**2. Methods**

Methods of reconstruction of distal aortic dissection: 1. thrombosis of false lumen by foreign bodies; 2. the creation of an artificial distal fenestration; 3. extraanatomical bypass surgery; 4. prosthetics between the two clamps; 5. prosthetics between the two clamps with the use of an extraanatomical bypass shunt; 6. prosthetics between the two clamps with the use of methods of extracorporal blood circulation; 7. prosthesis without the use of clamps by circulatory arrest; 8. endoprosthetics (stent grafts); 9. stenting; and 10. hybrid methods in the form of a combination of these techniques using different types of access.

Initially, the reconstruction of the descending aorta during dissection was carried out in nonradical ways, such as initiation of thrombosis of the false lumen by means of foreign elements or reduction of the diameter of the aorta outside by suture or exoprosthesis. In the future, methods of simple clamping of the aorta and its replacement were performed. Frozen arterial homografts and then synthetic vascular prostheses were used [30].

Despite such disadvantages as limiting the time of anastomosis not more than 30 min and the formation of tissue hypertension, in the areas above and below the imposition of clamps, the supporters of this method think because there is no need for systemic heparinization of the patient and the use of perfusion support. All these significantly reduce blood loss and surgery time [31]. In the early stages of surgery for rupture of the descending part of the thoracic aorta, the

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insufficient reliability [32].

prosthesis [34].

remains unsolved.

are controversial.

directly into the wall of the graft [36].

1.Method of extracorporeal blood circulation:

b.full bypass femoral artery—femoral vein.

pulmonary vein-femoral artery);

the use of clamps on the aorta.

technique of bypass grafting was also used: ascending aorta—abdominal aorta. At the same time, a homograft was used as a shunt. However, this technique was not ideal due to the technical complexity of the shunt, its bulkiness, and

In 1955, based on the work of DeBakey et al., the first experience of reconstructive interventions on thoracic aorta with dissection in 6 patients was published [33]. In 1965, they analyzed 10-year results of treatment of thoracic aortic dissection, including T III. Two surgical techniques were described. Earlier, it was the formation of artificial distal fenestration in the thoracic aorta and reconstruction of the true lumen below its level. The authors themselves recognize this technique does not correspond to the concept of restoring integrity and normal function of the aorta, but rather palliative. Another technique was the imposition of the leftfemoral bypass, the intersection of the aorta between the two clips superimposed directly at the ostium of the left subclavian artery and near the diaphragmatic opening, and the restoration of the integrity of the true lumen of the aorta and its replacement with a synthetic vascular prosthesis. At the same time, according to the authors, in the case of spreading the dissection proximal to the left subclavian artery, it could be sacrificed by ligation, or reimplanting its origin into a vascular

The use of cardiopulmonary bypass increased the safe time for anastomosis, but did not solve the problems associated with the imposition of clamps on the aorta, since in most patients with distal aortic dissection, the inlet of the false canal is located directly at the origin of the left carotid artery. In addition, the clamp applied at the level of the diaphragm to the aorta makes it difficult to form a qualitative distal anastomosis, and damage to the altered tissues of the aorta can cause its insolvency. Moreover, the problem of residual dissection below the diaphragm level

DeBakey et al. in 1966 established the principles of the surgical technique of treatment of aortic dissection, including excision of the dissected intimal flaps, overlapping the proximal enter in false lumen and reconstruction of the aorta by the implantation of synthetic tubular prosthesis. Based on this, techniques for recon-

In 1974, Stanley Crawford reported on his experience with thoracoabdominal aneurysms and dissections. In earlier observations, the implantation of a synthetic Dacron graft was undertaken as an extraanatomical shunt with subsequent overlapping of the aortic lumen and serial reimplantation of the aortic branches by vascular prostheses in the wall of the aortic graft. In later cases, the vascular graft was placed inside the aneurysm with reimplantation of the origin of visceral vessels

Currently, this technique is the basis for the open correction of extensive thoracoabdominal aortic dissection. However, the technical details of the operation

a.left-femoral bypass with or without oxygenation (left atrium eyelet or

2.Ways of protection of internal organs: normothermic perfusion with the

perfusion of visceral vessels; hypothermia; and total circulatory arrest without

struction of distal aortic dissection were further developed [35].

technique of bypass grafting was also used: ascending aorta—abdominal aorta. At the same time, a homograft was used as a shunt. However, this technique was not ideal due to the technical complexity of the shunt, its bulkiness, and insufficient reliability [32].

