Global experience with an inner branched arch endograft

Status of branched endovascular aortic arch repair

Multiple medical device manufacturers are developing branched endografts for thoracic endovascular aortic repair (TEVAR), to provide a minimally invasive alternative for the treatment of aortic arch pathologies in patients who are deemed unfit for open or hybrid arch repair. Different branched endografts have been introduced, with varying number, size and orientation of the branches that redirect flow to the supra-aortic arteries. We present an overview of the currently investigated devices and review their outcomes. The results of branched TEVAR are promising, yet stroke remains the predominant periprocedural concern. For now, these procedures should be limited to select expert centers where the design and deployment procedure of branched endografts can be further developed to reduce the risk of stroke.

Cerebral embolic protection during endovascular arch replacement

Despite excellent results in high volume centers, open repair of aortic arch pathology is highly invasive, and can result in significant morbidity and mortality in high risk patients. Near-total and hybrid approaches to aortic arch disease states have emerged as an alternative for patients deemed moderate to high risk for conventional repair. Advantages of these approaches include avoidance of extracorporeal circulation and hypothermic circulatory arrest as well as avoidance of cross clamping, all of which are not well tolerated in high risk patients. Anatomically high-risk patients with anastomotic aneurysms from previous arch reconstruction may also benefit from these less invasive approaches. Medical devices designed specifically for the aortic arch are developing at a rapid pace and continue to evolve. Dedicated devices for zone 0-2 aortic arch repair are currently available under special access or being studied in clinical trials. Unfortunately, stroke continues to be the Achilles heel of endovascular approaches to the aortic arch, with cerebral embolism being the culprit in the majority of such cases. This perspective article describes the epidemiology, procedures, and mitigation strategies for current near-total and hybrid approaches to aortic arch pathology, and specifically addresses current means of embolic protection and future direction.

A Feasibility Study of a New Unibody Branched Stent Graft Applied to Reconstruct the Canine Aortic Arch

OBJECTIVES

The aim was to evaluate the feasibility and safety of a new unibody branched stent graft for the reconstruction of the canine aortic arch.

METHODS

The unibody branched stent grafts included single branched stent grafts and double branched stent grafts. The main stent graft and branched limbs were sutured together. The branched stent grafts were folded into the introducer system, which consisted of a double channel catheter, a detachable sleeve, and an introducer sheath. The branched stent grafts were introduced and deployed into the aortic arch by the delivery system. Twenty adult mongrel dogs were used for the experiments. Ten dogs were implanted with single branched stent grafts; the other 10 were implanted with double branched stent grafts. The surviving animals were followed up for 3 months. Computed tomography angiography (CTA) was performed to observe the status of the branched stent grafts.

RESULTS

All the unibody branched stent grafts were successfully implanted into the canine aortic arches. The technical success rate was 100%. There was no cerebral infarction, paraplegia or incision infection. CTA showed that all the branched stent grafts were patent; there was no endoleak or stent migration.

CONCLUSIONS

The unibody branched stent graft system could be used to reconstruct the aortic arch. The animal experimental procedures demonstrated the safety and feasibility of the unibody branched stent graft system.

Case series of aortic arch disease treated with branched stent-grafts

Background

Surgical repair of aortic arch pathology is complex and associated with significant morbidity and mortality. Alternative approaches have been developed to reduce these risks, including the use of thoracic stent-grafts with fenestrations or in combination with bypass procedures to maintain supra-aortic trunk blood flow. Branched stent-grafts are a novel approach to treat aortic arch pathology.

Methods

Consecutive patients with aortic arch disease presenting to a single university hospital vascular centre were considered for branched stent-graft repair (October 2010 to January 2017). Patients were assessed in a multidisciplinary setting including a cardiologist, cardiac surgeon and vascular surgeon. All patients were considered prohibitively high risk for standard open surgical repair. The study used reporting standards for endovascular aortic repair and PROCESS (Preferred Reporting of Case Series in Surgery) guidelines.

