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1

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.

2

Biocompatibility Issue Of Tissue Engineered Heart Valves

Wilczek P.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3

2261--2266

EN

Tissue engineering is a new field of knowledge which creates the possibilities for producing bioactive cardiac prostheses that will characterize by biomechanical and morphological properties similar to native tissue. It is expected that it will be characterized by high durability, which is very important from the social and clinical point of view. The aim of the study was to compare the cytotoxic effect of enzymatic and detergent acellularization methods commonly used for the biological scaffold preparation. It seems that the use of enzymatic methods, allows efficient donor cells removal while maintaining the ability to autologous cell seeding. Heart valves bioprosthesis created using these techniques, may be a good alternative to the currently used prostheses.

PL

Inżynieria tkankowa jest nową dziedziną wiedzy, która stwarza możliwości wytwarzania protez serca bioaktywnych charakteryzujących się właściwościami biomechanicznymi i morfologicznymi zbliżonymi do tkanki rodzimej. Oczekuje się, że proteza serca będzie charakteryzować się wysoką trwałością, co jest bardzo ważne z punktu widzenia społecznego i klinicznego. Celem badania było porównanie efektu cytotoksycznego enzymatycznych i detergentowych metod usuwania komórek, powszechnie stosowanych do wytwarzania biologicznych rusztowań. Wydaje się, że stosowanie metod enzymatycznych, umożliwia wydajne usunięcie komórek dawcy przy zachowaniu zdolności do autologicznego posiewu komórek. Bioprotezy zastawek serca tworzone za pomocą tej techniki mogą być dobrą alternatywą dla obecnie stosowanych mechanicznych i biologicznych protez zastawek serca.

3

Angular position determination of heart valves in the pediatric ventricular assist device with use of computational fluid dynamics

Jodko D., Obidowski D., Reorowicz P., Kłosiński P., Jóźwik K.

Aktualne Problemy Biomechaniki

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2014

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z. 8

57--62

EN

This study shows a method than can be used to determine the best angular position of heart valves installed at the inlet and the outlet of a blood chamber during the diastolic phase with use of Computational Fluid Dynamics (CFD). Steady state simulations of the blood flow through the blood chamber of Pediatric Ventricular Assist Device (PVAD) have been performed with ANSYS CFX 14.0. Main assumptions in the present paper have included: motionless discs, rigid walls, non-Newtonian model of blood. The obtained results show that areas of blood stagnation in the blood chamber are smallest for one particular angular position of the inlet valve and are not significantly dependent on the angular position of the outlet valve.

4

Badania biologiczne warstw powierzchniowych w aspekcie zastosowania na pierścień zastawki serca

Gonsior M., Kustosz R., Borowski T., Ossowski M., Sanak M., Jakiełła B., Czarnowska E., Wierzchoń T.

Engineering of Biomaterials

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2011

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Vol. 14, no. 102

15--22

PL

Oryginalna sztuczna komora wspomagania serca POLVAD opracowana w Polsce, została zastosowana dotychczas w leczeniu ponad 210 pacjentów. Najdłuższe wspomaganie serca za pomocą komory POLVAD trwało ponad rok. Dla protezy tej opracowywana jest innowacyjna zastawka dyskowa, z nisko profilowym pierścieniem wykonanym ze stopu tytanu. Dla zminimalizowania trombogenności pierścienia zastawki opracowano dyfuzyjne warstwy powierzchniowe: azotowaną typu TiN+Ti2N+αTi(N) i tlenoazotowaną typu TiO2+TiN+Ti2N+αTi(N), wytwarzane obróbką jarzeniową na potencjale plazmy. Trombogenność różnych kompozycji warstw została porównana w aspekcie aktywacji i adhezji płytek krwi do powierzchni biomateriału. Oceniono również wpływ metody sterylizacji biomateriału na intensywność adhezji trombocytów do jego powierzchni. Warstwy TiN oraz TiO2wykazały najniższą trombogenność, przy czym dla warstwy TiN korzystniejsza jest sterylizacja gazowa, podczas gdy dla warstwy TiO2- sterylizacja plazmowa.

EN

The original ventricular assist device POLVAD developed in Poland was used in over 210 patients so far. The longest POLVAD heart assistance excided one year. The innovative tilting disk valve with low profile ring made of titanium is developed for POLVAD. To minimize the valve ring thrombogenicity the diffusive surface layers were manufactured: nitriding TiN+Ti2N+αTi(N) and oxynitriding TiO2+TiN+Ti2N+αTi(N), in the glow discharge process on the plasma potential level. The thrombogenicity of different layers compositionwas compared regarding platelets activation and platelets adhesion to the material surface. The influence of material sterilization method on the platelets adhesion intensity was evaluated in addition. The nitriding TiN and oxynitriding TiO2layers have demonstrated the lowest thrombogenicity while the gas sterilization was the most profitable for nitriding layers – TiN and the plasma sterilization for oxynitriding layers – TiO2.

5

Heart valve bioprothesis; effect of different acellularizations methods on the biomechanical and morphological properties of porcine aortic and pulmonary valve

Wilczek P.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2010

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Vol. 58, nr 2

337-342

EN

Tissue engineering is a promising tool for the creation of a new type of the heart valve bioprothesis. The biological scaffold composed of decellularized tissue has been successfully used for the constructions of the valve prosthesis. An analysis of the efficiency of the valve leaflet acellularization methods and the influence of those methods on the morphology and the biomechanical properties of the ECM (extra cellular matrix) was performed. Fresh porcine hearts obtained from a slaughterhouse were used in the experiments. The efficiency of the acellularization methods was dependent on the tissue type and the acellularoization methods used. The more effective were the enzymatic methods, both because of the cell removal efficiency and the effect on the biomechanical properties of the heart valve. The differences in the biomechanical and morphological properties of the porcine aortic and the pulmonary valve after different types of the acellularization process could influence the hemodynamic conditions of the heart after the valve replacement, which limited the range of the tissue types used for the creations of the tissue engineered heart valve.

6

Origin and design of a bileaflet heart valve

Wojnarowski J.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2006

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z. 26

389-394

EN

This paper presents the evolution of an artificial mechanical heart valve, paing particular attention to a bileaflet valve, which has in recent years acknowledged to be the most advanced and most effective solution of a constructed limb of the natural heart valve

7

Wpływ położenia kątowego pierścienia mechanicznej zastawki serca na parametry przepływu w łuku aorty

Witkowski D.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2006

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Nr 129, vol. 1

35-44

PL

W pracy przedstawiono wpływ położenia kątowego pierścienia zastawki względem aorty na parametry przepływu. Dla dysku wypukłego o promieniu 130 mm zostały przeprowadzone obliczenia, dla kąta pomiędzy osią symetrii kanału a osią symetrii pierścienia zastawki wynoszącego 0°, 90°, 180° oraz 270°. Przyjęto nieodkształcalne ścianki kanału oraz uproszczony model części serca przed zastawką. Poszczególne wymiary geometryczne oparte są na uśrednionych wartościach anatomicznych.

EN

An influence of the angular position of the heart valve placed in the aorta on flow parameters have been presented. The calculation results for discs with the concavity radii of 130 mm for an angle between the channel symmetry axis and the disc heart valve symmetry axis equal to 0°, 90°, 180° and 270° have been shown. Undeformable channel walls and a simplified model of the heart part upstream of the artificial heart valve have been assumed. Individual geometrical dimensions are based on averaged anatomical values.