Objective With considerion of aortic wall hyperelasticity and residual stress,to propose a numerical simulation method for predicting aortic blood pressure based on vascular compliance.Methods The residual stress solution method based on the closing opening angle was used to realize the analytical solution for the pressure-radius relationship of the idealized double-layered aortic wall model.The vascular compliance was calculated,and the pressure-radius relationship was applied to the moving boundary representing the motion of the aortic wall for numerical simulation,to obtain the relationship between vascular compliance and pulse pressure.The effects of with or without residual stress,hyperelasticity or linear elasticity constitutive relationships,as well as different ages on vascular compliance and aortic blood pressure were compared.The function of the stent graft was incorporated,by considering the stented region as a rigid wall,and the effects of different stent numbers and stent positions on aortic blood pressure were simulated.Results Vascular compliance with residual stress was higher than that without residual stress;correspondingly,when residual stress was considered,aortic pulse pressure was slightly lower than that without residual stress.Compared to the linear elastic model,the hyperelastic model predicted a smaller aortic pulse pressure value.The vascular compliance for different age groups showed 40-49 year-old＞60-69 year-old＞70 year-old and above;correspondingly,the pulse pressure for different age groups showed 40-49 year-old＜60-69 year-old＜70 year-old and above.When a stent with 60 mm length was implanted in the aorta,as the number of stents increasing,the aortic pulse pressure continued to rise,indicating that the wider the range of stent implantation,the higher the pulse pressure.The closer the stent implantation site was to the heart,the higher the pulse pressure.Conclusions The proposed simulation method in this study can accurately predict blood pressure and evaluate aortic compliance,providing theoretical and technical support for stent design and surgical plan optimization.

Objective With considerion of aortic wall hyperelasticity and residual stress,to propose a numerical simulation method for predicting aortic blood pressure based on vascular compliance.Methods The residual stress solution method based on the closing opening angle was used to realize the analytical solution for the pressure-radius relationship of the idealized double-layered aortic wall model.The vascular compliance was calculated,and the pressure-radius relationship was applied to the moving boundary representing the motion of the aortic wall for numerical simulation,to obtain the relationship between vascular compliance and pulse pressure.The effects of with or without residual stress,hyperelasticity or linear elasticity constitutive relationships,as well as different ages on vascular compliance and aortic blood pressure were compared.The function of the stent graft was incorporated,by considering the stented region as a rigid wall,and the effects of different stent numbers and stent positions on aortic blood pressure were simulated.Results Vascular compliance with residual stress was higher than that without residual stress;correspondingly,when residual stress was considered,aortic pulse pressure was slightly lower than that without residual stress.Compared to the linear elastic model,the hyperelastic model predicted a smaller aortic pulse pressure value.The vascular compliance for different age groups showed 40-49 year-old＞60-69 year-old＞70 year-old and above;correspondingly,the pulse pressure for different age groups showed 40-49 year-old＜60-69 year-old＜70 year-old and above.When a stent with 60 mm length was implanted in the aorta,as the number of stents increasing,the aortic pulse pressure continued to rise,indicating that the wider the range of stent implantation,the higher the pulse pressure.The closer the stent implantation site was to the heart,the higher the pulse pressure.Conclusions The proposed simulation method in this study can accurately predict blood pressure and evaluate aortic compliance,providing theoretical and technical support for stent design and surgical plan optimization.

Objective:To compare the aortic remodeling of the Fabulous stent system and standard thoracic aortic endovascular repair (TEVAR) on distal aorta type B aortic dissection (TBAD). Methods:The prospective data collected between Dec 2017 and Oct 2019 from 134 patients with type B aortic dissection (TBAD) who underwent treatment with the "Fabulous" stent system, and retrospective data from 159 TBAD patients receiving standard TEVAR from corresponding multicenter. By using propensity score matching analysis, we compared the prognosis and aortic remodeling outcomes in patients undergoing Fabulous and standard TEVAR treatments during a 1-year postoperative follow-up.Results:In this study, 62 patients in Fabulous group and 62 patients in standard TEVAR were included.There were no significant statistical differences in baseline characteristics between the two groups. In terms of aortic remodeling in bare stent region, Fabulous group had better change trends of diameter of true lumen [10.6 (4.4, 14.5) mm vs. 4.7 (0.9, 10.7) mm, P=0.001] and false lumen [-24.2 (-30.5, -4.9) mm vs. 0.7 (-11.8, 2.3) mm, P<0.001] than those in the standard TEVAR group. The rate of complete false lumen thrombosis was also higher in the Fabulous group (62.9% vs. 37.1%, P=0.042). Conclusion:The Fabulous stent system, when compared to standard TEVAR surgery, demonstrates good aortic remodeling outcomes in the distal aorta.

