| Background: Thoracic endovascular aortic repair(TEVAR)as the representative of minimally invasive surgery has become an attractive alternative treatment for Stanford type B aortic dissection.It was necessary to measure the anatomy parameters of aorta before TEVAR,thus make the specific planning including select appropriate endovascular aortic stent-graft based on the measurement.The stent-graft should be anchored to the undissected part of aorta proximal to the first tear to avoid adverse events such as re-dissections.In order to make sure the endovascular stent-graft firmly anchored in aorta,it needed a suitable ratio between the diameter of endovascular stent-graft and the diameter of aorta,the ratio was “oversizing” of stent-graft.Some studies have shown that the oversizing was related to many adverse events such as endoleak or re-dissections.However,there was no study about whether the choice of oversizing affects the preoperative planning of TEVAR,and how to select the oversizing of stent-graft for the patients with no normal proximal aorta.Methods: Firstly,we reviewed and analysis the literatures,guidelines and the stent-graft instruction for use(IFU)about the measurement of aortic parameters especially the diameter of aorta before TEVAR,and the guidelines and the IFU about the oversizing of stent-graft for aortic dissection.Then retrospective analysis of Stanford type B aortic dissection patients who underwent TEVAR in our center between from September 1998 to June 2014 in our center.Reveal the prevalence and consequences of unplanned stents in TEVAR for Stanford type B aortic dissection patients by finding the cases which with the additional stent-graft to bail out the unexpected events through analysis the hospital data,surgical data,follow-up data and imaging examinations.Explore the reasons,risk factors and solutions for unplanned stents.Finally,propose a new two-stage endovascular strategy for the retrograde type A aortic dissection patients who with no normal proximal aorta as the anchor zone for endovascular stent-graft.Through this two-stage endovascular strategy,coils combined Onyx glue embolization were performed to create a thrombogenic environment in retrograde false lumen of ascending aorta and aortic arch as the first stage operation,followed by TEVAR with chimney technique as second stage operation.Results: Under the inclusion and exclusion criteria,three hundred and twenty-two patients were enrolled with 83 patients(25.8%)underwent unplanned stent-graft implantation.Although there was no significant difference in 5 year survival rate between two groups,the operative time,hospital days and hospitalization expenses were higher or longer in unplanned group.Large distal stent-graft oversizing,short proximal neck length and short stent coverage length were risk factors for unplanned stents in TEVAR,while type ?a endoleak,bird beak and inappropriate shaping of stent-graft were the top three risk factors.For the 9 retrograde type A aortic dissection patients who with no normal proximal aorta as the anchor zone for endovascular stent-graft,the two-stage endovascular strategy went successfully.Complete thrombosis in retrograde false lumen of ascending aorta and aortic arch were found in all 9 patients before the second stage operation was performed.The rate of successful TEVAR was 100% and no morbidities,no stent-grafts induced new dissection or deaths were found in hospital and in 12-month follow-up period.Conclusions: Large distal stent-graft oversizing,short proximal neck length and short stent coverage length were risk factors and type ?a endoleak,bird beak and inappropriate shaping of stent-graft were the reasons for unplanned stents in TEVAR for TBAD.Knowing these can we reduce the utilization of unplanned stents with appropriate methods.The new two-stage endovascular strategy to enhance proximal landing zone of TEVAR may be a new optimal and safe treatment strategy for retrograde type A aortic dissection,and the strategy could prevent the stent-graft or stent-graft oversizing related adverse events... |
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