The frozen elephant trunk surgery: a systematic review analysis

Optimal size of Frozenix for true thoracic aneurysms: is downsizing an option?

OBJECTIVE

During total arch replacement (TAR) using frozen elephant trunk (FET) technique with Frozenix for true thoracic aortic aneurysm (tTAA), oversized FET tends to be chosen similar to the endovascular devise selection. However, the oversized FET is considered a risk factor for intimal injury. The appropriate size selection of FET remains insufficiently understood.

METHODS

Between October 2014 and March 2022, a total of 49 patients underwent TAR using Frozenix for tTAA. Out of 49 patients, four patients planned to staged surgery were excluded, 19 patients were operated on with an undersized Frozenix compared with the descending aorta (undersized FET group) and in 26 patients an equal or oversized Frozenix was used (oversized FET group). Clinical outcomes and postoperative diameter changes were investigated.

RESULTS

In-hospital mortality was 0%. The mean diameter of Frozenix and the descending aorta was 30.7 mm and 28.8 mm, respectively, in the oversized FET group, and 26.7 mm and 30.1 mm in the undersized FET group. Postoperative computed tomography (CT) demonstrated no endoleaks not only in the oversized FET group but also in the undersized FET group. CT also revealed that undersized FET had expanded more than the original diameter in all cases except for two, with an average of 2.47 ± 1.53 mm. Additionally, the descending aorta covered with Frozenix shrank in 10 patients (53%). Postoperative adverse aortic events were not observed.

CONCLUSIONS

Undersized Frozenix tightly fit the descending aorta and resulted in complete sealing without endoleaks. Oversized FET is not strictly necessary considering the size-related adverse complications.

Frozen elephant trunk technique using hybrid grafts: 15-year outcomes from a single-centre experience

OBJECTIVES

The purpose of the study is to compare the short- and long-term outcomes of the frozen elephant trunk (FET) technique based on 2 different hybrid grafts implanted from January 2007 to July 2022.

METHODS

The study includes patients who underwent an elective or emergency FET procedure. Short-term, long-term mortality and freedom from thoracic endovascular aortic repair (TEVAR) were the primary end points. Analyses were carried out separately for the periods 2007-2012 and 2013-2022.

RESULTS

Of the 367 enrolled, 49.3% received E-Vita Open implantation and 50.7% received Thoraflex Hybrid implants. Overall mean age was 61 years [standard deviation (SD) = 11] and 80.7% were male. The average annual volume of FET procedures was 22.7 cases/year. Compared to E-Vita Open, patients implanted with Thoraflex Hybrid grafts were more likely to receive distal anastomosis in zone 2 (68.3% vs 11.6%, P < 0.001) with a shorter stent portion, mean = 103mm (SD = 11.3) vs mean = 149 mm (SD = 12.7; P < 0.001) and they underwent a reduced visceral ischaemia time, mean = 42.5 (SD = 14.2) vs mean= 61.0 (SD = 20.2) min, P < 0.001. In the period 2013-2022, overall survival at 1, 2 and 5 years was 74.8%, 72.5% and 63.2% for Thoraflex and 73.2%, 70.7% and 64.1% for E-Vita, without significant differences between groups (log-rank test = 0.01, P = 0.907). Overall freedom from TEVAR at 1, 2 and 5 years was 66.7%, 57.6% and 39.3% for Thoraflex and 79%, 69.7% and 66% for E-Vita, with significant differences between groups (log-rank test = 5.28, P = 0.029). In a competing risk analysis adjusted for chronic/residual aortic syndromes and stent diameter, the Thoraflex group was more likely to receive TEVAR during follow-up (subdistribution hazard ratio SHR = 2.12, 95% confidence interval 1.06-4.22).

CONCLUSIONS

The FET technique addresses acute and chronic arch disease with acceptable morbidity and mortality. Downstream endovascular reinterventions are very common during follow-up.

