The Bologna experience with the Thoraflex™ hybrid frozen elephant trunk device

The frozen elephant trunk: an overview of hybrid prostheses

INTRODUCTION

Thoracic aortic pathologies implicating the aortic arch and the descending thoracic aorta (DTA) are primarily managed with total aortic arch replacement (TAR). This can be performed as a single-procedure hybrid fashion using the frozen elephant trunk technique (FET), which utilizes hybrid prosthesis. Nevertheless, FET presents certain challenges such as distal stent graft-induced new entry (dSINE), negative aortic remodeling, and reintervention.

AREAS COVERED

The narrative review provides an overview of the four majors FET prosthesis, highlighting their design features, mechanical properties, configurations, and variants, and evaluating their clinical outcomes reported in the literature. The leading prosthesises were compared through their mortality and survival rates, neurological outcomes, dSINE, aortic remodeling, and reintervention rates.

EXPERT OPINION

Four FET devices can be considered the main option on the global market; Thoraflex, E-Vita, Cronus, and Frozenix J Graft. Each hybrid prosthesis (HP) features unique design characteristics, resulting in varying clinical outcomes. Thoraflex and E-Vita are the most widely used and investigated HPs, whilst the use of Cronus and Frozenix is geographically confined to mainly manufacturers' countries. The rates of early mortality, stroke, SCI, dSINE, and reintervention rates were found to be comparable among the four devices, yet, Thoraflex seemed to offer the most optimal clinical profile.

In-hospital thromboembolic complications after frozen elephant trunk aortic arch repair

OBJECTIVE

This study evaluated the frequency and clinical impact of thromboembolic complications after frozen elephant trunk aortic arch repair using the Thoraflex device (Terumo Aortic).

METHODS

A total of 128 consecutive patients (mean age 67.9 ± 13.7 years, 31.0% female) underwent frozen elephant trunk aortic arch repair using the Thoraflex device between September 2014 and May 2021 in 4 Canadian centers. Patient baseline characteristics, intraoperative details, and frozen elephant trunk thromboembolic complications were collected retrospectively and analyzed.

RESULTS

Fifteen patients (11.7%) had thrombus visualized within the frozen elephant trunk stent graft on imaging (n = 8; 53.3%) or had a thromboembolic event (n = 9; 60.0%) before hospital discharge. Sites of embolism were mesenteric (n = 8; 88.9%), renal (n = 4; 44.4%), and iliofemoral (n = 1; 11.1%). Patients who experienced thromboembolic complications were more likely to have a history of autoimmune disease (n = 3; 20.0% vs n = 2; 1.8%; P = .01) and implantation of a longer frozen elephant trunk stent graft (150 mm vs 100 mm) (n = 13; 86.7% vs n = 45; 39.8%; P < .001). All patients with thromboembolic complications received therapeutic anticoagulation, and a smaller proportion required an open surgical (n = 5; 33.3%) or an endovascular (n = 2; 13.3%) intervention. Radiographic resolution of thromboembolic complications was observed in 86.7% of patients (n = 13). In-hospital mortality occurred in 1 patient, stroke occurred in 1 patient, and transient spinal cord injury occurred in 1 patient.

CONCLUSIONS

Thromboembolic complications occur more often than previously recognized after frozen elephant trunk aortic arch repair using the Thoraflex device and are associated with increased rates of surgical and endovascular reintervention. Prevention and management of these complications require further study.

Hybrid noncovered open stents in repair of DeBakey type 1 acute aortic dissections

OBJECTIVES

The indications for use, evidence base and experience with the novel noncovered open hybrid surgical stents for acute type A aortic dissection repair for concurrent stabilization of the 'downstream' aorta remains limited. We review the evidence base and the development of these stents.

METHODS

Data were collected from Pubmed/Medline literature search to develop and review the evidence base for safety and efficacy of non-covered surgical stents. Existing guidelines for use and developments were reviewed.

RESULTS

A single randomized control trial and 4 single-centre studies were included in the review with a total worldwide experience of 241 patients. The deployment was easy and did not add significantly to the primary operation. The mortality and new stroke ranged from 6.3-18.7%. Safe and complete deployment was accomplished in 92-100%. There was no device-related reintervention. There was a significant improvement in malperfusion in over 90% of the cases with varying degrees of remodelling (60-90%) of the downstream aorta.

CONCLUSIONS

Open noncovered stent grafts represent a major technical advancement as an adjunct procedure for acute dissection repairs, e.g. hemiarch repair. It has potential for wider use by non-aortic surgeons due to simplicity of technique. Limited safety and efficacy data confirm the device to be safe, feasible and reproducible with potential for wider adoption. However, long-term trial and registry data are required before recommendations for standard use outside of high-volume experienced aortic centres.

