Bulletin of the American Physical Society
74th Annual Meeting of the APS Division of Fluid Dynamics
Volume 66, Number 17
Sunday–Tuesday, November 21–23, 2021; Phoenix Convention Center, Phoenix, Arizona
Session M15: Biological Fluid Dynamics: Physiological Large Vessels I |
Hide Abstracts |
Chair: Debanjan Mukherjee, University of Colorado Boulder Room: North 129 A |
Monday, November 22, 2021 1:10PM - 1:23PM |
M15.00001: A fast approach to determine resistances and compliances of the Windkessel models in the simulation of aortic flow Zongze Li, Wenbin Mao Getting the dynamics of blood flow in the aorta by computational fluid dynamics (CFD) provides a comprehensive picture of cardiovascular diseases, especially when clinical imaging techniques cannot reach some of the important measurements. A set of outlet boundary conditions (BCs) for downstream branches should be chosen with care to get an accurate simulation. In recent decades, the Windkessel model is widely used to be coupled with CFD to get more realistic pressure waveforms and flowrate distributions. In this work, we will demonstrate an algorithm to get the appropriate resistance and compliance of each outlet with the consideration of flow resistances from the geometry, and coupled with lattice Boltzmann method to obtain patient-specific flow patterns in the aorta. The whole procedure is automated and very fast to achieve prescribed flow distributions and max and min pressures at each branch with only one extra simulation of steady flow at peak systole. The mean L2 norm errors of CFD results compared to prescribed values are for flowrate distribution – 0.24%, for pressure – 4.82 mmHg. |
Monday, November 22, 2021 1:23PM - 1:36PM |
M15.00002: Fluid-particle Interaction Using Immersed Finite Element Method With Applications in Arterial Flows Chayut Teeraratkul, Debanjan Mukherjee Fluid-particle interaction problems are prevalent in many physiological and biomedical applications. Despite several existing approaches, handling simultaneous coupling for multi-particle systems remains a challenge. In this work, an implementation of two way coupled fluid-particle interaction algorithm is presented. The fluid-particle coupling is resolved using an immersed finite element method in which the particle is handled as a Lagrangian mesh moving on top of a Eulerian fluid mesh. This allows for the fluid mesh to be generated independently from the solid structure, thereby simplifying the meshing process for multi-particle systems. The no-slip condition and the interaction force at the fluid-solid interface is enforced using a mesh-to-mesh interpolation via basis function transformation. Support size on which the fluid-structure interaction force is applied is the size of elements touching the particle domain and therefore optimal in an element-wise sense. Results from two canonical particle laden flows problems are presented to validate the implementation, followed by illustrative simulations for fluid-structure interactions driven by pulsatile large arterial hemodynamics in the common carotid artery. |
Monday, November 22, 2021 1:36PM - 1:49PM |
M15.00003: Morphological Features of Intraluminal Thrombus Drive Vessel Wall Stress and Oxygen Flow Rana Zakerzadeh, Alexis Throop, Martina Bukac The intraluminal thrombus (ILT) plays a key chemo-mechanical role in the evolution of abdominal aortic aneurysms (AAA), which is still not fully understood. While it has been shown that ILTs may reduce the aneurysmal wall stress by acting as a mechanical buffer, they also limit oxygen transport to the AAA wall, which may cause aortic wall degeneration. The objective of this talk is to investigate how key morphological features of ILT affect the transport of oxygen to the aortic wall as well as tissue’s deformation, and therefore provide a greater understanding of the potential ILT contribution to AAA rupture. With the use of advanced simulations of coupled fluid-poroelastic structure interaction and mass transport in patient-specific geometries of AAA, a physiologically realistic approach to simulate aortic wall stress and oxygen flow in–vivo is presented. Using this computational framework, the association between mechanical stresses and oxygen starvation in the wall in different geometries of aneurysms with varying ILT shapes and thicknesses is explored. The results provide valuable insight into the salient behavior of thrombi under flow in compliant arteries, as well as the effects of thrombi on blood flow, wall deformation, peak wall stresses within AAA, and local hypoxia. |
Monday, November 22, 2021 1:49PM - 2:02PM |
