title: Layer- and Direction-Specific Material Properties, Extreme Extensibility and Ultimate Material Strength of Human Abdominal Aorta and Aneurysm: A Uniaxial Extension Study.
abstract: Mechanical analysis has the potential to provide complementary information to aneurysm morphology in assessing its vulnerability. Reliable calculations require accurate material properties of individual aneurysmal components. Quantification of extreme extensibility and ultimate material strength of the tissue are important if rupture is to be modelled. Tissue pieces from 11 abdomen aortic aneurysm (AAA) from patients scheduled for elective surgery and from 8 normal aortic artery (NAA) from patients who scheduled for kidney/liver transplant were collected at surgery and banked in liquid nitrogen with the use of Cryoprotectant solution to minimize frozen damage. Prior to testing, specimen were thawed and longitudinal and circumferential tissue strips were cut from each piece and adventitia, media and thrombus if presented were isolated for the material test. The incremental Young's modulus of adventitia of NAA was direction-dependent at low stretch levels, but not the media. Both adventitia and media had a similar extreme extensibility in the circumferential direction, but the adventitia was much stronger. For aneurysmal tissues, no significant differences were found when the incremental moduli of adventitia, media or thrombus in both directions were compared. Adventitia and media from AAA had similar extreme extensibility and ultimate strength in both directions and thrombus was the weakest material. Adventitia and media from AAA were less extensible compared with those of NAA, but the ultimate strength remained similar. The material properties, including extreme extensibility and ultimate strength, of both healthy aortic and aneurysmal tissues were layer-dependent, but not direction-dependent.
authors.affiliation: Department of Radiology, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Box 218, Cambridge, CB2 0QQ, UK. zt215@cam.ac.uk.|Department of Engineering, University of Cambridge, Cambridge, UK. zt215@cam.ac.uk.
authors.forename: Zhongzhao
authors.initials: Z
authors.lastname: Teng
authors.affiliation: Department of Vascular Surgery, Changhai Hospital, 168 Changhai Rd., Shanghai, 200433, China.
authors.forename: Jiaxuan
authors.initials: J
authors.lastname: Feng
authors.affiliation: Department of Radiology, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Box 218, Cambridge, CB2 0QQ, UK.|Department of Vascular Surgery, Changhai Hospital, 168 Changhai Rd., Shanghai, 200433, China.
authors.forename: Yongxue
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Radiology, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Box 218, Cambridge, CB2 0QQ, UK.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Engineering, University of Cambridge, Cambridge, UK.
authors.forename: Michael P F
authors.initials: MP
authors.lastname: Sutcliffe
authors.affiliation: Division of Cardiovascular Medicine, University of Cambridge, Cambridge, UK.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Brown
authors.affiliation: Department of Vascular Surgery, Changhai Hospital, 168 Changhai Rd., Shanghai, 200433, China.
authors.forename: Zaiping
authors.initials: Z
authors.lastname: Jing
authors.affiliation: Department of Radiology, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Box 218, Cambridge, CB2 0QQ, UK.
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Gillard
authors.affiliation: Department of Vascular Surgery, Changhai Hospital, 168 Changhai Rd., Shanghai, 200433, China. vascsurg.ch@xueguan.net.
authors.forename: Qingsheng
authors.initials: Q
authors.lastname: Lu
mesh_terms: D000328:Adult; D000368:Aged; D001012:Aorta, Abdominal / Q000502:physiology*; D017544:Aortic Aneurysm, Abdominal / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged
keywords: Aneurysm; Aortic artery; Extensibility; Material property; Strength