Thoraflex Hybrid vs. AMDS: To replace the arch or to stent it in type A aortic dissection?

BACKGROUND

Acute type A aortic dissection (ATAAD) is a life-threatening medical emergency that requires urgent surgical intervention. The mainstay surgical approach to treating ATAAD with aortic arch involvement is total arch replacement (TAR). The frozen elephant trunk (FET) procedure involves TAR with hybrid endovascular stenting of the DTA in a single step using a hybrid prosthesis (HP). The prime example of a FET HP is Thoraflex Hybrid Prosthesis (THP). Another treatment option is the novel Ascyrus Medical Dissection Stent (AMDS) that is deployed as a non-covered stent along with the aortic arch as an adjunct to prior hemi-arch replacement.

AIMS

This comparative review highlights the clinical applications and outcomes of THP and AMDS in the treatment of ATAAD and discusses the main differences between both approaches.

METHODS

A comprehensive literature search was conducted using multiple electronic databases including PubMed, Google Scholar, Ovid, Scopus and Embase.

RESULTS

TAR with FET can be considered the superior approach to managing ATAAD with arch involvement relative to AMDS with hemi-arch replacement due to more optimal clinical outcomes. Upon comprehensively searching the literature, early mortality was substantially lower with FET ranging from 0-11% compared to 12.5-18.7% using AMDS, with more favourable long-term survival. The incidence of kidney injury and new stroke post-FET ranged from 3-20% and 5-16%, and 11-37.5% and 0-18.8% following AMDS implantation. However, evidence supporting the use of AMDS is extremely limited. Meanwhile, TAR with FET is a well-established and well-described procedure for ATAAD repair.

CONCLUSION

Despite the novel nature of AMDS, its clinical safety and effectiveness are yet to be proven. In conclusion, THP remains the best evidenced-based approach to treat ATAAD in this era.

Frozen Elephant Trunk Sizing: A 30,000-Feet Perspective with Thoraflex Hybrid Stent Graft

There is currently no standard, evidence-based approach for sizing the Thoraflex Hybrid prosthesis in frozen elephant trunk surgery. We present regional data on 906 Thoraflex grafts implanted in the United Kingdom between December 2012 and August 2021 to emphasize the heterogeneity in sizing practices and evaluate the impact this may have on clinical outcomes. Highlighting this heterogeneity will help develop an evidence-based approach to prosthesis sizing, thereby aiding decision-making for arch repair.

Successive surgical repair of a progressive aortic dissection in a case of Loeys-Dietz Syndrome

INTRODUCTION

The Frozen Elephant Trunk technique is a well-established treatment for aortic dissections (Stanford Type A) involving the aortic arch and descending aorta. The Thoraflex™ Hybrid prosthesis (Vascutek Ltd.), consisting of a proximal flexible conduit and a distal self-expanding covered stent, has consistently shown positive results in the treatment of this condition.

CASE DESCRIPTION

The following is a description of such a staged reconstruction using the Thoraflex™ Hybrid Ante-Flo™ device, performed in a patient previously diagnosed with Loeys-Dietz Syndrome. After clamping the aorta proximally, an incision was taken at the distal end of the stent. Here, the distal end of the new prosthesis was inserted into the true lumen of the descending aorta and the stent was deployed. Following this, a bypass was established via the left atrium, and blood was returned to the lower body using the perfusion arm of the prosthesis with the proximal part of the descending aorta clamped. The collar of the prosthesis was sutured proximally to the aorta near the inlying previous stent. Air was removed via the perfusion arm of the prosthesis, which was then oversewn.

DISCUSSION

To date, hybrid prostheses have only been used on the proximal aorta in patients with aortic aneurysms and aortic dissections (Stanford Type A).

CONCLUSION

Using the described technique, it is possible to reconstruct the aortic anatomy using the available prostheses with accuracy and minimal complications.

Institutional practice in sizing of the hybrid prosthesis in frozen elephant trunk surgery

BACKGROUND

The frozen elephant trunk (FET) technique for total arch replacement (TAR) is widely used for repair of aortic arch dissections and aneurysms. Despite its widespread adoption, there are no international or regional guidelines for the sizing of FET prostheses in TAR. We seek to highlight the heterogeneity thereof and pave the way for evidence-based guidelines to advise FET prosthesis sizing in TAR.