In 1955, based on the work of DeBakey et al., the first experience of reconstructive interventions on thoracic aorta with dissection in 6 patients was published [33]. In 1965, they analyzed 10-year results of treatment of thoracic aortic dissection, including T III. Two surgical techniques were described. Earlier, it was the formation of artificial distal fenestration in the thoracic aorta and reconstruction of the true lumen below its level. The authors themselves recognize this technique does not correspond to the concept of restoring integrity and normal function of the aorta, but rather palliative. Another technique was the imposition of the leftfemoral bypass, the intersection of the aorta between the two clips superimposed directly at the ostium of the left subclavian artery and near the diaphragmatic opening, and the restoration of the integrity of the true lumen of the aorta and its replacement with a synthetic vascular prosthesis. At the same time, according to the authors, in the case of spreading the dissection proximal to the left subclavian artery, it could be sacrificed by ligation, or reimplanting its origin into a vascular prosthesis [34].

The use of cardiopulmonary bypass increased the safe time for anastomosis, but did not solve the problems associated with the imposition of clamps on the aorta, since in most patients with distal aortic dissection, the inlet of the false canal is located directly at the origin of the left carotid artery. In addition, the clamp applied at the level of the diaphragm to the aorta makes it difficult to form a qualitative distal anastomosis, and damage to the altered tissues of the aorta can cause its insolvency. Moreover, the problem of residual dissection below the diaphragm level remains unsolved.

DeBakey et al. in 1966 established the principles of the surgical technique of treatment of aortic dissection, including excision of the dissected intimal flaps, overlapping the proximal enter in false lumen and reconstruction of the aorta by the implantation of synthetic tubular prosthesis. Based on this, techniques for reconstruction of distal aortic dissection were further developed [35].

In 1974, Stanley Crawford reported on his experience with thoracoabdominal aneurysms and dissections. In earlier observations, the implantation of a synthetic Dacron graft was undertaken as an extraanatomical shunt with subsequent overlapping of the aortic lumen and serial reimplantation of the aortic branches by vascular prostheses in the wall of the aortic graft. In later cases, the vascular graft was placed inside the aneurysm with reimplantation of the origin of visceral vessels directly into the wall of the graft [36].

Currently, this technique is the basis for the open correction of extensive thoracoabdominal aortic dissection. However, the technical details of the operation are controversial.

	- a.left-femoral bypass with or without oxygenation (left atrium eyelet or pulmonary vein-femoral artery);
	- b.full bypass femoral artery—femoral vein.

There are various options to use this technology. In particular, in the conditions of left-femoral bypass and normothermal perfusion, the procedure is performed from thoracophrenolumbotomy access in stages. In the beginning, the clamping of a proximal segment of the aorta is done, the formation of a proximal anastomosis with a vascular graft to the descending thoracic aorta is carried out, and the mobilization of the thoracic aorta is produced. The clamp on the distal portion of the aorta is placed, producing distal anastomosis, dissecting aneurysm, and lumbar arteries are stitched, producing temporary occlusion of the visceral arteries with balloons catheters. Produce perfusion of the renal arteries to protect against ischemia; the intercostal arteries are implanted to the prosthetic aorta at the site Th8-L1 to restore adequate blood supply to the spinal cord, and renal arteries and visceral branches are implanted [37].

Further improvement of this technique was carried out by sewing visceral branches into the vascular prosthesis of the aorta on separate islands or using an aortic vascular prosthesis originally made with branches for the implantation of visceral arteries [38, 39]. The difference between the methods lies in the fact that the implantation of the origin of the vessels on a single island reduces the time of the procedure, but there is a risk of relapse in the long term, as in the bloodstream there are large areas of altered aortic tissue with untreated arterial origins. When using the technique of Соselli, the origins of the visceral vessels are filed separately to those already present in the aortic graft that prevents recurrence of the aneurysm, but does not allow avoiding the complications associated with the tension and kinking of the vessels and extends the duration of the procedure.

