Mechanisms of aortic valve incompetence in aging: A finite element model

Background and aim of the study: The effect of aging on aortic valve and ro ot function was examined using a three-dimensional finite element model of the aortic root and valve. Methods: Three models representing normal (<35 years), middle (35-55 years) and older (>55 years) age groups, were created by assigning tissue thickne ss and stiffness that increased with age (using ANSYS software). Diastolic pressure was applied; stresses and strains were then evaluated for the valv e and root, and percent leaflet coaptation was calculated. Results: Leaflet stresses were increased with aging, whereas leaflet strain and coaptation were decreased with aging. Specifically, leaflet stresses w ere increased by 6-14% in the middle-age model, and by 2-11% in the older-a ge model, as compared with normal in specified leaflet regions. Conversely, leaflet strains were decreased by 27-41% and 42-50% in the middle-age and older-age models, respectively. This reduced strain resulted in markedly de creased coaptation (9% and 30% reduction for middle- and older-age models). In the root, stress remained fairly constant with age, but strain in the r oot was progressively reduced with age (11% and 35% reduction for the middl e and older-age models, respectively). Conclusions: In these models, increased stiffness and thickness due to agin g reduces leaflet deformation and restricts coaptation. Clinically, valvula r regurgitation may result due to leaflet thickening and stiffening with no rmal aging. Our model can now be utilized to evaluate the root-valve relati onship in the presence of bioprosthetic valves or root replacements.