Evaluation of embedded modular branched stent graft in treating aortic arch aneurysm using imaging-based computational flow analysis

Embedded modular branched stent graft(EMBSG)was a new option for aortic arch aneurysm.However,the therapeutic effect of this innovative stenting technique has not been fully assessed.Computational fluid dynamics and three-dimensional structural analyses were performed on three patients(Patient Ⅰ,Patient Ⅱ and Patient Ⅲ)with aortic arch aneurysm,both before and after EMBSG implantation.Patient-specific alterations from preoperative to postoperative were analyzed via morphological and functional metrics.Patient Ⅰ and Patient Ⅱ showed notable curvature changes and area reduction after intervention procedure.Three patients showed an increase in flow velocity after EMBSG implantation,while the pressure drop from ascending aorta to the aortic arch was remarkable in Patient I and Patient Ⅱ with the value of 7.09mmHg,and 10.95mmHg,respectively.Patient I and Patient Ⅱ also showed elevated time-averaged wall shear stress(TAWSS)in the stenting region,while Patient Ⅲ showed a trivial change in TAWSS after intervention procedure.Three patients showed low relative residence time after EMBSG insertion.The short-term results of EMBSG in treating aortic arch aneurysm were promising.Hemodynamic parameters have the potential to assist in the outcome evaluation and might be used to guide the stent graft design and wise selection,thereby improving the long-term therapeutic effect in managing complex vascular disease.

Grafting Branch Length and Density Dependent Performance of Zwitterionic Polymer Decorated Polypropylene Membrane

Branch length and density have critical effects on membrane performances; however, it is regarded to be traditionally difficult to investigate the relationship due to the uncontrolled membrane modification methods. In this study, zwitterionic polymer with controlled grafting branch chain length（degree of polymerization） and grafting density（grafting chains per membrane area） was tethered to the microporous polypropylene membrane surface based on the combination of reversible addition-fragmentation chain transfer（RAFT） polymerization technique with click reaction. The modified membranes were tested by filtrating protein dispersion to highlight the correlations of branch chain length and grafting density with the membrane permeation performances. The pure water flux, the flux recovery ratio are positively and significantly, and the irreversible fouling negatively and significantly correlated with grafting density. These results demonstrate that the larger the coverage of the membrane with poly{[2-（methacryloyloxy）ethyl]-dimethyl-（3-sulfopropyl） ammonium hydroxide}（PMEDSAH）, the higher the pure water flux and the higher the flux recover ratio, and the lower the irreversible fouling, which shows that high grafting density is favorable to fouling reducing.

Fenestrated and branched stent-grafts： present and future

The goals of future development of endovascular aortic stent grafting were towards. extension of the proximal seal, preservation of vital branches, deployment, and low profile delivery ease of systems. Fenestrated aortic stent graft is a viable option for treating aortic aneurysms with short necks, and more than 5000 grafts have been implanted worldwide. The first device available, the Zenith fenestrated graft （Cook Medical, USA）, involved placing a proximal tube fenestrated component, then accessing each target vessels from the contralateral side with a sheath, and bridging the connection with a covered stent. A bifurcated distal component is then placed to complete the endovascular repair.

Endovascular Management of Aortic Arch Diseases:Current Status and Future Trends

Treatment of aortic arch(AA)diseases is challenging for surgeons.Conventional open surgery remains the“gold standard”but is associated with significant morbidity and mortality despite improvements in techniques.In the last 2 decades,thoracic endovascular aortic repair(TEVAR)has become the first-line treatment for diseases of the descending aorta,and its indications have expanded gradually.Various strategies have been proposed to preserve supra-aortic branches in TEVAR:hybrid technique,chimney technique,fenestration technique(including custom-made fenestrated or“scalloped”stent grafts,in situ fenestration,and physician-modified fenestration),and branched stent grafts.Though acceptable outcomes of endovascular aortic repair have been documented,the evidence regarding its long-term safety and efficacy is lacking,and concerns remain about the risk of cerebrovascular events,retrograde type-A dissection,endoleaks,and branch occlusion.This review discusses the current status and progress of endovascular repair of the AA,and looks toward future trends.We believe that multidisciplinary collaboration of a“HENDO”team(professionals in hybrid repair,endovascular repair,open surgery,cardiovascular anesthesia,and genetics)is essential for future repair of the AA to provide the optimal treatment.