BACKGROUND In the context of aortic dissection,increasing pressure within the newly formed false lumen can result in the progressive compression of the true aortic channel.However,true lumen collapse in chronic type B...BACKGROUND In the context of aortic dissection,increasing pressure within the newly formed false lumen can result in the progressive compression of the true aortic channel.However,true lumen collapse in chronic type B aortic dissection(cTBAD)patients is rare,with few clinical or experimental studies to date having explored the causes of such collapse.CASE SUMMARY In the present report,we describe a rare case of true-lumen collapse in an 83-yearold patient diagnosed with cTBAD,and we discuss potential therapeutic interventions for such cases.Following thoracic endovascular aortic repair(TEVAR),computed tomography angiography revealed satisfactory stent-graft positioning,no endoleakage,true lumen enlargement,thrombus formation in the false lumen,and slight enlargement of the true lumen distal to the stent-graft.Computational hemodynamic analyses indicated that the wall shear stress and pressure within the false lumen were significantly reduced following TEVAR.CONCLUSION TEVAR treatment of cTBAD patients suffering from proximal true lumen collapse can facilitate some degree of effective remodeling.展开更多
Collapse is a disaster in Changbai Mountain area.Based on the present stage of collapse,the anthors summarized three types of collapse and analyzed their formation mechanism.This research makes sense to further study.
Seismic demand estimation for a structure is a critical issue for seismic performance assessment so that the potential damage can be estimated realistically. Many researchers proposed simplified methods to estimate th...Seismic demand estimation for a structure is a critical issue for seismic performance assessment so that the potential damage can be estimated realistically. Many researchers proposed simplified methods to estimate the demand of a structure under strong ground motions. However, most of them did not consider degradation and collapse potential of the structures. Even some of theme considered the degradation effect, stiffness and strength degradation effects were considered separately without collapse potential caused by dynamic instability. In this study, collapse potential of SDOF systems caused by dynamic instability with stiffness and strength degradation has been investigated. Nonlinear time history analyses were performed, using an energy-based, strength and stiffness degraded hysteretic model that considers the collapse potential, with 160 earthquake acceleration time histories. An equation was proposed for the estimation of collapse period of SDOF systems as a function of certain strength reduction factor, ductility level and post-capping stiffness ratio. Finally, effects of parameters of the considered hysteretic model and local site conditions on the collapse period were investigated.展开更多
文摘BACKGROUND In the context of aortic dissection,increasing pressure within the newly formed false lumen can result in the progressive compression of the true aortic channel.However,true lumen collapse in chronic type B aortic dissection(cTBAD)patients is rare,with few clinical or experimental studies to date having explored the causes of such collapse.CASE SUMMARY In the present report,we describe a rare case of true-lumen collapse in an 83-yearold patient diagnosed with cTBAD,and we discuss potential therapeutic interventions for such cases.Following thoracic endovascular aortic repair(TEVAR),computed tomography angiography revealed satisfactory stent-graft positioning,no endoleakage,true lumen enlargement,thrombus formation in the false lumen,and slight enlargement of the true lumen distal to the stent-graft.Computational hemodynamic analyses indicated that the wall shear stress and pressure within the false lumen were significantly reduced following TEVAR.CONCLUSION TEVAR treatment of cTBAD patients suffering from proximal true lumen collapse can facilitate some degree of effective remodeling.
文摘Collapse is a disaster in Changbai Mountain area.Based on the present stage of collapse,the anthors summarized three types of collapse and analyzed their formation mechanism.This research makes sense to further study.
文摘Seismic demand estimation for a structure is a critical issue for seismic performance assessment so that the potential damage can be estimated realistically. Many researchers proposed simplified methods to estimate the demand of a structure under strong ground motions. However, most of them did not consider degradation and collapse potential of the structures. Even some of theme considered the degradation effect, stiffness and strength degradation effects were considered separately without collapse potential caused by dynamic instability. In this study, collapse potential of SDOF systems caused by dynamic instability with stiffness and strength degradation has been investigated. Nonlinear time history analyses were performed, using an energy-based, strength and stiffness degraded hysteretic model that considers the collapse potential, with 160 earthquake acceleration time histories. An equation was proposed for the estimation of collapse period of SDOF systems as a function of certain strength reduction factor, ductility level and post-capping stiffness ratio. Finally, effects of parameters of the considered hysteretic model and local site conditions on the collapse period were investigated.