To prevent these complications, a modified technique of visceral arteries reimplantation was proposed. Its essence lies in the fact that used graft with four prestitched lateral branches. After applying the proximal and distal anastomoses, each lateral branch is wrapped around the main graft, forming a slightly curved loop around it. The opening of each visceral artery is sutured to the lateral branch. This method prevents bending of the lateral branches and allows for hemostasis with a good overview of all suture lines [40]. Estrera et al. describe a modification of the classical technique used by them in the correction of chronic complicated aortic dissection type B. The procedure is performed by bypass of the left ventricle on the scheme of the lower left pulmonary vein—distal aorta, through a vascular prosthesis attached to the aortic prosthesis. Is drainage of the cerebrospinal fluid, and neuromonitoring. After clamping the distal portion of the aorta and forming a wedge-shaped hole in the membrane between the true and false lumens, a distal anastomosis is formed to adequately supply them with blood. Then the clamp is shifted higher on the aortic prosthesis and the vascular prosthesis starts blood flow to the distal aorta, and then the aorta is clamped at the level of the left subclavian artery. The aorta is incised, intercostal arteries or clipped or made their temporary occlusion using a Fogarty catheter. A reversed elephant trunk is formed, then a proximal anastomosis is made. If necessary, intercostal arteries are drained into the vascular prosthesis on a single site, and prestitched to the aortic prosthesis with both ends. According to the authors of their more than 20 years of experience, it is shown that when using this technique, hospital mortality is 8.3%. Persistent neurological disorders occur in 1.3%, strokes 2.9%, the need for dialysis in 6%. 5-, 10-, 15-, and 20-year survival rates are 72%, 60%, 45%, and 39%, respectively [41].

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arteries, and the insertion of epidural catheter [43].

early and late postoperative period [47].

Deep hypothermia was used in 13 patients.

tomography (СT) were noted [48].

arrest with deep hypothermia may not always be effective enough.

At the same time, the technique of complete shutdown of the descending aorta from the systemic circulation using the methods of deep hypothermia without applying clamps to it has not lost its relevance [42]. According to some authors, this technique has significant advantages since it allows you to do without applying a clamp to the proximal portion of the descending thoracic aorta, as close as possible to impose anastomoses to the origin of the left subclavian artery and the aperture of the diaphragm, as well as in the case of retrograde dissection, if necessary, move to the distal portion of the aortic arch. The advantages of the technique include a bloodless surgical field, the return of a large amount of blood to the contour of the apparatus and hypothermic protection of the central nervous system, heart, and visceral organs. In addition, there is no need to use the drainage of cerebrospinal fluid, monitoring of evoked potentials, separate perfusion of renal and visceral

Its main drawback is the need to protect the brain and spinal cord, as well as internal organs from hypoxia and a limited time of safe duration of circulatory arrest, no more than 90 min at a body temperature of 18°C [44]. The cooling phase of the patient takes quite a long time since the decrease in body temperature should be uniform, complete, and prolonged [45]. The time to reach the optimum temperature can take from 30 to 50 min [46]. The method of warming the patient should also be done slowly and in compliance with a number of different conditions. In conditions of complicated distal aortic dissection, the technique of circulatory

The influence of different approaches to revascularization of intercostal and lumbar arteries during reconstructive interventions on the distal aorta on the prevention of paraplegia has not been studied enough. One hundred consecutively operated patients were performed open reconstruction of the distal lesions of the aorta with a consistent overlap of the segmental arteries. Early mortality was 6%. The average length of stay in the intensive care unit was 2.5 days, and the average length of stay in the hospital was 10.0 days. On average, 8.0 ± 2.6 pairs of segmental arteries were closed, with an average of 4.5 ± 2.1 covered segment pairs being in the area between T7 and L1, where is the artery of Adamkewicz. Postoperative paraplegia occurred in 2 patients. The authors conclude that the overlap without reimplantation of 15 pairs of intercostal and lumbar arteries during the reconstruction of the distal aorta is safe, and is accompanied by a moderate number of paraplegia in the

Radical surgery shows good immediate and long-term results in patients with hereditary connective tissue syndrome. In particular, in patients with Marfan syndrome, total replacement of the entire thoracoabdominal aorta and reconstruction of all visceral branches are recommended to avoid relapses in the long term, even if dilation in some segments is not expressed. In a study by Omura et al., a series of observations was reported in 20 patients with Marfan syndrome who underwent total replacement of the thoracoabdominal aorta for a dissecting aneurysm. All patients during the surgical intervention were performed cerebrospinal fluid drainage, distal perfusion of the aorta and selective perfusion of the internal organs.

