EVAR for Stanford Type B Dissections :  Experience & Lessons with 550 cases.

（作者）Fu Weiguo， Dong Zhihui， Wang Yuqi， Guo Daqiao， Xu Xin， Chin Bin， Jiang Junhao， Yang Jue， Shi Zhenyu.
（单位）Zhongshan Hospital， Fudan University， Shanghai

This presentation is to share the experience and lessons in endovascular aortic repair (EVAR) for 550 patients with Stanford type B dissection in terms of preoperative evaluation， operative techniques， ancillary strategies， follow-up， and， in particular， lessons. Firstly， the preoperative evaluation includes imaging protocol， sizing， intervention timing， and risk for ischemia of visceral arteries. Secondly， operative techniques focus on approach selection， judgment of true or false lumen， steps of the procedure and so on. Thirdly， the ancillary strategies involve creation of extra proximal landing zone and supportive reconstruction of visceral arteries， and the indication， technical skills and mid-to-long-term results will be discussed in detail. Fourthly， as an inevitable element of treatment， follow-up is to be described in terms of its protocol and outcome. Finally， we would like to pay emphasis on the lessons we have learnt from these 550 procedures: (1) Ischemic stroke took place in 6 cases（1%） because of air embolism， and thorough saline flush of the stent-graft before introduction is thus considered extremely important. (2) Development of type A dissection was another uncommon complication (11 cases， 2%)， in relation to Marfan syndrome， inappropriate endovascular manipulation as well as， potentially， the stent-graft itself.  (3) All 4 cases with Marfan syndrome in this group died within 14 days postoperatively， and 3 were complicated with newly occurred type A dissection and rupture was suspected in 1 case who died suddenly 1 week after discharge. Therefore， EVAR appears to have higher risk for dissection with Marfan syndrome， particularly as an initial treatment. (4) The guide wire could transfer from true lumen into false lumen by accident during catheter or guide wire exchange， leading to disastrous placement of the stent-graft into the false lumen (1 case). (5) Balloon inflation caused migration of the stent-graft in 3 patients at the early stage. Thereafter， it was not used in a routine fashion， and complete thrombosis of the false lumen at the thoracic aorta typically achieved at 3 months， even though slight proximal endoleak could be detected on the completion angiogram in most cases. (6) The stent-graft failed to be deployed in 1 case who was converted to open surgery immediately. So the facilities for transthoracic graft replacement are supposed to be available at the time of EVAR.