Assessment of calcified aortic valve leaflet deformations and blood flow dynamics using fluid-structure interaction modeling

Amindari, Armin; Saltık, Levent; Kirkkopru, Kadir; Yacoub, Magdi H.; Yalcin, Huseyin C.

doi:10.1016/j.imu.2017.09.001

Cited by 51 publications

(48 citation statements)

References 35 publications

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“…Aortic valve hemodynamics of a calcified leaflet was simulated using CFD method (Amindari et al 2017); however, numerical methods employed into fluid flow domain is discussed here for completeness of the present study. Velocity vectors obtained from CFD analysis were further processed with LCS technique to investigate the jet dynamics around the leaflets.…”

Section: Methodsmentioning

confidence: 99%

Characterization of Disturbed Hemodynamics due to Stenosed Aortic Jets with a Lagrangian Coherent Structures Technique

Olcay

Amindari

Kirkkopru

et al. 2018

JAFM

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The aortic valve is located at left ventricular outlet and is exposed to the highest pressure in the cardiovascular system. Problems associated with the valve leaflet movement can cause complications for the heart. Specifically, aortic stenosis (AS) arises when aortic leaflets do not efficiently open. In the present study, Lagrangian Coherent Structures (LCSs) were utilized by processing a variety of Computational Fluid Dynamics (CFD) models velocity vector data further to identify the characteristics of AS jets. Particularly, effective orifice areas (EOA) for different cases were accurately identified from unstable manifolds of finite time Lyapunov exponent (FTLE) fields. Calcified leaflets were modeled by setting the leaflet's Young modulus to 10 MPa and 20 MPa for moderately and severely calcified leaflets respectively while a healthy leaflet's Young modulus was assigned to be 2 MPa. Increase in calcification degree of the leaflet caused destruction of the vortex structures near the fibrosa layer of the leaflet indicating a malfunctioning for the movement mechanism of the leaflet. Furthermore, when we analyzed stable manifolds, we identified a blockage region at the flow upstream due to the stagnant blood here. Compared to a healthy case, for the calcified valve, this blockage region was enlarged, implying an increase in AS jet velocity and wall shear stress on leaflets. As a conclusion, results from the present study indicate that aortic leaflet malfunctioning could be accurately evaluated when LCS technique was employed by post processing velocity vector data from CFD. Such precise analysis is not possible using the Eulerian CFD approach or a Doppler echocardiography since these methods are based on only analyzing instantaneous flow quantities and they overlook fluid flow characteristics of highly unsteady flows.

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Section: Methodsmentioning

confidence: 99%

Characterization of Disturbed Hemodynamics due to Stenosed Aortic Jets with a Lagrangian Coherent Structures Technique

Olcay

Amindari

Kirkkopru

et al. 2018

JAFM

View full text Add to dashboard Cite

show abstract

“…As mentioned, the flexible valve is modelled with LSM, which is a common approach for cardiovascular valves [27]. This implies that each computational particle is linked with its neighbour particles by means of a force such as (2) where r0 is the initial distance between the two particles, r the distance at time t and k a Hookean constant. In LSM, the value of k is linked to the Young modulus E of the material [28].…”

Section: Figure 2 Pulsatile Flow Functionmentioning

confidence: 99%

“…is associated with high mortality risk and the need for aortic replacement [30]. The time at which the valve closes also varies with the severity of calcification; at γ=3.0 there is also evidence of regurgitation (back flow) a characteristic of a stenotic aortic valve [2,3,9]. The flow reduces as γ increases ( Figure 5); it decreases almost linearly up to a critical value γCR = 3, after which it decreases sharply.…”

Section: Stages Of Calcificationmentioning

confidence: 99%

“…Calcification, in particular, may result in calcific aortic valve disease (CAVD) caused by calcium deposits on the valve leaflets, which affects mainly the elderly population with an incidence rate of 2 -7% in the population above 65 years of age [2]. Over time, calcium build-up makes the aortic valve stiffer preventing full opening (stenosis) and hindering the blood flow from the left ventricle to the aorta.…”

Section: Introductionmentioning

confidence: 99%

“…Other studies focus [6][7][8][9][10] on investigating the stresses on the valve leaflets excluding the fluid flow behaviour in the model. Since the behaviour of the aortic valve depends on both the fluid and the leaflets, a fluid-structure interaction (FSI) approach is recommended to model the complex dynamic of this problem [2,11].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Using Discrete Multiphysics Modelling to Assess the Effect of Calcification on Hemodynamic and Mechanical Deformation of Aortic Valve

Mohammed¹,

Ariane²,

Alexiadis³

2020

Preprint

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This study proposes a 3D particle-base (discrete) multiphysics approach for modelling calcification in the aortic valve. Different stages of calcification (from mild to severe) were simulated, and their effect on the cardiac output assessed. The cardiac flow rate decreases with the level of calcification. In particular, there is a critical level of calcification below which the flow rate decreases dramatically. Mechanical stress on the membrane is also calculated. The results show that, as calcification progresses, spots of high mechanical stress appear. Firstly, they concentrate in the regions connecting two leaflets; when severe calcification is reached, then they extend to the area at the basis of the valve.

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Foam‐in‐vein: A review of rheological properties and characterization methods for optimization of sclerosing foams

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Varicose veins are chronic venous defects that affect >20% of the population in developed countries. Among potential treatments, sclerotherapy is one of the most commonly used. It involves endovenous injection of a surfactant solution (or foam) in varicose veins, inducing damage to the endothelial layer and subsequent vessel sclerosis. Treatments have proven to be effective in the short-term, however recurrence is reported at rates of up to 64% 5-year post-treatment. Thus, once diagnosed with varicosities there is a high probability of a permanently reduced quality of life. Recently, foam sclerotherapy has become increasingly popular over its liquid counterpart, since foams can treat larger and longer varicosities more effectively, they can be imaged using ultrasound, and require lower amounts of sclerosing agent. In order to minimize recurrence rates however, an investigation of current treatment methods should lead to more effective and long-lasting effects. The literature is populated with studies aimed at characterizing the fundamental physics of aqueous foams; nevertheless, there is a significant need for appropriate product development platforms. Despite successfully capturing the microstructural evolution of aqueous foams, the complexity of current models renders them inadequate for pharmaceutical development. This review article will focus on the physics of foams and the attempts at optimizing them for sclerotherapy. This takes the form of a discussion of the most recent numerical and experimental models, as well as an overview of clinically relevant parameters. This holistic approach could contribute to better foam characterization methods that patients may eventually derive long term benefit from.

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Assessment of calcified aortic valve leaflet deformations and blood flow dynamics using fluid-structure interaction modeling

Cited by 51 publications

References 35 publications

Characterization of Disturbed Hemodynamics due to Stenosed Aortic Jets with a Lagrangian Coherent Structures Technique

Characterization of Disturbed Hemodynamics due to Stenosed Aortic Jets with a Lagrangian Coherent Structures Technique

Using Discrete Multiphysics Modelling to Assess the Effect of Calcification on Hemodynamic and Mechanical Deformation of Aortic Valve

Foam‐in‐vein: A review of rheological properties and characterization methods for optimization of sclerosing foams

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