Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
influence of tissue stiffness on leaflet oscillation dynamics during a cardiac cycle.
Submission Author:
Joao Fleury , MG , Brazil
Co-Authors:
Joao Fleury, Matheus Carvalho Barbosa Costa, Saulo Gonçalves, Mário Silva, Rudolf Huebner
Presenter: Saulo Gonçalves
doi://10.26678/ABCM.COBEM2023.COB2023-0375
Abstract
Aortic valve stenosis is a cardiovascular disease caused by stiffening of heart valves tissue that prevents the valve leaflets from fully opening, reducing the effective orifice area and overloading the heart. Stiffened leaflets are also less efficient at stopping the blood flow in the opposite direction, causing a condition called regurgitation. Among the main strategies for the treatment of patients suffering from one of these conditions, can be mentioned the replacement of the valve with a bioprosthesis, which generally presents good hemodynamics and low thrombogenic potential, increasing the patient's life expectancy and life quality. Howerver the bioprostheses are subjected to flutter and other mechanisms that cause leaflet tissues degradation such as fatigue, calcification, hemolisys and thrombus formation, limiting its lifespan between 10 and 15 years. Aiming at a better understanding of the flutter phenomenon, the present study seeks to evaluate the effect of tissue stiffness on leaflet oscillation dynamics during a cardiac cycle using the finite element method. Starting from a geometry available in the literature, a computational model of the valve was developed. In order to isolate the effect of the material, the leaflets were analyzed for a constant thickness, valve diameter and valve protrusion height, changing the young's modulus of the material in each simulation. As loading mode, physiological transvalvular pressure was applied on the ventricular side of the leaflets. The study considered the transient analysis of two consecutive cardiac cycles, in which the contact between the leaflets was modeled as frictionless and the mesh sensitivity was evaluated for 3 different meshes. For each simulation, the leaflet opening area was calculated during the systolic peak. The frequency and amplitude of oscillation for each simulation was also evaluated. From this study, it is expected to obtain a correlation of increased oscillation frequencies of the leaflets as the modulus of elasticity of the material increases. For the valve opening area, an inverse correlation is expected, since the higher the elastic modulus, the greater the valve stiffness, tending to decrease the opening area. This study will increase understanding about the influence of valve material on flutter dynamics and will support the design of bioprosthesis less susceptible to flutter and therefore more durable.
Keywords
Aortic Valve, heart valve, Bioengenharia, Finite Element Method, Flutter, calcification, heart valve flutter
