An analysis of blood flow dynamics in AAA

Bernad, S. I.; Bernad, Elena-Silvia; Barbat, Tiberiu; Brisan, Cosmin; Albulescu, V.

doi:10.5772/17438

Cited by 6 publications

(6 citation statements)

References 22 publications

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“…The iso-surfaces of pressure are also provided in Figure 19(a) and (b). The flow structure is similar to previous study of Bernad et al (2011). Due to the highest inlet velocity at systolic peak, no separation is observed in AAA body.…”

Section: Numerical Examplessupporting

confidence: 84%

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A semi-implicit characteristic-based polynomial pressure projection for FEM to solve incompressible flows

Zhu

Gao

et al. 2021

HFF

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Purpose The purpose of this paper is to investigate a novel stabilization scheme to handle convection and pressure oscillation in the process of solving incompressible laminar flows by finite element method (FEM). Design/methodology/approach The semi-implicit stabilization scheme, characteristic-based polynomial pressure projection (CBP3) consists of the Characteristic-Galerkin method and polynomial pressure projection. Theoretically, the proposed scheme works for any type of element using equal-order approximation for velocity and pressure. In this work, linear 3-node triangular and 4-node tetrahedral elements are the focus, which are the simplest but most difficult elements for pressure stabilizations. Findings The present paper proposes a new scheme, which can stabilize FEM solution for flows of both low and relatively high Reynolds numbers. And the influence of stabilization parameters of the CBP3 scheme has also been investigated. Research limitations/implications The research in this work is limited to the laminar incompressible flow. Practical implications The verification and validation of the CBP3 scheme are conducted by several 2 D and 3 D numerical examples. The scheme could be used to deal with more practical fluid problems. Social implications The application of scheme to study complex hemodynamics of patient-specific abdominal aortic aneurysm is also presented, which demonstrates its potential to solve bio-flows. Originality/value The paper simulated 2 D and 3 D numerical examples with superior results compared to existing results and experiments. The novel CBP3 scheme is verified to be very effective in handling convection and pressure oscillation.

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Section: Numerical Examplessupporting

confidence: 84%

“…The number of fluid nodes is 124712, the number of fluid elements is 698229. According to Bernad et al (2011), dynamic viscosity of blood is 0.004 kg·m −1 ·s −1 , density is 1050 kg/m 3 , one cardiac cycle is T = 1 s . In this case study, three cardiac cycles are simulated.…”

Section: Numerical Examplesmentioning

confidence: 99%

A semi-implicit characteristic-based polynomial pressure projection for FEM to solve incompressible flows

Zhu

Gao

et al. 2021

HFF

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“…Extensive population studies have investigated the relationship between gestational age and the risk of stillbirth. All conclude that the risk is the highest in the second trimester (51% of all fetal fatalities occurred between the ages of 20 and 27 weeks) and gradually reduces with the increase of gestational age in pregnancies up to 37-38 weeks [106,107].…”

Section: Obstetrical Metrics That Influence the Neonatal Outcomementioning

confidence: 96%

Maternal Fever and Reduced Fetal Movement as Predictive Risk Factors for Adverse Neonatal Outcome in Cases of Congenital SARS-CoV-2 Infection: A Meta-Analysis of Individual Participant Data from Case Reports and Case Series

Bernad,

Duica,

Antoniadis

et al. 2023

Viruses

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Objectives: To determine risk factors for primary and secondary adverse neonatal outcomes in newborns with congenital SARS-CoV-2 infection.Data sources:PubMed/MEDLINE and Google Scholar from January 2020 to January 2022.Study eligibility criteria: newborns delivered after 24 weeks of gestation with confirmed/possible congenital SARS-CoV-2 infection, according to standard classification criteria.Methods: Execution of the IPD analyses followed the PRISMA-IPD statement. Univariate non-parametric tests compared numerical data distributions. Fisher’s exact or Chi-square test determined categorical variables’ statistical significance. Multivariate logistic regression revealed risk factors for adverse neonatal outcome.Results:Maternal fever was associated with symptomatic congenital infection (OR: 4.55, 95% CI:1.33–15.57). Two-thirds of women that reported decreased fetal movements were diagnosed with IUFD (p-value = 0.001). Reduced fetal movement increased the risk of intrauterine fetal death by 7.84 times (p-value = 0.016, 95% CI: 2.23–27.5). The risk of stillbirth decreased with gestational age at the time of maternal infection (p-value < 0.05, OR: 0.87, 95% CI: 0.79–0.97). Conclusions:Maternal fever and perception of reduced fetal movement may be predictive risk factors for adverse pregnancy outcome in cases with congenital SARS-CoV-2 infection.

