| Background and objectives Aortic dissection is a kind of aortic disease with acute onset, rapid progression and high mortality. The latest data shows that the annual incidence rate of acute aortic dissection reaches 5-30% per million population. Reports showed that one-to three-day mortality rate of acute aortic dissection without treatment was about 1-2% per hour, about 50%patients with aortic dissection died within 1 week, one-month mortality rate reached as high as 75%, and 90% patients with aortic dissection died within 1 year. Even undergoing clinical treatment, the in-hospital mortality rate of patients with aortic dissection still amounted to 23.9%,according to International Research for acute aortic dissection.Aortic dissection is characterized by the separation of normal aortic walls into two lumens such as true lumen and false lumen, which is caused by the high-speed inflow of blood under high pressure into aortic walls through the tear in aora intima due to various reasons, leading to a series of symptoms such as chest pain, syncope, severely poor internal organ perfusion or even death. It was reported that aortic dissection was mainly caused by the combination of such two factors as abnormalities in aortic tunica media and hemodynamic abnormality.(1).Lesions occurred in aortic tunica media mainly include Marfan syndrome, congenital cardiovascular malformations, idiopathic degenerative change in aortic tunica media, aortic atherosclerosis and aortic inflammatory diseases.(2).While hemodynamic abnormality is majorly caused by hypertension,and another cause cannot be ignored is pregnancy. Pregnancy associated with aortic dissection is very common and difficult to treat.Among various international aortic dissection typing methods, the De Bakey typing is widely used, which divides aortic dissection into three types according to the location of tear in aora intima and the involvement scope of dissection. Broadly speaking, type I and type II are usually treated by traditional surgery as they involve in ascending aorta, while type III only involves in thoracic aorta, so it is commonly treated by interventional methods; but with the deepening understanding in aortic dissection, especially in the selection of treatment methods, Stanford typing has been applied increasingly widely. Stanford typing divides aortic dissections into type A aortic dissection and type B aortic dissection, type A aortic dissection is characterized by the involvement of dissection in ascending aorta, and type B dissection features the involvement of dissection in the opening of left subclavian artery as well as in distant and distal descending aorta. Type A aortic dissection is recommended to be treated by clinical or traditional surgery, while type B dissection can be treated by adopting many methods depending on the size of tear in dissection and its involvement scope, relative size between true and false lumen as well as whether hematoma involves in aorta arch.There are three major clinical treatment methods for type B aortic dissection such as conservative drug therapy, traditional surgery and endovascular interventional treatment. With the progress in technology and the deepening of the understanding towards this disease, hybrid technology has also been widely applied in the clinical treatment of type B aortic dissection.Patients who cannot undergo surgery or interventional treatment due to intramural hematoma and penetrating ulcer or a variety of reasons can select internal drug conservative treatment, which can control systolic blood pressure and slow down left ventricular ejection velocity(dp/dt), to reduce the impact of high-speed blood flow on the aorta and to reduce the incidence of organ dysfunction caused by aortic rupture and the involvement to major branch arteries of aorta due to dissection as far as possible. But it is worthy to note that internal medicine conservative treatment only lowers the risk factors of dissection, instead of solving the problems of the closing of tear in aortic dissection and the opening of true lumen fundamentally, especially when huge tear on the verge of rupture is found in severe and complicated aortic dissection, or dissection involves in extensive parts, or some major branch arteries of aorta are severely involved, drug treatment can only be used as a preoperative transitional therapy, rather than the only or preferred therapy.Before the invention of interventional therapy, type B aortic dissection were mainly threated by traditional surgeries, among which vascular replacement was selected as first-line treatment method, but its surgical risk and postoperative complication rate was very high. With the development of interventional technology, especially of interventional materials, traditional surgery has been less used in the treatment of type B aortic dissection, but some chronic type B aortic dissections, especially those with larger tumors and major branch arteries of aorta involved by dissection, still adopt surgery as important clinical therapy.Since its application in the treatment of type B aortic dissection,endovascular interventional therapy has been used as the preferred treatment of this disease. Thoracic endovascular aortic repair(TEVAR)adopts covered stent to enlarge and open aortic true lumen through tear located in proximal part of aortic dissection, to basically restore blood flow supplied to internal organs, and in the meanwhile form false intraluminal thrombus, and then the thrombus will be absorbed gradually,to ultimately reconstruct normal lumen structure of aorta, and avoid of tumor-like change in residual false lumen of aortic dissection in the long term, so as to greatly reduce the risk of rupture. However, some complex type B aortic dissections cannot be cured completely by endovascular interventional therapy alone. In particular, as intracavitary interventional therapy cannot effectively cure complicated type B dissection and those with involvement to aorta arch, or with insufficient anchoring or with left subclavian arteries as major blood supply vessels, TEVAR has been improved constantly, "chimney" and "hybrid" are the representative of treatment of complex B type AD. Many researchers regard "chimney" as a transitional treatment technology, as TEVAR can solve some emergencies, but its complications, leakage rate and stent occlusion rate need further discussion and study. At present, some latest surgical treatment concepts also gradually integrate with endovascular interventional therapy, which is known as the "hybrid" technology.Through vascular reconstruction to expand interventional scope and increasing anchor areas, "hybrid" technology dispenses some complex type B dissections with traditional surgery, so as to greatly reduce surgical risks and perioperative mortality. As hybrid technology has been applied in clinical treatment for a short time, some centers only carried out short-term follow-ups, thus their statistics were not consistent. It is urgent to find out whether "hybrid" technology is easier to operate with lower incidence of complications and mortality