title: A constitutive modeling interpretation of the relationship among carotid artery stiffness, blood pressure, and age in hypertensive subjects.
abstract: Aging has a profound influence on arterial wall structure and function. We have previously reported the relationship among pulse wave velocity, age, and blood pressure in hypertensive subjects. In the present study, we aimed for a quantitative interpretation of the observed changes in wall behavior with age using a constitutive modeling approach. We implemented a model of arterial wall biomechanics and fitted this to the group-averaged pressure-area (P-A) relationship of the "young" subgroup of our study population. Using this model as our take-off point, we assessed which parameters had to be changed to let the model describe the "old" subgroup's P-A relationship. We allowed elastin stiffness and collagen recruitment parameters to vary and adjusted residual stress parameters according to published age-related changes. We required wall stress to be homogeneously distributed over the arterial wall and assumed wall stress normalization with age by keeping average "old" wall stress at the "young" level. Additionally, we required axial force to remain constant over the cardiac cycle. Our simulations showed an age-related shift in pressure-load bearing from elastin to collagen, caused by a decrease in elastin stiffness and a considerable increase in collagen recruitment. Correspondingly, simulated diameter and wall thickness increased by about 20 and 17%, respectively. The latter compared well with a measured thickness increase of 21%. We conclude that the physiologically realistic changes in constitutive properties we found under physiological constraints with respect to wall stress could well explain the influence of aging in the stiffness-pressure-age pattern observed.
authors.affiliation: Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands; b.spronck@maastrichtuniversity.nl.
authors.forename: Bart
authors.identifier: http://orcid.org/0000-0003-1076-1922
authors.initials: B
authors.lastname: Spronck
authors.affiliation: Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands; Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands;
authors.forename: Maarten H G
authors.initials: MH
authors.lastname: Heusinkveld
authors.affiliation: Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Department of Biomedical Engineering, MHeNS School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands; and.
authors.forename: Wouter P
authors.initials: WP
authors.lastname: Donders
authors.affiliation: Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands;
authors.forename: Anouk G W
authors.initials: AG
authors.lastname: de Lepper
authors.affiliation: Department of Internal Medicine, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands.
authors.forename: Jos
authors.initials: J
authors.lastname: Op't Roodt
authors.affiliation: Department of Internal Medicine, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands.
authors.forename: Abraham A
authors.initials: AA
authors.lastname: Kroon
authors.affiliation: Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands;
authors.forename: Tammo
authors.initials: T
authors.lastname: Delhaas
authors.affiliation: Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands;
authors.forename: Koen D
authors.initials: KD
authors.lastname: Reesink
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging; D062186:Arterial Pressure; D001696:Biomechanical Phenomena; D002339:Carotid Arteries / Q000378:metabolism / Q000503:physiopathology*; D003094:Collagen / Q000378:metabolism; D003198:Computer Simulation; D004549:Elastin / Q000378:metabolism; D005260:Female; D006801:Humans; D006973:Hypertension / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D013314:Stress, Mechanical; D059289:Vascular Stiffness
chemical_list: D003094:Collagen; D004549:Elastin
keywords: aging; collagen; constitutive modeling; elastin; pulse wave velocity