Search results for "dynamics"

showing 10 items of 9782 documents

Computer Modeling for the Prediction of Thoracic Aortic Stent Graft Collapse

2011

OBJECTIVE: To assess the biomechanical implications of excessive stent protrusion into the aortic arch in relation to thoracic aortic stent graft (TASG) collapse by simulating the structural load and quantifying the fluid dynamics on the TASG wall protrusion extended into a model arch. METHODS: One-way coupled fluid-solid interaction analyses were performed to investigate the flow-induced hemodynamic and structural loads exerted on the proximal protrusion of the TASG and aortic wall reconstructed from a patient who underwent traumatic thoracic aortic injury repair. Mechanical properties of a Gore TAG thoracic endoprosthesis (W. L. Gore and Assoc, Flagstaff, Ariz) were assessed via experimen…

Aortic archMalemedicine.medical_specialtyAortographymedicine.medical_treatmentHemodynamicsAorta ThoracicFOS: Medical engineeringProsthesis DesignAortographyBlood Vessel Prosthesis ImplantationImaging Three-DimensionalBlood vessel prosthesismedicine.arteryMaterials TestingmedicineHumansComputer Simulationthoracic aortic stent graft (TASG)Aortamedicine.diagnostic_testbusiness.industryEndovascular ProceduresHemodynamicsModels CardiovascularStentSettore ING-IND/34 - Bioingegneria Industrialenutritional and metabolic diseases90399 Biomedical Engineering not elsewhere classifiedCurvatures of the stomachSurgeryBiomechanical PhenomenaBlood Vessel ProsthesisProsthesis FailureEquipment Failure AnalysisRegional Blood FlowRadiographic Image Interpretation Computer-AssistedStentslipids (amino acids peptides and proteins)SurgeryStress Mechanicalbiological phenomena cell phenomena and immunitybusinessNuclear medicineTomography X-Ray ComputedCardiology and Cardiovascular MedicinePerfusionAlgorithmsJournal of Vascular Surgery
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An In Vitro Phantom Study on the Role of the Bird-Beak Configuration in Endograft Infolding in the Aortic Arch.

2015

Purpose: To assess endograft infolding for excessive bird-beak configurations in the aortic arch in relation to hemodynamic variables by quantifying device displacement and rotation of oversized stent-grafts deployed in a phantom model. Methods: A patient-specific, compliant, phantom pulsatile flow model was reconstructed from a patient who presented with collapse of a Gore TAG thoracic endoprosthesis. Device infolding was measured under different flow and pressure conditions for 3 protrusion extensions (13, 19, and 24 mm) of the bird-beak configuration resulting from 2 TAG endografts with oversizing of 11% and 45%, respectively. Results: The bird-beak configuration with the greatest protr…

Aortic archModels AnatomicRadiology Nuclear Medicine and ImagingTime FactorsFlow modelPulsatile flowEndograftStent-graft oversizingAorta Thoracic030204 cardiovascular system & hematologyRotation0302 clinical medicineForeign-Body MigrationStentThoracic aortaBird-beak configurationmedicine.diagnostic_testEndovascular ProceduresGraft Occlusion VascularModels CardiovascularAnatomyIn vitro experimentProsthesis FailureBlood Vessel ProsthesiTreatment OutcomePulsatile FlowPatient-specific modelStentsCardiology and Cardiovascular MedicineHumanAortographyTime FactorThoracic endovascular aortic repairProsthesis DesignAortographyImaging phantom03 medical and health sciencesBlood Vessel Prosthesis ImplantationBlood vessel prosthesismedicine.arterymedicineHumansDisplacement (orthopedic surgery)HemodynamicEndovascular Procedurebusiness.industryHemodynamicsDisplacementStent-graft infoldingBlood Vessel ProsthesisSurgerybusinessTomography X-Ray Computed030217 neurology & neurosurgeryStent-graft collapseJournal of endovascular therapy : an official journal of the International Society of Endovascular Specialists
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Framework for Fluid-Structure Interaction Analysis of Aortic Coarctation Resulting From Proximal Protusion of Thoracic Aortic Stent Graft Into the Ar…