Results

Some 30 patients (25 men) underwent attempted branch stent-graft repair. Mean age was 68 (range 37–84) years. Eighteen patients had chronic aortic dissection, 11 patients had an aneurysm and one had a penetrating ulcer. Fourteen patients had disease in aortic arch zone 0, six in zone 1 and ten in zone 2. Twenty-five patients had undergone previous aortic surgery and 24 required surgical revascularization of the left subclavian artery. Technical success was achieved in 27 of 30 patients. Four patients had an endoleak (type Ia, 1; type II, 3). The in-hospital mortality rate was three of 30. Mean length of follow-up was 12·0 (range 1·0–67·8) months, during which time 12 patients required an aortic-related reintervention.

Conclusion

Repair of aortic arch pathology using branched stent-grafting appears feasible. Before widespread adoption of this technology, further studies are required to standardize the technique and identify which patients are most likely to benefit.

Hybrid and total endovascular repair of the aortic arch

Background

Recent advances in endovascular technology have enabled minimally invasive repair of the aortic arch, with specifically designed stent-grafts. This article reviews hybrid and total endovascular repair in the management of aortic arch pathology.

Methods

Studies relating to aortic arch management were identified using MEDLINE and Embase, focusing on endovascular repair.

Results

Hybrid arch repair is associated with an early mortality rate of some 12 per cent, and carries significant risk of stroke (up to 15 per cent), paraplegia (up to 6 per cent), retrograde dissection (up to 6·5 per cent) and proximal endoleak (6 per cent). Despite patients being of overall higher perioperative risk, hybrid repair has morbidity and early mortality rates comparable to those of open arch replacement. However, rates of freedom from aortic rupture or reintervention are significantly lower in the longer term, owing to the incidence of endoleak. Total endovascular arch repair may be achieved by the use of parallel stents or in situ fenestration in the emergency setting, or use of custom-made devices (scalloped, fenestrated or branched stent-grafts) in the elective setting. Reports of these relatively novel technologies suggest acceptable short-term outcomes, but long-term data are still awaited.

Conclusion

Repair of aortic arch pathology presents a formidable challenge for endovascular technology. Open aortic arch repair remains the standard in younger, fitter patients, but endovascular technology and experience continue to evolve with encouraging early outcomes and expanding indications.

Endovascular repair of a leaking aortic-arch pseudoaneurysm using graft stent combined with chimney protection to left common carotid artery: Case report and review of literature

Aortic pseudoaneurysm (PsA) is a rare but serious condition that has high mortality and morbidity rates if untreated. We report a rare case of leaking aortic-arch PsA repaired by thoracic endovascular aortic repair using graft stent with the chimney technique to protect the left common carotid artery. Unlike other cases in the literature, our case was unique, having leaking PsA not related to previous cardiac surgery or aortic dissection. The successful management of this patient using thoracic endovascular aortic repair combined with the chimney technique suggests that this approach may be an attractive therapeutic alternative to treat aortic-arch PsA.

Open Versus Endovascular or Hybrid Thoracic Aortic Aneurysm Repair

Thoracic aortic aneurysms are associated with significant morbidity and mortality. There are multiple underlying etiologies, including genetic abnormalities, that have important implications in their natural history. The variable histologic, anatomic, and clinical presentations necessitate careful consideration of available treatment options. Surgical repair of these aneurysms has been the mainstay of treatment; however, these approaches can carry a relatively high risk of morbidity and mortality. Endovascular approaches have now become first-line therapy for descending thoracic aneurysms, and with advancements in graft technology, endovascular approaches are being increasingly employed for hybrid repairs of the aortic arch and even the ascending aorta. However, to date, clinical outcomes from randomized trials and long-term follow-up are limited. As technology continues to advance, there is the potential for further integration of surgical and endovascular treatments so that patients have the best opportunity for a favorable outcome.