M15.00004: Fluid mechanics of prostatic artery embolization Mostafa Mahmoudi, Chadrick Jennings, Keith Pereira, Andrew F Hall, Amirhossein Arzani Benign prostatic hyperplasia (BPH) is a prevalent disease associated with lower urinary tract symptoms and the most frequent benign tumor in men. To reduce BPH therapy complications, prostatic artery embolization (PAE) was developed over the past decade to replace the surgical options. PAE is a minimally invasive technique in which emboli are injected into the prostate arteries (PA), obstructing the blood flow in the hypervascular nodules. The major challenges in PAE are the catheter skill needed to navigate the tortuous small arteries and deliver emboli to the PA. In this work, we used patient-specific computational fluid dynamics modeling in SimVascular to study the hemodynamics in the iliac arterial tree considering a large network of bifurcations. Subsequently, the transport of embolic particulates in the PAE was simulated. The emboli were released at various locations across the iliac arterial tree. The emboli entering the PA were mapped back to their initial location to create particle destination maps. The results were compared to the finite-time Lyapunov exponent (FTLE) field, revealing the complex transport patterns. Our patient-specific model can be used to find the best spatial location for emboli injection and perform the embolization with minimal non-target delivery. |
Monday, November 22, 2021 2:02PM - 2:15PM |
M15.00005: Flow in the Circle of Willis during vasospasm: A poorly understood manifold for complex intracranial hemodynamics through patient-specific simulations. Angela Straccia, Dan Leotta, Fanette Chassagne, David Bass, Michael Levitt, Alberto Aliseda Vasospasm is an acute constriction of blood vessels following subarachnoid hemorrhage affecting 50-90% of patients. Perfusion to the brain is severely diminished, frequently leading to decreased patient responsiveness. While the role of flow paths in the Circle of Willis during embolic stroke is well-documented, changes during vasospasm remain unquantified. This study aims to quantify the differences in blood flow between pre-vasospasm and vasospasm conditions. Patient-specific computational fluid dynamics simulations are conducted by segmenting computed tomography scans and applying Womersley profile boundary conditions from transcranial Doppler ultrasound patient data. Bayesian analysis is applied to minimize uncertainty in model parameters – vessel diameters and mean velocities – and identify an optimal set that satisfies mass conservation. The final diameters and flow rates are compared to the distribution of values in the literature. Virtual angiograms using the diffusive-convective motion of a passive tracer are compared to clinical angiograms. Circle of Willis flows change significantly during vasospasm, including flow reversal in major intracranial vessels. |
Monday, November 22, 2021 2:15PM - 2:28PM |
M15.00006: The Effects of Left Ventricle Contractility on Aortic-Brain Hemodynamic Coupling Niema M Pahlevan, Faisal Amlani, Kevin S King, Arian Aghilinejad Abnormal aortic wave dynamics can impact the brain through two mechanisms: 1) reducing blood flow to the brain and 2) increasing pulsatile energy transmission to the brain. Clinical studies have shown that decreased flow affects lacunes, microinfarcts, white matter hyperintensities (WMH), (sub)cortical atrophy, and white/gray matter integrity. On the other hand, increased pulsatility affects Virchow−Robin spaces and microbleeds. Aortic arch stiffening leads to the loss of constructive wave dynamics that normally limit transmission of harmful pulsatile energy into the brain. Furthermore, clinical studies have shown that patients with heart failure (HF) who suffer from impaired left ventricle (LV) function have worse degrees of cognitive impairment than age-matched individuals without HF. Although previous studies have attempted to elucidate the complex relationship between aortic arch stiffness and pulsatility transmission to the brain, these studies have not adequately addressed the effect of interactions between aortic arch stiffness and LV contractility on such energy transmission nor on brain perfusion. To investigate these phenomena, we employ a computational approach using a high-order FC-based solver for coupled LV-arterial hemodynamic wave propagation. |
Monday, November 22, 2021 2:28PM - 2:41PM |
M15.00007: Numerical investigation of venous valve flow conditions in relation to development of disease Jacob T Biesinger, Matthew S Ballard Venous valves are vital to the proper function of the circulatory system. These valves open and close with pressure oscillations due to contraction and relaxation of the surrounding skeletal muscle, enabling return of blood from the lower extremities against gravity back to the heart. However, major diseases such as deep vein thrombosis (DVT) are known to originate in the vicinity of venous valves. DVT can further progress into pulmonary embolism (PE), a leading cause of death in the United States, and an especially serious concern for those who experience extended periods of physical inactivity (such as hospitalization or long plane rides). Here, we use a three-dimensional (3-D) fully-coupled fluid-solid interaction model based on the lattice-Boltzmann model and the lattice spring model to study the effect of valve morphology on disease-conducive flow conditions. Specifically, we investigate the effect of valve mechanical properties and 3-D shape on shear stress, fluid stasis and residence time, which are generally linked to thrombus formation in a variety of physiological locations. Our findings will help to enable better identification of at-risk patients to take measures to prevent DVT and PE. |
