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Hybrid Repair of Aortic Arch Aneurysms: Combined Open Arch Reconstruction and Endovascular Repair
Hybrid Repair of Aortic Arch Aneurysms: Combined Open Arch Reconstruction and Endovascular Repair Wilson Y. Szeto, MD,* and Joseph E. Bavaria, MD† Surgical management of aortic arch aneurysms remains a clinical challenge associated with significant perioperative morbidity and mortality. For the increasingly aging population with significant comorbidities, innovative hybrid aortic arch reconstructive techniques using thoracic endograft technology have been developed in an attempt to improve surgical outcome. With these hybrid arch reconstructive techniques, surgeons have extended the indications and provided an alternative surgical option to patients previously considered prohibitively high risk for conventional open repair of aortic arch aneurysms. Multiple techniques have been described in the literature. In this section, we will present: (1) the current results of hybrid aortic arch repair and (2) a new classification based on the anatomic extent of the aneurysm and the suitability of the landing zones. Semin Thorac Cardiovasc Surg 21:347-354 © 2009 Elsevier Inc. All rights reserved. KEYWORDS aneurysms, arch, endovascular
T
he management of thoracic aortic aneurysms involving the aortic arch remains a clinical challenge. Despite recent advances in surgical technique, conventional open repair of aortic arch aneurysms is still associated with significant perioperative morbidity and mortality.1-4 Neurologic adverse events remain the major significant complication contributing to mortality. Particularly in the atherosclerotic arch aneurysms, the risk of stroke may reach as high as 12%, with mortality rates of up to 20%.5-11 Strategies, including hypothermic circulatory arrest (HCA) with adjunct antegrade cerebral perfusion have been developed to minimize neurologic adverse events and improve clinical outcome. In selected patients with prohibitively significant comorbidities and not ideal for surgical intervention, surgeons have developed innovative hybrid procedures in an attempt to reduce the perioperative morbidity and mortality associated with open arch reconstruction. The goal of these hybrid procedures is to extend the indication and provide an alternative surgical option to patients previously felt to be prohibitively *Division of Cardiovascular Surgery, Department of Surgery, University of Pennsylvania Medical Center, Hospital of University of Pennsylvania, Penn Presbyterian Medical Center, Philadelphia, Pennsylvania. †Division of Cardiovascular Surgery, University of Pennsylvania Medical Center, Hospital of University of Pennsylvania, Philadelphia, Pennsylvania. Address reprint requests to Wilson Y. Szeto, MD, University of Pennsylvania Medical Center, Penn Presbyterian Medical Center, Philadelphia Heart Institute Suite 2A, 51 North 39th Street, Philadelphia, PA 19104. E-mail: [email protected]
1043-0679/09/$-see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1053/j.semtcvs.2009.11.007
high risk for conventional repair. The hybrid arch repair has 2 components: (1) an open conventional aortic arch reconstruction, and (2) a thoracic endovascular aortic repair (TEVAR). The conventional repair involves the proximal reconstruction of the ascending aorta and aortic arch. Completion of the hybrid arch repair is then accomplished with either concomitant or second-stage thoracic endovascular repair. In contrast to the conventional open total arch repair, these hybrid procedures have the potential advantage of avoiding or minimizing the length of HCA and possibly cardiopulmonary bypass (CPB). The hybrid arch repair has been reported in small series with encouraging results.12-16 Since these early reports, hybrid arch repair has evolved from simple debranching of the arch vessels to complex aortic arch reconstruction. In the following section, we present a review of the current techniques and results of hybrid aortic arch repair centered on a new classification of these procedures.17
Background and Rationale for Hybrid Repair of Aortic Arch Aneurysms The rationale for the development of the hybrid arch repair is based on 2 goals: (1) to reduce the perioperative morbidity and mortality associated with aortic arch reconstruction, and (2) to provide an alternative surgical option for patients with aortic arch aneurysms previously believed to be prohibitively 347
348 high risks for conventional open arch repair. By simplifying the proximal aortic reconstruction and substituting the distal repair component with a minimally invasive technique (ie, TEVAR), early investigators hope to develop an operative strategy with decreased perioperative morbidity and mortality. Nonetheless, hybrid arch repair of aortic arch aneurysms is complex and depends largely on the extent of the aneurysms. Aortic arch aneurysms may involve the ascending aorta and proximal transverse arch, transverse arch only, or distal transverse arch and proximal descending thoracic aorta. In cases of mega aorta syndrome, extensive thoracic aortic aneurysms with involvement of the entire ascending, arch and descending thoracic aorta have proven to be the most challenging clinical scenario.
Ascending and Transverse Arch Aneurysms When Griepp et al originally reported the use of HCA for transverse arch repair, the incidence of mortality and stroke reached as high as 25%.18 With advances in cerebral circulatory management, including retrograde and antegrade cerebral perfusion, arch-first technique, and intraoperative neuromonitoring, contemporary series have demonstrated significant improvement in perioperative morbidity and mortality. Sundt et al recently reported a longitudinal series of 95 open arch replacements with an overall mortality of 16.8% and a stroke rate of 9.5%.1 In subgroup analysis of their more recent experience after implementation of antegrade cerebral perfusion with axillary cannulation, they observed a dramatic reduction in mortality (6%) and stroke rate (6%). In a contemporary Japanese series of 472 patients undergoing arch reconstruction using antegrade cerebral perfusion with moderate hypothermia, Kazui et al reported a perioperative stroke risk of 3.2% and mortality of 9.3%.3 Although contemporary large series have demonstrated significant improvement in open aortic arch reconstruction, careful review of the data suggests that in selected subpopulations of patients, conventional operative techniques remain associated with significant morbidity and mortality. For the frail elderly individuals or patients with large atherosclerotic burden in the arch, total arch reconstruction has been associated with in-hospital mortality of up to 20% and incidence of stroke of up to 12%.5-11 Furthermore, patients with significant comorbidities, including history of previous stroke, diabetes, chronic renal insufficiency, and chronic obstructive pulmonary disease often are considered prohibitively high risk and denied conventional open arch reconstruction.
Ascending, Arch, Descending Thoracic Aorta Aneurysms (Mega Aorta Syndrome) Conventional repair of extensive thoracic aortic aneurysms involving the ascending, transverse arch, and descending thoracic aorta remains a clinical challenge associated with significant perioperative morbidity and mortality. The 2 current conventional surgical approaches are (1) single-stage repair and (2) 2-stage repair with proximal aortic arch reconstruction using the elephant trunk technique via a median
W.Y. Szeto and J.E. Bavaria sternotomy, followed by distal aortic reconstruction via a left thoracoabdominal incision. Single-Stage Repair The single-stage repair is an extensive operative technique and involves reconstruction of the ascending, transverse arch, and descending thoracic aortic aneurysms via a bilateral thoracotomy incision (clamshell incision) or a thoracosternotomy incision.19-23 In a series of 69 patients at a mean age of 61 years, Kouchoukos et al recently reported their experience of single-stage reconstruction via the bilateral thoracotomy approach.19 They reported a perioperative mortality of 7.2% with no incidence of stroke. Other smaller series have also reported similar mortality rates ranging from 6% to 14.7% with an incidence of stroke in the range 7.6%-20%.20-23 In these relatively small studies, the mean age of the patients ranged from 34.5 to 68 years. The limited number as well as the relatively young age of the patients in these series reflect the likely bias in the selection of these patients for this surgical approach. The single-stage repair is an extensive operative approach, and elderly patients with significant comorbidities are likely not candidates for this extensive surgical approach. Two-Stage Repair With Elephant Trunk The 2-stage approach involves a first-stage proximal reconstruction of the ascending aorta and aortic arch using the elephant trunk technique via a median sternotomy, followed by a second-stage distal thoracoabdominal aortic reconstruction via left thoracotomy. Similar to the single-stage strategy, it is an extensive surgical procedure, and appropriate patient selection is essential in achieving optimal outcome. Patients with significant comorbidities may not be candidates for this extensive reconstructive approach due to the requirement for 2 major operative procedures within a relatively short interval. In appropriately selected patients, results from centers of excellence have demonstrated acceptable outcome, with first-stage mortality ranging from 2.1% to 12% and secondstage mortality ranging from 4% to 9.6%.24-28 However, careful examination of data demonstrates that improvement for this approach continues to be much desired. In these series, interval mortality between first- and second-stage (ie, waiting for the second operation) ranged from 12% to 25%. Furthermore, in patients who have undergone the first-stage repair, only 44%-68% of them eventually proceeded to the secondstage repair. In essence, most patients who have undergone the first-stage proximal reconstruction simply did not return for their second-stage repair. With the 2-stage approach, completion of treatment is a major concern that ultimately affects clinical outcome and long-term survival.