In the 30-day postoperative period, no fatal outcomes were observed. The average follow-up period was 54 months. One patient died of interstitial pneumonia 38 months after surgery. The survival rate for 8 years was 91.2 ± 9.0%. Two patients required additional interventions on the aorta. Actuarial index of freedom from operations on the aorta for 8 years was 83.9% ± 10.5%; no patient needed a rethoracotomy. During follow-up, neither false nor asymptomatic aneurysms by computed

At the same time, the technique of complete shutdown of the descending aorta from the systemic circulation using the methods of deep hypothermia without applying clamps to it has not lost its relevance [42]. According to some authors, this technique has significant advantages since it allows you to do without applying a clamp to the proximal portion of the descending thoracic aorta, as close as possible to impose anastomoses to the origin of the left subclavian artery and the aperture of the diaphragm, as well as in the case of retrograde dissection, if necessary, move to the distal portion of the aortic arch. The advantages of the technique include a bloodless surgical field, the return of a large amount of blood to the contour of the apparatus and hypothermic protection of the central nervous system, heart, and visceral organs. In addition, there is no need to use the drainage of cerebrospinal fluid, monitoring of evoked potentials, separate perfusion of renal and visceral arteries, and the insertion of epidural catheter [43].

Its main drawback is the need to protect the brain and spinal cord, as well as internal organs from hypoxia and a limited time of safe duration of circulatory arrest, no more than 90 min at a body temperature of 18°C [44]. The cooling phase of the patient takes quite a long time since the decrease in body temperature should be uniform, complete, and prolonged [45]. The time to reach the optimum temperature can take from 30 to 50 min [46]. The method of warming the patient should also be done slowly and in compliance with a number of different conditions. In conditions of complicated distal aortic dissection, the technique of circulatory arrest with deep hypothermia may not always be effective enough.

The influence of different approaches to revascularization of intercostal and lumbar arteries during reconstructive interventions on the distal aorta on the prevention of paraplegia has not been studied enough. One hundred consecutively operated patients were performed open reconstruction of the distal lesions of the aorta with a consistent overlap of the segmental arteries. Early mortality was 6%. The average length of stay in the intensive care unit was 2.5 days, and the average length of stay in the hospital was 10.0 days. On average, 8.0 ± 2.6 pairs of segmental arteries were closed, with an average of 4.5 ± 2.1 covered segment pairs being in the area between T7 and L1, where is the artery of Adamkewicz. Postoperative paraplegia occurred in 2 patients. The authors conclude that the overlap without reimplantation of 15 pairs of intercostal and lumbar arteries during the reconstruction of the distal aorta is safe, and is accompanied by a moderate number of paraplegia in the early and late postoperative period [47].

Radical surgery shows good immediate and long-term results in patients with hereditary connective tissue syndrome. In particular, in patients with Marfan syndrome, total replacement of the entire thoracoabdominal aorta and reconstruction of all visceral branches are recommended to avoid relapses in the long term, even if dilation in some segments is not expressed. In a study by Omura et al., a series of observations was reported in 20 patients with Marfan syndrome who underwent total replacement of the thoracoabdominal aorta for a dissecting aneurysm. All patients during the surgical intervention were performed cerebrospinal fluid drainage, distal perfusion of the aorta and selective perfusion of the internal organs. Deep hypothermia was used in 13 patients.

In the 30-day postoperative period, no fatal outcomes were observed. The average follow-up period was 54 months. One patient died of interstitial pneumonia 38 months after surgery. The survival rate for 8 years was 91.2 ± 9.0%. Two patients required additional interventions on the aorta. Actuarial index of freedom from operations on the aorta for 8 years was 83.9% ± 10.5%; no patient needed a rethoracotomy. During follow-up, neither false nor asymptomatic aneurysms by computed tomography (СT) were noted [48].

Even though the results of surgical treatment of distal aortic dissection have improved over the last decade, they are still not optimal, and hospital mortality is 25–50% [49, 50]. Complications associated with the open method of surgical intervention are the following: spinal cord ischemia (6.8%), cerebral circulation disorders (9%), abdominal ischemia or intestinal infarction (4.9%), and acute renal failure (19%) [51, 52].

The widespread use of open radical operations is limited by the severity of the patient's condition, the presence of concomitant diseases, and its physiological reserve. A significant disadvantage of this technology is a very low possibility of its replication. Such operations with a low level of mortality can be carried out only in specialized aortic centers with 20–30 years of experience in such operations and close-knit teams of highly qualified specialists. In conditions of acute complicated DeBakey type III dissection, this is not always possible and requires simpler and no less reliable solutions.

