The chimney-graft technique for preserving supra-aortic branches: a review

Endovascular reconstruction of the aortic arch with new-generation dual-branch and triple-branch endograft: design, applicability, indications, outcomes, and future directions

INTRODUCTION

Repair of aortic arch pathologies such as degenerative aneurysms and dissections still represents a significant challenge for vascular and cardiac surgeons. We focused on the design, evolution, implementation, and prospects of endovascular dual branch technology for treatment of pathologies in the aortic arch.

AREAS COVERED

The literature search was conducted in a non-systematic fashion through the PubMed and Scopus databases; articles deemed relevant to the scope of the work and fully published in English language from January 12,000 until December 2023 were considered for inclusion. Two companies so far have developed and launched in market a dedicated arch dual branch platform: Terumo Aortic and Cook Medical.

EXPERT OPINION

A common limitation to the available technology is represented by the fact that urgent cases (i.e. large or rapidly growing aneurysms, symptomatic patients) cannot be treated because the customization process generally takes between 6 and 8 weeks, and there is an inherent risk for aorta-related adverse events to happen during the waiting time. While the future holds much promise, several technical hurdles still exist and further developments (in device design, operators' skills, patients' selection, and outcomes assessment) are needed to establish the safety and effectiveness of treatment particularly over the long-run.

Penetrating Aortic Ulceration Treated with Castor Branched Aortic Stent Graft—A Case Series

Penetrating aortic ulceration (PAU) is an acute aortic syndrome similar to aortic dissection and intramural hematoma. It is the result of a tunica intima ulceration due to atherosclerotic disease. This clinical condition can lead to serious complications and a poor short-term prognosis, especially in high-surgical-risk patients. We report three cases of patients referred to “Ospedale del Cuore” of Massa (Italy) with PAU at the aortic arch-proximal descending aorta level who could not undergo surgical intervention. For the first time in Italy, we successfully treated these patients with a full percutaneous implantation of a Castor branched aortic stent graft. Our case series shows that this type of endovascular graft is an effective, safe, and feasible treatment for PAU involving a distal aortic arch and avoiding surgery and related complications.

Mid-term Comparison of One-Piece Branched Stent-Graft and Chimney Technique Treating Aortic Arch Pathologies

PURPOSE

We compared the mid-term outcomes of a one-piece branched stent-graft with the chimney technique in the treatment of aortic arch pathologies.

METHODS

Between August 2012 and December 2017, a retrospective analysis of 279 patients with thoracic aortic dissection (TAD) or aneurysm (TAA) who underwent thoracic endovascular aortic repair with b-TEVAR (n = 69, 58 TAD and 11 TAA) or c-TEVAR (n = 210, 151 TAD and 59 TAA) was performed.

RESULTS

Forty-five double-chimney for the left subclavian artery (LSA) and left common carotid artery LCCA and 165 single-chimney for the LSA were performed in chimney-TEVAR (c-TEVAR) and 69 branched-TEVAR (b-TEVAR) with 36 single-branched stent-grafts and 33 branched stent-grafts combined with fenestration technique. The c-TEVAR group experienced more in-hospital complications than the b-TEVAR group (19.5 vs. 7.2%, p = 0.017), primarily because the c-TEVAR group experienced more in-hospital cerebral ischemia events (6.2 vs. 0%, p = 0.043) and intra-operative type I endoleaks (31.9 vs. 5.8%, p < 0.01). There were significantly more follow-up type I endoleaks (21.9 vs. 4.3%, p = 0.002), cerebral ischemia events (11.0 vs. 2.9%, p = 0.042), and re-interventions (12.9 vs. 4.3%, p = 0.048) in the c-TEVAR group than in the b-TEVAR group. However, follow-up mortality was not significantly different between the c-TEVAR and b-TEVAR groups (5.2 vs. 2.9%, p = 0.638).

CONCLUSION

In patients with aortic pathologies involving the arch branches, customized b-TEVAR may result in fewer cerebral ischemia events and endoleaks than c-TEVAR. However, c-TEVAR should be considered an off-the-shelf treatment option for patients in need of emergency treatment.

LEVEL OF EVIDENCE

Level 4, Case Series.

