Teng Zhongzhao, Feng Jiaxuan, Zhang Yongxue, Huang Yuan, Sutcliffe Michael P F, Brown Adam J, Jing Zaiping, Gillard Jonathan H, Lu Qingsheng
Department of Radiology, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Box 218, Cambridge, CB2 0QQ, UK.
Department of Engineering, University of Cambridge, Cambridge, UK.
Ann Biomed Eng. 2015 Nov;43(11):2745-59. doi: 10.1007/s10439-015-1323-6. Epub 2015 Apr 24.
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.
力学分析有潜力在评估动脉瘤易损性时为动脉瘤形态提供补充信息。可靠的计算需要各个动脉瘤组件的准确材料特性。如果要对破裂进行建模，量化组织的极限延伸性和极限材料强度很重要。从计划进行择期手术的患者的11个腹主动脉瘤（AAA）以及计划进行肾/肝移植的患者的8个正常主动脉（NAA）中获取组织块，在手术时采集并使用冷冻保护剂溶液保存在液氮中，以尽量减少冷冻损伤。在测试前，将标本解冻，从每个组织块上切下纵向和周向的组织条，如果有外膜、中膜和血栓，则将它们分离出来进行材料测试。NAA外膜的增量杨氏模量在低拉伸水平下与方向有关，但中膜并非如此。外膜和中膜在周向方向上具有相似的极限延伸性，但外膜更强。对于动脉瘤组织，比较两个方向上外膜、中膜或血栓的增量模量时未发现显著差异。AAA的外膜和中膜在两个方向上具有相似的极限延伸性和极限强度，血栓是最薄弱的材料。与NAA相比，AAA的外膜和中膜延伸性较小，但极限强度保持相似。健康主动脉和动脉瘤组织的材料特性，包括极限延伸性和极限强度，都与层有关，但与方向无关。
