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.

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.

Study of fluid flow through a channel deformed by piezoelement

2018 ◽  
Vol 13 (3) ◽  
pp. 1-10 ◽  
Author(s):  
I.Sh. Nasibullayev ◽  
E.Sh Nasibullaeva ◽  
O.V. Darintsev
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Boundary Conditions ◽  
Flow Rate ◽  
Contact Surface ◽  
Piezoelectric Element ◽  
Neumann Boundary ◽  
Differential Pressure ◽  
Physical Parameters ◽  
Flow Through

The flow of a liquid through a tube deformed by a piezoelectric cell under a harmonic law is studied in this paper. Linear deformations are compared for the Dirichlet and Neumann boundary conditions on the contact surface of the tube and piezoelectric element. The flow of fluid through a deformed channel for two flow regimes is investigated: in a tube with one closed end due to deformation of the tube; for a tube with two open ends due to deformation of the tube and the differential pressure applied to the channel. The flow rate of the liquid is calculated as a function of the frequency of the deformations, the pressure drop and the physical parameters of the liquid.

scholarly journals Vascular Stenosis Asymmetry Influences Considerably Pressure Gradient and Flow Volume

2016 ◽  
pp. 63-69 ◽  
Author(s):  
L. NOVAKOVA ◽  
J. KOLINSKY ◽  
J. ADAMEC ◽  
J. KUDLICKA ◽  
J. MALIK
Keyword(s):  
Pressure Drop ◽  
Flow Volume ◽  
Hemodynamic Changes ◽  
Flow Measurements ◽  
Stenosis Severity ◽  
Vascular Stenosis ◽  
Particle Imaging ◽  
Different Levels ◽  
Volume Decrease

Vascular stenosis is often described only by its percentage in both clinical and scientific praxis. Previous studies gave inconclusive results regarding the effect of stenosis eccentricity on its hemodynamic effect. The aim of this experimental study was to investigate and quantify the effect of stenosis severity and eccentricity on the pressure drop. A combination of pressure and flow measurements by Particle Imaging Velocimetry (PIV) method was used. Models of the same stenosis significance but with different levels of eccentricity were studied in vitro by PIV. This study has shown that stenosis asymmetry is associated with more profound pressure drop and flow volume decrease. On the contrary, pressure drop and flow volume decrease were not further significantly influenced by the level of asymmetry. Hemodynamic changes associated with stenosis eccentricity must be taken into account in both clinical and scientific studies.

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 Instantaneous Wave-Free Ratio Measurement During Intracranial Submaximal Angioplasty: Case Series and 2-Dimensional Operative Video

2020 ◽  
Vol 19 (4) ◽  
pp. 422-428
Author(s):  
Kunal Vakharia ◽  
Muhammad Waqas ◽  
Najya Fayyaz ◽  
Amanda Young ◽  
Elad I Levy ◽  
...  
Keyword(s):  
Case Series ◽  
Length Of Hospital Stay ◽  
Interventional Cardiology ◽  
Arterial Stenosis ◽  
Intracranial Arterial Stenosis ◽  
Ratio Measurement ◽  
Pressure Wire ◽  
Before And After ◽  
Stenosis Severity

Abstract BACKGROUND Instantaneous wave-free ratios (iFRs) are functional measures of arterial stenosis that have become essential to interventional cardiology procedures. Their use for intracranial submaximal angioplasty (angioplasty with an undersized balloon) has not been studied extensively. OBJECTIVE To describe the feasibility and technique of iFR measurement for stenosis assessment during intracranial angioplasty. METHODS We present a series of consecutive patients treated between January 1, 2017 and June 30, 2018 with submaximal intracranial angioplasty in whom pre- and postprocedure iFR measurements were obtained with a Verrata-Volcano pressure wire (Philips, Amsterdam, The Netherlands). We collected patient data on age, sex, comorbid conditions, presenting complaints, modified Rankin scale (mRS) score at admission, neurological findings, procedure duration, fluoroscopy time, intraprocedural complications, length of hospital stay, and mRS score at last clinical follow-up (favorable outcome, 0-2). Angiographic stenosis severity and iFR values were recorded before and after angioplasty. RESULTS A total of 12 patients underwent iFR-guided angioplasty during the study period. The median patient age was 69.5 yr (range 48-81 yr). All patients had symptomatic intracranial arterial stenosis (3-basilar, 2-vertebral, 6-middle cerebral, 1-internal carotid). Preangioplasty stenosis ranged from 55% to 90%. The median postangioplasty reduction in stenosis was 17% (range 9%-30%). Preangioplasty values ranged from 0.30 to 0.40 (n = 4). Postangioplasty values ranged from 0.6 to 0.9 (n = 5). iFR values improved considerably in all patients. No procedure-related complications occurred. The median follow-up was 8.9 mo (range 3-25 mo). Follow-up outcomes were favorable in 10 patients. CONCLUSION iFR measurement before and after intracranial angioplasty is feasible. It may be used to assess the adequacy of intracranial angioplasty.

