Preoperative Anatomy Evaluation,postoperative Aortic Remodeling And Endovascular Strategy Of Acute And Chronic Stanford Type B Aortic Dissection

Background and Objective:In 1999,Dake et al first reported the use of Thoracic Endovascular Aortic Repair(TEVAR)in the treatment of Stanford type B aortic dissection(TBAD).Due to its minimally invasive and good clinical results,TEVAR gradually become the main treatment of TBAD.Till now,TEVAR has gone through 20 years and has made great progress.Many studies,such as STABLE,ADSORB and INSTEAD trail,have shown that TEVAR has a positive effect in improving long-term aortic remodeling and reducing long-term complications.But the outcomes of different dissection phases after endovascular treatment are different.On the one hand,TEVAR has become the preferred treatment for complicated acute TBAD,and more and more studies also support the positive significance of endovascular treatment in uncomplicated acute TBAD.However,the current endovascular treatment of chronic aortic dissection is still controversial,and the controversy stems from the different anatomical morphology of acute and chronic aortic dissection.The descending aorta anatomy of the dissection needs to be given more attention: First,the main purpose of TEVAR is to seal the proximal entry tear by anchoring the proximal end of the stent graft to the healthy intimal,and the distal end of the stent graft is anchored to an uncomplete intimal;Second,the secondary intimal tears of descending and abdominal aorta are not sealed simultaneously;Finally,the current stent grafts are mostly straight and limited in length,and cannot be flexibly adapted to the anatomy of the distal descending aorta of theaortic dissection.Therefore,with the increasing use of TEVAR for the treatment of complex aortic lesions involving the aortic arch and descending aorta,stent graft-related complications such as distal stent-graft induced New entry,d SINE)and Distal thoracic aortic enlargement(DTAE)have gradually become the focus of clinical attention.Excessive radial force from oversizing,spring-back strength,aortic wall fragility,stent graft-aorta interaction and the endovascular treatment mode lead to the complications.On the other hand,aortic remodeling is another important metrics of the success of TEVAR.Previous studies have suggested that aortic remodeling of acute aortic dissection is better than the one in chronic aortic dissection.The aortic remodeling mainly includes false lumen shrinkage and false lumen thrombosis.However,the comprehensive and accurate definition and evaluation of aortic remodeling are not uniform.The measurements of aortic anatomical morphology have different parameters and lack of uniformity and comparability.The remodeling of the false lumen diameter and the false lumen thrombus is not exactly equivalent to the remodeling of the descending aorta,nor does it cover all aspects of arterial remodeling.Due to the importance of descending aortic anatomy in TEVAR,it is necessary to study the aortic remodeling of descending aorta after TEVAR.Finally,considering the anatomical morphology of the landing zone of the descending aorta,Feng et al proposed the Restrictive bare stent(RBS)technique in 2013 to reduce the mismatch between the stent graft and the compressed true lumen.The key point of this technique is to pre-place a bare stent in the descending aorta at the level of the intended distal end of the stent graft.Several Studies have confirmed the role of RBS.It can effectively reduce the incidence of d SINE and improve early aortic remodeling.However,previous studies have focused on the role of RBS in the distal stent graft oversizing,and the effects of RBS on the global anatomy of the descending aorta(such as the tortuousdescending aorta)and chronic TBAD with aneurysm degeneration have not been elucidated.The purpose of the studyThrough retrospective clinical analysis and meta-analysis methods,(1)comparative analysis of the aortic remodeling of the descending aortic and outcomes of endovascular treatment after TEVAR between acute and chronic aortic dissection,revealing the descending aortic anatomy of the acute and chronic aortic dissection and postoperative aortic remodeling;(2)Discussion of morphological changes,technical details and clinical outcomes of RBS technique in the treatment of TBAD;(3)Meta-analysis was used to quantitatively analyze the efficacy and safety of proximal stent-graft combined with distal-assisted bare stent(bare stent group)and standard proximal stent-graft(non-bare stent group)in order to provide clinical decision-making.MethodsThis study investigates the anatomical features,aortic remodeling and treatment strategies of acute and chronic TBAD in the following three aspects:(1)Firstly,through retrospective analysis of the center from 2012 to 2016,86 cases of TBAD treated by TEVAR,divided into acute group(n=63)and chronic group(n=23).The descending aortic anatomy was evaluated by preoperative and postoperative aortic CTA,including descending aortic taper ratio(TR),oversizing ratio(OR),descending aortic distorting(TI),radius of curve(Ro C)and mismatch rate(MR),degree of false lumen thrombosis and the true/false lumen area of various planes(L1: bronchial bifurcation level;L2: left atrial lower margin level;L3: celiac trunk level)and analyze the different anatomical features and aortic remodeling of the acute and chronic TBAD.(2)A retrospective study was conductedof 22 consecutive patients with TBAD who underwent RBS treatment between February2012 and June 2016.Indications for the RBS procedure included radiological evidence of true lumen(TL)compression or collapse and/or tortuosity index(TI)of the descending aorta >1.4.Technique success,descending aorta morphology and clinical outcomes were evaluated.