Is the frozen elephant trunk frozen?

Total aortic arch replacement using a frozen elephant trunk device: Results of a 1-year US multicenter trial

OBJECTIVE

In this prospective US investigational device exemption trial, we assessed the safety and 1-year clinical outcomes of the Thoraflex Hybrid device (Terumo Aortic) for the frozen elephant trunk technique to repair the ascending aorta, aortic arch, and descending thoracic aorta.

METHODS

For the trial, which involved 12 US sites, 65 patients without rupture were recruited into the primary study group, and 9 patients were recruited into the rupture group. All patients underwent open surgical repair of the ascending aorta, aortic arch, and descending thoracic aorta in cases of aneurysm and/or dissection. The primary end point was freedom from major adverse events (MAE), defined as permanent stroke, permanent paraplegia/paraparesis, unanticipated aortic-related reoperation (excluding reoperation for bleeding), or all-cause mortality.

RESULTS

In the primary study group, 2 patients were lost to follow-up at 1 year. Freedom from MAE at 1 year was 81% (51/63). Seven patients (11%) died (including 2 before 30 days or discharge), 3 patients (5%) suffered permanent stroke, and 3 (5%) developed permanent paraplegia/paraparesis. Twenty-six patients (41%) underwent planned extension procedures, including 22 endovascular procedures within a median of 122 (interquartile range, 64-156) days. In the aortic rupture group, 2 patients were lost to follow-up at 1 year. Freedom from MAE at 1 year was 71% (5/7). One patient (14%) died, 2 patients (29%) had permanent stroke, and none had permanent paraplegia/paraparesis. No extension procedures were performed in the rupture group.

CONCLUSIONS

One-year results with the Thoraflex Hybrid device are acceptable. Long-term data are necessary to assess the durability of these repairs.

The Fate of Conventional Elephant Trunk in the Frozen Elephant Trunk Era

Conventional elephant trunk (cET) and frozen elephant trunk (FET) are two distinct approaches to the surgical treatment of thoracic aortic aneurysms and dissections. With the advent and growing uptake of endovascular technologies, FET is becoming increasingly popular for its potential to be performed as a single-stage operation with better aortic remodeling and less risk of graft kinking than the traditional two-stage cET procedure. However, FET has been associated with a higher risk of spinal cord ischemia and its use in patients with connective tissue disorder remains controversial. The current review aimed to reflect on recent evidence surrounding the application of cET and FET to different types of aortic pathology in both acute and elective settings. Another scope of this review was to compare the characteristics of the currently available FET commercial devices on the global market. Our findings highlight that when the pathology is confined to the proximal descending aorta, such as in Dsine, intervention is often single-staged and false lumen (FL) thrombosis is achieved with good effect. FET remains limited by spinal cord injury and applicability in patients with connective tissue disorder, although some groups have started to circumvent associated complications, likely due to growing surgical expertise. Many other aortic diseases do require second-stage intervention, and even in these cases, there appears to be lower in-hospital mortality when using FET over cET. This is possibly due to the higher rate of endovascular completion facilitated by the completed landing zones created during FET. FET is trending toward becoming the universal treatment modality for extending repair to the descending aorta.

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.

Early and Long-Term Follow-Up for Chronic Type B and Type Non-A Non-B Aortic Dissection Using the Frozen Elephant Trunk Technique

Background: This study aimed to evaluate the early and long-term outcomes of a single center using a frozen elephant trunk (FET) procedure for chronic type B or non-A non-B aortic dissection.

Methods: From February 2009 to December 2019, 79 patients diagnosed with chronic type B or non-A non-B aortic dissection who underwent the FET procedure were included in the present study. We analyzed operation mortality and early and long-term outcomes, including complications, survival and interventions.

Results: The operation mortality rate was 5.1% (4/79). Spinal cord injury occurred in 3.8% (3/79), stroke in 2.5% (2/79), and acute renal failure in 5.1% (4/79). The median follow-up time was 53 months. The overall survival rates were 96.2, 92.3, 88.0, 79.8, and 76.2% at 1/2, 1, 3, 5 and 7 years, respectively. Moreover, 79.3% of patients did not require distal aortic reintervention at 7 years. The overall survival in the subacute group was superior to that in the chronic group (P = 0.047).

Conclusion: The FET technique is a safe and feasible approach for treating chronic type B and non-A non-B aortic dissection in patients who have contraindications for primary endovascular aortic repair. The technique combines the advantages of both open surgical repair and endovascular intervention, providing comparable early and long-term follow-up outcomes and freedom from reintervention.

