A Preliminary Study On The Relationship Between Endovascular Repair And Proximal Intimal Tear In Stanford Type B Aortic Dissection

Part I.Influence of proximal primary intimal tear on the outcome of Stanford type B aortic dissection after endovascular repair.Background:Considerable attention has been paid to endovascular repair of the thoracic aorta(TEVAR)in the treatment of Stanford type B aortic dissection because it is minimally invasive and has good short-term therapeutic effects.However,the complexity of aortic arch anatomy is becoming one of the biggest challenges for clinicians when performing TEVAR therapy.Among those,the location and size of the primary intimal tear affect the operation plan,having outcomes with the most postoperative complications.At present,there are no previous studies that have focused on the location and size of the primary intimal tear as factors affecting the outcome of thoracic endovascular repair.Purpose:1.To compare and analyze thoracic endovascular repair in Stanford type B aortic dissection assigned to two groups based on the location of the primary intimal tear in the distal aortic arch,including general situation,aortic arch performance,and mid-term outcome results.2.To perform comparative analysis of Stanford type B aortic dissection assigned to three groups based on the size of the primary intimal tear.The general condition,aortic arch imaging manifestations,surgical methods and mid-term follow-up results were analyzed among these three groups.It will also explore the impact of primary intimal tear size on prognosis,selection and improvement of treatment methods.Methods:This retrospective study included 334 patients with Stanford type B aortic dissection who underwent TEVAR between January 2010 and December 2015 in our hospital.The data collection included inpatient records,outpatient records,and follow-up data.All patients were assigned to two groups based on the location of the primary intimal tear in the distal aortic arch.The general characteristics,operative method,and outcome of the two groups were analyzed.Statistical analysis was conducted using SPSS 20 software(IBM SPSS Inc,Chicago,Illinois).Continuous variables were expressed as mean ± standard deviation and categorical variables were presented as frequency or percentage.T-tests and analysis of variance(ANOVA)were used to examine the difference between continuous variables,while the Chi-square test was used to analyze the differences between categorical variables.The rank sum test was applied for non-normal distribution or ordered variables.Risk ratios(RR)and 95%confidence intervals(CI)were used to assess possible risk factors for postoperative mortality.Survival and freedom from late aortic events statistics were computed using Kaplan-Meier analysis and compared between the two groups by use of the log-rank test.Primarily Kaplan-Meier was used for univariate factor survival analysis.Then,statistically significant variables were incorporated into the Cox proportional hazards model to explore the factors influencing postoperative mortality.A p-value of<0.05 was considered to indicate statistical significance.Results:1.General conditions and clinical dataAccording to the location of primary intimal tears:among the 334 cases collected in this study,there were 266 male patients(79.6%)of the total number of the patients.Among them,179 male patients(77.8%)were in the convexity group,and 87male patients(83.7%)were in the concavity group.There were 68 female patients(20.4%)of the total number of the patients.Among them,51 female patients(22.2%)were in the convexity group,and 17 female patients(16.3%)were in the concavity group.There was no statistically significant difference between the two groups(p = 0221).Overall,the minimum age was 28 years old,and the maximum age was 86 years old.The average age of onset was 55.68 ± 12.72 years old.In the convexity group,the minimum age was 28 years old,the maximum age was 86 years old,and the average age of onset was 56.80 ± 12.78 years old.In the concavity group,the minimum age was 28 years old,the maximum age was 83 years old,and the average age of onset was 53.21 ± 12.28 years old.There were statistically significant differences between the two groups(p =0.017).Additionally,there were statistically significant differences between the two groups after age grouping(p = 0.027).Regarding concomitant disease,229 patients(68.6%)had a history of high blood pressure history,including 161 patients(70.0%)in the convexity group and 68 patients(65.4%)in the concavity group.There was no statistically significant difference between the two groups(p = 0.400).Eleven patients(3.3%)suffered from Marfan syndrome,including six patients(2.6%)in the convexity group and five patients(3.8%)in the concavity group.There