Transcatheter Aortic Valve Implantation as a Bailout Procedure for Acute Aortic Valve Regurgitation During Endovascular Arch Repair

Purpose: To report emergent transcatheter aortic valve implantation (TAVI) to treat acute severe aortic regurgitation caused by valve cusp dysfunction following proximal migration of an endograft implanted in the ascending aorta during endovascular arch repair. Case Report: A 65-year-old man had been previously treated with thoracic and fenestrated endografts in a 2-stage procedure for a chronic type B dissection. At 2-year follow-up, aneurysmal evolution of the distal arch led to development of a proximal type Ia endoleak. The patient was deemed unfit for open repair because of severe nonrevascularizable coronary artery disease. A custom-made endograft was designed consisting of a double inner branch arch endograft with a proximal component to reline the ascending aorta to avoid iatrogenic type A dissection. The first component was successfully deployed. However, this device migrated toward the aortic valve when the delivery system of the branch device was advanced through the aortic valve. Aortography and transesophageal echography showed acute aortic regurgitation due to obstruction of the left coronary valve cusp. An emergency bailout TAVI procedure was performed to successfully treat the aortic regurgitation. Conclusion: TAVI can be used as a bailout procedure for acute aortic valve dysfunction during endovascular arch or ascending aorta repair.

Aortic aneurysm endovascular treatment with the parallel graft technique from the aortic arch to the iliac axis

BACKGROUND

The chimney technique has been developed for the treatment of complex aortic aneurysms. We analyzed the midterm to long-term outcomes of this approach from a single-center experience.

METHODS

From October 2008 to July 2016, 58 patients underwent endovascular aortic aneurysm repair using the chimney technique. Indications for treatment were thoracic aortic aneurysm (TAA) (N.=11), thoracoabdominal aortic aneurysm (TAAA) (N.=2), pararenal aortic aneurysm (PAAA) (N.=15), aortoiliac/isolated hypogastric artery aneurysm (N.=25), type I endoleak after previous TEVAR/EVAR (N.=4), proximal pseudoaneurysm after AAA open repair (N.=1). Elective (82.8%) and emergent (17.2%) procedures were included.

RESULTS

The immediate technical success was 100%. Single, double and triple chimneys were performed in 46, 10, and two patients, respectively. Overall, 61 target vessels (three left common carotid arteries, eight left subclavian arteries, three celiac trunks, three superior mesenteric arteries, 19 renal arteries and 25 hypogastric arteries) were involved. Postoperative mortality was 0. No neurologic complications were registered. Primary patency rate of the chimney stent/stent graft was 98.3%. Low-flow type I endoleak was observed in four patients (6.9%). Postoperative chimney graft re-intervention rate was 1.7%. The median follow-up was 32±20 months (range 3-96 months). Overall estimated survival at 12, 50, and 80 months was 100%, 89% and 44%, respectively. Estimated freedom from endoleak at 1, 12, 24, and 36 months was 96.5%, 95%, 95%, and 93%, respectively. One hypogastric artery stent-graft occluded at the 3rd month of follow-up. No reintervention was performed.

CONCLUSIONS

Our experience with the chimney technique for aortic aneurysms from the aortic arch to the iliac axis shows promising and durable mid- and long-term results. Endograft oversizing, associated with the chimney graft diameter and length choice remain fundamental to reduce the risk of the most frequent procedure complications: type I endoleak and CG occlusion. The wider use of this technique should be justified in patients considered at high risk for open repair and/or not suitable for the custom-made branched/fenestrated endografts.

Minimally Invasive Techniques for Total Aortic Arch Reconstruction

The cumulative experience with endovascular aortic repair in the descending thoracic and infrarenal aorta has led to increased interest in endovascular aortic arch reconstruction. Open total arch replacement is a robust operation that can be performed with excellent results. However, it requires cardiopulmonary bypass and circulatory arrest and, therefore, may not be tolerated by all patients. Minimally invasive techniques have been considered as an alternative and include hybrid arch debranching, parallel stent graft deployment in the chimney and snorkel configurations, and complete endovascular branched reconstruction with multi-branched devices. This review discusses the evolving use of endovascular techniques in the management of aortic arch pathology and considers their relevance in an era of safe and durable open aortic arch reconstruction.

