Acoustics and Computational Models for Diagnosing Arterial Blockages

2013 ◽  
Author(s):  
M. A. Al-Rawi ◽  
A. M. Al-Jumaily
Keyword(s):  
Blood Pressure ◽  
Wave Propagation ◽  
Femoral Artery ◽  
Computational Models ◽  
Arterial Wall ◽  
Fluid Dynamic ◽  
Arterial Disease ◽  
Flow Profile ◽  
Cfd Model ◽  
Wall Displacement

Arterial blockages can occur in small or large arteries for a variety of reasons, such as obesity, stress, smoking and high cholesterol. This paper presents a feasibility study on a novel method to detect the behaviour of the blood pressure wave propagation for arteries in both healthy and diseased conditions in order to develop a relatively inexpensive method for early detection of arterial disease. The trend of this behaviour is correlated to the early development of the arterial blockage at various locations. Invasive sets of data (gathered from experiments performed on animals) are implemented into a 3D Computational Fluid Dynamic (CFD) model to determine how the arterial wall compliance changes when any abnormalities occur to the blood flow profile. At the same time, a 1D acoustical model is developed to transfer the information gathered (wave propagation for blood pressure, flow and arterial wall displacement) from the CFD model. Wave forms were collected at a location which was invasively accessible (the femoral artery). The computational and acoustical models are validated against the clinical trials and show good agreement. Any changes to the arterial wall displacement could be detected by systolic and diastolic blood pressure values at the femoral artery.

scholarly journals Understanding sex differences in long-term blood pressure regulation: insights from experimental studies and computational modeling

2019 ◽  
Vol 316 (5) ◽  
pp. H1113-H1123 ◽  
Author(s):  
Sameed Ahmed ◽  
Rui Hu ◽  
Jessica Leete ◽  
Anita T. Layton
Keyword(s):  
Blood Pressure ◽  
Sex Differences ◽  
Computational Models ◽  
Experimental Studies ◽  
Pressure Control ◽  
Blood Pressure Regulation ◽  
Pressure Regulation ◽  
Physiological Processes ◽  
Key Players

Sex differences in blood pressure and the prevalence of hypertension are found in humans and animal models. Moreover, there has been a recent explosion of data concerning sex differences in nitric oxide, the renin-angiotensin-aldosterone system, inflammation, and kidney function. These data have the potential to reveal the mechanisms underlying male-female differences in blood pressure control. To elucidate the interactions among the multitude of physiological processes involved, one may apply computational models. In this review, we describe published computational models that represent key players in blood pressure regulation, and highlight sex-specific models and their findings.

scholarly journals Transpedal Approach in Failed Antegrade Attempt of Lower Limb Peripheral Arterial Disease—A Review with Different Treatment Strategies

2020 ◽  
Vol 29 (03) ◽  
pp. 143-148
Author(s):  
Ranjit Kumar Nath ◽  
Siva Subramaniyan ◽  
Neeraj Pandit ◽  
Deepankar Vatsa
Keyword(s):  
High Risk ◽  
Peripheral Arterial Disease ◽  
Femoral Artery ◽  
Lower Limb ◽  
Treatment Strategies ◽  
Arterial Disease ◽  
Retrograde Approach ◽  
Femoral Access ◽  
Antegrade Approach ◽  
Peripheral Arterial

AbstractTranspedal access is an evolving technique primarily used in patients after failed femoral antegrade approach to revascularize complex tibiopedal lesions. In patients who are at high risk for surgery the transpedal access may be the only option in failed antegrade femoral access to avoid amputation of the limbs. In recent years transpedal access is used routinely to revascularize supra-popliteal lesions due to more success and less complications over femoral artery approach. Retrograde approach parse will not give success in all cases and importantly success depends on techniques used. There are different techniques that need to be used depending on lesion characteristics, comorbidities, and hardware available to improve success with less complications. This review provides different strategies for successful treatment of iliac and femoral artery lesions by transpedal approach after failed antegrade femoral attempt.

scholarly journals Lower-limb hot-water immersion acutely induces beneficial hemodynamic and cardiovascular responses in peripheral arterial disease and healthy, elderly controls