Classification of Hybrid Arch Aneurysm Repair Since the introduction of TEVAR, hybrid approaches have been developed to achieve adequate proximal landing zones for endovascular treatment of descending thoracic aorta. Challenges and concerns regarding the proximal landing zone have resulted in the development of a classification of
Hybrid repair of aortic arch aneurysms
Figure 1 Landing zone classification for thoracic endovascular aortic repair. Landing zone 0 involves the ascending aorta proximal to the innominate artery. Zone 1 involves the aortic arch between the innominate and left common carotid artery. Zone 2 involves the aortic arch between the left common carotid artery and the left subclavian artery. Zone 3 involves the proximal descending thoracic aorta distal to the left subclavian artery. Zone 4 involves the mid descending thoracic aorta. (Color version of figure is available online at http://www.semthorcardiovascsurg.com.)
the proximal landing zones29 (Fig. 1). The earliest hybrid procedure for thoracic aortic aneurysms was performed in the endovascular treatment of proximal descending thoracic aortic aneurysms. In aneurysms requiring landing zone 2 (endograft deployment between the left common carotid artery and the left subclavian artery), a hybrid procedure involving a first-stage left carotid to left subclavian artery bypass or transposition is performed, followed by either a staged or concomitant TEVAR of the descending thoracic aorta. Thoracic aortic aneurysms involving the arch are essentially aneurysms requiring a proximal deployment of the endograft in the ascending aorta, or landing zone 0. With this approach, the arch branch vessels must be reconstructed to avoid neurologic adverse events and achieve clinical success. After arch vessel reconstruction, deployment of the endograft in the aortic arch is then performed to achieve aneurysmal exclusion. Multiple operative techniques have been described in the literature. We have proposed a classification of hybrid arch repair based on the anatomy of the aneurysm and the suitability of the proximal and distal landing zones (Fig. 2).17
Type I: Brachiocephalic Bypass and Endovascular Repair of the Aortic Arch Type I hybrid repair consists of brachiocephalic bypass with endovascular repair of the aortic arch, called as the “arch debranching” procedure.12-16,30,31 In contrast to the conventional open repair, type I hybrid repair of arch aneurysms has
349 the benefit of eliminating hypothermic circulatory arrest and potentially CPB, thus minimizing the risk of neurologic complications. Reserved for patients with isolated aortic arch aneurysms, these patients have satisfactory proximal landing zones in the ascending aorta and distal landing zones in the descending thoracic aorta for endovascular aortic repair. Bypass of the 3 arch vessels is performed for cerebral revascularization, followed by endograft deployment in the aortic arch (Fig. 2). In some patients with large arch aneurysms, left subclavian artery exposure may be difficult. Instead of attempting a difficult exposure via anterior approach from the median sternotomy, some investigators perform a left subclavian to left carotid artery bypass via a counter left supraclavicular incision. Other investigators will elect not to revascularize the left subclavian artery and simply bypass the innominate and left common carotid artery. When performing the proximal anastomosis of the brachiocephalic bypass to the ascending aorta, care must be taken to ensure adequate proximal landing zone of at least 2 cm in the ascending aorta to accommodate endograft deployment. If the ascending aorta is short and proximal anastomosis deep at the level of the sinotubular junction is required to create a 2-cm proximal landing zone, CPB with aortic occlusion may be necessary. If the ascending aorta is of adequate length, a side-biting clamp can be used, thus avoiding CPB. After revascularization (“debranching”) of the great vessels is accomplished, exclusion of the arch aneurysm is achieved with endovascular repair. The deployment of the endografts can be performed antegrade via the ascending aorta (usually through a separate conduit) in a concomitant approach. Endograft deployment can also be performed via a retrograde approach using the iliofemoral vasculature, either in a concomitant or staged approach. The antegrade approach has the benefit of eliminating potential iliofemoral vascular access complications. Furthermore, antegrade deployment ensures adequate length of the delivery system to reach the intended landing zones. Current thoracic endograft delivery systems are often not long enough to reach the ascending aorta in taller individuals with the retrograde approach. Antegrade deployment also allows for maximum precision in deployment as there is less transmitted torque through a shorter delivery system. Finally, the endograft may be manually manipulated via the open-chest to accommodate the curvature of the aortic arch.
Type II: Aortic Arch Reconstruction With the “Stented” Elephant Trunk Type II hybrid arch repair is the “stented” elephant trunk repair, and this technique is reserved for patients with ascending aortic aneurysms with limited extension into the distal arch. In contrast to the conventional open repair, exposure of the descending thoracic aorta in the left thorax to construct the distal anastomosis is avoided, thus reducing the length of HCA and perioperative morbidity and mortality. The ascending aorta is aneurysmal, and reconstruction of the ascending aorta (zone 0) is required to provide an adequate
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Figure 2 Classification of hybrid aortic arch repair based on aneurysm anatomy and landing zone suitability. Classification of hybrid aortic arch repairs is based on the extent of the aneurysm and the suitability of the proximal and distal landing zones. Type I hybrid arch repair (arch debranching) is suitable for an isolated arch aneurysm with satisfactory proximal and distal landing zones. Type II hybrid arch repair (“stented” elephant trunk) is suitable for a proximal ascending aortic aneurysm with extension into distal arch. Repair requires conventional proximal aortic reconstruction combined with endovascular repair of the distal arch and descending thoracic aorta. Type III hybrid arch repair (proximal aortic repair with completion endovascular repair of the thoracoabdominal aorta) is suitable for aneurysms of the ascending, transverse arch, and descending thoracic aorta. The proximal landing zone is aneurysmal and requires conventional open reconstruction. Aneursymal exclusion of the descending thoracic aorta to the level of the celiac artery is often required during the completion endovascular repair of the thoracoabdominal aorta. (Color version of figure is available online at http://www.semthorcardiovascsurg.com.)
proximal landing zone for endograft deployment. The distal landing zone at the level of the descending thoracic aorta is not aneurysmal, and therefore can provide a satisfactory distal landing zone for endograft deployment. During hypothermic circulatory arrest, the endograft is deployed antegrade via the open arch into the descending thoracic aorta. Hence, this technique has been commonly referred to as the “frozen” stented elephant trunk technique.32-38 Following endograft deployment, proximal reconstruction of the ascending aorta and aortic arch is performed using a Dacron graft with multiple branches for great vessel reconstruction. If minimizing the duration of HCA is preferred, the endograft can be deployed after arch reconstruction is completed and HCA is terminated. Then, the “stented” elephant trunk is deployed antegrade via the newly reconstructed ascending aorta via a fourth limb (Fig. 2). The endograft can also be deployed in a retrograde fashion via the iliofemoral vasculature (in a concomitant or staged approach). The benefits and disadvantages of the antegrade and retrograde approaches are similar to the type I repair.
Type III: The Elephant Trunk Repair With Completion Endovascular Repair of the Thoracoabdominal Aorta Type III repair is a 2-stage strategy consisting of a first-stage proximal reconstruction using either a conventional open arch elephant trunk technique or the “stented” elephant trunk technique (type II repair). A second-stage completion endovascular repair of the descending thoracic aorta using either the conventional or the “stented” elephant trunk as its proximal landing zone is performed (Fig. 2). This technique is reserved for patients with extensive thoracic aortic aneurysms with involvement of the ascending, transverse arch, and descending thoracic aorta, or the so-called mega aorta syndrome.39-43 In contrast to type I and II repairs, both the proximal landing zones in the ascending aorta as well as the distal landing zones in the descending thoracic aorta are aneurysmal and unsatisfactory for endovascular repair in type III repairs. Adequate proximal landing zone 0 can be reconstructed similar to type II repairs. However, distal aneurysmal extension into the descending thoracic aorta requires
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Table 1 Outcome of Hybrid Aortic Arch Repair n
Permanent Stroke
Paraplegia
In Hospital Mortality
Type I: Brachiocephalic bypass and endovascular repair of aortic arch Gottardi et al44 Hughes et al30 Szeto et al12 Saleh and Inglese14 Bergeron et al31
13 7 8 15 15
0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%)
— — — — —
3 (23.1%) 0 (0%) 1 (12.5%) 0 (0%) 1 (6.7%)
Type II: Aortic arch reconstruction with stented elephant trunk Shimamura et Baraki et al34 Liu et al37 Uchida et al38 Flores et al35
al45
126 39 60 35 25
7 (5.6%) 3 (7.7%) 2 (3.3%) 0 (0%) 4 (16%)
3 (2.3%) 0 (0%) 1 (1.6%) 0 (0%) 6 (24%)
4 (3.2%) 5 (12.8%) 2 (3.3%) 2 (5.7%) 3 (12%)
Type III: Elephant trunk with completion TEVAR al39
Kawaharada et Greenberg et al40 Brat, Docekal, and Jursa41 Matsuda et al42 Carroccio et al43
31 22 3 4 12
1 (3.2%) 0 (0%) 0 (0%) 0 (0%) —
0 (0%) 0 (0%) 0 (0%) 0 (0%) —
2 (6.4%) 1 (4.5%) 0 (0%) 0 (0%) 1 (8.3%)
TEVAR, Thoracic endovascular aortic repair.