Objective:To evaluate the medium-term efficacy and safety of the controlled supra-aortic pre-fenestration technique in the management of aortic arch lesions.Methods:The clinical and follow-up data of 167 patients with aortic arch lesions located in the Z1 and Z2 zones and undergoing endovascular treatment at the Department of Vascular Surgery, Tianjin Medical University General Hospital from Jul 2015 to Dec 2022 were retroactively analyzed.Results:The surgical success rate was 100% in both the pre-fenestration and non-pre-fenestration groups. Regarding technical success, the pre-fenestration group exhibited a rate of 97.26%, while the non-pre-fenestration group showed a rate of 95.74% ( P>0.05). Cost in the pre-fenestration group was lower compared to the non-pre-fenestration group ( P<0.05). The mean follow-up period were (63.92±25.23) months for the pre-fenestration group and (37.63±21.48) months for the non-pre-fenestration group. During the follow-up period, no significant differences were found in complications, reinterventions, and survival rates between the two groups ( P>0.05). Conclusion:Controlled supra-aortic pre-fenestration technique exhibits excellent medium-term efficacy and safety in the treatment of aortic arch diseases located in the Z1 and Z2 zones with lower total hospitalization costs.

Objective To calculate the pre-stretching of the microscopic components of the aortic wall under physiological homeostasis by considering a three-dimensional(3D)residual stress field.Methods The aortic wall was simplified into a double-layer ideal circular tube,and the 3D residual stress field of the vascular wall was calculated based on a 3D expansion angle experiment.Then,the in vivo stress distribution characteristics under mean blood pressure and the pre-stretching of each microscopic constituent of the vascular wall under a physiologically steady state were obtained.The inverse problem was constructed according to the internal pressure-radius relationship measured in vivo.Physiological homeostasis of the aorta was considered the reference state,and inversion identification of the material parameters of the aorta in vivo was realized while integrating the three residual stress fields.Results When residual stress was not considered,the mean stress of the middle membrane was greater than that of the outer membrane.When residual stress was considered,the outer membrane bore more stress than the middle membrane,and the outer membrane protected the middle membrane.The pre-stretching of the middle film with residual stress was lower than that without residual stress,whereas the pre-stretching of the outer film was higher than that without residual stress.Moreover,the pre-stretching of the outer membrane collagen fibers was greater than that of the middle membrane collagen fibers.The in vivo calculations of the material parameters of the aorta were performed using physiological homeostasis as the reference configuration,and the proportion of each component was consistent with the experimental results.However,the proportion of elastin in the outer membrane was significantly overestimated when the non-stress configuration was used as the initial configuration,which was inconsistent with the experimental results.Conclusions Residual stress significantly influences the pre-stretching and physiologically steady mechanical states of the microscopic components of the aortic wall.Therefore,it is necessary to fully consider the influence of residual stress to establish the physiologically steady state of the aortic wall accurately.Furthermore,it is also necessary to fully consider the 3D characteristics and layer specificity of residual stress in the in vivo identification of material parameters.

Objective To evaluate the short-term outcomes of thoracic endovascular aortic repair (TEVAR) with outer branched and inner branched endografts in the treatment of Stanford type B aortic dissection (TBAD), and to analyze the effects of endografts on blood flow status of aortic dissection by computational fluid dynamics (CFD). Methods The clinical data of TBAD patients treated with outer branched endograft technology in outer branched endograft group and inner branched endograft technology in inner branched endograft group in Department of Vascular Surgery Tianjin Medical University General Hospital from May 2018 to December 2021 were collected, and the short-term results of two groups were analyzed retrospectively. Based on CT angiography images of patients in two groups, one typical case in each group was selected to construct personalized 3D model and CFD numerical simulation was performed. The parameters including flow field velocity distribution, wall pressure and wall shear stress (WSS) before and after surgery were compared and analyzed. Results A total of 55 cases with TBAD were enrolled, consisting of 49 cased in outer branched endograft group and 6 cases in inner branched endograft group. There was no statistical difference in baseline data between two groups, and surgical success rate were both 100%. Reconstruction of left subclavical artery(LSA) simple was 41(83.7%) cases in outer branched endograft group and all 6 cases in inner branched endograft group. In outer branched endograft group there were 5 cases with reconstruction of left common carotid artery (LCCA) combined with bridging carotic clavical artery, 2 cases with reconstruction of LCCA combined with LSA embolism, and 1 case with reconstruction of LCCA combined with LSA window. Four cases were lost during follow-up in outer branched endograft group. There were no significant differences in the aorta-related mortality rate (P=1.000), branch patency rate (P=1.000) and avoidance of secondary intervention of target vessels between the two groups during the perioperative period and follow-up period (P=0.298). After endograft implantation of two groups the flow field disturbance in dissection lesions improved significantly, aortic blood flow pattern restored normal, and local abnormally increased WSS decreased. However, the interference of inner branch on aortic arch and blood flow of branch was more obvious than that of outer branch. Conclusions Both outer branched endograft and inner branched endograft TEVAR for reconstruction of LSA had good short-term results in the treatment of TBAD. Compared with inner branched endograft, outer branched endograft has a higher anatomical fit and can restore the normal blood flow to a greater extent for aortic arch.

