scholarly journals Reduced Order Models for Transstenotic Pressure Drop in the Coronary Arteries

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Mehran Mirramezani ◽  
Scott L. Diamond ◽  
Harold I. Litt ◽  
Shawn C. Shadden
Keyword(s):  
Pressure Drop ◽  
Coronary Arteries ◽  
Three Dimensional ◽  
Arterial Stenosis ◽  
Reduced Order ◽  
Stenosis Severity ◽  
Computational Fluid Dynamics Cfd ◽  
Algebraic Formula ◽  
Artery Disease ◽  
2D And 3D

The efficacy of reduced order modeling for transstenotic pressure drop in the coronary arteries is presented. Coronary artery disease is a leading cause of death worldwide and the computation of pressure drop in the coronary arteries has become a standard for evaluating the functional significance of a coronary stenosis. Comprehensive models typically employ three-dimensional (3D) computational fluid dynamics (CFD) to simulate coronary blood flow in order to compute transstenotic pressure drop at the arterial stenosis. In this study, we evaluate the capability of different hydrodynamic models to compute transstenotic pressure drop. Models range from algebraic formulae to one-dimensional (1D), two-dimensional (2D), and 3D time-dependent CFD simulations. Although several algebraic pressure-drop formulae have been proposed in the literature, these models were found to exhibit wide variation in predictions. Nonetheless, we demonstrate an algebraic formula that provides consistent predictions with 3D CFD results for various changes in stenosis severity, morphology, location, and flow rate. The accounting of viscous dissipation and flow separation were found to be significant contributions to accurate reduce order modeling of transstenotic coronary hemodynamics.

scholarly journals Focal pericoronary adipose tissue attenuation is related to plaque presence, plaque type, and stenosis severity in coronary CTA

2021 ◽  
Author(s):  
Runlei Ma ◽  
Marly van Assen ◽  
Daan Ties ◽  
Gert Jan Pelgrim ◽  
Randy van Dijk ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Coronary Arteries ◽  
Plaque Burden ◽  
Severe Stenosis ◽  
Plaque Type ◽  
Plaque Development ◽  
Calcified Plaque ◽  
Stenosis Severity ◽  
Dual Source ◽  
Artery Disease

Abstract Objectives To investigate the association of pericoronary adipose tissue mean attenuation (PCATMA) with coronary artery disease (CAD) characteristics on coronary computed tomography angiography (CCTA). Methods We retrospectively investigated 165 symptomatic patients who underwent third-generation dual-source CCTA at 70kVp: 93 with and 72 without CAD (204 arteries with plaque, 291 without plaque). CCTA was evaluated for presence and characteristics of CAD per artery. PCATMA was measured proximally and across the most severe stenosis. Patient-level, proximal PCATMA was defined as the mean of the proximal PCATMA of the three main coronary arteries. Analyses were performed on patient and vessel level. Results Mean proximal PCATMA was −96.2 ± 7.1 HU and −95.6 ± 7.8HU for patients with and without CAD (p = 0.644). In arteries with plaque, proximal and lesion-specific PCATMA was similar (−96.1 ± 9.6 HU, −95.9 ± 11.2 HU, p = 0.608). Lesion-specific PCATMA of arteries with plaque (−94.7 HU) differed from proximal PCATMA of arteries without plaque (−97.2 HU, p = 0.015). Minimal stenosis showed higher lesion-specific PCATMA (−94.0 HU) than severe stenosis (−98.5 HU, p = 0.030). Lesion-specific PCATMA of non-calcified, mixed, and calcified plaque was −96.5 HU, −94.6 HU, and −89.9 HU (p = 0.004). Vessel-based total plaque, lipid-rich necrotic core, and calcified plaque burden showed a very weak to moderate correlation with proximal PCATMA. Conclusions Lesion-specific PCATMA was higher in arteries with plaque than proximal PCATMA in arteries without plaque. Lesion-specific PCATMA was higher in non-calcified and mixed plaques compared to calcified plaques, and in minimal stenosis compared to severe; proximal PCATMA did not show these relationships. This suggests that lesion-specific PCATMA is related to plaque development and vulnerability. Key Points • In symptomatic patients undergoing CCTA at 70 kVp, PCATMAwas higher in coronary arteries with plaque than those without plaque. • PCATMAwas higher for non-calcified and mixed plaques compared to calcified plaques, and for minimal stenosis compared to severe stenosis. • In contrast to PCATMAmeasurement of the proximal vessels, lesion-specific PCATMAshowed clear relationships with plaque presence and stenosis degree.