2011

Thoracic aortic stent grafts (TASG) are commonly used to repair aortic anomalies or diseases in a minimally-invasive fashion. One complication of TASG is collapse, whereby blood is unable to completely flow through the graft as intended. Most TASG collapses occur in the setting of endovascular repair of traumatic thoracic aortic transection, where a typically smaller diameter aorta of pediatric patients is repaired with a relatively larger diameter endograft designed to treat aneurysmal disease [1]. It is hypothesized that the poor apposition of the leading edge of the proximal stent graft to the lesser curvature of the aortic arch can result increased hemodynamic force at the leading side …

Aortic archmedicine.medical_specialtyAortabusiness.industrymedicine.medical_treatmentaorti failureSettore ING-IND/34 - Bioingegneria IndustrialeHemodynamicsStentCurvatures of the stomachSurgeryAppositionsurgical procedures operativemedicine.arteryInternal medicineOcclusioncardiovascular systemCardiologyMedicinebusinessComplicationASME 2011 Summer Bioengineering Conference, Parts A and B
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Reference values of fetal aortic flow velocity waveforms and associated intra-observer reliability in normal pregnancies

2001

Objectives It was the aim of the present study to calculate new Doppler reference ranges for blood flow velocities (Vmax, Vmean, Vmin) and resistance indices (PI, RI) for the fetal descending aorta by automatic waveform analysis. Design Cross-sectional prospective study. Subjects Nine hundred and twenty-six low-risk pregnancies at 18–41 weeks' gestation. Methods Aortic blood flow velocities were derived with pulsed-wave color Doppler. Measurements were carried out at the level of the diaphragm. Reference ranges for the individual measuring parameters were constructed based on a growth function from a four-parameter class of monotonic continuous functions according to the smallest square pri…

Aortic archmedicine.medical_specialtyDuplex ultrasonographyAortaRadiological and Ultrasound Technologybusiness.industryObstetrics and GynecologyHemodynamicsGeneral MedicineBlood flowSurgerysymbols.namesakemedicine.anatomical_structureReproductive MedicineInternal medicinemedicine.arteryDescending aortaVascular resistancemedicinesymbolsCardiologyRadiology Nuclear Medicine and imagingbusinessDoppler effectUltrasound in Obstetrics and Gynecology
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Predicting Outcome of Aortic Dissection with Patent False Lumen by Computational Flow Analysis

2014

Although Type B aortic dissection (AoD) has better in-hospital survival than Type A AoD, the short- and long term outcome for patients remains challenging, with 50–80% deaths at 5-years. Dissection-related complications include rapid aortic expansion, impending rupture, and malperfusion syndromes. We aimed to assess hemodynamic implications of patients with patent false lumen (FL) of dissected aorta. Computational fluid dynamic analyses were performed on patient-specific aortic geometries reconstructed from computed tomography scans of 25 patients with AoDs, who were admitted in our hospital from 2007 to 2013. We used the development of acute complications and chronic aneurysmal evolution a…

Aortic dissectionAortamedicine.medical_specialtyFlowbusiness.industryBiomedical EngineeringFalse LumenHemodynamicsBlood flowmedicine.diseaseType B Aortic DissectionSurgerySettore ING-IND/14 - Progettazione Meccanica E Costruzione Di MacchineBlood pressuremedicine.arteryInternal medicineLinear regressionmedicineCardiologyTearsCFDCardiology and Cardiovascular MedicineAdverse effectbusinessCardiovascular Engineering and Technology
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Comparison of hemodynamic and structural indices of ascending thoracic aortic aneurysm as predicted by 2-way FSI, CFD rigid wall simulation and patie…