A Systematic Review of Contemporary Outcomes from Aortic Arch In Situ Laser Fenestration During Thoracic Endovascular Aortic Repair

BACKGROUND

In situ laser fenestrated endovascular aortic repair (L-FEVAR) is a novel and creative solution for complex aortic pathologies in the urgent and emergency setting. Outcomes of this technique, however, are poorly reported. We sought to evaluate the efficacy, safety, and outcomes of L-FEVAR in aortic arch pathologies.

METHODS

A systematic literature review and analysis were conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses and Cochrane guidelines. A search was conducted using Google, PubMed, and Scopus to identify studies evaluating L-FEVAR. Two independent reviewers determined study inclusion. Case reports and series including < 10 patients were excluded. Reviewers also assessed the methodological quality and extracted data regarding outcomes. A meta-analysis of endoleak event rates was conducted using a fixed-effect model due to small sample size.

RESULTS

Eight studies met inclusion criteria between 2013 and 2021. Most studies were retrospective (87.5%) with median follow-up duration of 12.5 months (range 10-42). There were 440 patients included (range 15-148), mostly men (64%). Mean age was 61 years (range 53-68). Included patients were all symptomatic with L-FEVAR being technically successful in 93.3% of cases. The main indication for aortic arch intervention was aortic dissection. Single fenestrations occurred most frequently (68%), followed by triple (22%) then double fenestrations (9%). Meta-analysis of 8 studies (n = 440) demonstrated an endoleak event rate of 0.06 (95% confidence interval 0.04-0.09, P < 0.001) with no observed statistically significant heterogeneity of effects (Q = 7.91, P = 0.34). The median operative time was 162 min (range 53-252) with median length of stay of 10 days (range 7-17). Primary branch patency was 96.6%. Secondary patency rate was 97%. Pooled complication rates such as endoleak occurred in 4.8%, stroke in 2.0%, spinal cord ischemia in 0.2%, retrograde dissection in 0.9%, and 30-day death in 2.0%. Access complications occurred in 0.4%. Antiplatelet regimen was poorly reported in the study cohort.

CONCLUSIONS

In situ laser fenestration is a feasible, safe, and effective approach to treat aortic arch disease in patients who are unsuitable for open or custom-made endovascular means. High technical success and excellent short-term branch patency can be achieved. These single-institution series exhibit promising short-term outcomes. In a similar paradigm to investigational device exemptions studies for custom-made and physician modified endografts, these preliminary data make a persuasive argument for larger long-term multi-institutional prospective study of this promising technique.

The evolution of arch surgery: Frozen elephant trunk or conventional elephant trunk?

Treatment of aortic arch aneurysms and dissections require highly complex surgical procedures with devastating complications and mortality rates. Currently, repair of the complete arch until the proximal descending thoracic aorta consists of a two-stage procedure, called elephant trunk (ET) technique, or a single stage a single-stage technique referred to as frozen elephant trunk (FET). There is conflicting evidence about the perioperative results of ET in comparison with FET. We carried out a meta-analysis to investigate possible differences in perioperative and early (up to 30 days) outcomes of ET vs. FET, particularly for mortality, spinal cord injury (SCI), stroke, and renal failure. We also performed a meta-regression to explore the effects of age and sex as possible cofactors. Twenty-one studies containing data from interventions conducted between 1997 and 2019 and published between 2008 and 2021 with 3153 patients (68.5% male) were included. ET was applied to 1,693 patients (53.7%) and FET to 1460 (46.3%). Overall mortality after ET was 250/1693 (14.8%) and after FET 116/1460 (7.9%). Relative risk (RR) and 95% confidence interval (CI) were 1.37 [1.04 to 1.81], p = 0.027. There was no significant effect of age and sex. SCI occurrence after the second stage of ET was 45/1693 (2.7%) and after FET 70/1,460 patients (4.8%) RR 0.53 [0.35 to 0.81], p = 0.004. Age and sex were not associated with the risk of SCI. No significant differences were observed between ET and FET in the incidence of stroke and renal failure. Our results indicate that ET is associated with higher early mortality but lower incidence of SCI compared to FET. When studies published in the last 5 years were analyzed, no significant differences in mortality or SCI were found between ET and FET. This difference is attributed to a decrease in mortality after ET, as the mortality after FET did not change significantly over time.