was no statistically significant difference between the two groups(p = 0.477).Fifteen patients(4.5%)had a history of trauma,including six patients(2.6%)in the convexity group and nine patients(8.7%)in the concavity group,with statistically significant differences(p = 0.029).According to the size of the proximal primary intimal tear,the 334 patients were divided into three groups.This included 177 patients in group I(35%),160 patients in group II(47.9%),and 57 patients in group III(17.1%).Among the three groups,there was no significant difference in age,sex,past history,complications and proportion of patients with Marfan syndrome.However,the ratio of patients with traumatic history in group II was higher than in the other two groups(p = 0.039).Preoperative imaging analysis showed that there was a significant difference in the cumulative aortic arch area between the three groups.In group ?,the cumulative aortic arch area S3 was more common in aortic dissection.The larger the proximal rupture,the easier the cumulative aortic arch area of S2 and S3(p = 0.032).However,in patients undergoing TEVAR,there was no significant correlation between the size of the proximal primary intimal tear and the location of the proximal primary intimal tear,either in the convex or concave side of the aortic arch,or in the imaging of the aortic arch types.2.TEVAR and post-TEVAR resultsA total of 334 patients underwent TEVAR therapy with a 100%technical success rate.The innominate artery was totally covered in four patients[convexity(100%)vs.concavity(0%)].The left common carotid artery was covered totally in 14 patients[convexity(78.6%)vs.concavity(21.4%)],and partially in five patients[convexity(0%)vs.concavity(100%)].The left subclavian artery was covered totally in 115 patients[convexity(68.7%)vs.concavity(31.3%)]and was covered partially in 45 patients[convexity(86%)vs.concavity(14%)].Thirty-one patients received chimney for the left common carotid artery[convexity(71%)vs.concavity(29%)],nine patients received chimney for the left subclavian artery[convexity(44.4%)vs.concavity(55.6%)],two patients received chimney in both the left subclavian artery and left common carotid artery(concavity group),and one patient in the convexity group received chimney for three branches.There were 10 hybrid operations.Seventeen patients died within 30 days post-TEVAR.Among them,six patients died of retrograde type A aortic dissection(five patients in the convexity group and one patient in the concavity group)and six patients died of aortic rupture(five patients in the convexity group and one patient in the concavity group).One patient died of multiple system and organ failure(convexity group);two patients died of cerebrovascular accident(one patient in each group);and two patients died of gastrointestinal bleeding(convexity group).Twenty-one patients died after 30 days of therapy.Among them,five patients died of retrograde type A aortic dissection(convexity group);six patients died of aortic rupture(convexity group);eight patients died of cancer;two patients died of cerebrovascular accident;and four patients died of other causes.Aortic related mortality in the concavity group was lower than that of the convexity group,with statistical significance(p = 0.035).The ratio of deaths in the three groups during follow-up was:cerebrovascular accident(0.3%vs 0.3%,0.3%vs 0.3%),retrograde type A aortic dissection(1.8%vs 0.3%,1.8%vs 0.3),and aortic rupture(0.3%vs 0.3,0.3%vs 0.9%).3.Survival analysis and influencing factorsThe one-year overall cumulative survival rate was 90.0%in the convexity group and 98.1%in the concavity group;the three-year overall cumulative survival rate was 85.9%in the convexity group and 94.5%in the concavity group;and the five-year overall cumulative survival rate was 83.1%in the convexity group and 91.0%in the concavity group.The overall survival rate of the concavity group was longer than that of the convexity group,which had statistical significance(Log-rank test p = 0.021).The factors influencing overall survival time were:hypertension,covering of the innominate artery and false lumen thrombosis condition.The one-year aortic-related cumulative survival rate was 93.9%in the convexity group and 98.1%in the concavity group;the three-year aortic-related cumulative survival rate was 92.8%in the convexity group and 98.1%in the concavity group;and five-year aortic-related cumulative survival rate was 91.0%in the convexity group and 98.1%in the concavity group.The aortic-related survival rate in the concavity group was longer than the convexity group,which had statistical significance(Log-rank test p=0.039).The factors influencing aortic-related survival time were:covering of the innominate artery,covering of the left common carotid artery and false lumen