Monday, November 22, 2021 2:41PM - 2:54PM |
M15.00008: The fluid-structure instability driving aortic aneurysm formation and growth Tom Y Zhao, Guy Elisha, Ethan Johnson, Sourav Halder, Ben C Smith, Bradley D Smith, Michael Markl, Neelesh A Patankar Aneurysms are pathological, localized dilations of a blood vessel that may occur throughout the human body. Thoracic aortic aneurysms are estimated to occur with a global prevalence of 2-3%. Rupture of an aneurysm carries high risk of mortality and morbidity for the patient. Growth rates are associated with risk of rupture or dissection, but prospective prediction of growth remains a challenge. The standard of care for assessment of an aneurysm entails surveillance imaging to assess aortic dimensions at intervals of 1 or more years. After clinical follow-up, a backward- looking comparison of sizes is made to identify growth. Over this period, the aneurysm may exhibit significant growth or rupture fatally. Thus, the current standard of care for tracking aneurysm progression can only identify growth after the fact. In this work, we hypothesize that a fluid-structure instability drives aneurysm formation and growth. A single dimensionless parameter is derived from first principles that encapsulate this instability. If the stability parameter at a local cross section of the blood vessel exceeds an analytically derived threshold, an aneurysm is expected to form or grow at the site. Otherwise, the location should remain stable with time. In a retrospective study of 117 patients with thoracic aortopathies, we show that the stability parameter can be used as a diagnostic physiomarker to forecast whether an aortic aneurysm grows or stays stable. The only input to calculate the parameter for each patient is a magnetic resonance imaging (MRI) scan taken at a single time point. This analytical determination is then compared with the clinical outcome reported from a follow-up at least one year after the baseline MRI. The area under the curve for a receiver operating characteristic analysis is 0.91. No training data is necessary to tune the physical parameter. |
Monday, November 22, 2021 2:54PM - 3:07PM |
M15.00009: On the Modeling of Mechanotransduction in Flow-Mediated Dilation Bchara Sidnawi, Zhen Chen, Chandra Sehgal, Sridhar Santhanam, Qianhong Wu We report a physics based mathematical model to describe the mechanotransduction at the luminal surface of the brachial artery during a flow-mediated dilation (FMD) process. To account for the effect of the released vasodilators in response to the sudden blood flow resurgence, a scalar property is introduced as a signal radially diffusing through the arterial wall, locally affecting its compliance. The model was evaluated on 19 in vivo responses of brachial artery FMD (BAFMD) in 12 healthy subjects. It successfully reproduces the time-dependent dilation of the brachial artery. The predicted artery’s outer-to-inner radius ratio was also found to be consistent with the measurements within an acceptable margin of error. Physically meaningful dimensionless parameters quantifying the artery’s physical state arose from the model, providing a description to how sensitive or responsive the artery is to the changes of wall shear stress (WSS). Future applications of this model, via incorporating inexpensive, relatively quick, and non-invasive imaging, could potentially help detect early stages of developing forms of cardiovascular diseases. |
Monday, November 22, 2021 3:07PM - 3:20PM |
M15.00010: Investigation of endothelial and stem cell biochemical response in biomimetic 3D printed blood vessel scaffolds Kartik V Bulusu, Timothy Esworthy, Lijie Grace Zhang, Michael W Plesniak In vitro investigation of human umbilical vein endothelial cell (HUVEC) and adipose-derived stem cell (ADSC) responses in a biomimetic 3D bioprinted blood vessel model under complex physiological flows was performed. The goal is to characterize the dynamic flow conditions which drive endothelial cell mechanotransduction, cellular growth, and morphological maturation, as well as the differentiation of ADSCs into endothelial-like phenotypes. Cylindrical vessel scaffolds were 3D printed using polylactic acid (PLA) material and the vessel lumen were inoculated with a co-culture of HUVEC and ADSC in a custom-built bioreactor system using cell growth medium ((DMEM, Corning®) and (ECM, Cell Applications Inc)). The vessels were installed in a sterile experimental flow loop facility capable of providing physiological flow forcing conditions. Cellular co-culture was subjected to wall shear stresses from physiological flow forcing for up to 8 hours each day and then followed by steady flow. Real-time flow conditions were monitored using disposable blood pressure transducers and an ultrasonic flow rate sensor. Post-facto analysis was performed on dissected vessels using confocal microscopy techniques, live/dead staining, and polymerase chain reaction (PCR) testing to probe cellular growth and proliferation indicators. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700