2017 ◽  
Vol 312 (3) ◽  
pp. R281-R291 ◽  
Author(s):  
Kate N. Thomas ◽  
André M. van Rij ◽  
Samuel J. E. Lucas ◽  
James D. Cotter
Keyword(s):  
Blood Pressure ◽  
Lower Limb ◽  
Water Immersion ◽  
Duplex Ultrasound ◽  
Arterial Disease ◽  
Hot Water ◽  
Healthy Elderly ◽  
Limb Perfusion ◽  
Peripheral Arterial ◽  
Hot Water Immersion

Passive heat induces beneficial perfusion profiles, provides substantive cardiovascular strain, and reduces blood pressure, thereby holding potential for healthy and cardiovascular disease populations. The aim of this study was to assess acute responses to passive heat via lower-limb, hot-water immersion in patients with peripheral arterial disease (PAD) and healthy, elderly controls. Eleven patients with PAD (age 71 ± 6 yr, 7 male, 4 female) and 10 controls (age 72 ± 7 yr, 8 male, 2 female) underwent hot-water immersion (30-min waist-level immersion in 42.1 ± 0.6°C water). Before, during, and following immersion, brachial and popliteal artery diameter, blood flow, and shear stress were assessed using duplex ultrasound. Lower-limb perfusion was measured also using venous occlusion plethysmography and near-infrared spectroscopy. During immersion, shear rate increased ( P < 0.0001) comparably between groups in the popliteal artery (controls: +183 ± 26%; PAD: +258 ± 54%) and brachial artery (controls: +117 ± 24%; PAD: +107 ± 32%). Lower-limb blood flow increased significantly in both groups, as measured from duplex ultrasound (>200%), plethysmography (>100%), and spectroscopy, while central and peripheral pulse-wave velocity decreased in both groups. Mean arterial blood pressure was reduced by 22 ± 9 mmHg (main effect P < 0.0001, interaction P = 0.60) during immersion, and remained 7 ± 7 mmHg lower 3 h afterward. In PAD, popliteal shear profiles and claudication both compared favorably with those measured immediately following symptom-limited walking. A 30-min hot-water immersion is a practical means of delivering heat therapy to PAD patients and healthy, elderly individuals to induce appreciable systemic (chronotropic and blood pressure lowering) and hemodynamic (upper and lower-limb perfusion and shear rate increases) responses.

CFD Analysis of the Coolant Mixing within the Upper Plenum of a Pressurized Water Reactor (PWR)

2013 ◽  
Vol 444-445 ◽  
pp. 411-415 ◽  
Author(s):  
Fu Cheng Zhang ◽  
Shen Gen Tan ◽  
Xun Hao Zheng ◽  
Jun Chen
Keyword(s):  
Temperature Distribution ◽  
Fluid Dynamic ◽  
Characteristic Temperature ◽  
Reactor Core ◽  
Flow Distribution ◽  
Sensitivity Study ◽  
Cfd Model ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor

In this study, a Computational Fluid Dynamic (CFD) model is established to obtain the 3-D flow characteristic, temperature distribution of the pressurized water reactor (PWR) upper plenum and hot-legs. In the CFD model, the flow domain includes the upper plenum, the 61 control rod guide tubes, the 40 support columns, the three hot-legs. The inlet boundary located at the exit of the reactor core and the outlet boundary is set at the hot-leg pipes several meters away from upper plenum. The temperature and flow distribution at the inlet boundary are given by sub-channel codes. The computational mesh used in the present work is polyhedron element and a mesh sensitivity study is performed. The RANS equations for incompressible flow is solved with a Realizable k-ε turbulence model using the commercial CFD code STAR-CCM+. The analysis results show that the flow field of the upper plenum is very complex and the temperature distribution at inlet boundary have significant impact to the coolant mixing in the upper plenum as well as the hot-legs. The detailed coolant mixing patterns are important references to design the reactor core fuel management and the internal structure in upper plenum.