Total endovascular repair of a malpositioneted frozen elephant trunk with Thoraflex hybrid prosthesis: A case report

We report a case of a 56-year-old male who underwent Frozen Elephant Trunk procedure for residual type A chronic aortic dissection, complicated by the release of the distal endovascular portion of the hybrid prosthesis in the false lumen. This complication was successfully treated with a totally endovascular approach.

Adverse complications of frozen elephant trunk, do we have enough quality data?

BACKGROUND

Frozen elephant trunk has in recent times become a mainstay for total arch replacement in aortovascular surgery and is indicated to treat a spectrum of complex aortic pathologies. However, despite associated excellent postoperative results it is incredibly important to recognize potential adverse complications such as negative aortic remodeling, endoleak, and distal stent-graft induced new entry so that outcomes can be further improved.

AIM OF THE STUDY

Below we provide commentary on a recent article in the Journal of Cardiac Surgery discussing the topic.

CONCLUSIONS

Despite the fascinating outcomes of this systematic review and meta-analysis the heterogeneity of the literature regarding these adverse outcomes remains an issue which can only be solved with large multicenter trials directly comparing graft types as well as indications for surgery.

Endovascular reintervention after frozen elephant trunk: where is the evidence?

The introduction of the single-step hybrid frozen elephant trunk (FET) procedure for total arch replacement has revolutionized the field of aortovascular surgery. FET has proven to achieve excellent results in the repair of complex thoracic aorta pathologies. However, there remains a risk of reintervention post-FET for a variety of causes. This secondary intervention can either be performed endovascular, with thoracic endovascular aortic repair (TEVAR), or via open surgery. Multiple FET hybrid prosthesis are commercially available, each requiring different rates of endovascular reintervention. The current review will focus on providing an overview of the reintervention rates for main causes in relation to the FET grafts on the market. In addition, strategies to prevent reintervention will be highlighted. A comprehensive literature search was conducted on multiple electronic databases including PubMed, Ovid, Scopus and Embase to highlight the evidence in the literature on endovascular reintervention after FET. The main causes for secondary intervention are distal stent graft-induced new entry (dSINE), endoleak and negative aortic remodeling, and to a much lesser extent, graft kinking and aorto-esophageal fistulae. In addition, it is clear that the Thoraflex Hybrid (Terumo Aortic, Inchinnan, UK) is the superior FET device, showing excellent reintervention rates for all the above causes. Interestingly, the choice of FET device as well as its size and length can help prevent the need for reintervention. The FET procedure is indeed associated with excellent clinical outcomes, however, the need for reintervention may still arise. Importantly, the Thoraflex Hybrid prosthesis has shown excellent results when it comes to endovascular reintervention. Finally, several strategies exist that can prevent reintervention.

Kinking of Frozen Elephant Trunk Hybrid Prostheses: Incidence, Mechanism, and Management

Introduction

Kinking of the Frozen Elephant Trunk (FET) stent graft is one of the most devastating complications of the FET procedure. It can present post-operatively with reduced arterial pressures in the lower limbs and intermittent claudication. However, it can also be visualized intra-operatively by the surgeons. Unresolved kinking of the stent graft can result in intraluminal thrombus formation and subsequent multi-organ septic emboli.

Aims

The main scope of this review is to collate, summarize and present all the evidence in the literature on kinking of FET stent grafts.

Methods

We carried out a comprehensive literature search on multiple electronic databases including PubMed, EMBASE, Ovid, and Scopus to collate all research evidence on the incidence, mechanism, and management of FET graft kinking.

