pressure, and shear stress contours in different systolic time sequences were explained and discussed. The maximum blood flow velocity in relaxation phase was obtained 1.62 m/s (normal valve), 3.78 m/s (25% stenosed valve), and 4.73 m/s (50% stenosed valve). In exercise condition, the maximum velocities are 2.86, 4.32, and 5.42 m/s respectively. The maximum blood pressure in relaxation phase was calculated 111.45 mmHg (normal), 148.66 mmHg (25% stenosed), and 164.21 mmHg (50% stenosed). However, the calculated values in exercise situation were 129.57, 163.58, and 191.26 mmHg. The validation of the predicted results was also conducted using existing literature. Conclusions: We believe that such model are useful tools for biomechanical experts. The further studies should be done using experimental data and the data are implemented on the boundary conditions for better comparison of the results.

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