The need for their search and the beginning of the era of percutaneous transcatheter interventions on the coronary arteries prompted researchers to create a vascular prosthesis that could be placed inside the lumen of the aorta to block the entrance opening of the false canal and isolate its wall without performing extensive surgical access. In 1988, Volodos reported on the first percutaneous endoprosthesis of the thoracic aorta with a self-fixing synthetic prosthesis for a large posttraumatic aneurysm [53].

With significant advantages due to the reduction of intraoperative trauma and no need to protect the brain and spinal cord, as well as internal organs, the methods of transcatheter reconstruction of the distal aortic dissection initially had a number of limitations and did not immediately gain a leading position in the treatment of complicated distal aortic dissection [54].

Stent graphs are ideal for implantation in straight areas of the aorta, where there are no large hemodynamic values of arterial trunks; such in the reconstruction of the distal dissection can only be a portion of the descending thoracic aorta, from the ostium of the left common carotid artery and ending with the level of renal arteries. Despite the fact that during the period from the left subclavian artery to the renal from the descending aorta does not depart large arterial branches, overlapping its area for more than 20 cm at this level can lead to the development of pronounced spinal disorders [55–57]. The wall of the aorta is constantly shrinking, conducting a pulse wave, and violation of its elastic properties during dissection creates a tendency to irreversible dilation of the aorta and its thinning up to rupture [58].

To prevent spontaneous dislocation of the stent graft, two proximal landing zones of at least 1.5 cm and a distal zone of at least 2 cm in length are required [59].

For successful fixation of the stent graft in the landing zones, it is necessary to overestimate the pressure on the aortic wall in the places of fixation, which is achieved by increasing its landing size by 2–3 mm or more. In this regard, one of the most dangerous complications associated with the implantation of a stent graft is the retrograde progression of the dissection [60, 61].

In addition, the number of complications included caudal migration of the prosthesis under the influence of the pulse wave; the collapse of a stent graft; and lack of precision of its positioning, because this process performed distantly is not under direct visual, and under angiographic control, which may lead to the implantation of stent graft in the false lumen of the aorta [62].

Specific complications of implantation of stent graft also considered para prosthesis leakage (endoleaks) [55–57]. Endoleak type Ia is a frequent complication in the reconstruction of TEVAR for distal aortic dissection and is caused by inadequate sealing of the endograft's in the proximal area [63]. This endoleak that occurred

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condition of the aorta [64].

surgery [68].

immediately after TEVAR for acute dissection of type B may indicate the unstable

In most cases, proximal intimal fenestration in distal dissection is located near the ostium of the left subclavian artery, due to the formation of reverse blood flow in the aorta in this area [58]. Thus, in 20–30% of cases, stent graft implantation requires closure of the left subclavian artery ostium [65]. Intentional overlapping of the left subclavian artery of the stent graft leads to a statistically significant increase in the risk of stroke [66] and the frequency of spinal cord ischemia [67]. In this regard, current recommendations include revascularization of the left subclavian artery (LSA) [65]. In one retrospective comparative study, there was a statistically significant increase in the number of strokes and upper limb ischemia in patients who did not undergo revascularization of LSA in comparison with patients who underwent revascularization of LSA by reimplantation of its ostium or bypass

In order to reduce the aggressiveness of the intervention and increase the landing zone, the endovascular technique of parallel stent grafts is used, that is, implantation of a separate stent graft into the left subclavian artery, its placement parallel to the main stent graft, and removal of its orifice beyond the proximal landing zone of the main stent graft, the so-called chimney or snorkel technique [69]. Chimney is the method of choice in patients with complex aortic arch anatomy to extend the proximal landing zone and provide perfusion of the aortic arch branches [70]. This technique can be used in patients with aberrant right subclavian artery in the case of acute type B aortic dissection [71]. In addition, this endovascular technique can be

The technique of chimneys has a number of limitations, such as entanglement and bending of branches, but the most significant of them is the aggravation of the danger of the formation of endoleaks of type I, due to the loose fit of the main stent

To solve these problems for the purpose of endo prosthesis of the aortic arch, a number of commercially available endografts with preattached branches are produced; endoprostheses have a wide size range and do not need individual manufacture. Despite the shown good results in relation to the early postoperative mortality, the number of strokes, and the frequency of repeated interventions in patients with increased surgical risk, this procedure requires detailed preliminary calculations, is difficult to perform, and is more suitable for patients with residual dissection after