compared with conventional surgery.In summary, this study aims at address the above problems by comparing the effects of several treatment approaches in the treatment of complex type B aortic dissection, to understand whether "hybrid" surgery has advantages in the treatment of complex type B aortic dissection compared with other therapies.Part 1 Comparative study on the clinical efficacy between "hybrid" technology combined with TEVAR and traditional surgery in the treatment of complex B type dissectionObjective To explore the treatment strategies of complex type B aortic dissection by comparing mortality, incidence of perioperative complications and outcome of the patients in the short and mid-term follow-up between "hybrid" technology combined with TEVAR and traditional surgery in the treatment of complex B dissection.Method Retrospective analysis was performed on the clinical data of patients who underwent traditional surgery or "hybrid" technology combined with TEVAR in the treatment of complex type B aortic dissection from January 2008 to June 2016, and the surgical group was composed of 12 patients, while the hybrid group of 78 patients. Complication rate,mortality and aortic reconstruction conditions detected by aorta CTA between surgical group and hybrid group during hospitalization and follow-up period were statistically analyzed, and?2 test or Fisher's exact test were performed to compare complications, mortality and postoperative conditions between these two groups, t test was applied to compare reconstruction conditions of aorta between these two groups,and Kaplan-Meier method and log-rank method were adopted to calculate cumulative survival rate and survival rates of the two groups respectively.Result The curative efficacy and incidence of complications between the two groups were statistically significant, and there was no significant difference in mortality and aortic reconstruction between the two groups.Cumulative survival rate between the two groups was not statistically significant.Conclusion "Hybrid" technology combined with TEVAR had advantages of minimally invasive, less bleeding, fast recovery than traditional surgery in the treatment of complex B aortic dissection. But long-term follow-up and large sample data still need to be further studied. For the severe type B dissection with aortic arch disease, traditional surgery can reduce the incidence of complications.Part 2 Comparative study on the clinical efficacy between "hybrid" technology combined with TEVAR and simple interventional therapy in the treatment of complex B type dissectionObjectiveTo explore the treatment strategies of complex type B aortic dissection by comparing mortality, rate of leakage and retrograde Type A Aortic Dissection, outcome of the patients in the short and mid-term follow-up between "hybrid" technology combined with TEVAR and simple interventional therapy in the treatment of complex type B dissection.MethodRetrospective analysis was performed on the clinical data of patients who underwent simple interventional therapy or "hybrid" technology combined with TEVAR in the treatment of complex type B aortic dissection from January 2008 to June 2016, and the interventional group was composed of 28 patients, while the hybrid group of 78 patients. Rate of leakage, improvement conditions and aortic reconstruction conditions detected by aorta CTA between interventional group and hybrid group during hospitalization and follow-up period were statistically analyzed,and ?2 test or Fisher's exact test were performed to compare rates of leakage between these two groups, and t test was applied to compare reconstruction conditions of aorta between these two groups.ResultHybrid group was significantly higher than intervention group in the rate of postoperative leakage and retrograde Type AAortic Dissection with the difference being statistically significant. Hybrid group was also higher than intervention group during follow-up period, showing statistically significant differences. While the two groups showed no differences in aortic reconstruction, without statistical significance.ConclusionHybrid technology had great advantage in short and middle-term curative efficacy as well in the treatment of complex B aortic dissection. For the elderly patients of surgery could not be performed, aortic arch disease was mild can be consided to perform simple TEVAR treatment, but must focus on the management of preoperative preparation period.combination with "chimney" interventional therapy in the treatment of complex B type dissection Part 3 Comparative study on the clinical efficacy between "hybrid" technology combined with TEVAR and TEVAR inObjectiveTo explore the treatment strategies of complex type B aortic dissection by comparing the clinical curative effects, rate of leakage,proximal morphology of long-term covered stent, patency rate of aorta arch and aortic reconstructions between "hybrid" technology combined with TEVAR and TEVAR in combination with "chimney" interventional therapy in the treatment of complex B dissection.MethodRetrospective analysis was performed on the clinical data of patients who underwent TEVAR in combination with "chimney" interventional therapy or "hybrid" technology combined with TEVAR in the treatment of complex type B aortic dissection from January 2008 to June 2016, and the chimney group was composed of 22 patients, while the hybrid group of 78 patients. Rate of leakage, proximal morphology of long-term covered stent, patency rate of three vessels at aorta arch and aortic reconstructions detected by aorta CTA between chimney group and hybrid group during hospitalization and follow-up period were statistically analyzed, and ?2 test or Fisher's exact test were performed to compare rate of leakage, proximal morphology of long-term covered stent and patency rate of three vessels at aorta arch between these two groups,and t test was applied to compare reconstruction conditions of aorta between these two groups.Result"Hybrid" technology combined with TEVAR was significantly superior than TEVAR in combination with "chimney" interventional therapy in terms of rate of leakage and morphology of covered stent in the treatment of complex type B aortic dissection, while the two groups had no apparent difference in patency rate of three vessels at aorta arch and aortic reconstructions.ConclusionIn the treatment of complex type B aortic dissection, TEVAR combined with "chimney" interventional therapy can basically reconstruct blood flow of branch arteries of aorta arch, with the merits of simple operation and minimal invasion, but the leakage of stents cannot be completely avoided. While TEVAR combined with "chimney"interventional therapy has no obvious advantages in "proximal morphology of covered stent. In terms of patency rate of vessels at aorta arch, though "hybrid" technology combined with TEVAR has advantage in short term follow-up, the long-term follow-up still needs a large amount of data for analysis, as the original anatomical position of vessels at aorta arch changes. |
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