Application of CFD Model for Inlet Flow Region of 17×17 Fuel Assembly

2006 ◽  
Author(s):  
Milorad B. Dzodzo ◽  
Bin Liu ◽  
Pablo R. Rubiolo ◽  
Zeses E. Karoutas ◽  
Michael Y. Young
Keyword(s):  
Fuel Assembly ◽  
Fluid Dynamic ◽  
Flow Distribution ◽  
Flow Region ◽  
Fretting Wear ◽  
Jet Flows ◽  
Cfd Model ◽  
Lateral Velocity ◽  
Fuel Assemblies ◽  
Inlet Conditions

A numerical investigation was performed to study the variation in axial and lateral velocity profiles occurring downstream of the inlet nozzle of a typical Westinghouse 17×17 PWR fuel assembly. A Computational Fluid Dynamic (CFD) model was developed with commercial CFD software. The model comprised the lower region of the fuel assembly, including: the Debris Filter Bottom Nozzle (DFBN), P-grid, Bottom Inconel grid, one and half grid span, as well as the lower core plate hole. The purpose of the study was to obtain insight into the flow redistribution resulting from the interaction of the jet arising from the lower core plate hole and the fuel assembly structure. In particular the axial and lateral velocities before and after the nozzle were studied. The results, axial and lateral velocity contours, streamlines and maximum axial and lateral velocity distributions at various elevations are presented and discussed in relation to the potential risk of high turbulent excitation over the rod and the resulting rod-to-grid fretting-wear damage. The CFD model results indicated that the large jet flows from the lower core plate are effectively dissipated by DFBN nozzle and the grids components of the fuel assembly. The breakup of the large jets in the DFBN and the lower grids helps to reduce the steep velocity gradients and thus the rod vibration and fretting-wear risk in the lower part of the fuel assembly. The presented CFD model is one step towards developing advanced tools that can be used to confirm and evaluate the effect of complex PWR structures on flow distribution. In the future the presented model could be integrated in a larger CFD model involving several fuel assemblies for evaluating the lateral velocities generated due to the non-uniform inlet conditions into the various fuel assemblies.

Abstract 016: Cells Programmed for the Renin Phenotype Contribute to Vascular Pathology in Renin Deficient Mice

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Masafumi Oka ◽  
Silvia Medrano ◽  
Maria Luisa S Sequeira-Lopez ◽  
R A Gomez
Keyword(s):  
Arterial Wall ◽  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Renin Angiotensin System ◽  
Arterial Disease ◽  
Vascular Pathology ◽  
Wall Thickening ◽  
Knock Out ◽  
Reporter Mice ◽  
Specific Proteins

Deletions of the renin-angiotensin system genes or pharmacological inhibition in early life result in a distinctive renal pathology: concentric and disorganized intra-renal arteriolar thickening. The origin and distribution of the cells contributing to the arterial disease are not known. Because the arteriolar thickening disappears with ablation of renin cells, we hypothesized that renin cell precursors contribute to the arterial pathology. To reveal the origin and distribution of the cells responsible for the arterial thickening we generated several mouse lines for fate tracing and also stained for cell identity specific proteins. Kidneys from Ren1c-/- (n=6) and Ren1c+/- (n=6) mice were immunostained for renin, αSMA and PECAM1. Arterial wall thickness was measured using a light microscope and the Leica MM AF ® version1.5 software. Renin cells (unable to produce renin because of the knock out) were identified using Ren1c-/-; Ren1c-YFP mice, where the yellow fluorescent protein is expressed by the Ren1c-YFP transgene designed to label all cells with an active renin promoter. In addition, we tracked the expression and distribution of aldo-keto reductase 1b7, AKR1b7, which mark cells programmed for the renin phenotype even when renin is absent. As expected, Ren1c-/- kidneys showed no renin and thicker intra-renal arteries (Arterioles: Ren1c+/- , 8.26 ± 2.5 μm vs. Ren1c-/- , 14.3 ± 3.8 μm, P<0.0001 , larger arteries: Ren1c+/- , 29.2 ± 11.1 μm vs. Ren1c-/- , 42.1 ± 11.1 μm, P<0.0001 ) AKR1b7+ and YFP+ cells were retained and observed throughout the renal arterioles. To investigate the fate and distribution of cells from the renin lineage, we used Ren1c-Cre and R26R.LacZ or mT/mG reporter mice (6 knock out and 6 control mice per strain). Cells from the renin lineage surrounded arterioles and persisted within larger arterial walls whereas PECAM1+ endothelial cells did not contribute to the arterial wall thickening. In control mice, renin cells were confined to the juxtaglomerular area. We conclude that precursor cells programmed for the renin phenotype maintain their molecular program and together with vascular smooth muscle cells contribute to nephro-vascular disease.

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