The procedure of implantation of scalloped or fenestered stent grafts is less complicated; stent-graft with a half-opening on the edge or opening for the mouths of brachiocephalic vessels well adheres to the altered aortic wall, is easier to manufacture, and is more accessible than branched stent graft. However, fenestrated stent grafts are more prone to dislocation and show the worst results for the number

All of the above techniques are also successfully used for revascularization of visceral branches. In addition, they have the same advantages and disadvantages as in the application of the aortic arch, as fenestrated stent grafts and the periscope technique, are well suited for the treatment of patients with complex anatomy in the region of the visceral branches of the aorta [77]. Technology chimney and periscopes are also used for the relief of endoleaks type I after EVAR prior to increase in the proximal and distal landing zones for endografts [78] . However, according to some authors, the application of chimney technology for revascularization of the visceral branches of the aorta in the late postoperative period increases the risk of violations of the patency of visceral implants and development of endoleaks [79].

used for revascularization of all branches of the aortic arch [72].

reconstruction of the proximal aorta for type A dissection [74, 75].

graft to the wall of the aorta in the landing zone [73].

of strokes and 30-day mortality [76].

immediately after TEVAR for acute dissection of type B may indicate the unstable condition of the aorta [64].

In most cases, proximal intimal fenestration in distal dissection is located near the ostium of the left subclavian artery, due to the formation of reverse blood flow in the aorta in this area [58]. Thus, in 20–30% of cases, stent graft implantation requires closure of the left subclavian artery ostium [65]. Intentional overlapping of the left subclavian artery of the stent graft leads to a statistically significant increase in the risk of stroke [66] and the frequency of spinal cord ischemia [67]. In this regard, current recommendations include revascularization of the left subclavian artery (LSA) [65]. In one retrospective comparative study, there was a statistically significant increase in the number of strokes and upper limb ischemia in patients who did not undergo revascularization of LSA in comparison with patients who underwent revascularization of LSA by reimplantation of its ostium or bypass surgery [68].

In order to reduce the aggressiveness of the intervention and increase the landing zone, the endovascular technique of parallel stent grafts is used, that is, implantation of a separate stent graft into the left subclavian artery, its placement parallel to the main stent graft, and removal of its orifice beyond the proximal landing zone of the main stent graft, the so-called chimney or snorkel technique [69]. Chimney is the method of choice in patients with complex aortic arch anatomy to extend the proximal landing zone and provide perfusion of the aortic arch branches [70]. This technique can be used in patients with aberrant right subclavian artery in the case of acute type B aortic dissection [71]. In addition, this endovascular technique can be used for revascularization of all branches of the aortic arch [72].

The technique of chimneys has a number of limitations, such as entanglement and bending of branches, but the most significant of them is the aggravation of the danger of the formation of endoleaks of type I, due to the loose fit of the main stent graft to the wall of the aorta in the landing zone [73].

To solve these problems for the purpose of endo prosthesis of the aortic arch, a number of commercially available endografts with preattached branches are produced; endoprostheses have a wide size range and do not need individual manufacture. Despite the shown good results in relation to the early postoperative mortality, the number of strokes, and the frequency of repeated interventions in patients with increased surgical risk, this procedure requires detailed preliminary calculations, is difficult to perform, and is more suitable for patients with residual dissection after reconstruction of the proximal aorta for type A dissection [74, 75].

The procedure of implantation of scalloped or fenestered stent grafts is less complicated; stent-graft with a half-opening on the edge or opening for the mouths of brachiocephalic vessels well adheres to the altered aortic wall, is easier to manufacture, and is more accessible than branched stent graft. However, fenestrated stent grafts are more prone to dislocation and show the worst results for the number of strokes and 30-day mortality [76].

All of the above techniques are also successfully used for revascularization of visceral branches. In addition, they have the same advantages and disadvantages as in the application of the aortic arch, as fenestrated stent grafts and the periscope technique, are well suited for the treatment of patients with complex anatomy in the region of the visceral branches of the aorta [77]. Technology chimney and periscopes are also used for the relief of endoleaks type I after EVAR prior to increase in the proximal and distal landing zones for endografts [78] . However, according to some authors, the application of chimney technology for revascularization of the visceral branches of the aorta in the late postoperative period increases the risk of violations of the patency of visceral implants and development of endoleaks [79].

