Biomechanical failure properties and microstructural content of ruptured and unruptured abdominal aortic aneurysms

Madhavan L Raghavan; Mauro M Hanaoka; Jarin A Kratzberg; Maria de Lourdes Higuchi; Erasmo Simao da Silva

doi:10.1016/j.jbiomech.2011.06.004

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Biomechanical failure properties and microstructural content of ruptured and unruptured abdominal aortic aneurysms

Journal article

Peer reviewed

Biomechanical failure properties and microstructural content of ruptured and unruptured abdominal aortic aneurysms

Madhavan L Raghavan, Mauro M Hanaoka, Jarin A Kratzberg, Maria de Lourdes Higuchi and Erasmo Simao da Silva

Journal of biomechanics, Vol.44(13), pp.2501-2507

09/02/2011

DOI: 10.1016/j.jbiomech.2011.06.004

PMID: 21763659

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Abstract

To test the hypothesis that ruptured abdominal aortic aneurysms (AAA) are globally weaker than unruptured ones. Four ruptured and seven unruptured AAA specimens were harvested whole from fresh cadavers during autopsies performed over an 18-month period. Multiple regionally distributed longitudinally oriented rectangular strips were cut from each AAA specimen for a total of 77 specimen strips. Strips were subjected to uniaxial extension until failure. Sections from approximately the strongest and weakest specimen strips were studied histologically and histochemically. From the load-extension data, failure tension, failure stress and failure strain were calculated. Rupture site characteristics such as location, arc length of rupture and orientation of rupture were also documented. The failure tension, a measure of the tissue mechanical caliber was remarkably similar between ruptured and unruptured AAA (group mean±standard deviation of within-subject means: 11.2±2.3 versus 11.6±3.6N/cm; p=0.866 by mixed model ANOVA). In post-hoc analysis, there was little difference between the groups in other measures of tissue mechanical caliber as well such as failure stress (95±28 versus 98±23N/cm2; p=0.870), failure strain (0.39±0.09 versus 0.36±0.09; p=0.705), wall thickness (1.7±0.4 versus 1.5±0.4mm; p=0.470) , and % coverage of collagen within tissue cross section (49.6±12.9% versus 60.8±9.6%; p=0.133). In the four ruptured AAA, primary rupture sites were on the lateral quadrants (two on left; one on left-posterior; one on right). Remarkably, all rupture lines had a longitudinal orientation and ranged from 1 to 6cm in length. The findings are not consistent with the hypothesis that ruptured aortic aneurysms are globally weaker than unruptured ones. ► We studied whether ruptured abdominal aortic aneurysms are weaker than unruptured ones. ► Multiple specimens were obtained from each of 13 aneurysms harvested at necropsy. ► Specimen caliber was assessed by mechanical testing, histology and histochemistry. ► Ruptured aneurysms were not globally weaker than unruptured ones.

Mechanical testing

Failure properties

Abdominal aortic aneurysm

Rupture

Details

Title: Subtitle: Biomechanical failure properties and microstructural content of ruptured and unruptured abdominal aortic aneurysms
Creators: Madhavan L Raghavan - Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
Mauro M Hanaoka - University of São Paulo Medical School, São Paulo, SP, Brazil
Jarin A Kratzberg - Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
Maria de Lourdes Higuchi - University of São Paulo Medical School, São Paulo, SP, Brazil
Erasmo Simao da Silva - University of São Paulo Medical School, São Paulo, SP, Brazil
Resource Type: Journal article
Publication Details: Journal of biomechanics, Vol.44(13), pp.2501-2507
Publisher: Elsevier Ltd
DOI: 10.1016/j.jbiomech.2011.06.004
PMID: 21763659
ISSN: 0021-9290
eISSN: 1873-2380
Grant note: name: American Heart Association Heartland, award: #0365408Z
Language: English
Date published: 09/02/2011
Academic Unit: Roy J. Carver Department of Biomedical Engineering
Record Identifier: 9984064250502771

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