Ab ovo: Factors Affecting the Radial Stiffness of Thoracic Aorta Stent-Grafts

The aim of the investigation was to study the factors influencing the radial stiffness of the thoracic aorta stent-grafts with the stent elements made of nitinol tubes by laser cutting and thermal shape setting.

Risk factor analysis of clinical outcomes of total aortic arch replacement and frozen elephant trunk with aortic balloon occlusion

Background

Total aortic arch replacement (TAR) with frozen elephant trunk (FET) requires hypothermic circulatory arrest (HCA) for 20 min, which increases the surgical risk. We invented an aortic balloon occlusion (ABO) technique that requires 5 min of HCA on average to perform TAR with FET and investigated the possible merit of this new method in this study.

Methods

This retrospective study included consecutive patients who underwent TAR and FET (consisting of 130 cases of ABO group and 230 cases of conventional group) in Fuwai Hospital between August 2017 and February 2019. In addition to the postoperative complications, the alterations of blood routine tests, alanine transaminase (ALT) and aspartate transaminase (AST) during in-hospital stay were also recorded.

Results

The 30-day mortality rates were similar between ABO group (4.6%) and conventional group (7.8%, P = 0.241). Multivariate analysis showed ABO reduced postoperative acute kidney injury (23.1% vs. 35.7%, P = 0.013) and hepatic injury (12.3% vs. 27.8%, P = 0.001), and maintained similar cost to patients (25.5 vs. 24.9 kUSD, P = 0.298). We also found that AST was high during intensive care unit (ICU) stay and recovered to normal before discharge, while ALT was not as high as AST in ICU but showed a rising tendency before discharge. The platelet count showed a rising tendency on postoperative day 3 and may exceed the preoperative value before discharge.

Conclusions

The ABO achieved the surgical goal of TAR with FET with an improved recovery process during the in-hospital stay.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01643-3.

Outcome of the frozen elephant trunk procedure as a redo operation

 

OBJECTIVES

The goal of this study was to determine the outcome of patients undergoing an elective frozen elephant trunk (FET) procedure as a redo operation following previous cardiac surgery.

METHODS

One hundred and eighteen consecutive patients underwent FET procedures between October 2010 and October 2019 at our centre. Patients were registered in a dedicated database and analysed retrospectively. Clinical and follow-up characteristics were compared between patients undergoing a FET operation as a primary (primary group) or a redo procedure (redo group) using logistic regression and Cox regression analysis. Emergency procedures (n = 33) were excluded from the analysis.

RESULTS

A total of 36.5% (n = 31) of the FET procedures were redo operations (redo group) and 63.5% (n = 54) of the patients underwent primary surgery (primary group). There was no significant difference in the 30-day mortality [primary group: 7.4%; redo group: 3.2%; 95% confidence interval (CI) (0.19-35.29); P = 0.63] and the 3-year mortality [primary group: 22.2%; redo group: 16.7%; 95% CI (0.23-3.23); P = 0.72] between redo and primary cases. Furthermore, the adjusted statistical analysis did not reveal significant differences between the groups in the occurrence of transient or permanent neurological deficit, paraplegia, acute renal failure and resternotomy. The redo group showed a higher rate of recurrent nerve palsy, which did not reach statistical significance [primary group: 3.7% (n = 2); redo group: 19.4% (n = 6); P = 0.091].

CONCLUSIONS

Elective FET procedures as redo operations performed by a dedicated aortic team following previous cardiac surgery demonstrate an adequate safety profile.

[Quo vadimus? Fundamental problems of developing hybrid prostheses of thoracic aorta]

This article is a review briefly characterizing the state of the art of hybrid surgery of the thoracic aorta using the frozen elephant trunk technique worldwide and in Russia, also discussing unsolved problems of fundamental science, being key issues in creation of new models of hybrid prostheses of the thoracic aorta. The main attention is paid to the problem of radial stiffness of the stent-graft portion of the prosthesis. Performed is a detailed analysis of the factors influencing this characteristic of the sent graft: shape, size and number of cells of the stent element, thickness of the nitinol wire it is made of, method of edge connection, nitinol properties depending on the alloy grade and methods of thermoforming. It is shown that excessive stiffness leads to the development of d-SINE syndrome. This is followed by discussing the problem of optimal stiffness of stent grafts, based on the design of stent graft elements and elastic properties of the wall of the true channel of a dissecting aortic aneurysm. Also proposed is an approach to solving the problem of d-SINE, consisting in creation of conical stent grafts and/or a gradual decrease of radial stiffness of stent elements in the direction of the distal portion. Comprehensively addressed are disadvantages of the graft portion of the prosthesis, in 95% of items made of polyethylene terephthalate fiber: susceptibility to degradation associated with manufacturing defects and intraoperative microdamages, abrasive effect in the zone of contact with stent elements, partial postoperative hydrolysis and an inflammatory reaction to a foreign body, often being clinically pronounced. Also touched upon are certain aspects of creating hermetic coatings of the graft portion, with the use of vancomycin possessing low cytotoxicity as part of an antibacterial component being promising. As a whole, it is demonstrated that advances in creating a novel generation of hybrid prostheses should be associated with new approaches and materials, to be obtained at the junction of medicine and fundamental sciences.