Results

Incidence of kinking is variable, ranging from 0% to 8% in the literature, with varying rates associated with each stent graft type. The Thoraflex Hybrid^TM prosthesis seemed to be the most commonly used and superior graft, and out of all the 15 cases of kinking reported in the literature, 5 (33.3%) were associated with just the Frozenix graft which had the highest incidence. There are multiple theories regarding the mechanism of kinking, including the direction of blood flow, the length of the stent grafts used, and the position of the prosthesis in relation to the flexure of the aorta. Multiple reparative management techniques have been suggested in the literature and include total endovascular repair, open repair, balloon dilatation, and deploying a second stent graft.

Conclusion

Graft kinking is one of the most critical complications of the FET technique. Its life-threatening sequelae warrant appropriate follow-up of these patients post-operatively, in addition to time management if kinking is suspected. Given the limited evidence in the literature, future studies should incorporate graft kinking into their outcomes reporting.

Development of aortic arch surgery in Bologna and reflections on current strategy of cerebral protection

Complications after open arch repair much decreased over time thanks to better methods of organ and cerebral protection. The crossroads was the introduction of antegrade cerebral perfusion as a method of cerebral protection. Other intraoperative techniques also contributed to facilitate arch reconstruction, such as performing circulatory arrest at higher core temperature, using hybrid grafts or endografts, and monitoring cerebral functions during the procedure. As part of this exciting process, we go back in Bologna in the early 1970s to relive some of these fundamental steps on aortic arch surgery. Today a large number of issues on cerebral protection remain for which we have incomplete responses. Probably, a super specialized approach and endovascular techniques will continue to improve the quality of care of patients with different arch pathologies.

Incidence of Distal Stent Graft Induced New Entry vs. Aortic Remodeling Associated With Frozen Elephant Trunk

Background

The introduction of the frozen elephant trunk (FET) technique for total arch replacement (TAR) has revolutionized the field of aortivascular surgery by allowing hybrid repair of complex aortic pathologies in a single step through combining an open surgical approach with an endovascular one. FET has been associated with favorable aortic remodeling, however, its is also associated with development of distal stent graft induced new entry (dSINE) tears postoperatively. The rate of aortic remodeling and the incidence of dSINE have been linked together, in addition, there seems to be a relationship between these two variables and FET insetion length as well as graft size.

Aims

The scope of this review is to highlight the rate of aortic remodeling as well the incidence of dSINE associated with different FET devices available commercially. This review also aimed to investigate the relationship between aortic remodeling, dSINE, FET insertion length and FET graft size.

Methods

We conducted a comprehensive literature search using multiple electronic databases including PubMed, Ovid, Scopus and Embase in order to collate all research evidence on the above mentioned variables.

Results

Thoraflex™ Hybrid Plexus seems to yield optimum aortic remodeling by promoting maximum false thrombosis as well true lumen expansion. Thoraflex Hybrid™ is also associated with the lowest incidence of dSINE post-FET relative to the other FET devices on the market. Aortic remodeling and dSINE do influence each other and are both linked with FET graft length and size.

Conclusion

The FET technique for TAR shows excellent aortic remodeling but is associated with a considerable risk of dSINE development. However, Thoraflex™ Hybrid has demonstrated itself to be the superior FET device on the aortic arch prostheses market. Since aortic remodeling, dSINE, FET insertion length and stent graft size are all interconnect, the choice of FET device length and size must be made with great care for optimum results.

“Branch-First total arch replacement”: a valuable alternative to frozen elephant trunk in acute type A aortic dissection?

The "Branch-First total arch replacement" technique has been used extensively in both elective and acute situations, including in type A aortic dissection. The focus of the Branch-First technique is to reduce the risk of neurological and end-organ dysfunction associated with arch replacement by optimising neuroprotection, distal organ perfusion and myocardial protection. The Branch-First technique is a valuable alternative to the frozen elephant trunk (FET) technique in type A aortic dissection, providing a stable landing zone for subsequent interventions on the distal aorta should they be required. Combining the Branch-First technique with FET in appropriate cases can further improve outcomes. We discuss the merits of the Branch-First technique, and contrast them to those of FET techniques for repair of type A aortic dissection.