(3)MEDLINE,EMBASE,and the Cochrane Central Register for Controlled Trials databases and key references were searched from January 2006 to January 2018.Eight articles were met the inclusion criteria.Then,we evaluated the mortality,perioperative complications,conversion to open surgery,secondary intervention rates and aortic remodeling of these procedures and investigated the efficacy and safety of assisted bare stent combined with proximal stent graft and proximal TEVAR in the treatment of aortic dissection.Furthermore,the role of distal bare stent technique in reducing stent-related complications was also analyzed.Results? The true lumen(TL)area at the L1 level,FL area and total lumen area at the L1,L2,and L3 levels of chronic TBAD patients were all significantly higher than those of acute TBAD patients before TEVAR(P<.05).Furthermore,the local and global anatomy of descending aorta including TR,OR and TI values were all significantly higher in chronic TBAD than in acute TBAD before TEVAR(P< 0.05).But MR and ROC values showed no differences between chronic TBAD and acute TBAD before TEVAR.Furthermore,there were no statistical differences in the changes of TR,Ro C and MR values between the acute TBAD and chronic TBAD groups from preoperative to postoperative.However,the changes in OR and TI values were significantly higher in the chronic TBAD group than that in the acute TBAD group(OR: 1.80 ± 0.86 in acute TBAD and 2.98 ± 1.85 in chronic TBAD,P =0.028;TI: 0.00 ± 0.09 in acute TBAD and 0.09 ± 0.10 in chronic TBAD,P< 0.000).In acute TBAD,the TL area showed a significant increase at the levels of L1 and L2 and remained stable at the level of L3.The FL area significantly decreased at all three levels.The total lumen area decreased at the levels of L1 and L3,but it increased before the decrease at the level of L2.In the chronic group,TEVAR significantly increased the TL area at all three levels.The FL area and total lumen area remained stable at the level of L1,and they both increased before decreasing at the levels of L2 and L3.Complete thrombosis in the FL of L1 occurred in 88.89%(56/63)of the acute TBAD patients and 85.71%(18/21)of the chronic TBAD patients,and there was no difference between the two groups(p = 0.6972).Complete FL thrombosis occurred less frequently in L2,in 50.79%(32/63)of the acute TBAD patients and 33.33%(7/21)of the chronic TBAD patients,and there was no difference between the two groups(P = 0.6622).Complete FL thrombosis occurred less frequently in the L3,in 7.94%(5/63)of the acute TBAD patients and 4.76%(1/21)of the chronic TBAD patients,and there was no difference between the two groups(P = 0.6135).? Technical success rate was 100%.Patients treated with the RBS technique were often accompanied by TL collapse(45.5%)or TI>1.4(59.1%).One-month postoperative CTA showed that the taper ratio,oversizing ratio of the stent graft and TI values were significantly decreased compared with preoperative CTA values(P<0.05).The 30-day mortality rate was 0%.95.2% had a thrombosed false lumen in the segment of aortic coverage,and TL diameters were increased in 40.3% ±11% and 37.5%±17.9% of patients in the thoracic and abdominal segments,respectively.During the follow-up from 16 to 64months(33±19 months),no distal stent graft-induced new entry,endoleak and paraplegia were observed.One patient died from rupture of a chronic TBAD with aneurysm degeneration.? Meta-analysis demonstrated there was no significant difference in aortic-related mortality(OR=0.52,95% CI: 0.21-1.26,P=0.15).There was no statistically significant difference in the occurrence rate of aortic rupture,endoleak and renal failure(OR=0.38,95% CI: 0.07-2.26,P=0.29;OR=0.81,95% CI: 0.32-2.05,P=0.66;OR=1.09,95% CI:0.56-2.14,P=0.80),there was no statistically significant difference in the occurrence rate of cerebrovascular events and spinal cord ischemia(OR=1.10,95% CI: 0.34-3.59,P=0.87;OR=0.63,95% CI: 0.21-1.84,P=0.39).There was no statistically significant difference in the incidence of retrograde type A dissection(OR=1.38,95% CI: 0.35-5.40,P=0.65).The incidence of stent-induced new entry was lower in TEVAR combined with the bare stent group than that in proximal TEVAR group(OR=0.07,95% CI: 0.01-0.39,P<0.001),there was no statistically significant difference in conversion open surgery rate between the two groups(OR=0.31,95% CI: 0.05-1.96,P=0.21).The second intervention rate was lower in the bare stent group than in the simple stent graft group(OR=0.38,95% CI: 0.22-0.65,P<0.001).Aortic remodeling at 1-year follow-up: there was no statistically significant difference in the rate of false lumen thrombosis between the two groups in thoracic segment(OR=1.78,95% CI: 0.64-4.95,P=0.27)and abdominal segment(OR = 2.43,95% CI:0.66-8.99,P=0.18).Conclusion? TEVAR is an effective method for the treatment of acute and chronic aortic dissection with acceptable technical success rates,mortality and complication rates.Local and global anatomy in acute TBAD is superior to chronic TBAD before TEVAR.TEVAR plays an active role in the expansion of TL in acute and chronic aortic dissection but has limited role in the trend of aneurysm degeneration.In addition,TEVAR is more pronounced inremodeling of distal stent graft oversizing ratio in acute TBAD and the remodeling of TI is the opposite,but the remodeling of TR is similar between acute and chronic TBAD.? Stents with size gradient(taper stents or restricted bare stents)may be more consistent with the descending aorta morphology of chronic TBAD,but further studies are needed.? The RBS technique may effectively improve the descending aorta morphologic remodeling,potentially addressing the limitations of current grafts.However,the rupture of chronic TBAD with aneurysm degeneration was not prevented by the RBS technique in all patients.Further prospective clinical studies are warranted to evaluate the procedure's long-term efficacy.? The distal assisted bare stent combined with the proximal stent-graft can reduce the incidence of stent-induced new entry and partial thrombosis of thoracic aorta,but there is no difference in surgical mortality,partial complications,and arterial remodeling.