endograft exclusion of the entire descending thoracic aorta. A completion endovascular repair with endograft deployment at the level of the celiac artery is often required. Although possible, antegrade deployment of multiple endografts distally to the level of the celiac artery via the ascending aorta may be technically challenging. Given the extensive involvement of the descending thoracic aorta and the requirement for multiple endografts, a 2-stage retrograde approach from the iliofemoral vasculature may be more feasible and advantageous. The benefit of the type III hybrid arch repair is substantial. In contrast to the conventional open single-stage repair, performance of the distal anastomosis via a morbid incision (ie, the bilateral thoracotomy or thoracosternotomy) is avoided. In contrast to the conventional open 2-stage approach, the second stage (ie, thoracic endovascular repair) of the hybrid repair is minimally invasive, and therefore the interval to second stage may be significantly shortened. For most patients, the second endovascular completion stage can be performed within a relatively short period, perhaps even the same index hospitalization. In essence, the type III hybrid repair offers these patients a less morbid second stage, and potentially a shorter interval to second-stage completion reconstruction. These factors likely will result into a higher percentage of patients undergoing the second-stage repair, resulting in better outcome and possibly long-term survival.
Results of Hybrid Arch Aneurysm Repair Type I: Brachiocephalic Bypass and Endovascular Repair of the Aortic Arch At the University of Pennsylvania, we reported our initial experience with type I repairs in 8 patients who were not
candidates for conventional open arch reconstruction secondary to prohibitively significant comorbidities. All 8 patients had atherosclerotic arch aneurysms with a mean diameter of 8 cm. Technical success with complete aneurysmal exclusion was achieved in all patients. In-hospital mortality was 12.5% (1/8 patients). Transient neurologic event occurred in 2 patients with both patients having full recovery and no residual deficit at the time of discharge. At the time of publication with a follow-up of 11.7 months, there was no incidence of endoleak.12 Gottardi et al recently reported their experience with the hybrid arch repair in patients with aortic arch pathology. From 1996 to 2007, 73 patients with aortic arch pathology were treated with hybrid arch repairs. Of these 73 patients, 13 underwent total aortic arch debranching, or type I repair, for atherosclerotic aneurysms (n ⫽ 9) and penetrating ulcers (n ⫽ 4). In-hospital mortality occurred in 3 patients.44 Other series have reported similar incidence of perioperative stroke and mortality (Table 1). The incidence of mortality in this exceptionally high-risk group of patients has been acceptable, ranging from 0% to 23.1%. Interestingly, the risk of permanent stroke has been low; however, one must be cautioned that the incidence of transient neurologic events has been reported to be as high as 25%. In this population of patients deemed to be prohibitively high risk for conventional arch reconstruction, these results are considered acceptable when compared with the incidence of stroke (up to 8%) and in-hospital mortality (up to 10%) in contemporary series of open arch reconstruction.1-4 However, the number of patients in these series is relatively small and larger studies with longer follow-up will be needed before definitive conclusions can be made.
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Type II: Aortic Arch Reconstruction With the “Stented” Elephant Trunk The largest series of the “stented” elephant trunk technique was recently reported by Shimamura et al in 2008.45 From 1994 to 2004, 126 patients with aortic arch pathology and extension into the distal arch were treated with the “frozen” stented elephant trunk technique followed by proximal arch reconstruction. Of the 126 patients, 69 patients were atherosclerotic aneurysms. Operative mortality at 30 days was 3.2%. Perioperative neurologic complications included stroke (5.6%) and spinal cord ischemia (6.3%). Five (3.9%) late endoleaks were observed during a mean follow-up period of 60.4 months. Survival was 81.1%, 63.3%, and 53.7% at 1, 5, and 8 years. Baraki et al reported their experience with 39 patients undergoing the “frozen” stented elephant trunk technique. Neurologic adverse events occurred in 5 patients, but complete resolution with no residual deficit occurred in 2 patients. In-hospital mortality was 12.8% (5/39 patients).34 Flores et al recently identified predictors of spinal cord ischemia and paraplegia in patients undergoing the “frozen” stented elephant trunk technique.35 In his series of 25 patients, paraplegia occurred in 24% (6/25 patients). The combination of a distal landing zone of T7 or greater and a history of abdominal aortic aneurysm repair was the strongest predictor of spinal cord injury. Other series have reported similar incidence of stroke (0%-16%), spinal cord ischemia (0%-24%), and 30-day mortality (3.2%-12.8%) (Table 1). Although these are relatively small series, the results of type II repairs seem acceptable when compared with the results of first-stage repair of the conventional elephant trunk procedure. For patients with arch aneurysms extending into the distal arch and proximal descending thoracic aorta, type II repairs with the “stented” elephant trunk technique seems to be an acceptable alternative to conventional open repair.
Type III: The Elephant Trunk Repair With Completion Endovascular Repair of the Thoracoabdominal Aorta In a series of 31 patients, Kawaharada et al reported their hybrid treatment of aortic arch and descending thoracic aortic aneurysms comprising a conventional first-stage proximal reconstruction with the elephant trunk technique followed by completion endovascular repair of the distal thoracoabdominal aorta.39 The interval between the first and second stage ranged from 0 to 14 months with a mean interval of 3.1 months. Technical success was achieved in all patients, with 100% of patients completing the second stage. For the first stage, there was no death and 1 patient suffered from a temporary stroke. For the second stage, the in-hospital mortality was 6.4% (2/31 patients). There was no stroke, and no paraplegia observed. On follow-up, the 2- and 5-year survival was 83.5% and 73.3%, respectively. Caudal migration of the endograft occurred in 3 patients, requiring open conversion for treatment of endoleak for all 3 patients.39 Greenberg et al reported the Cleveland Clinic experience in 22 patients with extensive thoracic aortic aneurysms involving the ascending aorta, arch, and descending thoracic
W.Y. Szeto and J.E. Bavaria aorta.40 Conventional elephant trunk procedure with proximal reconstruction was performed with interval completion endovascular repair of the thoracoabdominal aorta. The interval between the first and second stages ranged from 3 days to 102 months (mean, 17.8 months). However, the mean interval was reduced to 7 months if the first stage was performed at the same institution. Technical success was achieved in all patients. There was no incidence of stroke or paraplegia, with 3 cases of transient paraparesis. Thirty-day mortality was 4.5% with 1- and 2-year survival at 84.2% and 84.2%, respectively. Other smaller series have demonstrated similar results, with acceptable first- and second-stage mortality (Table 1). Furthermore, the data suggest that type III hybrid arch repairs decrease the interval duration between first- and second-stage reconstruction and consequently result in a higher percentage of patients proceeding to secondstage repair and completing their treatment.