METHODS

An online questionnaire was sent to 22 specialist aortic surgeons from 13 different countries across North America, Europe, Asia, and Australia, inquiring about each surgeon's approach to FET prosthesis sizing. The results were then pooled for frequency analysis.

RESULTS

All 22 surgeons responded to the questionnaire. Zone 2 is preferred implantation zone for AAD, CAD, and TAA (selected by 72.7%, 72.7%, and 68.2% respectively). The maximal diameter of the true lumen in the DTA is the most common index measurement for AAD and CAD (40.9% and 59.1%, respectively). Stent-graft diameters equal to the index measurement is the most common approach for AAD and CAD (77.3% and 45.5%, respectively) while 59.1% of surgeons oversize the index diameter by 10% for TAA; 100 mm is the preferred length for 50.0%, 27.3%, and 40.9% of surgeons in AAD, CAD, and TAA respectively.

CONCLUSIONS

There is considerable heterogeneity in sizing practices for FET prostheses internationally, with variable evidence for its impact on clinical outcomes. This issue would be aided by the development of evidence-based guidelines to inform clinical decision making.

What Is the Long-Term Clinical Efficacy of the Thoraflex™ Hybrid Prosthesis for Aortic Arch Repair?

Background

The widespread adoption of the frozen elephant trunk (FET) technique for total arch reconstruction (TAR) in aortic arch aneurysm and dissection has led to the development of numerous commercial single-piece FET devices, each with its own unique design features. One such device, Thoraflex™ Hybrid (Terumo Aortic, Glasgow, Scotland), has enjoyed widespread use since its introduction. We present and appraisal of its long-term clinical efficacy, based on international data.

Materials and Methods

Pre-, intra-, and postoperative data associated with Thoraflex™ Hybrid implantations for aortic arch dissection, aneurysm, and penetrating atherosclerotic ulcer (PAU) up to April 2019 was gathered and is presented herein. Follow-up data at discharge, 3-, 6-, 12-, 24-, 36-, 48-, 60-, 72-, and 84- months post-implantation are included.

Results

Data associated with 931 cases of Thoraflex™ Hybrid implantation are included. Mean age at implantation was 63 ± 12 years. 55% of patients included were male. Aortic dissection accounted for 48% (n = 464) of cases. Mean cardiopulmonary bypass and circulatory arrest durations were 202 +72 and 69 ± 50 min, respectively. 30-day mortality was 0.6% (n = 6), while overall mortality was 14 (1.5%). Freedom from adverse events at 84 months was 95% (n = 869). Postoperative complications included neurological deficit, multi-organ failure, cardiorespiratory compromise, and infection.

Discussion

Thoraflex™ Hybrid's unique design is advantageous in comparison to market alternatives. Our data is consistent with that reported in literature and suggests Thoraflex™ Hybrid is associated with favourable rates of mortality and morbidity.

Conclusion

Thoraflex™ Hybrid remains a central player in the aortic arch prosthesis market. Its use it widespread and is associated with favourable design features and clinical outcomes relative to market alternatives.

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.

Review of frozen elephant trunk repair with the Thoraflex Hybrid device

The frozen elephant trunk technique has revolutionized aortic arch repair to enable more extensive arch and descending thoracic aortic treatment in a single setting. We review the current evidence supporting the use of the Thoraflex Hybrid (Terumo Aortic, FL, USA) device and discuss advantages, pitfalls and future design considerations.

Total arch replacement and frozen elephant trunk for acute type A aortic dissection

OBJECTIVE

The present study aimed to evaluate the outcomes of total aortic arch replacement with proximalization of distal anastomosis using the frozen elephant trunk technique with the J Graft FROZENIX (Japan Lifeline, Tokyo, Japan) and Gelweave Lupiae (Vascutek Terumo Inc, Scotland, United Kingdom) graft (distal anastomosis performed in zones 1 and 2) in patients with acute Stanford type A acute aortic dissection.

METHODS

A total of 50 patients underwent total aortic arch replacement using the frozen elephant trunk technique, deploying the J Graft FROZENIX into zone 1 or 2 (zone 1: n = 17, zone 2: n = 33) in combination with the Gelweave Lupiae graft for acute Stanford type A acute aortic dissection. Patient characteristics, intraoperative data, and early and midterm outcomes were analyzed.

RESULTS

The overall in-hospital mortality rate was 4% (2 patients). The in-hospital mortality rate in patients with visceral malperfusion was 11% (1/9). There were no patients with paraplegia and stent graft-induced new entry. Resection or closure of the most proximal entry tear was achieved in 100% of 42 patients who had postoperative computed tomography. The overall survival was 87.9%, 84.1%, and 84.1% at 1, 2, and 3 years, respectively. However, 1 patient required endovascular extension for the dilatation of the descending thoracic aorta 4 months after the initial surgery.