Thoracic Endovascular Aortic Repair With Single/Double Chimney Technique for Aortic Arch Pathologies

Purpose: To summarize a single-center experience using the single/double chimney technique in association with thoracic endovascular aortic repairs (TEVAR) for aortic arch pathologies. Methods: From November 2007 to March 2016, 122 patients (mean age 50.4±12.7 years, range 29–80; 92 men) with aortic arch pathologies underwent TEVAR combined with single (n=101) or double (n=21) chimney grafts to reconstruct the supra-aortic branches: 21 innominate arteries, 114 left common carotid arteries, and 8 left subclavian arteries (LSA). Pathologies included type B aortic dissection (n=47), aortic arch dissection (n=49), retrograde type A aortic dissection (n=8), thoracic aortic aneurysm (n=7), penetrating aortic arch ulcer (n=9), and post-TEVAR type I endoleak (n=2). Follow-up examinations included computed tomography at 0.5, 3, 6, and 12 months and yearly thereafter. Results: The aortic stent-grafts were deployed in zone 0 (n=21), zone 1 (n=93), and zone 2 (n=8). One (0.8%) of the 122 patients died at 4 days due to a perforated peptic ulcer. Type Ia endoleaks were found intraoperatively in 13 (10.7%) patients, including 3 with the double chimney technique. Type II endoleaks occurred in 6 (4.9%) patients; 3 were treated with duct occluders in the LSA. Postoperative chimney graft migration occurred in 1 (0.8%) patient with double chimneys; additional stent-grafts were deployed in both chimneys. Median follow-up was 32.3 months, during which 1 (0.8%) patient died after a stroke at 3 months. Chimney stent-graft patency was observed in the remaining 120 patients. Two (1.7%) secondary TEVARs were performed for distal aortic dissection. Nine asymptomatic type Ia endoleaks and 1 type II endoleak persisted in follow-up; a type II endoleak in 1 patient with Marfan syndrome sealed in 52 months. Conclusion: TEVAR with the chimney technique provides a safe, minimally invasive alternative with good chimney graft patency and low postoperative mortality during midterm follow-up. The double chimney technique should be used judiciously owing to its potential complications.

Treatment of an Aortic Arch Aneurysm with Scalloped and Fenestrated Thoracic Stent Graft and Left Carotid to Subclavian Artery Bypass

We report a successful treatment of thoracic arch aneurysm using a combination of hybrid approach and a customized stent graft in a frail patient with challenging anatomy and concomitant large retrosternal goiter. The patient is an 82-year-old lady with multiple comorbidities who presented to her general practitioner for anorexia and significant weight loss. She was incidentally found to have a 6.6-cm saccular distal aortic arch aneurysm, a 5.5-cm infrarenal abdominal aortic aneurysm, and a large goiter adjacent to the left common carotid artery (CCA) with retrosternal extension. The arch aneurysm was successfully managed with an open left common carotid to left subclavian bypass followed by thoracic endovascular aneurysm repair (EVAR) with a Cook stent graft customized to the patient's anatomy incorporating a proximal scallop for the brachiocephalic artery and a fenestration for the left CCA, and Amplatzer plug for occlusion of the ostium of the left subclavian artery. There was no endoleak and she was discharged uneventfully. She is planned for staged EVAR of her abdominal aortic aneurysm at a later date. In the presence of difficult arch aneurysm anatomies, the hybrid approach with bespoke stent grafts is a feasible alternative to open aortic arch replacement.

Hybrid Repair of Ruptured Arch Aneurysm Without Sternotomy Through an Unusual Extraanatomic Bypass

A 42-year-old man experienced a complex aortic arch aneurysm rupture. He had previously undergone an operation for type A dissection and had extremely poor cardiac performance as well as deep sternal infection after the first procedure. The conventional open repair was considered to be a high risk for this patient. We therefore performed an alternative hybrid aortic procedure. The supraarch vessels were perfused through an extraanatomic bypass from an unusual and remote route, namely, the abdominal aorta. Then, stent grafts were implanted in the previously replaced aortic prostheses to exclude the aortic aneurysm. The patient recovered uneventfully with no neurologic adverse events.

Fenestrated and Branched Aortic Grafts

BACKGROUND

Abdominal and thoracic aortic aneurysms are diagnosed in 40 and 10 to 15 out of 100 000 persons per year, respectively. Fenestrated (fEVAR) and branched (bEVAR) stent grafts have been developed for abdominal juxtarenal and thoracoabdominal aneurysms. We discuss the patency and complication rates of fEVAR and bEVAR procedures and compare them with the outcome of open surgery.

METHODS

This review is based on pertinent publications from 2011 to 2014 that were retrieved by a selective literature search. The clinical outcomes of case series involving a total of more than 1500 patients are presented. The discussion takes account of recommendations contained in the literature and the authors' own experience.

