Objectives:Distal segment aortic enlargement(DSAE)is a common complication that influences the long-term prognosis of type B aortic dissection(TBAD)after thoracic endovascular aortic repair(TEVAR).In this study,a mult...Objectives:Distal segment aortic enlargement(DSAE)is a common complication that influences the long-term prognosis of type B aortic dissection(TBAD)after thoracic endovascular aortic repair(TEVAR).In this study,a multivariate analysis was performed to find potential factors predictive of DSAE.Methods:A single-center retrospective study was performed from 1999 to 2016.Included in the study were complicated TBAD patients who underwent TEVAR with uncovered residual tears.Based on the diameter of the distal segment of the uncovered aorta,we assigned patients to an enlargement group and a non-enlargement group.Data extracted from the medical records included demographic and clinical characteristics and followup computed tomography angiography data.The primary endpoints were the all-cause mortality and the presumably aortic-related events that required reintervention during the follow-up period.Results:For the 333 patients,all-cause mortality was 38(11.41%),and 76(22.82%)patients underwent reintervention.A total of 70(21.02%)patients experienced DSAE,among them were 2 patients who died of aortic rupture and 58 patients who accepted reintervention.Multivariate analysis reviewed independent risk factors of postoperative DSAE,including current smoking,the residual length of the patent false lumen,the postoperative number of dissection tears in the thoracic aorta and type III aortic arch;as well as protective factors,including the application of a restrictive bare stent(RBS),the length of covered stent in the descending thoracic aorta,and the distance from the residual first tear to the left subclavian artery(LSA).Conclusion:DSAE after TEVAR for patients with a complicated TBAD can be influenced by their current smoking habit,the residual length of patent false lumen,the postoperative number of dissection tears in the thoracic aorta and the aortic arch type.Meanwhile,RBS usage,the length of the covered stent in the descending thoracic aorta and the distance from the residual first tear to the LSA could have positive effect on the prognosis.展开更多
The segment erector is a key part of the shield machines for tunnel engineering. The available segment erectors are all of serial configuration which is suffering from the problems of low rigidity and accumulative mot...The segment erector is a key part of the shield machines for tunnel engineering. The available segment erectors are all of serial configuration which is suffering from the problems of low rigidity and accumulative motion errors. The current research mainly focuses on improving assembly accuracy and control performance of serial segment erectors. An innovative design method is proposed featuring motion group-decoupling, based on which a new type of segment erector is developed and investigated. Firstly, the segment installation manipulation is analyzed and decomposed into three motion groups that are decoupled. Then the type synthesis for the 4-DOF motion group is performed based on the general function（GF） set theory and a new configuration of （1T？1R？1PS3UPS） is attained according to the segment manipulation requirements. Consequently, the kinematic models are built and the reducibility and accuracy are analyzed. The dexterity is verified though numerical simulation and no singular points appear in the workspace. Finally, a positioning experiment is carried out by using the prototype developed in the lab that demonstrates a 13.1% improvement of positioning accuracy and the feasibility of the new segment erector. The presented group-decoupling design method is able to invent new type of hybrid segment erectors that avoid the accumulative motion error of erecting.展开更多
基金supported by the National Nature Science Foundation of China[grant number 81800403].
文摘Objectives:Distal segment aortic enlargement(DSAE)is a common complication that influences the long-term prognosis of type B aortic dissection(TBAD)after thoracic endovascular aortic repair(TEVAR).In this study,a multivariate analysis was performed to find potential factors predictive of DSAE.Methods:A single-center retrospective study was performed from 1999 to 2016.Included in the study were complicated TBAD patients who underwent TEVAR with uncovered residual tears.Based on the diameter of the distal segment of the uncovered aorta,we assigned patients to an enlargement group and a non-enlargement group.Data extracted from the medical records included demographic and clinical characteristics and followup computed tomography angiography data.The primary endpoints were the all-cause mortality and the presumably aortic-related events that required reintervention during the follow-up period.Results:For the 333 patients,all-cause mortality was 38(11.41%),and 76(22.82%)patients underwent reintervention.A total of 70(21.02%)patients experienced DSAE,among them were 2 patients who died of aortic rupture and 58 patients who accepted reintervention.Multivariate analysis reviewed independent risk factors of postoperative DSAE,including current smoking,the residual length of the patent false lumen,the postoperative number of dissection tears in the thoracic aorta and type III aortic arch;as well as protective factors,including the application of a restrictive bare stent(RBS),the length of covered stent in the descending thoracic aorta,and the distance from the residual first tear to the left subclavian artery(LSA).Conclusion:DSAE after TEVAR for patients with a complicated TBAD can be influenced by their current smoking habit,the residual length of patent false lumen,the postoperative number of dissection tears in the thoracic aorta and the aortic arch type.Meanwhile,RBS usage,the length of the covered stent in the descending thoracic aorta and the distance from the residual first tear to the LSA could have positive effect on the prognosis.
基金supported by National Natural Science Foundation of China(Grant No. 51275284)Program for New Century Excellent Talents in University of China(Grant No. NCET-10-0567)the Research Fund of State Key Lab of Mechanical Systems and Vibration(Grant No.MSV-ZD-2010-02)
文摘The segment erector is a key part of the shield machines for tunnel engineering. The available segment erectors are all of serial configuration which is suffering from the problems of low rigidity and accumulative motion errors. The current research mainly focuses on improving assembly accuracy and control performance of serial segment erectors. An innovative design method is proposed featuring motion group-decoupling, based on which a new type of segment erector is developed and investigated. Firstly, the segment installation manipulation is analyzed and decomposed into three motion groups that are decoupled. Then the type synthesis for the 4-DOF motion group is performed based on the general function（GF） set theory and a new configuration of （1T？1R？1PS3UPS） is attained according to the segment manipulation requirements. Consequently, the kinematic models are built and the reducibility and accuracy are analyzed. The dexterity is verified though numerical simulation and no singular points appear in the workspace. Finally, a positioning experiment is carried out by using the prototype developed in the lab that demonstrates a 13.1% improvement of positioning accuracy and the feasibility of the new segment erector. The presented group-decoupling design method is able to invent new type of hybrid segment erectors that avoid the accumulative motion error of erecting.