The strategy of cardiopulmonary bypass for total aortic arch replacement and the frozen elephant trunk technique with aortic balloon occlusion

Objective

To investigate the use of the aortic balloon occlusion technique to assist total aortic arch replacement (TAR) with frozen elephant trunk (FET) to shorten the lower body circulatory arrest (CA) time and raise the nadir temperature during cardiopulmonary bypass.

Methods

This retrospective study reviewed consecutive patients that underwent aortic balloon occlusion to assist TAR with FET and patients that received conventional TAR with FET procedures. Preoperative characteristics, perioperative characteristics and postoperative outcomes were compared between the two groups.

Results

The study included130 patients treated with aortic balloon occlusion and 230 patients treated with conventional TAR with FET. The 30-day mortality rate was similar between the aortic balloon occlusion and conventional groups (4.62% versus 7.83%, respectively). Multivariate analysis showed that aortic balloon occlusion reduced the incidence of acute kidney injury, hepatic injury and red blood cell transfusion. The application of aortic balloon occlusion reduced the mean ± SD CA time from 17.24 ± 4.36 min to 6.33 ± 5.74 min, with the target nadir nasal temperature being increased from 25°C to 28°C.

Conclusion

The aortic balloon occlusion technique achieved significant improvements in reducing complications, but this did not translate into lower 30-day mortality.

Early outcome of aortic balloon occlusion during total aortic arch replacement with the frozen elephant trunk technique for aortic dissection

OBJECTIVES

The aim of this study was to propose and evaluate the new operative technique of aortic balloon occlusion in total aortic arch replacement (TAR) with the frozen elephant trunk that can significantly decrease the time of circulatory arrest and increase the hypothermic cardiopulmonary bypass (CPB) temperature.

METHODS

Between 2010 and 2018, 1335 patients with aortic dissection who underwent TAR with the frozen elephant trunk were included in the study. The newest 80 cases were treated with aortic balloon occlusion. To illustrate the difference with the new procedure, 1255 conventional TAR cases served as the historical control. Femoral and right axillary artery cannulations were used for CPB and antegrade selective cerebral perfusion. Circulatory arrest was implemented at the nasopharyngeal temperature of 28°C with continuous antegrade selective cerebral perfusion. After the stent graft was inserted into the true lumen of the descending aorta, the aortic balloon in a sheath was deployed into the stent graft and positioned at the metal part of the stent graft. When the balloon was inflated with enough saline to compress the stent graft, the sheath was simultaneously pressed by hand to properly fix the balloon and avoid displacement. Then femoral perfusion could be resumed.

RESULTS

The aortic balloon occlusion technique was successful in all patients, with the median duration of circulatory arrest being 5 (interquartile range 3-7) min. The 30-day mortality rate was 6.25% (5/80), whereas with the conventional method it was 9.40% (118/1255). The postoperative conscious revival (8.67 vs 11.40 h, P < 0.001) and mechanical ventilation times (19.70 vs 24.45 h, P = 0.02) were significantly shorter. Decreases in postoperative acute kidney injuries (13.75% vs 32.11%, P = 0.001) and liver injuries (8.75% vs 37.61%, P < 0.001) were also observed. The patients were transfused with lesser quantities of red blood cells, plasma and platelets.

CONCLUSIONS

The aortic balloon occlusion technique is a feasible way to shorten circulatory arrest significantly, to obviate the need for deep hypothermia in TAR with the frozen elephant trunk and to provide favourable protective effects on the central nervous, haematological and visceral systems. With these satisfactory results, this technique deserves further investigation.

The frozen elephant trunk surgery: a systematic review analysis

The frozen elephant trunk might be considered one of the most appreciated innovations during the last decades to treat complex thoracic aortic lesions. Many useful tips have been progressively introduced to standardize the procedures and, nowadays, the improved post-operative outcomes contributed to spread the procedure. The following article will provide a comprehensive review analysis of the Frozen Elephant Trunk (FET) technique, throughout the current available devices, possible surgical indications and primary post-operative complications.