RESULTS

Open surgery and aortic stent grafting have not been compared in any randomized trial to date. We identified 7 clinical series that included a total of 1270 fEVAR patients and 5 with a total of 408 bEVAR patients. The perioperative mortality after fEVAR procedures was 0-4%. Spinal cord ischemia arose in 1% of cases. The stent patency rate in visceral vessels ranged from 93 to 98%. bEVAR procedures were associated with both higher mortality (4-7%) and more common spinal cord ischemia (4-13%). 5-8% of all patients needed dialysis perioperatively, and the stent patency rate in visceral vessels was 94-97%. Preoperative renal insufficiency was a risk factor for peri-interventional death. Impaired renal function after fEVAR/bEVAR procedures was mainly associated with intermittent lower limb ischemia.

CONCLUSION

The results of fEVAR/bEVAR procedures in the last 5 years are similar to those of open surgery. The high postoperative rate of spinal cord ischemia remains a serious problem in the endovascular treatment of thoracoabdominal aortic aneurysms. The decision to implant a stent graft by an endovascular approach or to treat surgically should be made on a case-to-case basis in an interdisciplinary vascular conference.

A Comprehensive Review of In Situ Fenestration of Aortic Endografts

OBJECTIVE

Despite technical advances of fenestrated and branched endografts, endovascular exclusion of aneurysms involving renal, visceral, and/or supra-aortic branches remains a challenge. In situ fenestration (ISF) of standard endografts represents another endovascular means to maintain perfusion to such branches. This study aimed to review current indications, technical descriptions, and results of ISF.

METHOD

A review of the English language literature was performed in Medline databases, Cochrane Database, Web of Science, and Scopus using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Sixty-seven relevant papers were selected. Thirty-three papers were excluded, leaving 34 articles as the basis of the present review.

RESULTS

Most experimental papers evaluated ISF feasibility and assessed the consequences of ISF on graft fabric. Regarding clinical papers, 73 ISF procedures have been attempted in 58 patients, including 26 (45%) emergent and three (5%) bailout cases. Sixty-five (89%) ISF were located at the level of the arch, and eight (11%) in the abdominal aorta. Graft perforation was performed by physical, mechanical, or unspecified means in 33 (45%), 38 (52%), and two vessels (3%), respectively. ISF was technically successful in 68/73 (93%) arteries. At 30 days, two (3.4%) patients died in the setting of an aorto-bronchial fistula and an aorto-oesophageal fistula, respectively. No post-operative death, major complication, or endoleak was described as secondary to the ISF procedure. With follow-up between 0 and 72 months, four (6.9%) late deaths were noted, unrelated to the aorta. One (1.7%) LSA stent was stenosed without symptoms.

CONCLUSIONS

Although there may be publication bias, multiple techniques were described to perform ISF with satisfactory short-term results. Long-term data remain scarce. Aortic endograft ISF is an off-label procedure that should not be used outside emergent bailout techniques or investigational studies. A comparison with alternative techniques of preserving aortic side branches is needed.

Results From a Nationwide Registry on Scalloped Thoracic Stent-Grafts for Short Landing Zones

Purpose: To report the perioperative results and short-term follow-up of patients treated with scalloped thoracic stent-grafts. Methods: A multicenter registry in the Netherlands captured data on 30 patients (mean age 68 years; 17 men) with thoracic aortic pathology and a short (<20 mm) proximal or distal landing zone who received a custom-made scalloped stent-graft between January 2013 and February 2016. Patients were treated for saccular (n=13) aneurysms, fusiform (n=9) aneurysms, pseudoaneurysms (n=4), or chronic type B dissections (n=4). The scallop was used to preserve flow in the left subclavian artery (LSA) (n=17), left common carotid artery (n=5), innominate artery (n=1), and celiac trunk (n=7). In 7 (23%) patients, the scallop also included the adjacent artery. Results: Technical success was achieved in 28 (93%) patients. In 1 patient, a minor type Ia endoleak was observed intraoperatively, which was no longer visible on computed tomography angiography at 3 months. In another patient, the LSA was unintentionally obstructed due to migration of the stent-graft on deployment. Concomitant carotid-carotid or carotid-subclavian bypass was performed in 4 patients. There was no retrograde type A dissection or conversion to open surgery. In-hospital mortality was 3%, and the perioperative ischemic stroke rate was 3%. At a mean follow-up of 9.7 months (range <1 to 31), 29 of 30 target vessels were patent. Conclusion: The scalloped stent-graft appears to be a safe and relatively simple alternative for the treatment of thoracic aortic lesions with short landing zones. Larger patient series and long-term follow-up are required to confirm these early results.