Total Endovascular Aortic Arch Repair: From Dream to Reality

The gold-standard therapy for the treatment of aortic arch pathologies is conventional open surgery. Recently, total endovascular aortic arch replacement with branched stent-grafts has been introduced into clinical practice with the aim of reducing invasiveness especially in selected high-risk patients. The aim of this review is to describe the two most commonly used branched devices for endovascular arch stent-grafting: Nexus (Endospan, Herzlia, Israle) and RelayBranch (Terumo Aortic, Glasgow, United Kingdom). Nexus is a CE-certified off-the-shelf, single branch, double stent graft system. It consists of two different components: a main module for the aortic arch and the descending aorta with a side-branch for the brachiocephalic artery (BCA), and a curved module for the ascending aorta that lands into the sino-tubular junction and connects to the main module through a side-facing self-protecting sleeve. Nexus may be used in urgent-emergency cases and also in patients with only one suitable supra-aortic target vessel but, on the other hand, it makes cerebral blood flow dependent on one source vessel only. The RelayBranch Thoracic Stent-Graft System is a custom made, double branched endograft with a wide window on its superior portion to accommodate two inner tunnels for BCA and left common carotid artery connection; bilateral cervical accesses are generally used to advance guidewires for catheterization of the inner tunnels in a retrograde fashion. RelayBranch can be customized on every patient’s specific anatomy and provides a double blood source for the brain, but it cannot be used in urgent-emergency conditions. Therefore, in order to optimize outcomes, the choice of the most appropriate device should be made considering pros and cons of each system and patient’s anatomy by an experienced aortic team. In conclusion, total endovascular aortic arch exclusion is a promising reality in selected high-risk patients.

Chimney Graft Technique Combined With Embolization for Treating Ruptured Aortic Arch Lesions

Background: This study aimed to share the experience in applying the chimney graft technique combined with embolization for treating aortic arch rupture under emergency conditions and evaluating early-term results in these patients. Methods: This study retrospectively included patients with ruptured aortic arch lesions who received the chimney graft technique combined with embolization between March 2016 and March 2021. The primary endpoint was a technical success, deemed as successful stent graft deployment to the planned location, patency of the target branch vessel, and absence of significant type I endoleak. The secondary endpoint was clinical success defined with the size of false lumen in follow-up remaining unchanged or decreasing over time, 30-day mortality, complication, and primary patency of chimney graft. Results: This study included 12 patients (age, 61 ± 12 years; male, 83%). Five patients (42%) received single chimney, one patient (8%) received double chimney, and six patients (50%) received triple chimney. Intraoperative type I endoleak occurred in six patients (50%) who underwent endovascular embolization in the primary operation. Post-operative type I endoleak, evaluated by computed tomography angiography examination following the primary operation, occurred in seven patients (58%), including one patient who received endovascular embolization two times. All patients with post-operative type I endoleak were successfully re-treated using coil and Onyx glue within 1 week, and the median length of stay was 22 ± 11 days (range: 7-44 days). Overall technical success was 100%. Eleven patients had completed their follow-up (median, 12 months, range: 1-34 months), and one patient was out of contact. The 30-day mortality was 9% (1/11, post-operative death of a patient with cerebral hemorrhage). No major complications and no chimney compression, migration, occlusion, or stenosis were recorded during follow-up. Seven patients (58%) have ≥6 months of clinical follow-up time with appropriate imaging. In four (57%) of these patients, diameter stabilization was detected, whereas three (43%) experienced significant reduction (≥5 mm). Conclusion: The patients in this study had satisfactory early-term outcomes. The chimney graft technique combined with coil and Onyx glue embolization may be a safe and effective treatment for ruptured aortic arch lesions under emergency conditions.

Management of arch aneurysms with a single-branch thoracic endograft in zone 0

Background

We present preliminary data from a patient cohort undergoing thoracic endovascular aortic repair for Ishimaru zone 0 and 1 using a novel branched arch endograft.

