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Age-related increase in wall stress of the human abdominal aorta: An in vivo study
Linköping University, Department of Medicine and Health Sciences, Physiology . Linköping University, Faculty of Health Sciences.
Department of Clinical Physiology, University Hospital Malmö, University of Lund.
Department of Surgery, Helsingborg Hospital.
Linköping University, Department of Medicine and Health Sciences, Physiology . Linköping University, Faculty of Health Sciences.ORCID iD: 0000-0002-9095-403X
2005 (English)In: Journal of Vascular Surgery, ISSN 0741-5214, Vol. 42, no 5, 926-931 p.Article in journal (Refereed) Published
Abstract [en]

Background

The regulation of wall stress in the abdominal aorta (AA) of humans might be of specific interest, because the AA is the most common site for aneurysm formation in which wall stress seems to be an important pathophysiological factor. We studied the age-related changes in wall stress of the AA in healthy subjects, with the common carotid artery (CCA) as a comparison.

Methods

A total of 111 healthy subjects were examined with B-mode ultrasonography to determine the lumen diameter and intima-media thickness (IMT) in the AA and the CCA.

Results

Aortic IMT was affected by age in men and by both age and lumen diameter in women. Carotid IMT was affected by age and pulse pressure in both men and women. Wall stress was higher in the AA than in the CCA (P < .001), and men had higher wall stress than women in both the AA (P < .001) and the CCA (P < .05). Furthermore, wall stress was constant during life in the CCA of men and women and in the AA of women. In the male aorta, however, wall stress increased with age (P < 0.01).

Conclusions

Arterial diameters increase with age, and a compensatory thickening of the arterial wall prevents the circumferential wall stress from increasing. However, this compensatory response is insufficient in the male AA and results in an increase in stress with age. These findings might explain the propensity for aneurysms to develop in the AA of men.

Place, publisher, year, edition, pages
2005. Vol. 42, no 5, 926-931 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-13179DOI: 10.1016/j.jvs.2005.07.010OAI: oai:DiVA.org:liu-13179DiVA: diva2:17983
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2017-03-27
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.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1053
Keyword
Aorta, wall stress, remodeling, IMT, gender, diabetes mellitus, aging, collagen, elastin
National Category
Surgery
Identifiers
urn:nbn:se:liu:diva-11556 (URN)9789173939447 (ISBN)
Public defence
2008-05-16, Originalet, Qulturum, Hus B4, Länssjukhuset Ryhov, Jönköping, 09:00 (English)
Opponent
Supervisors
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2017-12-08

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Åstrand, HåkanLänne, Toste

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