Air Embolism During TEVAR

Purpose: To investigate the amount of gas released from Zenith thoracic stent-grafts using standard saline flushing vs the carbon dioxide flushing technique. Methods: In an experimental bench setting, 20 thoracic stent-grafts were separated into 2 groups of 10 endografts. One group of grafts was flushed with 60 mL saline and the other group was flushed with carbon dioxide for 5 minutes followed by 60 mL saline. All grafts were deployed into a water-filled container with a curved plastic pipe; the deployment was recorded and released gas was measured using a calibrated setup. Results: Gas was released from all grafts in both study groups during endograft deployment. The average amount of released gas per graft was significantly lower in the study group with carbon dioxide flushing (0.79 vs 0.51 mL, p=0.005). Conclusion: Thoracic endografts release significant amounts of air during deployment if flushed according to the instructions for use. Application of carbon dioxide for the flushing of thoracic stent-grafts prior to standard saline flush significantly reduces the amount of gas released during deployment. The additional use of carbon dioxide should be considered as a standard flush technique for aortic stent-grafts, especially in those implanted in proximal aortic segments, to reduce the risk of air embolism and stroke.

Analysis of Risk Factors for Early Type I Endoleaks After Thoracic Endovascular Aneurysm Repair

Purpose: To evaluate risk factors for early (<30 days) type I endoleak following thoracic endovascular aortic repair (TEVAR). Methods: A retrospective study was conducted of 439 consecutive patients (mean age 74.0±10.0 years; 333 men) who underwent TEVAR at a single center between June 2006 and June 2013. Pathologies included 237 aortic arch aneurysms and 202 descending thoracic aortic aneurysms (dTAA). Maximum TAA diameter was 63.6±13.7 mm. Among the distal aortic arch aneurysms, 124 required coverage of the left subclavian artery (LSA), while the remaining 113 arch aneurysms had debranching (n=40), the chimney technique (n=52), and a branched stent-graft (n=13). Eight patients with dilatation of the ascending aorta underwent arch replacement with elephant trunk prior to TEVAR. Predictive factors for type I endoleak were explored in univariate analysis and examined for each outcome using logistic regression models; results are given as the odds ratio (OR) and 95% confidence interval (CI). Results: Among 439 TEVAR cases, 37 (8.4%) had type I endoleaks on imaging at 1 month; 31 were in the 237 arch cases (13.1%). Endoleak investigation by site indicated a low incidence (3.0%) for dTAAs and markedly low (1.4%) in zone 4. Significantly more endoleaks were observed in zones 0–2 than in zone 4 (p<0.001). On univariate analysis, significant associations were found between endoleak and LSA coverage (OR 5.8, 95% CI 2.4 to 14.4, p<0.001), operative time ≥240 minutes (OR 3.7, 95% CI 1.5 to 6.2, p=0.002), and ≥270 mL of contrast (OR 2.8, 95% CI 1.4 to 5.8, p=0.004). Among the aortic branch reconstruction procedures, the chimney technique was the only maneuver associated with a significant risk of endoleak (OR 5.3, 95% CI 2.3 to 11.2, p<0.001). Arch state was not correlated with endoleaks, but ≥38-mm proximal neck diameter (OR 3.6, 95% CI 1.2 to 10.8, p=0.023), stent-graft diameter ≥40 mm (OR 9.9, 95% CI 1.4 to 30.5, p=0.015), and excessively oversized (≥14%) stent-grafts (OR 3.5, 95% CI 1.2 to 10.3, p=0.020) were; the proximal neck length was not correlated with endoleaks if a proximal neck length >10 mm can be secured. Conclusion: Risks for early type I endoleaks after TEVAR for aneurysm were landing zone 0–2, LSA coverage, large proximal neck and stent-graft diameters, excessive oversizing, and the use of the chimney technique.