2018

Patient-specific computational modeling is increasingly being used to predict structural and hemodynamic parameters, especially when current clinical tools are not accessible. Indeed, pathophysiology of ascending thoracic aortic aneurysm (ATAA) has been simulated to quantify the risk of complications by novel prognostic parameters and thus to improve the clinical decision-making process related to the intervention of ATAAs. In this study, the relevance of aneurysmal wall elasticity in determining parameters of clinical importance, such as the wall shear stress (WSS), is discussed together with the significance of applying realistic boundary conditions to consider the aortic stretch and twis…

Aortic valveAdultMalePatient-Specific Modelingmedicine.medical_specialtyComputer science0206 medical engineeringFinite Element Analysisaorti failureHeart Valve DiseasesHemodynamicsFluid-solid interaction (FSI)Health Informatics02 engineering and technology030204 cardiovascular system & hematologyComputational fluid dynamicsThoracic aortic aneurysm03 medical and health sciences0302 clinical medicineBicuspid aortic valveBicuspid Aortic Valve DiseaseInternal medicinemedicineShear stressHumansComputer SimulationAgedAortic Aneurysm ThoracicStructural mechanicsbusiness.industryFinite element analysis (FEA)Models CardiovascularMiddle Agedmedicine.diseaseAscending thoracic aortic aneurysm020601 biomedical engineeringFinite element methodElasticityComputer Science Applicationsmedicine.anatomical_structureComputational fluid-dynamic (CFD)Aortic Valvecardiovascular systemCardiologyFemaleStress Mechanicalbusiness
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In Silico Shear and Intramural Stresses are Linked to Aortic Valve Morphology in Dilated Ascending Aorta

2017

Objective/Background: The development of ascending aortic dilatation in patients with bicuspid aortic valve (BAV) is highly variable, and this makes surgical decision strategies particularly challenging. The purpose of this study was to identify new predictors, other than the well established aortic size, that may help to stratify the risk of aortic dilatation in BAV patients.Methods: Using fluid-structure interaction analysis, both haemodynamic and structural parameters exerted on the ascending aortic wall of patients with either BAV ( n = 21) or tricuspid aortic valve (TAV; n = 13) with comparable age and aortic diameter (42.7 +/- 5.3 mm for BAV and 45.4 +/- 10.0 mm for TAV) were compared…

Aortic valveMalePatient-Specific ModelingComputed Tomography AngiographyHeart Valve DiseasesHemodynamics02 engineering and technology030204 cardiovascular system & hematology0302 clinical medicineBicuspid aortic valveBicuspid Aortic Valve DiseaseRisk FactorsAortaSinotubular JunctionModels CardiovascularSettore ING-IND/34 - Bioingegneria IndustrialeComputational modelingAneurysm of ascending aortaMiddle AgedAortic AneurysmHeart Valve Diseasemedicine.anatomical_structureAortic Valvecardiovascular systemCardiologyWall shear streFemaleCardiology and Cardiovascular MedicineBlood Flow VelocityDilatation PathologicHumanmedicine.medical_specialtyBicuspid aortic valve0206 medical engineeringAortography03 medical and health sciencesInternal medicinemedicine.arteryAscending aortamedicineHumansAgedAortabusiness.industryRisk FactorSignificant differenceHemodynamicsmedicine.disease020601 biomedical engineeringAortic wallRegional Blood FlowSurgeryStress Mechanicalbusiness
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Difference in hemodynamic and wall stress of ascending thoracic aortic aneurysms with bicuspid and tricuspid aortic valve.