Comparison of Hybrid Arch Repair With Conventional Open Arch Repair Despite preliminary data suggesting early success with hybrid aortic arch repair in high-risk patients, questions and concerns remain regarding its benefits when compared with conventional open techniques. With the lack of large series and long-term results, many investigators have reservations regarding the hybrid repair and have cautioned against overly enthusiastic embrace without more definitive data. To date, there has been no randomized study comparing hybrid repair versus conventional open repair, and unlikely to be one in the future. However, data from retrospective series discussed earlier as well as a few retrospective comparative studies do suggest that hybrid aortic arch repair is a valid and an acceptable option, particularly in the high-risk population of patients. Kim et al recently reported their experience with the management of extensive aneurysms of the ascending, arch, and descending thoracic aorta (mega aorta syndrome).46 From 1992 to 2007, 103 patients underwent operative repair of extensive thoracic aortic aneurysms in a single institution. The operative strategies were (1) conventional single-stage repair (n ⫽ 29), (2) 2-stage repair with conventional elephant trunk and completion open repair of the thoracoabdominal aorta (open, n ⫽ 50), and (3) hybrid 2-stage repair with conventional elephant trunk and completion endovascular repair, or the type III hybrid arch repair (hybrid, n ⫽ 24). Between the 3 groups, there was no difference in the incidence of stroke, paraplegia, and the overall mortality (mortality: 24% single-stage, 14% open, 17% hybrid). Examining the 2 approaches of the 2-stage repairs, there was no difference between the open and the hybrid group in both the first-stage mortality (10% open versus 8% hybrid) and the second-stage mortality (10% open versus 11% hybrid). But in striking contrast with the open group, 7 of 18 patients in the hybrid group underwent the completion endovascular repair of the thoracoabdominal aorta during the index hospitalization, with a shorter second-stage hospital stay (5.5 days versus 16.5 days, P ⬍ 0.01), fewer transfusions (P ⬍
Hybrid repair of aortic arch aneurysms 0.01), and lower incidence of acute renal injury (P ⫽ 0.04). Similar to other series, a significant number of patients in the conventional 2-stage open approach did not proceed to the second-stage, with a completion rate of only 47% (20 of 43 patients). The reasons for completion failure included lost to follow-up (n ⫽ 17, 34%), first-stage mortality (n ⫽ 4, 8%), interval mortality (n ⫽ 1, 2%), and deemed unfit or too high risk for second-stage (n ⫽ 1, 2%). For this closely monitored group of patients, it remains unclear and the information is not provided as to why lost to follow-up is the primary reason for completion failure in as many as 17 of 23 patients. In a striking contrast in the hybrid group, the second-stage completion rate was 78% (18 of 23 patients). The reasons for completion failure were lost to follow-up (n ⫽ 1, 4.2%), first-stage mortality (n ⫽ 2, 8.3%), and interval mortality (n ⫽ 2, 8.3%). Although the conventional open single-stage procedure has a completion rate of 100%, many critics of this approach have stated that the single-stage approach is simply too extensive of an operation, and likely not suitable for high-risk patients. In this study, the data certainly suggest and supports this concern. When examined together, the incidence of operative mortality, paraplegia, stroke, or acute kidney injury was significantly higher in the single-stage group at 62% (single-stage), compared with 38% (open), and 29% (hybrid) (P ⫽ 0.04) in the other 2 groups. Based on their experience, the type III hybrid arch repair has become this institution’s preferred operative technique for patients with mega aorta syndrome. At the University of Pennsylvania, we recently reviewed our experience with operative repair of aortic arch aneurysms.47 From 2000 to 2009, a total of 1196 open arch procedures were performed, with 45 elective open total arch reconstruction at a single institution. From 2005 to 2009 in the same institution, 64 hybrid arch repairs were performed, with 27 patients undergoing elective hybrid total arch reconstruction for aneurysmal disease. The hybrid arch repairs were reserved for patients considered prohibitively high risk for conventional repair and included 17 type I repairs, 2 type II repairs, and 8 type III repairs. Preoperative demographics demonstrated a significantly older population in the hybrid group when compared with the open group (71.3 years versus 62.8 years, P ⫽ 0.008) as well as a significantly higher incidence of atherosclerotic aneurysms in the hybrid group (96% versus 58%, P ⬍ 0.001). Although not a statistical difference, there was a trend favoring the outcome in the hybrid group when compared with the open group for inhospital mortality (11% versus 16%), stroke (4% versus 9%), permanent paraplegia (7% versus 0%), and renal failure requiring hemodialysis (11% versus 7%). Furthermore, in patients older than 75 years, a major reduction in mortality was observed in the hybrid group when compared with the open group (8% versus 36%, P ⬍ 0.05). These 2 single-institutional retrospective studies suggest that for older patients with extensive thoracic aortic aneurysms involving the ascending, arch, and descending thoracic aorta, hybrid aortic arch repair may be the preferred operative approach.
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Future Direction Despite encouraging results, the current hybrid reconstructive techniques for arch aneurysms still require surgical incisions, CPB, and HCA with the associated potential morbidity. Current hybrid aortic arch repair may well be a bridging strategy until the development of a total endovascular platform for arch reconstruction is refined and achieves widespread clinical applicability. To date, 2 different conceptual strategies have been reported in the total endovascular treatment of aortic arch aneurysms. Reported by Inoue et al, a unimodular custom-designed multibranch stent graft has been successfully implanted in 17 patients, with no perioperative mortality or stroke.48 Chuter et al have reported a modular design involving supra-aortic arch debranching.49 After a carotid– carotid bypass, deployment of an ascending aortic graft with an innominate artery branch is performed retrograde from the right carotid artery. Arch exclusion is completed with a thoracic endograft distal to the innominate branch.
Conclusion The hybrid arch repair for aortic arch aneurysms continues to evolve with improvement in perioperative morbidity and mortality. The data suggest that hybrid arch repairs are safe and effective, with the highest benefit for high-risk patients, particularly in those with extensive thoracic aortic aneurysms (mega aorta syndrome). However, the data remain limited and we must be cautious in our enthusiastic embrace of this new technology. The results of hybrid arch repairs must be measured against the results of proven conventional open surgical techniques. Larger series of hybrid arch repairs with longer follow-up must be examined before we should extend the applications of these techniques to patients with lower risk.
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cold blood: A 13-year experience. Ann Thorac Surg 67:1874-1878, 1999; discussion 1891-1894 Kazui T, Washiyama N, Muhammad BA, et al: Total arch replacement using aortic arch branched grafts with the aid of antegrade selective cerebral perfusion. Ann Thorac Surg 70:3-8, 2000; discussion 8-9 Borst HG, Buhner B, Jurmann M: Tactics and techniques of aortic arch replacement. J Cardiovasc Surg 9:538-547, 1994 Coselli JS, Buket S, Djukanovic B: Aortic arch operation: Current treatment and results. Ann Thorac Surg 59:19-26, 1995; discussion 26-27 Szeto WY, Bavaria JE, Bowen FW, et al: The hybrid total arch repair: Brachiocephalic bypass and concomitant endovascular aortic arch stent graft placement. J Cardiovasc Surg 22:97-102, 2007; discussion 103104 Melissano G, Civilini E, Bertoglio L, et al: Endovascular treatment of aortic arch aneurysms. Eur J Vasc Endovasc Surg 29:131-138, 2005 Saleh HM, Inglese L: Combined surgical and endovascular treatment of aortic arch aneurysms. J Vasc Surg 44:460-466, 2006 Gottardi R, Seitelberger R, Zimpfer D, et al: An alternative approach in treating an aortic arch aneurysm with an anatomic variant by supraaortic reconstruction and stent-graft placement. J Vasc Surg 42:357-360, 2005 Schumacher H, Bockler D, Bardenheuer H, et al: Endovascular aortic arch reconstruction with supra-aortic transposition for symptomatic contained rupture and dissection: Early experience in 8 high-risk patients. J Endovasc Ther 10:1066-1074, 2003 Desai ND, Szeto WY: Complex aortic arch aneurysm and dissections: Hybrid techniques for surgical and endovascular therapy. Curr Opin Cardiol (in press) Griepp RB, Stinson EB, Hollingsworth JF, et al: Prosthetic replacement of the aortic arch. J Thorac Cardiovasc Surg 70:1051-1063, 1975 Kouchoukos NT, Mauney MC, Masetti P, et al: Optimization of aortic arch replacement with a one-stage approach. Ann Thorac Surg 83: S811-S814, 2007; discussion S824-S831 Hu XP, Chang Q, Zhu JM, et al: One-stage total or subtotal aortic replacement. Ann Thorac Surg 82:542-546, 2006 Beaver TM, Martin TD: Single-stage transmediastinal replacement of the ascending arch, and descending thoracic aorta. Ann Thorac Surg 72:1232-1238, 2001 Doss M, Woehleke T, Wood JP, et al: The clamshell approach for the treatment of extensive thoracic aortic disease. J Thorac Cardiovasc Surg 126:814-817, 2003 Massimo CG, Perna AM, Cruz Quadron EA, et al: Extended and total simultaneous aortic replacement: Latest technical modifications and improved results with thirty-four patients. J Cardiovasc Surg 12:261269, 1997 Safi HJ, Miller CC 3rd, Estrera AL, et al: Optimization of aortic arch replacement: Two-stage approach. Ann Thorac Surg 83:S815-S818, 2007; discussion S824-S831 Svensson LG, Kim KH, Blackstone EH, et al: Elephant trunk procedure: Newer indications and uses. Ann Thorac Surg 78:109-116, 2004; discussion 109-116 Etz CD, Plestis KA, Kari FA, et al: Staged repair of thoracic and thoracoabdominal aortic aneurysms using the elephant trunk technique: A consecutive series of 215 first stage and 120 complete repairs. Eur J Cardio Thorac Surg 34:605-614, 2008; discussion 614-615 LeMaire SA, Carter SA, Coselli JS: The elephant trunk technique for staged repair of complex aneurysms of the entire thoracic aorta. Ann Thorac Surg 81:1561-1569, 2006; discussion 1569 Schepens MA, Dossche KM, Morshuis WJ, et al: The elephant trunk technique: Operative results in 100 consecutive patients. Eur J Cardio Thorac Surg 21:276-281, 2002 Mitchell RS, Ishimaru S, Criado FJ, et al: Third International Summit on thoracic aortic endografting: Lessons from long-term results of thoracic stent-graft repairs. J Endovasc Ther 12:89-97, 2005 Hughes GC, Nienaber JJ, Bush EL, et al: Use of custom Dacron branch
31.
