Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Influence of Thickness on Flutter in Prosthetic Biological Heart Valves
Submission Author:
Matheus Carvalho Barbosa Costa , MG
Co-Authors:
Matheus Carvalho Barbosa Costa, Joao Fleury, Saulo Gonçalves, Mário Silva, Rudolf Huebner, Artur Avelar
Presenter: Saulo Gonçalves
doi://10.26678/ABCM.COBEM2023.COB2023-0372
Abstract
Aortic valves are structures formed by three flexible leaflets and present the function of ensuring unidirectional flow between the left ventricle and the aorta artery. The dysfunction of these valves is the main cause of death among the group of adversities that affect the cardiovascular system. Replacement of damaged native valves with prostheses made from biological materials is the main strategy for the treatment of patients affected by dysfunction of these valves. However, bioprostheses are characterized by a low durability, between 10-15 years, mainly caused by the oscillatory movement of the cusps due to the interaction with the blood flow, a phenomenon known as flutter. Despite related with the increase of calcification, fatigue, hemolysis and thrombus formation of biological prostheses, flutter is barely studied in the dynamics of these valves. Studies indicate that the geometric parameter of the valves is an important factor affecting the dynamic response of the leaflets and may influence in flutter condition, which accelerate the process of deterioration of prosthetic valves. The present study aims to evaluate the influence of leaflets thickness on the dynamics of the bioprotheses using the Finite Element technique. For this purpose, aortic valve prosthesis geometry was developed, based on geometrical models available in the literature, and only the thickness was changed for each simulation. For the calculations, the Ansys Mechanical software was used. Transvalvular pressure was applied on the side facing the left ventricle and a fixed support was considered on the sides of the leaflets. Solid elements were used in the simulations and the mesh sensitivity test was performed considering three different meshes, in which each mesh was refined to present two times more elements than the previous mesh. The first-order Ogden hyperelastic constitutive model was used to calculate the deformation energy function of the valve material. It is expected that with increasing aortic valve thickness, the valve opening area and vibration amplitude tend to decrease. In addition, it is expected that the vibration frequency tends to increase with the thickness increase, because is observed an increase in the stiffness of the leaflets. Thus, it is expected to determine a correlation capable of predicting the behavior of the vibration parameters with the thickness of the leaflets. With the present work, it is possible to observe that numerical studies can be a viable alternative to evaluate and quantify the processes responsible for the deterioration of prosthetic heart valves.
Keywords
Aortic Valve, Bioprotheses, Finite Element Method, Flutter, thickness, Shell elements