Neurophysiological Intraoperative Monitoring During Aortic Arch Surgery

Circulatory management during replacement of the aortic arch is complex and involves a period of circulatory arrest to provide a bloodless field during arch vessel anastomosis. To guard against ischemic brain injury, tissue metabolic demand is reduced by systemically cooling the patient prior to circulatory arrest. Neurophysiological intraoperative monitoring (NIOM) is often used during the course of these procedures to provide contemporaneous assessment of brain status to help direct circulatory management decisions and detect brain ischemia. In this review, we discuss the characteristics of electrocerebral activity through the process of cooling, circulatory arrest, and rewarming as depicted through commonly used NIOM modalities, including electroencephalography and peripheral nerve somatosensory-evoked potentials. Attention is directed toward the role NIOM has traditionally played during deep hypothermic circulatory arrest, where it is used to define the point of electrocerebral inactivity or maximal cerebral metabolic suppression prior to initiating circulatory arrest while also discussing the evolving utility of NIOM when systemic circulatory arrest is initiated at more moderate degrees of hypothermia in conjunction with regional brain perfusion. The use of cerebral tissue oximetry by near-infrared spectroscopy as an alternative NIOM modality during surgery of the aortic arch is addressed as well. Finally, special considerations for NIOM and the detection of spinal cord ischemia during hybrid aortic arch repair and emerging operative techniques are also discussed.

Challenges of "Reverse" Aortic Arch Debranching for Repair of the Ascending Aorta by Thoracic Endovascular Aortic Repair

INTRODUCTION

Ascending aortic pathology presents a unique challenge for treatment by thoracic endovascular aortic repair (TEVAR), because of lack of adequate endograft landing zones. This report describes a unique "reverse" extra-anatomical aortic arch debranching procedure performed to enable TEVAR of the ascending aorta.

REPORT

A 71-year-old male presented with a large ascending aortic pseudoaneurysm secondary to previous arch repair anastomosis. This pathology was treated by TEVAR of the ascending aorta. To create a sufficient landing zone for the endovascular stent graft, a "reverse" extra-anatomical aortic arch debranching procedure was performed. This involved a left subclavian artery to left carotid artery bypass, left to right carotid-to-carotid bypass, ligation of proximal left common carotid artery, and embolization of the innominate artery origin.

DISCUSSION

TEVAR of the ascending aorta can be made feasible through a novel debranching procedure that creates sufficient landing zones for the endograft. This surgical approach may prove useful in patients who present with aortic arch pathology and comorbidities that prevent open surgical repair.

Short- and Long-term Results of Hybrid Arch and Proximal Descending Thoracic Aortic Repair

Purpose: To evaluate the short- and long-term outcomes of hybrid repair of the arch and proximal descending aorta in a single tertiary center for aortic disease. Methods: A retrospective analysis was performed of 55 patients (median age 67 years; 36 men) who underwent hybrid repair of thoracic aortic pathology with involvement of the arch between January 2005 and May 2015 at a single tertiary center. The pathologies included 40 (73%) with aneurysmal disease, 10 (18%) acute type B aortic dissections, 2 with acute aortic syndrome, an acute type A dissection, and left and aberrant right subclavian artery aneurysms. Seven (13%) procedures were performed as an emergency. Demographics and procedure characteristics were collected for analysis of survival and reinterventions. Results: Complete aortic debranching was performed in 14 (25%) to facilitate endograft placement in zone 0; debranching was partial in 20 (36%) patients for zone 1 deployments and 21 (38%) for zone 2. Primary technical success was achieved in 51 (93%) cases. One patient died in-hospital from aneurysm rupture following aortic debranching prior to stent-graft repair. In another, the stent-graft procedure proved infeasible and was abandoned. The other 2 technical failures were due to type Ia endoleaks. Five (9%) patients died in-hospital (4 of 48 elective and 1 of 7 emergency cases); 2 of these patients died within 30 days (4%). Eight (14%) patients had a stroke, 6 of 48 elective and 2 of the 7 emergency patients. Spinal cord ischemia was reported in 3 (6%) patients. Mean follow-up was 74.6 months. Overall cumulative survival was 70% at 1 year, 68% at 2 years, and 57% at 5 years. Reintervention to the proximal landing zone for type Ia endoleak was required in 6% of cases. The overall rate of aortic reintervention was 18% at 1 year, 21% at 2 years, and 36% at 5 years. Overall extra-anatomic graft patency was 99%. Conclusion: Hybrid repair of the aortic arch and proximal descending thoracic aorta is technically feasible, with acceptable short-term mortality. There is a low rate of proximal landing zone reintervention when hybrid techniques are used to create an adequate proximal landing zone. Extra-anatomic bypass grafts have good long-term patency. Ongoing disease progression means that further distal aortic interventions are often necessary in patients with extensive disease.