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grafts for “hybrid” aortic debranching during endovascular repair of thoracic and thoracoabdominal aortic aneurysms. J Thorac Cardiovasc Surg 136:21-28, 28, e1-e6, 2008 Bergeron P, Mangialardi N, Costa P, et al: Great vessel management for endovascular exclusion of aortic arch aneurysms and dissections. Eur J Vasc Endovasc Surg 32:38-45, 2006 Karck M, Chavan A, Hagl C, et al: The frozen elephant trunk technique: A new treatment for thoracic aortic aneurysms. J Thorac Cardiovasc Surg 125:1550-1553, 2003 Schoenhoff FS, Schmidli J, Eckstein FS, et al: The frozen elephant trunk: An interesting hybrid endovascular-surgical technique to treat complex pathologies of the thoracic aorta. J Vasc Surg 45:597-599, 2007 Baraki H, Hagl C, Khaladj N, et al: The frozen elephant trunk technique for treatment of thoracic aortic aneurysms. Ann Thorac Surg 83:S819S823, 2007; discussion S824-S831 Flores J, Kunihara T, Shiiya N, et al: Extensive deployment of the stented elephant trunk is associated with an increased risk of spinal cord injury. J Thorac Cardiovasc Surg 131:336-342, 2006 Usui A, Fujimoto K, Ishiguchi T, et al: Cerebrospinal dysfunction after endovascular stent-grafting via a median sternotomy: The frozen elephant trunk procedure. Ann Thorac Surg 74:S1821-S1824, 2002; discussion S1825-S1832 Liu ZG, Sun LZ, Chang Q, et al: Should the “elephant trunk” be skeletonized? Total arch replacement combined with stented elephant trunk implantation for Stanford type A aortic dissection. J Thorac Cardiovasc Surg 131:107-113, 2006 Uchida N, Ishihara H, Shibamura H, et al: Midterm results of extensive primary repair of the thoracic aorta by means of total arch replacement with open stent graft placement for an acute type A aortic dissection. J Thorac Cardiovasc Surg 131:862-867, 2006 Kawaharada N, Kurimoto Y, Ito T, et al: Hybrid treatment for aortic arch and proximal descending thoracic aneurysm: Experience with stent grafting for second-stage elephant trunk repair. Eur J Cardio Thorac Surg 36:956-961, 2009 Greenberg RK, Haddad F, Svensson L, et al: Hybrid approaches to thoracic aortic aneurysms: The role of endovascular elephant trunk completion. Circulation 112:2619-2626, 2005 Brat R, Docekal B, Jursa R: Combined surgical and endovascular treatment of extensive thoracic aortic aneurysm. J Cardiovasc Surg (Torino) 47:187-190, 2006 Matsuda H, Tsuji Y, Sugimoto K, et al: Secondary elephant trunk fixation with endovascular stent grafting for extensive/multiple thoracic aortic aneurysm. Eur J Cardio Thorac Surg 28:335-336, 2005 Carroccio A, Spielvogel D, Ellozy SH, et al: Aortic arch and descending thoracic aortic aneurysms: Experience with stent grafting for secondstage “elephant trunk” repair. Vascular 13:5-10, 2005 Gottardi R, Funovics M, Eggers N, et al: Supra-aortic transposition for combined vascular and endovascular repair of aortic arch pathology. Ann Thorac Surg 86:1524-1529, 2008 Shimamura K, Kuratani T, Matsumiya G, et al: Long-term results of the open stent-grafting technique for extended aortic arch disease. J Thorac Cardiovasc Surg 135:1261-1269, 2008 Kim T, Martin TD, Lee WA, et al: Evolution in the management of the total thoracic aorta. J Thorac Cardiovasc Surg 137:627-634, 2009 Milewski RK, Szeto WY, Desai ND, et al: Have hybrid procedures replaced open aortic arch reconstruction in high risk patients: A comparative study of open arch debranching with endovascular stent graft placement and conventional open total and distal aortic arch reconstruction. J Thorac Cardiovasc Surg (in press) Inoue K, Hosokawa H, Iwase T, et al: Aortic arch reconstruction by transluminally placed endovascular branched stent graft. Circulation 100:II316-II321, 1999 (suppl) Chuter TA, Buck DG, Schneider DB, et al: Development of a branched stent-graft for endovascular repair of aortic arch aneurysms. J Endovasc Ther 10:940-945, 2003
T
he management of thoracic aortic aneurysms involving the aortic arch remains a clinical challenge. Despite recent advances in surgical technique, conventional open repair of aortic arch aneurysms is still associated with significant perioperative morbidity and mortality.1-4 Neurologic adverse events remain the major significant complication contributing to mortality. Particularly in the atherosclerotic arch aneurysms, the risk of stroke may reach as high as 12%, with mortality rates of up to 20%.5-11 Strategies, including hypothermic circulatory arrest (HCA) with adjunct antegrade cerebral perfusion have been developed to minimize neurologic adverse events and improve clinical outcome. In selected patients with prohibitively significant comorbidities and not ideal for surgical intervention, surgeons have developed innovative hybrid procedures in an attempt to reduce the perioperative morbidity and mortality associated with open arch reconstruction. The goal of these hybrid procedures is to extend the indication and provide an alternative surgical option to patients previously felt to be prohibitively *Division of Cardiovascular Surgery, Department of Surgery, University of Pennsylvania Medical Center, Hospital of University of Pennsylvania, Penn Presbyterian Medical Center, Philadelphia, Pennsylvania. †Division of Cardiovascular Surgery, University of Pennsylvania Medical Center, Hospital of University of Pennsylvania, Philadelphia, Pennsylvania. Address reprint requests to Wilson Y. Szeto, MD, University of Pennsylvania Medical Center, Penn Presbyterian Medical Center, Philadelphia Heart Institute Suite 2A, 51 North 39th Street, Philadelphia, PA 19104. E-mail: [email protected]
1043-0679/09/$-see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1053/j.semtcvs.2009.11.007
high risk for conventional repair. The hybrid arch repair has 2 components: (1) an open conventional aortic arch reconstruction, and (2) a thoracic endovascular aortic repair (TEVAR). The conventional repair involves the proximal reconstruction of the ascending aorta and aortic arch. Completion of the hybrid arch repair is then accomplished with either concomitant or second-stage thoracic endovascular repair. In contrast to the conventional open total arch repair, these hybrid procedures have the potential advantage of avoiding or minimizing the length of HCA and possibly cardiopulmonary bypass (CPB). The hybrid arch repair has been reported in small series with encouraging results.12-16 Since these early reports, hybrid arch repair has evolved from simple debranching of the arch vessels to complex aortic arch reconstruction. In the following section, we present a review of the current techniques and results of hybrid aortic arch repair centered on a new classification of these procedures.17
Background and Rationale for Hybrid Repair of Aortic Arch Aneurysms The rationale for the development of the hybrid arch repair is based on 2 goals: (1) to reduce the perioperative morbidity and mortality associated with aortic arch reconstruction, and (2) to provide an alternative surgical option for patients with aortic arch aneurysms previously believed to be prohibitively 347
348 high risks for conventional open arch repair. By simplifying the proximal aortic reconstruction and substituting the distal repair component with a minimally invasive technique (ie, TEVAR), early investigators hope to develop an operative strategy with decreased perioperative morbidity and mortality. Nonetheless, hybrid arch repair of aortic arch aneurysms is complex and depends largely on the extent of the aneurysms. Aortic arch aneurysms may involve the ascending aorta and proximal transverse arch, transverse arch only, or distal transverse arch and proximal descending thoracic aorta. In cases of mega aorta syndrome, extensive thoracic aortic aneurysms with involvement of the entire ascending, arch and descending thoracic aorta have proven to be the most challenging clinical scenario.
