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FEA of displacements and stresses of aortic heart valve leaflets during the opening phase

Bialas O., Żmudzki J.

Journal of Achievements in Materials and Manufacturing Engineering

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2019

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Vol. 92, nr 1-2

29--35

EN

Purpose: Modelling of biomechanical behaviour of heart valve materials aids improvement of biofunctional feature. The aim of the work was assessment of influence of material thickness of leaflets of artificial aortic valve on displacements and stresses during opening phase using finite element analysis (FEA). Design/methodology/approach: The model of aortic valve was developed on the basis of average anatomical valve shapes and dimensions. Nonlinear dynamic large displacements analysis with assumption of isotropic linear elastic material behaviour was used in simulation (Solidworks). The modulus of elasticity of 5.0 MPa was assumed and Poisson ratio set to 0.45. The rigidly supported leaflets was loaded by pressure increasing in the range 0-55 mmHg in time 0.1 s. Leaflets with material thickness 0.13 and 0.15 and 0.17 mm were analysed. The thickness was simulated with shell finite elements. Findings: The highest stresses were observed in the areas of fixation of the leaflets near the scaffold and were lower than dangerous value of fatigue of polyurethanes. Increasing the thickness of valve leaflet material in the range of 40 micrometres resulted in reduction of the valve outlet by almost 10 percent. Research limitations/implications: The FEA was limited to the isotropic linear-elastic behaviour of the material albeit can be used to assess leaflet deformation during dynamic load. Practical implications: Leaflets design may be start from efficient FEA which helps estimation of material impact on stress and fold formation which can affect local blood flow. Originality/value: Aortic heart valve leaflet material can be initially tested in dynamic conditions during opening phase with using FEA.

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Fluid-Structure Interaction Modeling of Aortic Valve Stenosis at Different Heart Rates

Bahraseman H. G., Languri E. M., Yahyapourjalaly N., Espino D. M.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 3

11--20

EN

Purpose: This paper proposes a model to measure the cardiac output and stroke volume at different aortic stenosis severities using a fluid–structure interaction (FSI) simulation at rest and during exercise. Methods: The geometry of the aortic valve is generated using echocardiographic imaging. An Arbitrary Lagrangian–Eulerian mesh was generated in order to perform the FSI simulations. Pressure loads on ventricular and aortic sides were applied as boundary conditions. Results: FSI modeling results for the increment rate of cardiac output and stroke volume to heart rate, were about 58.6% and –14%, respectively, at each different stenosis severity. The mean gradient of curves of cardiac output and stroke volume to stenosis severity were reduced by 57% and 48%, respectively, when stenosis severity varied from healthy to critical stenosis. Conclusions: Results of this paper confirm the promising potential of computational modeling capabilities for clinical diagnosis and measurements to predict stenosed aortic valve parameters including cardiac output and stroke volume at different heart rates.

3

Fizyczne i numeryczne modelowanie jednowarstwowego płatka zastawki aortalnej

Kopernik M., Nowak J.

Mechanik

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2008

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R. 81, nr 11

958-958

PL

Omówiono opracowanie modelu jednowarstwowego płatka zastawki aortalnej, co pozwala zaprojektować protezę zastawki pracującej docelowo w organizmie człowieka. Opisano kształt zastawki serca, sformułowano podstawowe wymagania stawiane protezom zastawek oraz przybliżono mechanizm otwierania się zastawki serca. Następnie omówiono model elementów skończonych zaproponowany dla zastawki serca, warunki brzegowe i wyniki uzyskane z przeprowadzonych symulacji. Przedstawiono najbardziej charakterystyczne rozkłady naprężeń w płatku zastawki oraz jego przemieszczenia. Analizę wrażliwości wykonano dla modelu zastawki względem jego kluczowych parametrów: kształtu i materiału.

EN

Discussed is a model of monolayer cusp of aortic valve, which will make it possible to design the valve prosthesis for open-ended mounting in human body. The most specific pattern of stress distribution in the cusp of valve and its movements are presented.