scholarly journals Correlations Between Heparinated Blood Glucose Determined with Automatic Analyzers and the Severity of the Acute Coronary Disease

2019 ◽  
Vol 70 (8) ◽  
pp. 2923-2925
Author(s):  
Maria Cristina Vladeanu ◽  
Iris Bararu Bojan ◽  
Iuliana Ardeleanu ◽  
Andrei Bojan ◽  
Dan Iliescu ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Unstable Angina ◽  
Coronary Disease ◽  
Coronary Arteries ◽  
Arterial Stenosis ◽  
Vessel Disease ◽  
Coronary Lesions ◽  
Artery Disease ◽  
Severity Of The Disease ◽  
Acute Coronary Artery Disease

Diabetes is one of the most important cardiovascular risk factors. Hyperglycemia leads to several metabolic alterations, thus creating conditions for a poor cardiovascular outcome. Our study phocussed on the prevalence of glucidic metabolism alterations in the acute coronary disease, as well as the association between hyperglycemia, diabetes and severe coronary lesions. We performed a study on 58 patients with acute coronary artery disease, divided in two groups, unstable angina and acute myocardial infarction and we evaluated the severity of the disease based on the angiographical results: no vessel disease (no significant lesions), one-vessel disease (one arterial stenosis/occlusion), two-vessel disease (two stenotic coronary arteries) and three-vessel disease (lesions of all three coronary arteries). Blood samples were collected in heparinated tubes and rapidly transferred to the laboratory for analysis, using automated glucose analyzers, in order to prevent errors due to glycolysis. More than half of the patients were diabetic and glycemic values were significantly higher in patients with myocardial infarction (126.67 vs 163.64 mg/dL). The prevalence of diabetes was significantly higher among the three vessel disease patients, both with unstable angina (38.9%; p=0.037) and with myocardial infarction (35.1%; p=0.345). In conclusion, diabetes and hyperglycemia create the setting for acute coronary disease, especially with lesions of all the three coronary arteries.

Abstract 17377: Quantification of Arterial Stenosis Severity Based on the Changes in the Perfusion Wave Dynamics; a Novel Technology for Monitoring Peripheral Artery Disease

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Tomer Heitner ◽  
Amit Livneh ◽  
Jonathan Lorber ◽  
Ron Karmeli ◽  
Amir Landesberg
Keyword(s):  
Early Detection ◽  
Peripheral Artery Disease ◽  
Unmet Need ◽  
The Elderly ◽  
Arterial Stenosis ◽  
Slow Phase ◽  
Peripheral Artery ◽  
Phase Duration ◽  
Stenosis Severity ◽  
Artery Disease

Introduction: Current screening modalities for peripheral artery disease (PAD) lack sensitivity especially in the elderly and diabetics, and there is an unmet need for early detection of restenosis after revascularization. Hypothesis: We have hypothesized that arterial stenosis is associated with adaptive arteriolar vasodilatation, which alters the downstream perfusion dynamics and prolongs the initial phase of the perfusion upstroke. These changes can be utilized for quantification of the arterial stenosis severity. Methods: We measured the lower leg perfusion with impedance plethysmography and compared it with other modalities used in the clinic and the gold-standard angiography. The various phases of the perfusion wave were identified by analyzing the first and second derivatives of the plethysmography. The signals were acquired from PAD patients before and after they underwent revascularization, to validate the ability to detect stenosis and successful revascularization. Results: Eighteen consenting patients were recruited (61±10 years old) and nineteen legs were treated. The perfusion upstroke encompasses 2 or 3 distinctive phases. An initial slow phase that is followed by a brisk upstroke and a final sallower augmentation in some patients. The slow phase duration (SPd) was 113±45 ms in extremities with above-knee (AK) arterial stenosis (n=17) while significantly shorter SPd of 26±0 ms was observed in limbs without AK stenoses (P = 0.011). In the AK extremities, the SPd significantly decreased to 52±40 ms after successful revascularization (P<0.01). Moreover, in AK cases with a satisfactory post-operative result (Duplex assessment), the SPd dramatically decreased from 103±35 ms before revascularization to 35±18 ms afterward (P<0.01, n=12). Conclusions: Analysis of the perfusion dynamic provides a gamut of precious indices. The SPd is a novel index that can detect and quantify the severity of arterial stenosis. The technology can significantly improve the surveillance of PAD patients and may be used for early detection of restenosis.