Frozen Elephant Trunk in Aortic Arch Disease: Different Devices for Different Pathologies

The frozen elephant trunk technique (FET) requires the use of a pre-assembled hybrid prosthesis consisting of a standard Dacron vascular portion to replace the aortic arch and a stent graft component, which is placed into the proximal descending thoracic aorta (DTA) anterogradely in the proximal descending thoracic aorta. In Europe, two hybrid prostheses are available: the E-evita Open Plus hybrid stent graft system provided by JOTEC (Hechingen, Germany) and the ThoraflexTM Hybrid (Vascutek, Inchinnan Scotland). Recommendations for use are extensive pathologies of the arch in case of acute and chronic aortic dissection, degenerative aneurysm and intramural hematoma. The FET approach allows the replacement of the whole arch in one stage with the option of direct treatment of the proximal descending thoracic aorta based on the stent component, creating a safe landing zone for further endovascular treatment more distally. The remarkable feature of this technique is the possibility to perform more proximally (from zone 3 to zone 0) the distal anastomosis in to the arch. This allows for an easier distal anastomosis, reduced hypothermic circulatory arrest time and decreased risk of paraplegia (<5%). Early results are promising and according to the most recent series the rate of developing post-operative renal insufficiency ranges from 3 to 10%, the risk of stroke from 3% to 8% and mortality from 8-15%. The aim of the article will be to provide some knowledge about the use and application of FET procedures in different aortic situations.

"Proximalization is Advancement"-Zone 3 Frozen Elephant Trunk vs Zone 2 Frozen Elephant Trunk: A Literature Review

Over the decades, the Frozen Elephant Trunk (FET) technique has gained immense popularity allowing simplified treatment of complex aortic pathologies. FET is frequently used to treat aortic conditions involving the distal aortic arch and the proximal descending aorta in a single stage. Surgical preference has recently changed from FET procedures being performed at Zone 3 to Zone 2. There are several advantages of Zone 2 FET over Zone 3 FET including reduction in spinal cord injury, visceral ischemia, neurological and cardiovascular sequelae. In addition, Zone 2 FET is a technically less complicated procedure. Literature on the comparison between Zone 3 and Zone 2 FET is scarce and primarily observational and anecdotal. Therefore, further research is warranted in this paradigm to substantiate current surgical treatment options for complex aortic pathologies. In this review, we explore literature surrounding FET and the reasons for the shift in surgical preference from Zone 3 to Zone 2.

Frozen elephant trunk in total arch replacement: A systematic review and meta-analysis of outcomes and aortic proximalization

BACKGROUND AND AIM OF THE STUDY

The frozen elephant trunk (FET) procedure became a popular entity for utilization in aortic arch aneurysm disease. However, its proper mortality and morbidities as well as the predictors of outcomes are poorly identified. This systematic review and meta-analysis explore FET outcomes and its predictors with a focus on zone aortic proximalization.

METHODS

We searched PubMed/MEDLINE, EMBASE, and Scopus databases from their beginning to June 2020 to find studies reporting the outcomes of the FET procedure for the total arch replacement (TAR).

RESULTS

A total of 64 studies including 7967 patients were evaluated. The pooled estimates of cerebrovascular accidents, paraplegia, renal failure, and in-hospital mortality were 7.104 (95% confidence interval [CI], 5.691-8.661; I²  = 78.53%), 3.465 (95% CI, 2.852-4.136; I²  = 15.96), 14.969 (95% CI, 11.361-18.977; I²  = 91.26%), and 8.933 (95% CI, 7.128-10.919; I²  = 78.51%), respectively. Stratification by the geographical locations and by the aortic pathologies led to lower heterogeneity, but not for renal failure. The distal anastomosis in Zone 2 was associated with a lower rate of renal failure compared with Zone 3 (odds ratio, 0.54; 95% CI, 0.36-0.81; p = .003; I²  = 0%).

CONCLUSIONS

The FET procedure for TAR can be performed with acceptable mortality and morbidities among patients with complex aortic pathologies. Moreover, the distal anastomosis in Zone 2 was associated with lower renal failure compared to Zone 3.