Complete Antegrade Transapical Deployment of a Branched Aortic Arch Endograft: A Porcine Feasibility Study

PURPOSE

To describe and prove the concept of a technique for complete transapical deployment of a single-branch aortic arch endograft in a porcine model.

METHODS

Eight domestic pigs underwent antegrade transapical delivery of a single-branch arch endograft, including a mating stent-graft to the innominate artery. Technical feasibility, operating time, radiation parameters, and hemodynamic changes were studied according to a standardized protocol during baseline (T0), after establishing the transapical access and through-and-through wire (T1), and after stent-graft deployment (T2). Myocardial and cerebral blood flow status was assessed using fluorescent microspheres (FM) and transit-time flow measurement (TTFM) monitoring.

RESULTS

Transapical access, introduction and deployment of the endograft, side branch catheterization, and deployment of the mating stent-graft were feasible in 6 of 8 animals. One animal died due to irreversible heart rhythm disorders and one due to accidental graft rotation during deployment, resulting in unintended coverage of the innominate artery. The mean operating and fluoroscopy times were 223±11 minutes and 27.2±6.3 minutes, respectively. During introduction and deployment of the stent-graft, transient aortic valve insufficiency occurred in all animals. Hemodynamic stability recovered within 10 minutes after retrieval of the delivery system in all animals. The innominate artery was patent, with unchanged TTFM measurements throughout the procedure. FM evaluation revealed stable cerebral blood flow.

CONCLUSION

An antegrade transapical access to the aortic arch for implantation of a single-branch endograft is feasible in a porcine model with reversible impact on hemodynamic measures during deployment. Transapical access allows deployment of a complex endograft through a single large-bore access site in a porcine model.

Multivariate Analysis of Risk Factors of Cerebral Infarction in 439 Patients Undergoing Thoracic Endovascular Aneurysm Repair

The aim of the study is to identify the potential risk factors of cerebral infarction associated with thoracic endovascular aneurysm repair (TEVAR). TEVAR was developed as a less invasive surgical alternative to conventional open repair for thoracic aortic aneurysm treatment. However, outcomes following TEVAR of aortic and distal arch aneurysms remain suboptimal. Cerebral infarction is a major concern during the perioperative period. We included 439 patients who underwent TEVAR of aortic aneurysms at a high-volume teaching hospital between July 2006 and June 2013. Univariate and multivariate logistic regression analyses were performed to identify perioperative cerebral infarction risk factors. Four patients (0.9%) died within 30 days of TEVAR; 17 (3.9%) developed cerebral infarction. In univariate analysis, history of ischemic heart disease and cerebral infarction and concomitant cerebrovascular disease were significantly associated with cerebral infarction. "Shaggy aorta" presence, left subclavian artery coverage, carotid artery debranching, and pull-through wire use were identified as independent risk factors of cerebral infarction. In multivariate analysis, history of ischemic heart disease (odds ratio [OR] 6.49, P = 0.046) and cerebral infarction (OR 43.74, P = 0.031), "shaggy aorta" (OR 30.32, P < 0.001), pull-through wire use during surgery (OR 7.196, P = 0.014), and intraoperative blood loss ≥800 mL (OR 24.31, P = 0.017) were found to be independent risk factors of cerebral infarction. This study identified patient- and procedure-related risk factors of cerebral infarction following TEVAR. These results indicate that patient outcomes could be improved through the identification and management of procedure-related risk factors.