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“…Earlier studies pointed out that flow in the abdominal aorta is non-laminar, and include vortices and recirculation zones, especially in AAA. 21,24,27 Disturbed flow can result in increasing stresses acting on the aneurysm wall and may be responsible for further aortic dilatation. 28 Therefore, excluding the aneurysm sac from the arterial circulation, for example during EVAR, should minimise complex flows at the inflow and outflow segments of the stent at healthy aortic wall.…”

Section: Haemodynamicsmentioning

confidence: 99%

Haemodynamics in Different Flow Lumen Configurations of Customised Aortic Repair for Infrarenal Aortic Aneurysms

Overeem¹,

Vries

Boersen

et al. 2019

European Journal of Vascular and Endovascular Surgery

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WHAT THIS PAPER ADDS This paper investigates the haemodynamics in three different flow lumen configurations of a custom, noncontained, non-cross linked polymer based endovascular approach in treating abdominal aortic aneurysms. The most favourable configuration was established by identifying flow velocity, vorticity, wall shear stress, and time averaged wall shear stress in an in vitro set up with laser particle imaging velocimetry. Based on the results, future research should focus on clinical applicability. Objective: Customised aortic repair (CAR) is a new and minimally invasive technique for the endovascular treatment of abdominal aortic aneurysms (AAAs). The aneurysm is completely sealed with a non-contained, non-cross linked polymer, while a new flow lumen is created with balloons. For CAR, the haemodynamically most favourable balloon and flow lumen configuration has not been established before; therefore, four flow parameters were assessed in an in vitro model. Methods: Three in vitro balloon configurations were implanted in an in vitro AAA model; a configuration with crossing balloons (CC) and two parallel configurations (PC1 and PC2). These three models were consecutively placed in a flow system that mimics physiological flow conditions. Laser particle imaging velocimetry (PIV) was used to resolve spatial and temporal flow patterns during the cardiac cycle. In house built algorithms were used to analyse the PIV data for the computing of (i) flow velocity; (ii) vorticity; (iii) wall shear stress (WSS); and (iv) time averaged wall shear stress (TAWSS). Results: Suprarenal flow patterns were similar in all models. The CC showed a higher infrarenal velocity than PC1 and PC2 (38 cm/s vs. 23 cm/s vs. 23 cm/s), and a higher vorticity at the crossing of the lumens (CC: 337/s; PC1 127/s; PC2: 112/s). The lowest vorticity was observed in PC2, especially in the infrarenal neck (CC: 200/s; PC1 164/s; PC2: 98/s). Although WSS and TAWSS varied between configurations, values were in the within non-pathological range. Conclusion: The flow lumens created by three balloon configurations used in an in vitro model of CAR have been studied, and resulted in different haemodynamics. The differences in velocity and lower vorticity, especially at the crossing section of the two balloons, showed that PC2 has favourable haemodynamics compared with the CC and PC1. Future research will be focused on the clinical applicability of CAR based on the PC2 design.

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An analysis of blood flow dynamics in AAA

Abstract: Hard cover, 222 pagesPublisher InTech

Cited by 6 publications

References 22 publications

A semi-implicit characteristic-based polynomial pressure projection for FEM to solve incompressible flows

A semi-implicit characteristic-based polynomial pressure projection for FEM to solve incompressible flows

Maternal Fever and Reduced Fetal Movement as Predictive Risk Factors for Adverse Neonatal Outcome in Cases of Congenital SARS-CoV-2 Infection: A Meta-Analysis of Individual Participant Data from Case Reports and Case Series

Haemodynamics in Different Flow Lumen Configurations of Customised Aortic Repair for Infrarenal Aortic Aneurysms

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