Ascending and Transverse Arch Aneurysms When Griepp et al originally reported the use of HCA for transverse arch repair, the incidence of mortality and stroke reached as high as 25%.18 With advances in cerebral circulatory management, including retrograde and antegrade cerebral perfusion, arch-first technique, and intraoperative neuromonitoring, contemporary series have demonstrated significant improvement in perioperative morbidity and mortality. Sundt et al recently reported a longitudinal series of 95 open arch replacements with an overall mortality of 16.8% and a stroke rate of 9.5%.1 In subgroup analysis of their more recent experience after implementation of antegrade cerebral perfusion with axillary cannulation, they observed a dramatic reduction in mortality (6%) and stroke rate (6%). In a contemporary Japanese series of 472 patients undergoing arch reconstruction using antegrade cerebral perfusion with moderate hypothermia, Kazui et al reported a perioperative stroke risk of 3.2% and mortality of 9.3%.3 Although contemporary large series have demonstrated significant improvement in open aortic arch reconstruction, careful review of the data suggests that in selected subpopulations of patients, conventional operative techniques remain associated with significant morbidity and mortality. For the frail elderly individuals or patients with large atherosclerotic burden in the arch, total arch reconstruction has been associated with in-hospital mortality of up to 20% and incidence of stroke of up to 12%.5-11 Furthermore, patients with significant comorbidities, including history of previous stroke, diabetes, chronic renal insufficiency, and chronic obstructive pulmonary disease often are considered prohibitively high risk and denied conventional open arch reconstruction.
Ascending, Arch, Descending Thoracic Aorta Aneurysms (Mega Aorta Syndrome) Conventional repair of extensive thoracic aortic aneurysms involving the ascending, transverse arch, and descending thoracic aorta remains a clinical challenge associated with significant perioperative morbidity and mortality. The 2 current conventional surgical approaches are (1) single-stage repair and (2) 2-stage repair with proximal aortic arch reconstruction using the elephant trunk technique via a median
W.Y. Szeto and J.E. Bavaria sternotomy, followed by distal aortic reconstruction via a left thoracoabdominal incision. Single-Stage Repair The single-stage repair is an extensive operative technique and involves reconstruction of the ascending, transverse arch, and descending thoracic aortic aneurysms via a bilateral thoracotomy incision (clamshell incision) or a thoracosternotomy incision.19-23 In a series of 69 patients at a mean age of 61 years, Kouchoukos et al recently reported their experience of single-stage reconstruction via the bilateral thoracotomy approach.19 They reported a perioperative mortality of 7.2% with no incidence of stroke. Other smaller series have also reported similar mortality rates ranging from 6% to 14.7% with an incidence of stroke in the range 7.6%-20%.20-23 In these relatively small studies, the mean age of the patients ranged from 34.5 to 68 years. The limited number as well as the relatively young age of the patients in these series reflect the likely bias in the selection of these patients for this surgical approach. The single-stage repair is an extensive operative approach, and elderly patients with significant comorbidities are likely not candidates for this extensive surgical approach. Two-Stage Repair With Elephant Trunk The 2-stage approach involves a first-stage proximal reconstruction of the ascending aorta and aortic arch using the elephant trunk technique via a median sternotomy, followed by a second-stage distal thoracoabdominal aortic reconstruction via left thoracotomy. Similar to the single-stage strategy, it is an extensive surgical procedure, and appropriate patient selection is essential in achieving optimal outcome. Patients with significant comorbidities may not be candidates for this extensive reconstructive approach due to the requirement for 2 major operative procedures within a relatively short interval. In appropriately selected patients, results from centers of excellence have demonstrated acceptable outcome, with first-stage mortality ranging from 2.1% to 12% and secondstage mortality ranging from 4% to 9.6%.24-28 However, careful examination of data demonstrates that improvement for this approach continues to be much desired. In these series, interval mortality between first- and second-stage (ie, waiting for the second operation) ranged from 12% to 25%. Furthermore, in patients who have undergone the first-stage repair, only 44%-68% of them eventually proceeded to the secondstage repair. In essence, most patients who have undergone the first-stage proximal reconstruction simply did not return for their second-stage repair. With the 2-stage approach, completion of treatment is a major concern that ultimately affects clinical outcome and long-term survival.
Classification of Hybrid Arch Aneurysm Repair Since the introduction of TEVAR, hybrid approaches have been developed to achieve adequate proximal landing zones for endovascular treatment of descending thoracic aorta. Challenges and concerns regarding the proximal landing zone have resulted in the development of a classification of
Hybrid repair of aortic arch aneurysms
Figure 1 Landing zone classification for thoracic endovascular aortic repair. Landing zone 0 involves the ascending aorta proximal to the innominate artery. Zone 1 involves the aortic arch between the innominate and left common carotid artery. Zone 2 involves the aortic arch between the left common carotid artery and the left subclavian artery. Zone 3 involves the proximal descending thoracic aorta distal to the left subclavian artery. Zone 4 involves the mid descending thoracic aorta. (Color version of figure is available online at http://www.semthorcardiovascsurg.com.)
the proximal landing zones29 (Fig. 1). The earliest hybrid procedure for thoracic aortic aneurysms was performed in the endovascular treatment of proximal descending thoracic aortic aneurysms. In aneurysms requiring landing zone 2 (endograft deployment between the left common carotid artery and the left subclavian artery), a hybrid procedure involving a first-stage left carotid to left subclavian artery bypass or transposition is performed, followed by either a staged or concomitant TEVAR of the descending thoracic aorta. Thoracic aortic aneurysms involving the arch are essentially aneurysms requiring a proximal deployment of the endograft in the ascending aorta, or landing zone 0. With this approach, the arch branch vessels must be reconstructed to avoid neurologic adverse events and achieve clinical success. After arch vessel reconstruction, deployment of the endograft in the aortic arch is then performed to achieve aneurysmal exclusion. Multiple operative techniques have been described in the literature. We have proposed a classification of hybrid arch repair based on the anatomy of the aneurysm and the suitability of the proximal and distal landing zones (Fig. 2).17
Type I: Brachiocephalic Bypass and Endovascular Repair of the Aortic Arch Type I hybrid repair consists of brachiocephalic bypass with endovascular repair of the aortic arch, called as the “arch debranching” procedure.12-16,30,31 In contrast to the conventional open repair, type I hybrid repair of arch aneurysms has
349 the benefit of eliminating hypothermic circulatory arrest and potentially CPB, thus minimizing the risk of neurologic complications. Reserved for patients with isolated aortic arch aneurysms, these patients have satisfactory proximal landing zones in the ascending aorta and distal landing zones in the descending thoracic aorta for endovascular aortic repair. Bypass of the 3 arch vessels is performed for cerebral revascularization, followed by endograft deployment in the aortic arch (Fig. 2). In some patients with large arch aneurysms, left subclavian artery exposure may be difficult. Instead of attempting a difficult exposure via anterior approach from the median sternotomy, some investigators perform a left subclavian to left carotid artery bypass via a counter left supraclavicular incision. Other investigators will elect not to revascularize the left subclavian artery and simply bypass the innominate and left common carotid artery. When performing the proximal anastomosis of the brachiocephalic bypass to the ascending aorta, care must be taken to ensure adequate proximal landing zone of at least 2 cm in the ascending aorta to accommodate endograft deployment. If the ascending aorta is short and proximal anastomosis deep at the level of the sinotubular junction is required to create a 2-cm proximal landing zone, CPB with aortic occlusion may be necessary. If the ascending aorta is of adequate length, a side-biting clamp can be used, thus avoiding CPB. After revascularization (“debranching”) of the great vessels is accomplished, exclusion of the arch aneurysm is achieved with endovascular repair. The deployment of the endografts can be performed antegrade via the ascending aorta (usually through a separate conduit) in a concomitant approach. Endograft deployment can also be performed via a retrograde approach using the iliofemoral vasculature, either in a concomitant or staged approach. The antegrade approach has the benefit of eliminating potential iliofemoral vascular access complications. Furthermore, antegrade deployment ensures adequate length of the delivery system to reach the intended landing zones. Current thoracic endograft delivery systems are often not long enough to reach the ascending aorta in taller individuals with the retrograde approach. Antegrade deployment also allows for maximum precision in deployment as there is less transmitted torque through a shorter delivery system. Finally, the endograft may be manually manipulated via the open-chest to accommodate the curvature of the aortic arch.