Methods

This US multicenter early feasibility investigational device exemption clinical trial treated 9 patients with a mean age 72.8 ± 8.0 years (77.8% male). The endograft was designed with a single side branch designed to facilitate aortic coverage proximal to the innominate or left carotid artery while maintaining branch vessel patency. Pathology treated included fusiform (n = 2) or saccular (n = 7) aneurysm, with a maximum aortic diameter of 6.3 ± 0.7 cm. Treatment was into zone 0 in 8 patients, and zone 1 in 1 patient.

Results

All patients underwent initial successful first-stage supra-aortic trunk revascularization using a variety of techniques, without the occurrence of stroke. For the second thoracic endovascular aortic repair stage, median total treatment length was 20 cm. The primary end point of device delivery and branch vessel patency was achieved in 100% of patients, without 30-day mortality or spinal cord ischemia. Cerebrovascular events were observed in 2 patients through 30 days. No type I or III endoleaks were reported and all side branches were patent at 12-month imaging follow-up.

Conclusions

Endovascular repair of Ishimaru zone 0 or 1 arch aortic aneurysms can be achieved with a novel branched arch endograft. Future studies will evaluate the mid-term outcomes with this device in other pathologies and further define the occurrence of postoperative neurologic events.

Endovascular Aortic Arch Reconstruction with Parallel Grafts: A Dilemma of Excessive Endograft Oversizing

Background

Preservation of supra-aortic branches in thoracic endovascular aortic repair plays a role in associated neurological outcomes, and the strategy varies.

Objectives

This study aimed to evaluate the safety and efficacy of a parallel graft technique to reconstruct the aortic arch.

Methods

From August 2014 to July 2018, a total of 25 patients with thoracic aortic pathologies requiring arch reconstruction were included. All patients underwent thoracic aortic endovascular repair (TEVAR) with a zone 1 landing aortic stent graft, a chimney graft to preserve the left common carotid artery, and a periscope graft to preserve the left subclavian artery. The associated outcomes and complications were reported.

Results

Eighteen patients presented with aortic dissection, 4 with a thoracic aortic aneurysm, 1 with a penetrating aortic ulcer, 1 with a traumatic aortic injury, and 1 case of re-TEVAR. The technical success rate was 96% (24/25), but the case of immediate failure died of retrograde type A dissection. Over a mean follow-up of 32.33 months, another retrograde type A aortic dissection was detected in 1 month, and a case of early failure (< 1 year) and 3 cases of late failure (> 1 year) whose primary aortic problems recurred were detected.

Conclusions

This study demonstrates a total endovascular approach to preserve supra-aortic branches with a parallel graft technique. However, the dilemma of excessive graft oversizing was disclosed due to the risk of retrograde type A dissections and an unsatisfactory durability in this small series.

Endovascular exclusion of the entire aortic arch with branched stent-grafts after surgery for acute type A aortic dissection

Background

The treatment of residual pathology of the aortic arch after surgical repair for type A acute dissection (AAD) represents a therapeutic challenge. Recently, new branched endovascular devices have expanded the possibility of aortic arch stent-grafting (ASG) with proximal landing in zone 0. The aim of this retrospective, single-center study was to evaluate outcomes of patients with a history of surgical repair for AAD undergoing ASG with branched devices.

Methods

We analyzed patients undergoing ASG after treatment for type AAD with 2 different branched devices: Nexus (dual-module, single branch, off-the-shelf) and RelayBranch (single-module, dual branch, custom-made). Before ASG, surgical bypass of supra-aortic vessels was performed according to patient's anatomy and to the selected device. All patients underwent clinical and computed tomography scan evaluation before hospital discharge, at 6 months, and on a yearly basis thereafter.

Results

From March 2017 to April 2019, 4 consecutive patients underwent ASG after surgery for AAD at our institution. Mean time from surgery for AAD to ASG was 20 months. Mean age at the time of ASG was 72 years. Nexus and Relay were implanted in 2 patients each. All patients survived and were successfully discharged. Mean intensive care unit stay and hospital stay were 3 and 19 days, respectively. We did not observe any major adverse events. At a mean follow-up of 28 months, all patients are alive and computed tomography scans showed good anatomic results with no endoleaks.

Conclusions

This preliminary experience shows that ASG after surgery for AAD is feasible and provides encouraging clinical and anatomic early results.