scholarly journals Research on Duct Flow Field Optimisation of a Robot Vacuum Cleaner

10.5772/50903 ◽  
2011 ◽  
Vol 8 (5) ◽  
pp. 65 ◽  
Author(s):  
Xiao-bo Lai ◽  
Hai-shun Wang ◽  
Hua-shan Liu
Keyword(s):  
Pressure Drop ◽  
Flow Field ◽  
Velocity Vector ◽  
Fluid Model ◽  
Three Dimensional ◽  
Theoretical Modelling ◽  
Duct Flow ◽  
Vacuum Cleaner ◽  
Arbitrary Plane ◽  
Computational Fluid Dynamics Cfd

The duct of a robot vacuum cleaner is the length of the flow channel between the inlet of the rolling brush blower and the outlet of the vacuum blower. To cope with the pressure drop problem of the duct flow field in a robot vacuum cleaner, a method based on Pressure Implicit with Splitting of Operators (PRISO) algorithm is introduced and the optimisation design of the duct flow field is implemented. Firstly, the duct structure in a robot vacuum cleaner is taken as a research object, with the computational fluid dynamics (CFD) theories adopted; a three-dimensional fluid model of the duct is established by means of the FLUENT solver of the CFD software. Secondly, with the k-∊ turbulence model of three-dimensional incompressible fluid considered and the PRISO pressure modification algorithm employed, the flow field numerical simulations inside the duct of the robot vacuum cleaner are carried out. Then, the velocity vector plots on the arbitrary plane of the duct flow field are obtained. Finally, an investigation of the dynamic characteristics of the duct flow field is done and defects of the original duct flow field are analysed, the optimisation of the original flow field has then been conducted. Experimental results show that the duct flow field after optimisation can effectively reduce pressure drop, the feasibility as well as the correctness of the theoretical modelling and optimisation approaches are validated.

RBF-based mesh morphing approach to perform icing simulations in the aviation sector

2019 ◽  
Vol 91 (4) ◽  
pp. 620-633 ◽  
Author(s):  
Corrado Groth ◽  
Emiliano Costa ◽  
Marco Evangelos Biancolini
Keyword(s):  
High Performance ◽  
Three Dimensional ◽  
Ansys Fluent ◽  
Content Type ◽  
Mesh Morphing ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Analyses ◽  
2D And 3D ◽  
First Time ◽  
Practical Implications

Purpose Numerical simulation of icing has become a standard. Once the iced shape is known, however, the analyst needs to update the computational fluid dynamics (CFD) grid. This paper aims to propose a method to update the numerical mesh with ice profiles. Design/methodology/approach The present paper concerns a novel and fast radial basis functions (RBF) mesh morphing technique to efficiently and accurately perform ice accretion simulations on industrial models in the aviation sector. This method can be linked to CFD analyses to dynamically reproduce the ice growth. Findings To verify the consistency of the proposed approach, one of the most challenging ice profile selected in the LEWICE manual was replicated and simulated through CFD. To showcase the effectiveness of this technique, predefined ice profiles were automatically applied on two-dimensional (2D) and three-dimensional (3D) cases using both commercial and open-source CFD solvers. Practical implications If ice accreted shapes are available, the meshless characteristic of the proposed approach enables its coupling with the CFD solvers currently supported by the RBF4AERO platform including OpenFOAM, SU2 and ANSYS Fluent. The advantages provided by the use of RBF are the high performance and reliability, due to the fast application of mesh smoothing and the accuracy in controlling surface mesh nodes. Originality/value As far as authors’ knowledge is concerned, this is the first time in scientific literature that RBF are proposed to handle icing simulations. Due to the meshless characteristic of the RBF mesh morphing, the proposed approach is cross solver and can be used for both 2D and 3D geometries.

