Pulsatile Flow Investigation in Development of Thoracic Aortic Aneurysm:
                        An In-Vitro Validated Fluid Structure Interaction Analysis

In this study, fluid-structure interaction (FSI) simulation was carried out to predict wall shear stress (WSS) and blood flow patterns in a thoracic aortic aneurysm (TAA) where haemodynamic stresses on the diseased aortic wall are thought to lead to the growth, progression and rupture of the aneurysm. Based on MR images, a patient-specific TAA model was reconstructed. A newly developed two-equation laminar-turbulent transitional model was employed and realistic velocity and pressure waveforms were used as boundary conditions. Analysis of results include turbulence intensity, wall displacement, WSS, wall tensile stress and comparison of velocity profiles between MRI data, rigid and FSI simulations. Velocity profiles demonstrated that the FSI simulation gave better agreement with the MRI data while results for the time-averaged WSS (TAWSS) and oscillatory shear index (OSI) distributions showed no qualitative differences between the simulations. With the FSI model, the maximum TAWSS value was 13% lower, whereas the turbulence intensity was significantly higher than the rigid model. The FSI simulation also provided results for wall mechanical stress in terms of von Mises stress, allowing regions of high wall stress to be identified.

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Fluid-structure interaction analysis of eccentricity and leaflet rigidity on thrombosis biomarkers in bioprosthetic aortic valve replacements

10.1101/2022.01.06.475272 ◽

2022 ◽

Author(s):

David Oks ◽

Mariano Vazquez ◽

Guillaume Houzeaux ◽

Constantine Butakoff ◽

Cristobal Samaniego

Keyword(s):

Aortic Valve ◽

Computational Model ◽

High Performance ◽

Interaction Analysis ◽

Thrombus Formation ◽

Fluid Structure Interaction ◽

Simulation Software ◽

Fluid Structure ◽

Structure Interaction

This work introduces the first 2-way fluid-structure interaction (FSI) computational model to study the effect of aortic annulus eccentricity on the performance and thrombogenic risk of cardiac bioprostheses. The model predicts that increasing eccentricities yield lower geometric orifice areas (GOAs) and higher normalized transvalvular pressure gradients (TPGs) for healthy cardiac outputs during systole, agreeing with in vitro experiments. Regions with peak values of residence time and shear rate are observed to grow with eccentricity in the sinus of Valsalva, indicating an elevated risk of thrombus formation for eccentric configurations. In addition, the computational model is used to analyze the effect of varying leaflet rigidity on both performance, thrombogenic and calcification risks with applications to tissue-engineered prostheses, observing an increase in systolic and diastolic TPGs, and decrease in systolic GOA, which translates to decreased valve performance for more rigid leaflets. An increased thrombogenic risk is detected for the most rigid valves. Peak solid stresses are also analyzed, and observed to increase with rigidity, elevating risk of valve calcification and structural failure. The immersed FSI method was implemented in a high-performance computing multi-physics simulation software, and validated against a well known FSI benchmark. The aortic valve bioprosthesis model is qualitatively contrasted against experimental data, showing good agreement in closed and open states. To the authors' knowledge this is the first computational FSI model to study the effect of eccentricity or leaflet rigidity on thrombogenic biomarkers, providing a novel tool to aid device manufacturers and clinical practitioners.

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A comparison between different asymmetric abdominal aortic aneurysm morphologies employing computational fluid–structure interaction analysis

European Journal of Mechanics - B/Fluids ◽

10.1016/j.euromechflu.2007.03.003 ◽

2007 ◽

Vol 26 (5) ◽

pp. 615-631 ◽

Cited By ~ 27

Author(s):

Zhonghua Li ◽

Clement Kleinstreuer

Keyword(s):

Abdominal Aortic Aneurysm ◽

Aortic Aneurysm ◽

Interaction Analysis ◽

Fluid Structure Interaction ◽

Fluid Structure ◽

Structure Interaction ◽

Abdominal Aortic

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Fluid–structure interaction of turbulent pulsatile flow within a flexible wall axisymmetric aortic aneurysm model

European Journal of Mechanics - B/Fluids ◽

10.1016/j.euromechflu.2007.12.003 ◽

2009 ◽

Vol 28 (1) ◽

pp. 88-102 ◽

Cited By ~ 47

Author(s):

Khalil M. Khanafer ◽

Joseph L. Bull ◽

Ramon Berguer

Keyword(s):

Aortic Aneurysm ◽

Pulsatile Flow ◽

Fluid Structure Interaction ◽

Fluid Structure ◽

Structure Interaction ◽

Flexible Wall ◽

Aneurysm Model

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Comparative Fluid-Structure Interaction Analysis on Influence of Banding Conditions to Ascending Aorta Aneurysm Formation in Rat

10.21203/rs.3.rs-89400/v1 ◽

2020 ◽

Author(s):

Juan Su ◽

Jun Fan ◽

Qing Tang ◽

Shijie Chang ◽

Xianzheng Sha

Keyword(s):

Aortic Aneurysm ◽

Interaction Analysis ◽

Fluid Structure Interaction ◽

Ascending Aorta ◽

Ascending Aortic Aneurysm ◽

Fluid Structure ◽

Aorta Aneurysm ◽

Structure Interaction ◽

Concentrated Flow ◽

Precise Experiment

Abstract Background: Ascending aortic aneurysm in an important cause of mortality in cardiovascular diseases. Stenosis of aortic is considered to be a risk factor as the ascending aortic aneurysm grows. Animal models have been demonstrated that ascending aortic aneurysm could be induced by supra valvular banding of the ascending aortic. Our objective is to compare different banding conditions on the formation of aneurysms for more precise experiment and improving the preclinical value. Therefore, three comparison banding groups of banding altitude, banding severity and banding angle are established based on rat. Then flow pattern, wall shear stress (WSS) and vessel deformation of each model are calculated and discussed using transient two-way fluid-structure interaction (FSI) analysis in order to explore the influence of different banding methods on the generation of ascending aorta aneurysm.Results: Banding methods lead to different shapes or amplitudes of flow beam, WSS and vessel dilation. Eccentric flow beam, local high WSS accompany with vessel dilation are formed above the banding ring in all banding models because of the banding operation compared with normal model. More concentrated flow beam with bigger velocity, higher local WSS and more obvious expansion deformation above the banding ring are prone to happen in the middle segment banding with 60% banding severity and banding angle of 30 degree.Conclusion: According to the results, a higher position, relatively severe banding, and an acute banding angle are more favor to promote the generation of ascending aortic aneurysm.

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