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In vivo estimation of the contribution of elastin and collagen on the mechanical properties in the abdominal aorta of man: effect of age and gender
Linköping University, Department of Medical and Health Sciences, Physiology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Management and Engineering, Mechanics. Linköping University, The Institute of Technology.
Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
Malmö University Hospital.
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2011 (English)In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 110, no 1, 8750-8757 p.Article in journal (Refereed) Published
Abstract [en]

The mechanical properties of the aorta affect cardiac function and are related to cardiovascular morbidity/mortality. This study was designed to evaluate the isotropic (mainly elastin, elastiniso) and anisotropic (mainly collagen, collagenani) material parameters within the human aorta in vivo. Thirty healthy men and women in three different age categories (23–30, 41–54, and 67–72 yr) were included. A novel mechanical model was used to identify the mechanical properties and the strain field with aid of simultaneously recorded pressure and radius in the abdominal aorta. The magnitudes of the material parameters relating to both the stiffness of elastiniso and collagenani were in agreement with earlier in vitro studies. The load-bearing fraction attributed to collagenani oscillated from 10 to 30% between diastolic and systolic pressures during the cardiac cycle. With age, stiffness of elastiniso increased in men, despite the decrease in elastin content that has been found due to elastolysis. Furthermore, an increase in stiffness of collagenani at high physiological pressure was found. This might be due to increased glycation, as well as changed isoforms of collagen in the aortic wall with age. A marked sex difference was observed, with a much less age-related effect, both on elastiniso and collagenani stiffness in women. Possible factors of importance could be the effect of sex hormones, as well as differing collagen isoforms, between the sexes.

Place, publisher, year, edition, pages
AMER PHYSIOLOGICAL SOC , 2011. Vol. 110, no 1, 8750-8757 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-13180DOI: 10.1152/japplphysiol.00579.2010ISI: 000286140900022OAI: diva2:17984
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2012-03-24
In thesis
1. Regulation of aortic wall mechanics and stress: An experimental study in man
Open this publication in new window or tab >>Regulation of aortic wall mechanics and stress: An experimental study in man
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The abdominal aorta (AA) in man is a vulnerable artery prone to atherosclerosis as well as aneurysmatic dilation. The underlying aortic composition, mechanical properties as well as the mechanisms responsible for age-related changes and vascular disease are however largely unknown. The aims of this study were 1) to characterize the age- and gender-related changes of the aortic wall components in vivo, using a mechanical model based on ultrasound measurements of pulsatile aortic diameter changes combined with intra-arterial pressure; 2) to validate ultrasound measurements of diameter and intima-media thickness (IMT) of the AA in order to calculate wall stress; 3) to study the stress driven remodeling response of the aortic wall in healthy individuals and the influence of age and gender; and 4) to study wall stress and remodeling of the AA in diabetic patients in order to elucidate the protective influence of diabetes on abdominal aortic aneurysm formation.

The stiffness of the isotropic material (mainly elastin) increased in males despite the known decrease in elastin content with age. Further, an exponential increase in stiffness of the anisotropic material (mainly collagen) in males at high physiological pressure was found. This might be due to changed isoforms of collagen and increased glycation with age. Females were less affected than males.

The reproducibility of the ultrasound measurements of diameter and IMT in the AA was acceptable (CV; 4% and 11% respectively), making it possible to calculate circumferential aortic wall stress in vivo. The age-related remodeling of the arterial wall led to increased diameter, and compensatory thickening of the wall preventing the circumferential wall stress from increasing in the common carotid artery of males and females, and the AA of females. However, the compensatory increase in wall thickness was defect in the male AA, where stress increased with age. Pulsatile stress influenced the material parameters of the AA, leading to increased stiffness of anisotropic material (mainly collagen), whereas stiffness of isotropic material (mainly elastin) was unaffected.

Patients with diabetes mellitus had increased aortic wall thickness than controls, generating less circumferential stress. This coincides with the known reduction of abdominal aortic aneurysms in diabetic patients and may act as a protective factor.

Place, publisher, year, edition, pages
Institutionen för medicin och hälsa, 2008. 74 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1053
Aorta, wall stress, remodeling, IMT, gender, diabetes mellitus, aging, collagen, elastin
National Category
urn:nbn:se:liu:diva-11556 (URN)978-91-7393-944- 7 (ISBN)
Public defence
2008-05-16, Originalet, Qulturum, Hus B4, Länssjukhuset Ryhov, Jönköping, 09:00 (English)
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2009-08-22

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Åstrand, HåkanStålhand, JonasKarlsson, MattsLänne, TosteKarlsson, J
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PhysiologyFaculty of Health SciencesMechanicsThe Institute of TechnologyApplied Thermodynamics and Fluid MechanicsDepartment of Thoracic and Vascular Surgery in Östergötland
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