Assessment of Aortic Stenosis Severity Using Pressure Drop Coefficient: A Retrospective Study in Humans

2013 ◽  
Author(s):  
Anup K. Paul ◽  
Mohamed Effat ◽  
Jason J. Paquin ◽  
Rupak K. Banerjee
Keyword(s):  
Retrospective Study ◽  
Pressure Drop ◽  
Aortic Stenosis ◽  
Clinical Decision Making ◽  
Dynamic Pressure ◽  
Clinical Decision ◽  
Diagnostic Parameters ◽  
Stenosis Severity ◽  
Preliminary Study ◽  
A Prospective Study

Accurate assessment of the stenosis severity is critical in patients with aortic stenosis (AS). The ambiguities and reduced sensitivities of the current diagnostic parameters can result in sub-optimal clinical decision making. In this preliminary study, we investigate the functional diagnostic parameter CDP (ratio of the transvalvular pressure drop to the proximal dynamic pressure) for the assessment of AS severity by correlating with the current diagnostic parameters. CDP was calculated using diagnostic parameters obtained from retrospective chart reviews. CDP values were calculated independently from Doppler and catheterization measurements. CDP exhibited better correlation with transvalvular pressure drop and jet velocity simultaneously, than when correlated independently with the same diagnostic parameters. CDP increases with increasing AS severity, which is consistent with hydrodynamic principles. This retrospective study is a prelude to a prospective study to evaluate CDP for AS severity assessment.

Designing Offshore Pipeline Safety Systems Utilising Flow and Pressure in Multi Design Pressure Pipeline Systems

2008 ◽  
Author(s):  
Gjertrud Elisabeth Hausken ◽  
Jo̸rn-Yngve Stokke ◽  
Steinar Berland
Keyword(s):  
Pressure Drop ◽  
Flow Measurement ◽  
Large Diameter ◽  
Pressure Sensors ◽  
Safety System ◽  
Pipeline System ◽  
Outlet Pressure ◽  
Pipeline Systems ◽  
Pipeline Safety ◽  
Design Pressure

The Norwegian Continental Shelf (NCS) has been a main arena for development of subsea pipeline technology over the last 25 years. The pipeline infrastructure in the North Sea is well developed and new field developments are often tied in to existing pipeline systems, /3/. Codes traditionally require a pipeline system to be designed with a uniform design pressure. However, due to the pressure drop when transporting gas in a very long pipeline, it is possible to operate multi design pressure systems. The pipeline integrity is ensured by limiting the inventory and local maximum allowable pressure in the pipeline using inlet and outlet pressure measurements in a Safety Instrumented System (SIS). Any blockage in the pipeline could represent a demand on the safety system. This concept was planned to be used in the new Gjo̸a development when connecting the 130 km long rich gas pipeline to the existing 450 km long FLAGS pipeline system. However, a risk assessment detected a new risk parameter; the formation of a hydrate and subsequent blockage of the pipeline. In theory, the hydrate could form in any part of the pipeline. Therefore, the pipeline outlet pressure could not be used in a Safety Instrumented System to control pipeline inventory. The export pressure at Gjo̸a would therefore be limited to FLAGS pipeline code. Available pressure drop over the Gjo̸a pipeline was hence limited and a large diameter was necessary. Various alternatives were investigated; using signals from neighbour installations, subsea remote operated valves, subsea pressure sensors and even a riser platform. These solutions gave high risk, reduced availability, high operating and/or capital expenses. A new idea of introducing flow measurement in the SIS was proposed. Hydraulic simulations showed that when the parameters of flow, temperature and pressure, all located at the offshore installation, were used; a downstream blockage could be detected early. This enabled the topside export pressure to be increased, and thereby reduced the pipeline diameter required. Flow measurement in Safety Instrumented Systems has not been used previously on the NCS. This paper describes the principles of designing a pipeline safety system including flow measurement with focus on the hydraulic simulations and designing the safety system. Emphasis will be put on improvements in transportation efficiency, cost reductions and operational issues.

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.

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