Methodology for Hemodynamic Assessment of a Three-Dimensional Printed Patient-Specific Vascular Test Device

2019 ◽  
Vol 13 (3) ◽  
Author(s):  
Gavin A. D'Souza ◽  
Michael D. Taylor ◽  
Rupak K. Banerjee
Keyword(s):  
Pressure Drop ◽  
3D Printing ◽  
Medical Devices ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Patient Specific ◽  
Test Device ◽  
Dimensionless Pressure ◽  
Hemodynamic Assessment ◽  
Stenosis Severity

Assessing hemodynamics in vasculature is important for the development of cardiovascular diagnostic parameters and evaluation of medical devices. Benchtop experiments are a safe and comprehensive preclinical method for testing new diagnostic endpoints and devices within a controlled environment. Recent advances in three-dimensional (3D) printing have enhanced benchtop tests by allowing generation of patient-specific and pathophysiologic conditions. We used 3D printing, coupled with image processing and computer-aided design (CAD), to develop a patient-specific vascular test device from clinical data. The proximal pulmonary artery (PA) tree including the main, left, and right pulmonary arteries, with a stenosis within the left PA was selected as a representative anatomy for developing the vascular test device. Three test devices representing clinically relevant stenosis severities, 90%, 80%, and 70% area stenosis, were evaluated at different cardiac outputs (COs). A mock circulatory loop (MCL) generating pathophysiologic pulmonary pressure and flow was used to evaluate the hemodynamics within the devices. The dimensionless pressure drop–velocity ratio characteristic curves for the three stenosis severities were obtained. At a fixed CO, the dimensionless pressure drop increased nonlinearly with an increase in (a) the velocity ratio for a fixed stenosis severity and (b) the stenosis severity at a specific velocity ratio. The dimensionless pressure drop observed in vivo was similar (within 1%) to that measured in moderate area stenosis of 70% because both flows were viscous dominated. The hemodynamics of the 3D printed test device can be used for evaluating diagnostic endpoints and medical devices in a preclinical setting under realistic conditions.

Effect of Blade Numbers on Pressure Drop of Axial Cyclone Separators by CFD

2011 ◽  
Vol 55-57 ◽  
pp. 343-347 ◽  
Author(s):  
Yi Gang Luan ◽  
Hai Ou Sun
Keyword(s):  
Pressure Drop ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Three Dimensional Model ◽  
Navier Stokes Equations ◽  
Pressure Drops ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Resistance Performance

In this article, computational fluid dynamics(CFD) method is used to predict the effect of blade numbers on the pressure drop of axial cyclone separators. A three-dimensional model is built to acquire the resistance of axial cyclone separators with different blade numbers. The flow field inside cyclone separators is calculated using 3D Reynolds-averaged Navier-Stokes equations. And turbulence model is used to simulate the Reynold stress. Also pressure drop of cyclone separators with different blade numbers is expressed as a function of different inlet velocities. At the same inlet velocity with increasing the blade numbers, pressure drops of cyclones reduce greatly. And changing the blade number of cyclone separator is an effective method to improve its resistance performance.

scholarly journals Experimental Investigation of the Effects of Arterial Geometries in Different Severities of Symmetrical Stenosis on Pressure Drop and Pump Power

2021 ◽  
Author(s):  
Fatin SONMEZ ◽  
Orhan YILDIRIM ◽  
Sendogan KARAGOZ ◽  
Fuat GUNDOGDU
Keyword(s):  
Pressure Drop ◽  
Test Area ◽  
Differential Pressure ◽  
Arterial Stenosis ◽  
Peristaltic Pump ◽  
Outlet Pressure ◽  
Stenosis Severity ◽  
High Pulse ◽  
Human Arteries ◽  
Pump Inlet

Abstract Biomedical studies is among the multidisciplinary studies attracting most interest in recent years. Blood and vessel interactions and consequent hemodynamic effects cause cardiovascular diseases. A testing setup constituted by a peristaltic pump (similar to the heart mechanism) system was installed. The purpose of the experimental study presented is to investigate the effect, pressure drop, peristaltic pump inlet and outlet pressure and most importantly, the amount of power consumed by the peristaltic pump regarding arterial stenosis severity with varying areal stenosis percentages. The tests were performed for the pulse values from 54 to 168 bpm by setting up models with 0%, 60%, 70% and 80% symmetrical stenosis severities. In the study, the pressure difference in the test area increased concomitantly with elevated pulse value and increased stenosis severity. This situation revealed that as the intensity of narrowing increases in vessels, the narrowing space differential pressure increases, and this amount increases even more with increased exertion. The pressure at the peristaltic pump outlet increased concomitantly with elevated pulse value and increased stenosis severity. The peristaltic pump overworked to overcome the increased differential pressure related to the increased pulse value and stenosis severity. This result of the experimental data reveals the necessity to avoid activities requiring high pulse in human arteries similarly with a high percentage of stenosis.