Art of operative techniques: treatment options in arch penetrating aortic ulcer

Penetrating aortic ulcer (PAU) of the arch has a focal extent which often represents an adequate anatomic target for thoracic endovascular aortic repair (TEVAR). However, the anatomic constraints represented by the supra-aortic vessels pose either clinical or technical challenges that increase when the PAU develops proximally in the arch. Currently, different types of endografts are commercially available and have been used to treat aortic arch lesions. These include branched/fenestrated endografts for a total endovascular approach, and standard devices that can be used in combination with open/hybrid surgical operations, with the aim to exploit the minimally invasive nature of TEVAR by extending the proximal landing zone when necessary. We describe several current techniques adopted in such settings.

Open Conversion for Type A Ascending Aortic Dissection after Thoracic Endovascular Aortic Repair by the Chimney Graft Technique

An 83-year-old man with aortic arch aneurysm underwent zone 0 thoracic endovascular aortic repair (TEVAR) by the chimney graft technique with two supra-aortic arch debranching grafts and developed subacute type A ascending aortic dissection. We performed emergency open conversion with circulatory arrest under deep hypothermia. The tip of the chimney graft (around the sino-tubular junction in the ascending aorta) was stiff, making it difficult to inspect the lumen and perform anastomosis. Deep hypothermic circulatory arrest and cutting the endograft stents to mobilize the graft were necessary for secure anastomosis.

Fenestrated endovascular repair of aortic arch aneurysm in patients with bovine arch using the Najuta stent graft

We describe the case of a 74-year-old man with a thoracic aortic aneurysm with a bovine arch who underwent fenestrated endovascular repair of aortic arch aneurysm using the Najuta stent graft (Kawasumi Laboratories, Inc, Tokyo, Japan). He has had a previous endovascular aneurysm repair and femoropopliteal bypass for abdominal aortic aneurysm combined with peripheral arterial disease. The Najuta stent graft was inserted and deployed at zone 0 with delicate positional adjustment of the fenestration of the stent graft to the brachiocephalic trunk. There was no endoleak or complication. His postoperative course was uneventful. At 7-month follow-up, complete exclusion of the aneurysm was noted. The Najuta stent graft repair of aortic arch aneurysms is a safe and effective treatment option for patients with a bovine arch.

Endovascular total arch replacement techniques and early results

During the last 20 years, a clear shift has been observed towards thoracic endovascular aortic repair for different aortic pathologies. However, total endovascular repair of the aortic arch remains technically demanding. Simultaneous perfusion of all supra-aortic arteries without longer cerebral ischemia time, whilst trying to avoid cerebral embolization, labels endovascular aortic arch repair with highest level of technical difficulty and surgical expertise. The aim of this article is to present an overview of the current technical options for endovascular aortic arch repair and their early results. Currently, early results are reported from four endovascular arch replacement techniques: hybrid repair, total endovascular approach, chimney grafts and in-situ fenestration. The early results of these different arch replacement techniques are promising, especially the total arch replacement with custom-made fenestrated or branched stent-grafts. Long-term results are unknown, and larger series results and comparative studies are needed to determine safety and efficacy.

Outcomes of thoracic endovascular aortic repair using aortic arch chimney stents in high-risk patients

BACKGROUND

Aortic arch disease is a challenging clinical problem, especially in high-risk patients, in whom open repair can have morbidity and mortality rates of 30% to 40% and 2% to 20%, respectively. Aortic arch chimney (AAC) stents used during thoracic endovascular aortic repair (TEVAR) are a less invasive treatment strategy than open repair, but the current literature is inconclusive about the role of this technology. The focus of this analysis is on our experience with TEVAR and AAC stents.

METHODS

All TEVAR procedures performed from 2002 to 2015 were reviewed to identify those with AAC stents. Primary end points were technical success and 30-day and 1-year mortality. Secondary end points included complications, reintervention, and endoleak. Technical success was defined as a patient's surviving the index operation with deployment of the AAC stent at the intended treatment zone with no evidence of type I or type III endoleak on initial postoperative imaging. The Kaplan-Meier method was used to estimate survival.