Humans ; Endovascular Aneurysm Repair ; Stents ; Blood Vessel Prosthesis ; Aortic Dissection/surgery* ; Endovascular Procedures ; Aortic Aneurysm, Thoracic/surgery* ; Treatment Outcome ; Blood Vessel Prosthesis Implantation ; Retrospective Studies

Objective To simulate the interaction between the stent graft (SG) and the aortic wall with finite element (FE) analysis by considering the influence of residual stress field, so as to study the stent influence on stress distributions of the aortic wall. Methods The three-dimensional (3D) residual stress field was generated in an idealized bi-layered thick-wall aortic model via a stress-driven anisotropic growth model by reducing the transmural stress gradient. Upon virtually deploying the SG, the stress on the aortic wall was calculated. Results The 3D residual stress field, corresponding to an opening angle of 117.5°, was shown to reduce the transmural stress gradient in both the circumferential and axial directions. The maximum stress was found at the contact area between aortic wall and wave peak of the stent. At 20% oversize ratio of the stent, the maximum stresses on the aortic wall in circumferential and axial direction were 412 and 132 kPa, respectively, while the in-plane shear stresses σrθ and σrz were both 78 kPa. Under residual stress, the maximum radial, circumferential and axial stresses were decreased by 14.9%, 40.5% and 33.8%, respectively, while the maximum shear stresses σrθ ，σrz，σθz were reduced by 2.5%, 7.1% and 27%, respectively. With the increase of oversize ratio from 10% to 20%, the maximum radial, circumferential and axial stresses were increased by 316%, 129% and 41%, respectively, while the maximum shear stresses σrθ ，σrz，σθz were increased by 661%, 450% and 466%, respectively. Conclusions The residual stress can effectively reduce the transmural stress gradient. Both the residual stress and the oversize ratio of the stent play an important role in modulating the wall stress distribution and the maximum stress.

Objective To propose a one-way fluid-structure interaction (FSI) method based on an idealized aortic dissection model, so as to analyze the hemodynamics and wall stress in the false lumen (FL) under the influence of multiple overlapping uncovered stents (MOUS). Methods Upon establishment of the numerical model, the models were divided into two categories according to whether the model involved FL perfused branch artery. The characteristics of hemodynamics and wall stress state in the post-operative scenarios were simulated under different surgical strategies. The wall stress state of the FL before and after thrombosis formation was also compared and analyzed. ResultsThe release process of the stents had little influence on wall stress of the FL. The high velocity and high wall shear stress (WSS) area in the FL could not be reduced by using the MOUS alone. If only the proximal entry tear was blocked with a covered stent-graft, the distal end would maintain a region of high flow rate and high WSS. The combination of covered stent-graft and MOUS would result in a region of low flow rate and low WSS, as well as reduced wall pressure and wall stress in the FL. Compared with the model with FL perfused branch arteries, the model without it was more likely to form a region of low flow rate and low WSS after surgery. However, blood pressure in the FL was relatively higher. The formation of thrombus in the FL could greatly reduce wall stress in the area covered by the thrombus. Conclusions The method proposed in this study can simultaneously investigate hemodynamics and wall stress characteristics of the FL, and provide support for studying mechanical mechanism of FL thrombolysis induced by MOUS and the post-operative aortic expansion.

Objective:To compare the efficacy and safety of different treatment methods for thoracoabdominal aortic aneurysm(TAAA).Methods:The clinical data of 39 TAAA patients admitted to our department from Jan 2010 to Feb 2018 were retrospectively analyzed.Results:There were 25 patients in endovascular group, 11 in open group and 3 in hybrid group. The mean age in the endovascular group was significantly higher than that in the open group ( P<0.05). The blood loss and operation time in the endovascular group were significantly lower than those in the open group and the hybrid group ( P<0.05). There was no significant difference in the operation success rate, the complication rate in post-operative 30 days and the rate of re-intervention ( P>0.05) among the three groups. The post-operative 30 days mortality was significantly higher in the hybrid group than that in the endovascular group and open group ( P<0.05). During the follow-up period, the complication rate in the endovascular group was significantly higher than that in the open group ( P<0.05). Conclusion:Endovascular surgery is more suitable for elderly patients because of shorter operation time, less trauma and bleeding.