Type II: Aortic Arch Reconstruction With the “Stented” Elephant Trunk Type II hybrid arch repair is the “stented” elephant trunk repair, and this technique is reserved for patients with ascending aortic aneurysms with limited extension into the distal arch. In contrast to the conventional open repair, exposure of the descending thoracic aorta in the left thorax to construct the distal anastomosis is avoided, thus reducing the length of HCA and perioperative morbidity and mortality. The ascending aorta is aneurysmal, and reconstruction of the ascending aorta (zone 0) is required to provide an adequate
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Figure 2 Classification of hybrid aortic arch repair based on aneurysm anatomy and landing zone suitability. Classification of hybrid aortic arch repairs is based on the extent of the aneurysm and the suitability of the proximal and distal landing zones. Type I hybrid arch repair (arch debranching) is suitable for an isolated arch aneurysm with satisfactory proximal and distal landing zones. Type II hybrid arch repair (“stented” elephant trunk) is suitable for a proximal ascending aortic aneurysm with extension into distal arch. Repair requires conventional proximal aortic reconstruction combined with endovascular repair of the distal arch and descending thoracic aorta. Type III hybrid arch repair (proximal aortic repair with completion endovascular repair of the thoracoabdominal aorta) is suitable for aneurysms of the ascending, transverse arch, and descending thoracic aorta. The proximal landing zone is aneurysmal and requires conventional open reconstruction. Aneursymal exclusion of the descending thoracic aorta to the level of the celiac artery is often required during the completion endovascular repair of the thoracoabdominal aorta. (Color version of figure is available online at http://www.semthorcardiovascsurg.com.)
proximal landing zone for endograft deployment. The distal landing zone at the level of the descending thoracic aorta is not aneurysmal, and therefore can provide a satisfactory distal landing zone for endograft deployment. During hypothermic circulatory arrest, the endograft is deployed antegrade via the open arch into the descending thoracic aorta. Hence, this technique has been commonly referred to as the “frozen” stented elephant trunk technique.32-38 Following endograft deployment, proximal reconstruction of the ascending aorta and aortic arch is performed using a Dacron graft with multiple branches for great vessel reconstruction. If minimizing the duration of HCA is preferred, the endograft can be deployed after arch reconstruction is completed and HCA is terminated. Then, the “stented” elephant trunk is deployed antegrade via the newly reconstructed ascending aorta via a fourth limb (Fig. 2). The endograft can also be deployed in a retrograde fashion via the iliofemoral vasculature (in a concomitant or staged approach). The benefits and disadvantages of the antegrade and retrograde approaches are similar to the type I repair.
Type III: The Elephant Trunk Repair With Completion Endovascular Repair of the Thoracoabdominal Aorta Type III repair is a 2-stage strategy consisting of a first-stage proximal reconstruction using either a conventional open arch elephant trunk technique or the “stented” elephant trunk technique (type II repair). A second-stage completion endovascular repair of the descending thoracic aorta using either the conventional or the “stented” elephant trunk as its proximal landing zone is performed (Fig. 2). This technique is reserved for patients with extensive thoracic aortic aneurysms with involvement of the ascending, transverse arch, and descending thoracic aorta, or the so-called mega aorta syndrome.39-43 In contrast to type I and II repairs, both the proximal landing zones in the ascending aorta as well as the distal landing zones in the descending thoracic aorta are aneurysmal and unsatisfactory for endovascular repair in type III repairs. Adequate proximal landing zone 0 can be reconstructed similar to type II repairs. However, distal aneurysmal extension into the descending thoracic aorta requires
Hybrid repair of aortic arch aneurysms
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Table 1 Outcome of Hybrid Aortic Arch Repair n
Permanent Stroke
Paraplegia
In Hospital Mortality
Type I: Brachiocephalic bypass and endovascular repair of aortic arch Gottardi et al44 Hughes et al30 Szeto et al12 Saleh and Inglese14 Bergeron et al31
13 7 8 15 15
0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%)
— — — — —
3 (23.1%) 0 (0%) 1 (12.5%) 0 (0%) 1 (6.7%)
Type II: Aortic arch reconstruction with stented elephant trunk Shimamura et Baraki et al34 Liu et al37 Uchida et al38 Flores et al35
al45
126 39 60 35 25
7 (5.6%) 3 (7.7%) 2 (3.3%) 0 (0%) 4 (16%)
3 (2.3%) 0 (0%) 1 (1.6%) 0 (0%) 6 (24%)
4 (3.2%) 5 (12.8%) 2 (3.3%) 2 (5.7%) 3 (12%)
Type III: Elephant trunk with completion TEVAR al39
Kawaharada et Greenberg et al40 Brat, Docekal, and Jursa41 Matsuda et al42 Carroccio et al43
31 22 3 4 12
1 (3.2%) 0 (0%) 0 (0%) 0 (0%) —
0 (0%) 0 (0%) 0 (0%) 0 (0%) —
2 (6.4%) 1 (4.5%) 0 (0%) 0 (0%) 1 (8.3%)
TEVAR, Thoracic endovascular aortic repair.
endograft exclusion of the entire descending thoracic aorta. A completion endovascular repair with endograft deployment at the level of the celiac artery is often required. Although possible, antegrade deployment of multiple endografts distally to the level of the celiac artery via the ascending aorta may be technically challenging. Given the extensive involvement of the descending thoracic aorta and the requirement for multiple endografts, a 2-stage retrograde approach from the iliofemoral vasculature may be more feasible and advantageous. The benefit of the type III hybrid arch repair is substantial. In contrast to the conventional open single-stage repair, performance of the distal anastomosis via a morbid incision (ie, the bilateral thoracotomy or thoracosternotomy) is avoided. In contrast to the conventional open 2-stage approach, the second stage (ie, thoracic endovascular repair) of the hybrid repair is minimally invasive, and therefore the interval to second stage may be significantly shortened. For most patients, the second endovascular completion stage can be performed within a relatively short period, perhaps even the same index hospitalization. In essence, the type III hybrid repair offers these patients a less morbid second stage, and potentially a shorter interval to second-stage completion reconstruction. These factors likely will result into a higher percentage of patients undergoing the second-stage repair, resulting in better outcome and possibly long-term survival.
Results of Hybrid Arch Aneurysm Repair Type I: Brachiocephalic Bypass and Endovascular Repair of the Aortic Arch At the University of Pennsylvania, we reported our initial experience with type I repairs in 8 patients who were not
candidates for conventional open arch reconstruction secondary to prohibitively significant comorbidities. All 8 patients had atherosclerotic arch aneurysms with a mean diameter of 8 cm. Technical success with complete aneurysmal exclusion was achieved in all patients. In-hospital mortality was 12.5% (1/8 patients). Transient neurologic event occurred in 2 patients with both patients having full recovery and no residual deficit at the time of discharge. At the time of publication with a follow-up of 11.7 months, there was no incidence of endoleak.12 Gottardi et al recently reported their experience with the hybrid arch repair in patients with aortic arch pathology. From 1996 to 2007, 73 patients with aortic arch pathology were treated with hybrid arch repairs. Of these 73 patients, 13 underwent total aortic arch debranching, or type I repair, for atherosclerotic aneurysms (n ⫽ 9) and penetrating ulcers (n ⫽ 4). In-hospital mortality occurred in 3 patients.44 Other series have reported similar incidence of perioperative stroke and mortality (Table 1). The incidence of mortality in this exceptionally high-risk group of patients has been acceptable, ranging from 0% to 23.1%. Interestingly, the risk of permanent stroke has been low; however, one must be cautioned that the incidence of transient neurologic events has been reported to be as high as 25%. In this population of patients deemed to be prohibitively high risk for conventional arch reconstruction, these results are considered acceptable when compared with the incidence of stroke (up to 8%) and in-hospital mortality (up to 10%) in contemporary series of open arch reconstruction.1-4 However, the number of patients in these series is relatively small and larger studies with longer follow-up will be needed before definitive conclusions can be made.
352
Type II: Aortic Arch Reconstruction With the “Stented” Elephant Trunk The largest series of the “stented” elephant trunk technique was recently reported by Shimamura et al in 2008.45 From 1994 to 2004, 126 patients with aortic arch pathology and extension into the distal arch were treated with the “frozen” stented elephant trunk technique followed by proximal arch reconstruction. Of the 126 patients, 69 patients were atherosclerotic aneurysms. Operative mortality at 30 days was 3.2%. Perioperative neurologic complications included stroke (5.6%) and spinal cord ischemia (6.3%). Five (3.9%) late endoleaks were observed during a mean follow-up period of 60.4 months. Survival was 81.1%, 63.3%, and 53.7% at 1, 5, and 8 years. Baraki et al reported their experience with 39 patients undergoing the “frozen” stented elephant trunk technique. Neurologic adverse events occurred in 5 patients, but complete resolution with no residual deficit occurred in 2 patients. In-hospital mortality was 12.8% (5/39 patients).34 Flores et al recently identified predictors of spinal cord ischemia and paraplegia in patients undergoing the “frozen” stented elephant trunk technique.35 In his series of 25 patients, paraplegia occurred in 24% (6/25 patients). The combination of a distal landing zone of T7 or greater and a history of abdominal aortic aneurysm repair was the strongest predictor of spinal cord injury. Other series have reported similar incidence of stroke (0%-16%), spinal cord ischemia (0%-24%), and 30-day mortality (3.2%-12.8%) (Table 1). Although these are relatively small series, the results of type II repairs seem acceptable when compared with the results of first-stage repair of the conventional elephant trunk procedure. For patients with arch aneurysms extending into the distal arch and proximal descending thoracic aorta, type II repairs with the “stented” elephant trunk technique seems to be an acceptable alternative to conventional open repair.