2012

The aortic dissection (AoD) of an ascending thoracic aortic aneurysm (ATAA) initiates when the hemodynamic loads exerted on the aneurysmal wall overcome the adhesive forces holding the elastic layers together. Parallel coupled, two-way fluid–structure interaction (FSI) analyses were performed on patient-specific ATAAs obtained from patients with either bicuspid aortic valve (BAV) or tricuspid aortic valve (TAV) to evaluate hemodynamic predictors and wall stresses imparting aneurysm enlargement and AoD. Results showed a left-handed circumferential flow with slower-moving helical pattern in the aneurysm's center for BAV ATAAs whereas a slight deviation of the blood flow toward the anterolater…

Aortic valveMalemedicine.medical_specialtyFluid–structure interaction Aortic dissection Ascending thoracic aortic aneurysm Bicuspid aortic valveBiomedical EngineeringBiophysicsHeart Valve DiseasesAorta ThoracicThoracic aortic aneurysmArticleAortic aneurysmBicuspid aortic valveBicuspid Aortic Valve DiseaseInternal medicinemedicine.arteryCoronary CirculationAscending aortamedicineThoracic aortaHumansOrthopedics and Sports Medicinecardiovascular diseasesAgedAortic dissectionAortabusiness.industryRehabilitationHemodynamicsModels CardiovascularMiddle Agedmedicine.diseaseElasticityAortic Aneurysmmedicine.anatomical_structureAortic ValveCardiologycardiovascular systemFemaleTricuspid ValvebusinessJournal of biomechanics
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Echocardiographic and angiographic evaluation of left ventricular function during percutaneous transluminal aortic valvuloplasty.

1992

Transesophageal echocardiography was used to study the effect of the balloon inflation on left ventricular function in 20 patients with critical aortic stenosis undergoing balloon valvuloplasty. Balloon inflation caused an increase of end-diastolic (15% to 34%) and end-systolic (57% to 72%) left ventricular volume. Left ventricular wall stress increased from 30 +/- 10 x 10(3) dyn/cm2 at diastole and 121 +/- 40 x 10(3) dyn/cm2 at systole to 44 +/- 11 x 10(3) dyn/cm2 and 191 +/- 55 x 10(3) dyn/cm2, respectively, when the balloon was inflated (P less than 0.05). Turbulent regurgitant jet across the mitral valve increased from 15 +/- 2% to 25 +/- 3% during balloon inflation (P less than 0.01). …

Aortic valveMalemedicine.medical_specialtymedicine.medical_treatmentDiastoleMyocardial InfarctionBalloonCoronary AngiographyVentricular Function LeftCatheterizationRisk FactorsMitral valveInternal medicineCoronary CirculationmedicineHumansSystoleCardiac OutputAgedAged 80 and overbusiness.industryHemodynamicsMitral Valve InsufficiencyBlood flowAortic Valve StenosisMiddle Agedmedicine.diseaseAortic valvuloplastyStenosismedicine.anatomical_structureEchocardiographyAortic Valvecardiovascular systemCardiologyFemaleCardiology and Cardiovascular MedicinebusinessCatheterization and cardiovascular diagnosis
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On the severity of aortic stenosis in ascending aortic aneurysm: A computational tool to examine ventricular-arterial interaction and aortic wall str…

2020

Abstract An ascending thoracic aortic aneurysm (ATAA) is a life-threatening cardiovascular consequence of vessel dilatation that portends adverse events and death. From a clinical perspective, ATAA should not be treated as an isolated disease, and surgery is often carried out in the presence of AS, aortic insufficiency or a calcified valve leaflet. Aortic stenosis (AS) is common in ATAAs and leads to both vessel rigidity and left ventricular (LV) impairment. In this study, lumped-parameter modeling and computational analysis were used to assess the change in the wall shear stress (WSS) and intramural wall stress of patient-specific ATAA models with different degrees of AS (i.e., mild to sev…

Aortic valvemedicine.medical_specialtyHemodynamicsThoracic aortic aneurysmImaging dataAortic aneurysmInternal medicinemedicineGeneral Materials ScienceIn patientFinite-element analysisCivil and Structural EngineeringShear stressbusiness.industryAortic stenosisMechanical EngineeringAscending thoracic aortic aneurysmCondensed Matter Physicsmedicine.diseaseAortic wallStenosismedicine.anatomical_structureMechanics of Materialscardiovascular systemCardiologyCFDbusinessMechanics Research Communications
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