Recently, for the revascularization of the visceral and iliac arteries, the sandwich technique has become widespread, which is a later modification of the chimney or periscope technique and is used to stop extended aortic lesions. In this case, the origin of the visceral branches prostheses is opened into the lumen of another stent graft, implanted on top of the first and overlapping it in a certain area. The feature of this technique is that there is a greater risk of developing "gutter" endoleaks, aorta overlap for a much longer distance, visceral arteries requires stent graft greater length. Nevertheless, this technique gives good results both in the near and in the long term and is not accompanied by a high frequency of spinal complications [80, 81].

According to a meta-analysis of the results of repeated open interventions after TEVAR in the aortic dissection, which consisted of 2029 cases in the TEVAR 2403 cases of aortic dissection, with an average follow-up period of 34 months, the most common reasons for reintervention was endoleak type I (35.2%), redo dissection (14.4%), and perfusion of the false lumen (9.3%) [82].

In another study of 2531 patients who had TEVAR performed for acute complicated aortic dissection type B, mortality within 30 days after the intervention was noted in 7.3% of cases; in comparison with the 2347 patients treated with conservative treatment for acute uncomplicated aortic dissection type B, where the mortality rate was 2.4%. In the group of 1276 patients where open surgery was performed, the mortality rate was 19%. Patients who were performed TEVAR had more favorable results in relation to remodeling of the aorta and survival associated with lesions of the aorta than patients treated with medical therapy [83].

Given the presence of a large number of endoleaks after TEVAR, it is suggested that this technique is not quite suitable for the treatment of aortic dissection since most patients do not have a suitable anatomy [84].

However, one study showed that TEVAR is safe to perform in chronic distal aortic dissection, but there are limitations due to the complex anatomy of the dissection. Unfavorable factors are the departure of less than two vessels from the true lumen of the aorta, the large diameter of the aorta before surgery and the location of the primary rupture at a greater curvature [85].

In addition, infrequent (0.4%) but quite a formidable complication is infection of stent grafts, developing mainly in weakened patients with immunosuppression. In this case, open intervention with complete excision of the infected material and extraanatomic revascularization or revascularization in situ is required [86].

In order to avoid many of these complications, the use of a bare metal balloon expandable stent was proposed for decompression of the false aortic lumen [87–89].

The stent can be opened to the required diameter, but not more than 4.5 cm, which is one of the significant limitations. It can also be used on any part of the aorta, since the opening of the stent cells has an area of at least 1 cm2 , which allows for unhindered perfusion of the branches of the aorta in any zone. The main disadvantage of the bare metal stent is that it does not completely cover the perfusion along the false lumen, since, as a rule, when dissection, there are a large number of small gaps along the false channel. However, in conservative treatment of type B dissection, there is also a valid false channel, and patients do without surgery for years. During implantation of the stent, the main task is the stabilization of the lumen of the aorta due to the redirection of the main mass of blood in the true lumen rather than achieving a perfect angiographic effect. The principal negative points are also considered that the bare metal stent is balloon expandable and this can lead to the progression of the dissection [90].

Nevertheless, if certain techniques are followed, such as controlled hypotension and gradual slow opening of the balloon, it is possible to achieve adequate stent adherence to the aortic wall even at the level of the aortic arch and brachiocephalic

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**3. Conclusion**

were widely introduced (5%) [100].

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complications [94].

branches. The high degree of replication of the technique and the absence and versatility of bare metal stents are undeniable advantages. The combination of stenting with implantation of stent graft also gives good results in the implantation of the stent in the area of origin of the artery of Adamkewicz Th8-L1, as well as visceral and brachiocephalic branches. As a monomethod, the implantation of a bare metal

There is another more common technique of false lumen decompression, which is an endovascular balloon fenestration of the false lumen of the aorta in the distal region and a stent implantation in visceral branches. This technique improves patient outcomes in the long term, especially in relation to be aortospecifically

As hybrid interventions for aortic dissection, two methods are described in the literature; one of them is the implantation of combined prostheses where a vascular prosthesis with preprepared one or several branches for implantation of brachiocephalic arteries is made together with a stent graft, which is implanted in the upper and middle portion of the descending aorta. This method is called "frozen elephant trunk" by analogy with the two-stage operation proposed by Borst in 1982. The technique is used in patients with proximal dissection passing to the descending