Type III: The Elephant Trunk Repair With Completion Endovascular Repair of the Thoracoabdominal Aorta In a series of 31 patients, Kawaharada et al reported their hybrid treatment of aortic arch and descending thoracic aortic aneurysms comprising a conventional first-stage proximal reconstruction with the elephant trunk technique followed by completion endovascular repair of the distal thoracoabdominal aorta.39 The interval between the first and second stage ranged from 0 to 14 months with a mean interval of 3.1 months. Technical success was achieved in all patients, with 100% of patients completing the second stage. For the first stage, there was no death and 1 patient suffered from a temporary stroke. For the second stage, the in-hospital mortality was 6.4% (2/31 patients). There was no stroke, and no paraplegia observed. On follow-up, the 2- and 5-year survival was 83.5% and 73.3%, respectively. Caudal migration of the endograft occurred in 3 patients, requiring open conversion for treatment of endoleak for all 3 patients.39 Greenberg et al reported the Cleveland Clinic experience in 22 patients with extensive thoracic aortic aneurysms involving the ascending aorta, arch, and descending thoracic
W.Y. Szeto and J.E. Bavaria aorta.40 Conventional elephant trunk procedure with proximal reconstruction was performed with interval completion endovascular repair of the thoracoabdominal aorta. The interval between the first and second stages ranged from 3 days to 102 months (mean, 17.8 months). However, the mean interval was reduced to 7 months if the first stage was performed at the same institution. Technical success was achieved in all patients. There was no incidence of stroke or paraplegia, with 3 cases of transient paraparesis. Thirty-day mortality was 4.5% with 1- and 2-year survival at 84.2% and 84.2%, respectively. Other smaller series have demonstrated similar results, with acceptable first- and second-stage mortality (Table 1). Furthermore, the data suggest that type III hybrid arch repairs decrease the interval duration between first- and second-stage reconstruction and consequently result in a higher percentage of patients proceeding to secondstage repair and completing their treatment.
Comparison of Hybrid Arch Repair With Conventional Open Arch Repair Despite preliminary data suggesting early success with hybrid aortic arch repair in high-risk patients, questions and concerns remain regarding its benefits when compared with conventional open techniques. With the lack of large series and long-term results, many investigators have reservations regarding the hybrid repair and have cautioned against overly enthusiastic embrace without more definitive data. To date, there has been no randomized study comparing hybrid repair versus conventional open repair, and unlikely to be one in the future. However, data from retrospective series discussed earlier as well as a few retrospective comparative studies do suggest that hybrid aortic arch repair is a valid and an acceptable option, particularly in the high-risk population of patients. Kim et al recently reported their experience with the management of extensive aneurysms of the ascending, arch, and descending thoracic aorta (mega aorta syndrome).46 From 1992 to 2007, 103 patients underwent operative repair of extensive thoracic aortic aneurysms in a single institution. The operative strategies were (1) conventional single-stage repair (n ⫽ 29), (2) 2-stage repair with conventional elephant trunk and completion open repair of the thoracoabdominal aorta (open, n ⫽ 50), and (3) hybrid 2-stage repair with conventional elephant trunk and completion endovascular repair, or the type III hybrid arch repair (hybrid, n ⫽ 24). Between the 3 groups, there was no difference in the incidence of stroke, paraplegia, and the overall mortality (mortality: 24% single-stage, 14% open, 17% hybrid). Examining the 2 approaches of the 2-stage repairs, there was no difference between the open and the hybrid group in both the first-stage mortality (10% open versus 8% hybrid) and the second-stage mortality (10% open versus 11% hybrid). But in striking contrast with the open group, 7 of 18 patients in the hybrid group underwent the completion endovascular repair of the thoracoabdominal aorta during the index hospitalization, with a shorter second-stage hospital stay (5.5 days versus 16.5 days, P ⬍ 0.01), fewer transfusions (P ⬍
Hybrid repair of aortic arch aneurysms 0.01), and lower incidence of acute renal injury (P ⫽ 0.04). Similar to other series, a significant number of patients in the conventional 2-stage open approach did not proceed to the second-stage, with a completion rate of only 47% (20 of 43 patients). The reasons for completion failure included lost to follow-up (n ⫽ 17, 34%), first-stage mortality (n ⫽ 4, 8%), interval mortality (n ⫽ 1, 2%), and deemed unfit or too high risk for second-stage (n ⫽ 1, 2%). For this closely monitored group of patients, it remains unclear and the information is not provided as to why lost to follow-up is the primary reason for completion failure in as many as 17 of 23 patients. In a striking contrast in the hybrid group, the second-stage completion rate was 78% (18 of 23 patients). The reasons for completion failure were lost to follow-up (n ⫽ 1, 4.2%), first-stage mortality (n ⫽ 2, 8.3%), and interval mortality (n ⫽ 2, 8.3%). Although the conventional open single-stage procedure has a completion rate of 100%, many critics of this approach have stated that the single-stage approach is simply too extensive of an operation, and likely not suitable for high-risk patients. In this study, the data certainly suggest and supports this concern. When examined together, the incidence of operative mortality, paraplegia, stroke, or acute kidney injury was significantly higher in the single-stage group at 62% (single-stage), compared with 38% (open), and 29% (hybrid) (P ⫽ 0.04) in the other 2 groups. Based on their experience, the type III hybrid arch repair has become this institution’s preferred operative technique for patients with mega aorta syndrome. At the University of Pennsylvania, we recently reviewed our experience with operative repair of aortic arch aneurysms.47 From 2000 to 2009, a total of 1196 open arch procedures were performed, with 45 elective open total arch reconstruction at a single institution. From 2005 to 2009 in the same institution, 64 hybrid arch repairs were performed, with 27 patients undergoing elective hybrid total arch reconstruction for aneurysmal disease. The hybrid arch repairs were reserved for patients considered prohibitively high risk for conventional repair and included 17 type I repairs, 2 type II repairs, and 8 type III repairs. Preoperative demographics demonstrated a significantly older population in the hybrid group when compared with the open group (71.3 years versus 62.8 years, P ⫽ 0.008) as well as a significantly higher incidence of atherosclerotic aneurysms in the hybrid group (96% versus 58%, P ⬍ 0.001). Although not a statistical difference, there was a trend favoring the outcome in the hybrid group when compared with the open group for inhospital mortality (11% versus 16%), stroke (4% versus 9%), permanent paraplegia (7% versus 0%), and renal failure requiring hemodialysis (11% versus 7%). Furthermore, in patients older than 75 years, a major reduction in mortality was observed in the hybrid group when compared with the open group (8% versus 36%, P ⬍ 0.05). These 2 single-institutional retrospective studies suggest that for older patients with extensive thoracic aortic aneurysms involving the ascending, arch, and descending thoracic aorta, hybrid aortic arch repair may be the preferred operative approach.
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Future Direction Despite encouraging results, the current hybrid reconstructive techniques for arch aneurysms still require surgical incisions, CPB, and HCA with the associated potential morbidity. Current hybrid aortic arch repair may well be a bridging strategy until the development of a total endovascular platform for arch reconstruction is refined and achieves widespread clinical applicability. To date, 2 different conceptual strategies have been reported in the total endovascular treatment of aortic arch aneurysms. Reported by Inoue et al, a unimodular custom-designed multibranch stent graft has been successfully implanted in 17 patients, with no perioperative mortality or stroke.48 Chuter et al have reported a modular design involving supra-aortic arch debranching.49 After a carotid– carotid bypass, deployment of an ascending aortic graft with an innominate artery branch is performed retrograde from the right carotid artery. Arch exclusion is completed with a thoracic endograft distal to the innominate branch.
Conclusion The hybrid arch repair for aortic arch aneurysms continues to evolve with improvement in perioperative morbidity and mortality. The data suggest that hybrid arch repairs are safe and effective, with the highest benefit for high-risk patients, particularly in those with extensive thoracic aortic aneurysms (mega aorta syndrome). However, the data remain limited and we must be cautious in our enthusiastic embrace of this new technology. The results of hybrid arch repairs must be measured against the results of proven conventional open surgical techniques. Larger series of hybrid arch repairs with longer follow-up must be examined before we should extend the applications of these techniques to patients with lower risk.
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