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Noninvasive ultrasound measurements of aortic intima-media thickness: Implications for in vivo study of aortic wall stress
Linköping University, Department of Medicine and Health Sciences, Physiology . Linköping University, Faculty of Health Sciences.
Department of Surgery, Helsingborg Hospital, Helsingborg, Sweden.
Department of Clinical Physiology, Malmö University Hospital, Malmö, Sweden.
Linköping University, Department of Medicine and Health Sciences, Physiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
2003 (English)In: Journal of Vascular Surgery, ISSN 0741-5214, Vol. 37, no 6, 1270-1276 p.Article in journal (Refereed) Published
Abstract [en]

Object: The abdominal aorta (AA) has a predilection for aneurysm formation. An etiologic factor may be underlying aortic wall stress. The purpose of this study was to examine whether the intima-media thickness (IMT) of the AA, as a surrogate to arterial wall thickness, can be measured noninvasively with satisfactory results to calculate circumferential wall stress, and to evaluate regional and gender differences in wall stress.

Methods: Sixty-five middle-aged healthy subjects were examined with B-mode ultrasound to determine the diameter and IMT in the infrarenal AA, common carotid artery (CCA), common femoral artery (CFA), and popliteal artery (PA). Blood pressure was measured noninvasively in the brachial artery. Wall stress was calculated according to the law of LaPlace.

Results: Intraobserver variability for the IMT in the AA showed a coefficient of variation of 11%. IMT was thickest in the AA compared with the CCA, CFA, and PA (P < .001). There was a gender difference in IMT in the CFA (P < .05) and PA (P < .01) but not in the AA. Greater wall stress was found in the AA than in the CCA (P < .001) and PA (P < .001), with men having greater wall stress in all studied arterial regions.

Conclusions: Aortic IMT can be satisfactorily studied in vivo with noninvasive B-mode ultrasound. There are gender differences in IMT and wall stress, and the largest wall stress is found in the AA in men, which might be important in aneurysm development.

Place, publisher, year, edition, pages
2003. Vol. 37, no 6, 1270-1276 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-13178DOI: 10.1016/S0741-5214(02)75344-5OAI: diva2:17982
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2009-08-21
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, HåkanLänne, Toste
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Physiology Faculty of Health SciencesDepartment of Thoracic and Vascular Surgery
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