A Retrospective Comparative Study Of Biomechanical Indexes Of Ruptured And Intact Abdominal Aortic Aneurysms

Objection:The maximum diameter of Abdominal Aortic Aneurysm(AAA)is currently an important indicator for judging the risk of AAA rupture and whether surgical intervention is needed.As Finite Element Analysis is gradually applied to the clinic,this study uses finite element analysis to retrospectively analyze the biomechanical indexes of intact and ruptured AAA,which aims to explore potential indicators for predicting and evaluating the risk of rupture abdominal aortic aneurysm.Method:A total of 927 patients with subrenal rupture and intact abdominal aortic aneurysms admitted to the Department of Vascular Surgery,China-Japan Union Hospital of Jilin University from January 2013 to December 2020 are collected.The computed tomography angiography images of each patient are browsed.According to the exclusion and inclusion criteria.Finally,82 cases of eligible ruptured and intact abdominal aortic aneurysms are selected,and the maximum diameter of these 82 pieces of abdominal aortic aneurysm are acquired.Through maximum diameter matching(RAAA: IAAA=1: 1-2),18 eligible cases of rupture abdominal aortic aneurysm(RAAA)are finally obtained,and25 cases of intact abdominal aortic aneurysm(IAAA)in intact group.All43 cases of CTA images are imported into Mimics Research 20.0software in DICOM format for geometric model reconstruction.And smoother 3D geometric models of AAA are obtained.Then the geometric models are imported into ansys 19.0 to wage the finite element analysis.After setting the relevant control parameters,the pressure distribution cloud map on the surface of AAA is obtained.Finally,we are able to acquire the peak wall stress(PWS)and measure the thickness of the intra luminal thrombus(ILT).Basing on the calculation formula of the wall strength reported in previous literature,we can gain the value of wall strength and rupture potential index(RPI).Finally,spss 22.0 software is used for statistical analysis to compare basic characteristics,intra luminal thrombus thickness,wall strength,PWS and RPI in rupture AAA and intact AAA.Result:All AAAs are no history of diabetes.Compared with the smoking history of the rupture group and the intact group,there is a statistically significant difference in smoking history(14/4 VS 10/15,P<0.05).There was no statistically significant difference in age(69.33±7.380 VS66.36±7.648),gender(11/7 VS 18/7),history of hypertension(10/8 VS8/17),hyperlipidemia(10/8 VS 11/14),coronary heart disease(6/12 VS9/16)and peripheral blood vessels disease(13/5 VS 15/10),and all P values are greater than 0.05.Compared with the PWS(60.0712±16.2353 VS 40.6862±17.2104,P=0.001),the difference between the rupture group and the intact group is statistically significant.Compared with the ILT thickness of the rupture group and the intact group(0.4856±0.1328 VS0.5768 ± 0.1317,P=0.031),the difference is statistically significant.Compared with the wall strength(P=0.980),there is no significant difference in the wall strength between rupture group and intact group.Compared with the rupture potential index between rupture group and intact group(0.0549 ± 0.0133 VS 0.0380 ± 0.0170,P=0.001),the difference is statistically significant.Conclusion:Peak wall stress(PWS),rupture potential index(RPI),and ILT thickness at the point of PWS are significant factors for abdominal aortic aneurysm occurring rupture.Biomechanical indicators(PWS,RPI)may be potential indicators for predicting and evaluating the rupture of abdominal aortic aneurysm.