RESULTS

Twenty-seven patients (age, 69 ± 12 years; male, 70%) were identified, and all were described as being at prohibitive risk for open repair by the treating team. Relevant comorbidity rates were as follows: coronary artery disease/myocardial infarction, 59%; oxygen-dependent emphysema, 30%; preoperative creatinine concentration >1.8 mg/dL, 19%; and congestive heart failure, 15%. Presentations included elective (67%; n = 18), symptomatic (26%; n = 7), and ruptured (7%; n = 2). Eleven patients (41%) had prior endovascular or open arch/descending thoracic repair. Indications were degenerative aneurysm (49%), chronic residual type A dissection with aneurysm (15%), type Ia endoleak after TEVAR (11%), postsurgical pseudoaneurysm (11%), penetrating ulcer (7%), and acute type B dissection (7%). Thirty-two brachiocephalic vessels were treated: innominate (n = 7), left common carotid artery (LCCA; n = 24), and left subclavian artery (n = 1). Five patients (19%) had simultaneous innominate-LCCA chimneys. Brachiocephalic chimney stents were planned in 75% (n = 24), with the remainder placed for either LCCA or innominate artery encroachment (n = 8). Overall technical success was 89% (one intraoperative death, two persistent type Ia endoleaks in follow-up). The 30-day mortality was 4% (n = 1; intraoperative death of a patient with a ruptured arch aneurysm), and median length of stay was 6 (interquartile range, 4-9) days. Seven (26%) patients experienced a major complication (stroke, three [all with unplanned brachiocephalic chimney]; respiratory failure, three; and death, one). Nine (33%) patients underwent aorta-related reintervention, and no chimney occlusion events occurred during follow-up (median follow-up, 9 [interquartile range, 1-23] months). The 1-year and 3-year survival is estimated to be 88% ± 6% and 69% ± 9%, respectively.

CONCLUSIONS

TEVAR with AAC can be performed with high technical success and acceptable morbidity and mortality in high-risk patients. Unplanned AAC placement during TEVAR results in an elevated stroke risk, which may be related to the branch vessel coverage necessitating AAC placement. Acceptable midterm survival can be anticipated, but aorta-related reintervention is not uncommon, and diligent follow-up is needed.

Iliorenal periscope graft to maintain blood flow to accessory renal artery

Parallel endografts such as "chimney" and "periscope" are being increasingly used to maintain blood flow to visceral and supra-aortic branches in patients with different aortic disorders. We present a new technique, "iliorenal periscope graft", in a patient with abdominal aortic aneurysm undergoing endovascular aortic repair. In this case, left accessory renal artery flows were provided by an iliorenal periscope graft that extends from the left accessory renal artery to the right common iliac artery in a retrograde fashion.

Saccular Aneurysms of the Transverse Aortic Arch: Treatment Options Available in the Endovascular EraBased on a Presentation at the 2013 VEITH Symposium, November 19-23, 2013 (New York, NY, USA)

Saccular aneurysms of the aortic arch, whether single or multiple, are uncommon. The choice of repair technique is influenced by patients' comorbidities and age. Repairing saccular aneurysms with traditional open techniques can be technically demanding; therefore, endovascular technology and a variety of hybrid approaches have been developed to facilitate such repairs and, potentially, to improve clinical outcomes, especially in high-risk patients. There have been no large, randomized studies to compare the outcomes of these different treatment options in patients with single or multiple saccular aneurysms of the arch. In this review, we outline the etiology and common locations of these aneurysms, the different open, completely endovascular, and hybrid techniques used to treat them, and the treatment selection process.