Three-Dimensional CFD Simulation of Prime Mover Stirling Engine

2017 ◽  
Author(s):  
E. Rogdakis ◽  
P. Bitsikas ◽  
G. Dogkas
Keyword(s):  
Pressure Drop ◽  
Gas Flow ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Stirling Engine ◽  
Work Output ◽  
Maximum Loss ◽  
Maximum Value ◽  
Computational Fluid Dynamics Cfd ◽  
The Mean

A three-dimensional Computational Fluid Dynamics - CFD simulation is conducted on a Stirling engine. The temperature in the engine spaces and the temperature profile along the regenerator are graphically presented, along with the density and the gas flow patterns in selected parts of the engine. The maximum value of pressure drop is slightly more than 6% of the mean engine pressure at the same instance. The maximum loss due to pressure drop is equal to 5 kW. In addition, the CFD results are compared to those coming from a one-dimensional model. The comparison includes data regarding the pressure of the gas during the engine cycle, the gas mass flow-rate in all the engine spaces, the respective points of flow reversal and the gas pressure drop. Finally, the net work output and efficiency of the engine are calculated. The net work output of the engine is equal to 6.7 kW and the engine’s efficiency is equal to 51%. The possible sources of further losses are discussed.

scholarly journals Detection of symptom-related coronary arteries in patients with coronary artery disease using real-time three-dimensional stress echocardiography with adenosine triphosphate

2021 ◽  
pp. 26-32
Author(s):  
N. J. Nelasov ◽  
A. V. Pomortsev ◽  
E. A. Arzumanjan ◽  
O. L. Eroshenko ◽  
M. N. Morgunov ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Coronary Arteries ◽  
Healthy Subjects ◽  
Stress Test ◽  
Three Dimensional ◽  
Visual Assessment ◽  
Left Ventricular ◽  
Normative Values ◽  
Stress Echo ◽  
Artery Disease

Aim 1) To develop normative values of global and regional left ventricular longitudinal deformation (LVLD) during real time three-dimensional stress echocardiography with adenosine triphosphate (ATP) and utilization of automated function imaging technology (4D Stress-Echo + LVLD with ATP); 2) to compare the effectiveness of detection of symptom-related coronary arteries during 4D Stress-Echo with ATP using: a) traditional visual assessment of regional myocardial contractility and b) step-by-step analysis of segmental LVLD.Material and Methods 15 healthy subjects and 32 patients with coronary artery disease (CAD) were examined after coronary angiography. All individuals underwent 4D Stress-Echo + LVLD with ATP (Vivid E95, General Electric).Results The normative values of global LVLD at three stages of the pharmacological stress-test (before, during and after ATP infusion) were –19.5 (95% CI: -20.4 – -19.0), –21.6 (95% CI: -22.8 – -20.4) and –19.5 (95% CI: -20.3 – -18.6), respectively; the values of LVLD in each of the 17 segments of left ventricular myocardium in healthy subjects were also determined. In patients with CAD visual control of contractility during stress test revealed dynamic decrease in local thickening of the myocardium, appearance of new zones of contractility disorders and expansion of previously noted in 31.2% of cases, while analysis of deformation detected the appearance of new zones of deformation disturbances and expansion of previously found – in 68.7% (р = 0.0055). Stress-induced worsening of myocardial deformation during ATP infusion in the zones of blood supply of left anterior descending coronary artery, circumflex artery and right coronary artery (with presence of hemodynamically significant stenoses and occlusions detected during coronary angiography) were found in 28.0, 77.7 and 65.2% respectively (р1-3 = 0.0194; р1-2 = 0.0019; р2-3 = 0.2864).Conclusion The normal values of global and segmental LVLD for each stage of 4D Stress-Echo + LVLD with ATP were determined. 4D Stress-Echo + LVLD with ATP can significantly increase the effectiveness of symptom-related coronary arteries identification in patients with CAD in comparison with traditional Stress-Echo with visual assessment of local myocardial contractility.

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