CONCLUSIONS

Total aortic arch replacement with the frozen elephant trunk technique (zone 1-2) and Gelweave Lupiae graft was safe and effective in simplifying surgery for acute Stanford type A acute aortic dissection.

The frozen elephant trunk technique in an emergency: THORAFLEX French National Registry offers new insights

OBJECTIVES

Our goal was to study the immediate outcome after an emergency frozen elephant trunk procedure with a Thoraflex™ Hybrid prosthesis (THP) in patients included in the EPI-Flex national registry and operated on in 21 French centres.

METHODS

All patients operated on in France between April 2016 and April 2019 for acute aortic syndromes and who had an frozen elephant trunk procedure with a THP were included in the study. The main end point was in-hospital mortality. The secondary end point was neuromorbidity, including paraplegia. The evolution of the main end point was monitored using a variable life-adjusted display graph with cumulative sum derivatives in order to stop inclusions in case the observed mortality became out of range compared to an expected mortality between 15% and 20%.

RESULTS

Enrolment ended on the scheduled date and included 109 patients. Most cases (54%) were performed at 3 centres, where more than 10 THP each were implanted (10-26). The observed mortality in the large-volume centres (22%) was comparable to that observed in the low-volume centres (20%). The individually risk-adjusted cumulative sum revealed that observed in-hospital mortality was statistically in line with that predicted by the log EuroSCORE. Analysis of the secondary end point revealed 8% cases of paraplegia, all of which appeared after treatment of the thoracic type A aortic dissection.

CONCLUSIONS

In France, THP for emergency frozen elephant trunk surgery outside high-volume centres did not result in excessive in-hospital deaths. However, a word of caution must be expressed regarding the prevention of medullar ischaemia even in emergency aortic surgery.

Aortic arch replacement with frozen elephant trunk technique - a single-center study

BACKGROUND

The frozen elephant trunk (FET) technique was developed to facilitate the two-stage surgery of extensive pathologies of the thoracic aorta and is now routinely applied in acute and chronic aortic syndromes.

METHODS

From 11/2006 to 07/2017, 68 patients underwent aortic arch repair using the FET technique. Patients received either the Jotec E-vita Open graft (n = 57) or the Vascutek Thoraflex hybrid prosthesis (n = 11). Both, group 1 (acute aortic dissection type A and B; symptomatic penetrating aortic ulcer) and group 2 (aortic aneurysm; chronic aortic dissection) included 34 patients each.

RESULTS

Early mortality was 13.2% (14.7% in group 1 vs. 11.7% in group 2, p = 0.720). Neurological complications occurred in 12 patients (17.6%) (stroke: 8.8 vs. 11.7%; p = 0.797 and spinal cord injury: 8.8 vs. 5.9%; p = 0.642 in groups 1 vs. 2 respectively). Cardiopulmonary bypass time and cross clamp time were significantly longer in group 1 (252.2 ± 73.5 and 148.3 ± 34 min vs. 189.2 ± 47.8 and 116.3 ± 34.5 min; p <  0.001). The overall 1-, 3- and 7-year-survival was 80.9, 80.9 and 74.2% with no significant differences between groups 1 and 2. Expansion of true lumen after FET implantation was significant at all levels in both groups for patients with aortic dissection. One-, 3-, and 7-year-freedom from secondary (re-)intervention for patients for aortic dissection was 96.9, 90.2 and 82.7% with no significant differences between groups 1 and 2; p = 0.575.

CONCLUSION

The FET technique can be applied in acute aortic syndromes with similar risks regarding adverse events or mortality when compared to chronic degenerative aortic disease. Postoperative increase in true lumen diameter mirrors decrease of false lumen diameter, goes along with favorable midterm outcome and prolongs freedom from secondary interventions in acute aortic dissection.

Management of Retrograde False Lumen Perfusion After Hybrid Arch Repair in Acute Aortic Dissection

Patients with acute aortic dissections involving the arch and descending aorta can effectively be treated using the frozen elephant trunk technique. We describe here the novel technique of temporary banding of the descending aorta onto the stent of the hybrid graft in 3 patients who developed unmanageable bleeding from the distal suture line due to retrograde false lumen perfusion and disintegration of the adventitia. Retrograde false lumen perfusion was stopped and therefore bleeding controlled in all patients. Temporal aortic banding represents a novel, feasible, and effective bailout technique for otherwise unmanageable bleeding with fatal outcome in hybrid arch surgery.