A case of ruptured aortic arch aneurysm successfully treated by thoracic endovascular aneurysm repair with chimney graft

We report the case of aortic arch aneurysm rupture treated successfully with thoracic endovascular aneurysm repair (TEVAR) accompanied by aortic arch debranching using the chimney graft technique. A 94-year-old man was transported to the hospital after complaining of chest pain for one day. Contrast-enhanced computed tomographic (CT) images revealed an aortic arch aneurysm rupture. Considering the patient's age and postoperative activities of daily living, TEVAR was used. In order to place an indwelling stent graft from the ascending aorta to the periphery, the chimney graft technique was used to debranch the brachiocephalic artery. Hemodynamics was stabilized postsurgically. Plain CT performed 20 days postoperatively confirmed that the intrathoracic hematoma had decreased in size. Although respiratory failure was persistent, there were improvements and the patient was extubated 34 days postoperatively and discharged from the intensive care unit 37 days postoperatively. On postoperative day 75, he was discharged from the hospital to an elder care facility. Few reports have focused on stent grafting for treating aortic arch aneurysm rupture. TEVAR using the chimney graft technique could be an effective treatment option for patients with a decreased ability to tolerate surgery.

The chimney technique for preserving the left subclavian artery in thoracic endovascular aortic repair

OBJECTIVES

The objective of the present study was to evaluate short- and mid-term outcomes of the left subclavian artery (LSA) chimney stent implantation (LSACSI) during thoracic endovascular aortic repair (TEVAR), and to summarize our experience with this technique.

METHODS

From June 2010 to September 2012, 59 patients (49 men; mean age of 57.4 ± 13.3 years, range from 26 to 83 years) who underwent TEVAR and LSACSI were enrolled. Patients suffered from Stanford type B aortic dissection (n = 27), penetrating aortic ulcer (n = 18), aortic arch aneurysm (n = 9), pseudoaneurysm of the aortic arch (n = 4) and proximal type I endoleak after TEVAR of aortic dissection (n = 1). Elective settings were performed in 72% and emergent in 38% of all patients. Follow-up was performed at postoperative 3 months, 6 months and yearly thereafter.

RESULTS

The technical success rate was 98.3% (58/59), and 69 thoracic stent grafts were used. Sixty-two chimney stents, including 55 uncovered and 7 covered stents, were implanted in 59 LSAs. The overall immediate endoleak rate was 15.3% (9/59); type I endoleak was observed in 5 patients and type II in 4 patients. The difference in the immediate endoleak rate related to the anatomy between the outer and the inner curvature was statistically significant (35 vs 4%, P = 0.018). Chimney stent compression was observed in 3 patients and another stent was deployed inside the first one. Perioperative complications included stroke (3.4%, 2/59) and left upper limb ischaemia (1.7%, 1/59). The median follow-up period was 16.5 (range 1–39 months). The mortality rate during follow-up was 5.4% (3/56). Complications during follow-up included endoleak [overall, n = 8 (14.3%, 8/56); type I, n = 5; type II, n = 3], retrograde type A aortic dissection (n = 1), collapse (n = 3, 5.4%) or occlusion (n = 2, 3.6%) of the chimney stent.

CONCLUSIONS

Short- and mid-term results showed that it is feasible to preserve the patency of the LSA in TEVAR with the chimney technique for thoracic aortic pathologies close to the LSA. However, TEVAR combined with LSACSI was not advocated for lesions located at the outer curve of the aortic arch due to a high possibility of endoleak.

Best surgical option for arch extension of type B dissection: the endovascular approach

Despite advances in surgical techniques and postoperative management, the in-hospital mortality rate for patients undergoing conventional open surgical repair for type B dissections is still significant. In light of this, the less invasive surgical procedure for acute type B aortic dissections, defined as thoracic endovascular aortic repair (TEVAR), was developed. Despite some controversy, the use of TEVAR for the management of type B aortic dissections has become commonplace. Generally, the main entry tear in type B aortic dissection is located in the vicinity of the orifice of the left subclavian artery (LSA). The proximal landing zone in the aortic arch must be secured as long as the aim of TEVAR for type B dissection is primary entry closure. This requires hybrid surgery that includes the use of open surgical procedures, such as debranching for revascularization of cervical branches. Despite the presence of challenging anatomic conditions in the aortic arch, hybrid repair has evolved as an increasingly viable alternative, and promising early and long-term results have been reported. As the next step, fenestrated and branched TEVAR techniques have recently been reported with satisfactory early results. In the coming years, there will be intense competition to develop the devices themselves, improve delivery systems, and supplement devices with auxiliary functions. Thus there is high expectations for the next generation and how they will improve and advance treatment methods of TEVAR for type B aortic dissections.