thrombosis condition.In terms of postoperative complications,there was no significant difference between the size of the proximal primary intimal tear and the major postoperative complications,including retrograde type A aortic dissection,distal stent graft-induced new entry to the false lumen,and all-cause mortality.There was no significant difference between the three groups in survival analysis.Conclusions:1.Thoracic endovascular aortic repair for treatment of Stanford type B aortic dissection has gained popularity worldwide because it is minimally invasive,has less bleeding,a quicker recovery,and other advantages.2.Patients with primary intimal tear in the the convexity group are elder.The thoracic aortic arch is involved more than in the concavity group,leading to the necessity of more proximal landing zone and covering of the aortic arch branch.In such cases,the chimney technique and the hybrid technique must be used,which increases postoperative complications.3.The overall survival rate for Stanford type B aortic dissection patients in the concavity group was higher than in the convexity group.4.The aortic-related survival rate for Stanford type B aortic dissection patients in the concavity group was higher than in the convexity group.5.The incidence of postoperative complications and mortality was higher in the convexity group than in the concavity group.6.The greater the proximal primary intimal tear,the easier it is to involve the aortic arch.Part ?.Influence of primary intimal tear location in type B aortic dissection as a factor portending retrograde type A aortic dissection after endovascular repairBackground and Purpose:Retrograde type A aortic dissection(RTAAD)is an uncommon but lethal post-operative complication,and the precise mechanism behind the occurrence of RTAAD remains unclear.Several reports have attributed the occurrence of this lethal complication to patient-specific or procedural factors.In previous studies,the location of the primary intimal tear in type B aortic dissections was found to be a predictor for developing primary or secondary complications.The aim of this study was to investigate the effect of the position of the primary intimal tear on the distal convexity as a factor predisposing patients for developing RTAAD after endovascular repair for type B aortic dissectionsMethods:From January 2010 to December 2015,334 patients with Stanford type B aortic dissections identified from a retrospective thoracic endovascular repair database were assigned to two groups based on the location of the primary intimal tear in the distal aortic arch.All statistical analyses were conducted with SPSS 20(IBM SPSS Inc,Chicago,Illinois).Data are expressed as the mean ± standard deviation for continuous variables and as frequencies and percentages for categorical variables.The Student's t-test was used for comparing the continuous variables,whereas a chi-square or Fisher's exact test was used for categorical variables.A p value<0.05 was considered to indicate statistical significance.Kaplan-Meier curves were used to delineate the aortic event-free survival rates.Risk ratios(RRs)were calculated with 95%confidence intervals(CI)to evaluate the strength of the association between potential risk factors and the occurrence of RTAAD.A multistage Cox proportional hazards analysis modelled the association between follow-ups and RTAAD.Results:The location of the primary intimal tear was identified in 230 patients(68.9%)in the convexity group and 104 patients(31.1%)in the concavity group.After intervention,20 patients(convexity:7.8%,concavity:1.9%)developed RTAAD.The incidence rate was higher in the convexity group(7.8%and 1.9%,p = 0.035).The mortality rate for patients with RTAAD was 11/18(61%)in the convexity group and 1/2(50%)in the concavity group.Only two of 12 patients with Marfan syndrome developed RTAAD(one in each group).A univariate analysis identified the location of the primary intimal tears.Areas involved by dissection and the covering of the brachiocephalic trunk were significantly associated with RTAAD.A multivariate analysis revealed that a primary entry tear at the distal convexity might be a predictor for developing RTAAD with a tendency toward statistical significance(p = 0.053)and a relative risk of 4.243(95%CI,0.984-18.286).Conclusions:1.RTAAD is an uncommon but fatal post-TEVAR complication.This complication can be related to multiple factors;consequently,every possible factor should be considered to avoid its occurrence.2.Taking the location of the primary intimal tear into account,patients with primary intimal tears located in the distal convexity may be more likely to develop RTAAD than patients with primary intimal tears in the distal concavity.3.Open surgery is the main treatment for RTAAD post-TEVAR.