Another hybrid technique is debranching or a technique of open switching the branches of the aorta with subsequent implantation of a stent graft. This technique is widely used to increase the landing zone for stent graft, both in the area of the aortic arch and visceral branches [96, 97]. The advantages are less intraoperative trauma and no need for circulatory arrest, brain perfusion, and spinal cord protection. The disadvantages include the availability of open access and the interval between stages, which are not always acceptable with urgent intervention about the progression of distal dissection. In addition, a large number of complications at the stage of vascular switching accompany the technique of visceral debranching [98]. In the literature, for some reason, little attention is paid to the description of methods of prosthetics of the descending thoracic aorta and simultaneous implantation of bare metal stents in the visceral zone or on the contrary in the region of large spinal branches, in particular the Adamkewicz artery, under video or X-ray control with extensive distal aortic dissection. This technique significantly reduces operating access, limiting it to a thoracotomy, thus allowing for simultaneous intervention, for example, revascularization of the myocardium provides a good quality of anastomosis of the aorta, and significantly it reduces the time of circulatory arrest and at the same time provides good permeability of all visceral branches [99]. According to the 17-year follow-up of the International Registry of Acute Aortic Dissection (IRAD), most patients are treated conservatively; however, in recent years, the frequency of this treatment has decreased from 75 to 57%. The number of endovascular interventions performed has increased from 7 to 31%, the frequency of open surgical operations has decreased from 17 to 8%, and hybrid techniques

Thus, it can be stated that transcatheter methods of treatment are first-line methods with complicated distal aortic dissection and suitable for this anatomy of the dissection. In case of impossibility of performance, transcatheter intervention should consider the implementation of an open or hybrid repair. Conservative management of patients is preferable in uncomplicated distal dissection. Improving knowledge in the field of brain and spinal cord physiology, as well as transcatheter

stent gives good results in posttraumatic aortic dissection [91–93].

thoracic aorta in order to reduce Borst procedure to one stage [95].

#### *Methods of Reconstruction for Distal Aortic Dissection DOI: http://dx.doi.org/10.5772/intechopen.93339*

branches. The high degree of replication of the technique and the absence and versatility of bare metal stents are undeniable advantages. The combination of stenting with implantation of stent graft also gives good results in the implantation of the stent in the area of origin of the artery of Adamkewicz Th8-L1, as well as visceral and brachiocephalic branches. As a monomethod, the implantation of a bare metal stent gives good results in posttraumatic aortic dissection [91–93].

There is another more common technique of false lumen decompression, which is an endovascular balloon fenestration of the false lumen of the aorta in the distal region and a stent implantation in visceral branches. This technique improves patient outcomes in the long term, especially in relation to be aortospecifically complications [94].

As hybrid interventions for aortic dissection, two methods are described in the literature; one of them is the implantation of combined prostheses where a vascular prosthesis with preprepared one or several branches for implantation of brachiocephalic arteries is made together with a stent graft, which is implanted in the upper and middle portion of the descending aorta. This method is called "frozen elephant trunk" by analogy with the two-stage operation proposed by Borst in 1982. The technique is used in patients with proximal dissection passing to the descending thoracic aorta in order to reduce Borst procedure to one stage [95].

Another hybrid technique is debranching or a technique of open switching the branches of the aorta with subsequent implantation of a stent graft. This technique is widely used to increase the landing zone for stent graft, both in the area of the aortic arch and visceral branches [96, 97]. The advantages are less intraoperative trauma and no need for circulatory arrest, brain perfusion, and spinal cord protection. The disadvantages include the availability of open access and the interval between stages, which are not always acceptable with urgent intervention about the progression of distal dissection. In addition, a large number of complications at the stage of vascular switching accompany the technique of visceral debranching [98].

In the literature, for some reason, little attention is paid to the description of methods of prosthetics of the descending thoracic aorta and simultaneous implantation of bare metal stents in the visceral zone or on the contrary in the region of large spinal branches, in particular the Adamkewicz artery, under video or X-ray control with extensive distal aortic dissection. This technique significantly reduces operating access, limiting it to a thoracotomy, thus allowing for simultaneous intervention, for example, revascularization of the myocardium provides a good quality of anastomosis of the aorta, and significantly it reduces the time of circulatory arrest and at the same time provides good permeability of all visceral branches [99].

According to the 17-year follow-up of the International Registry of Acute Aortic Dissection (IRAD), most patients are treated conservatively; however, in recent years, the frequency of this treatment has decreased from 75 to 57%. The number of endovascular interventions performed has increased from 7 to 31%, the frequency of open surgical operations has decreased from 17 to 8%, and hybrid techniques were widely introduced (5%) [100].
