PURPOSE: To test the hypothesis that ruptured abdominal aortic aneurysms (AAA) are globally weaker than unruptured ones. METHODS: 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. RESULTS: 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±23 N/cm(2); 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 6 cm in length. CONCLUSION: The findings are not consistent with the hypothesis that ruptured aortic aneurysms are globally weaker than unruptured ones.
PURPOSE: To test the hypothesis that ruptured abdominal aortic aneurysms (AAA) are globally weaker than unruptured ones. METHODS: 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. RESULTS: 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±23 N/cm(2); 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 6 cm in length. CONCLUSION: The findings are not consistent with the hypothesis that ruptured aortic aneurysms are globally weaker than unruptured ones.
Authors: Justyna A Niestrawska; Christian Viertler; Peter Regitnig; Tina U Cohnert; Gerhard Sommer; Gerhard A Holzapfel Journal: J R Soc Interface Date: 2016-11 Impact factor: 4.118
Authors: Zhongzhao Teng; Jiaxuan Feng; Yongxue Zhang; Yuan Huang; Michael P F Sutcliffe; Adam J Brown; Zaiping Jing; Jonathan H Gillard; Qingsheng Lu Journal: Ann Biomed Eng Date: 2015-04-24 Impact factor: 3.934