In situ laser fenestration of the Thoraflex Hybrid frozen elephant trunk for emergent revascularization of the left subclavian artery and laser fenestration for spinal cord perfusion

In situ laser fenestration (ISLF) has emerged as a promising technique for emergent revascularization of the left subclavian artery in the case of thoracic endovascular aortic repair coverage, presenting excellent technical success rates in most studies. We describe a case of ISLF of the Thoraflex Hybrid frozen elephant trunk device to achieve immediate left subclavian artery revascularization. We demonstrate the feasibility and technical success of using ISLF in this setting, providing a less invasive alternative to conventional surgical revascularization when required.

The left subclavian artery (LSA) might need to be covered in 26% to 40% of patients undergoing thoracic endovascular aortic repair (TEVAR) to achieve an adequate proximal seal. 1 Revascularization of the LSA is recommended in elective TEVAR but can also be required in the acute setting.Various methods are available, such as carotidesubclavian bypass, subclavian artery transposition, and endovascular approaches using branched or fenestrated devices, as well as chimney techniques, all with pros and cons. 1 In situ laser fenestration (ISLF) has emerged as a new promising technique for emergent revascularization of the LSA, presenting excellent technical success rates of >95% in most studies and an LSA patency rate of 97% to 100%. 2 Previous studies have shown that Dacronbased stent grafts (eg, Zenith Alpha; Cook Medical Inc) are suitable for the ISLF technique.In contrast, polytetrafluoroethylene-based stent grafts (eg, Gore cTAG; W.L. Gore & Associates) should be avoided due to the potential liberation of toxic molecular substances after thermal ablation, the difficulty to perforate using a laser, and the propensity for fabric tears on dilatation of the fenestration. 2,3e Thoraflex Hybrid frozen elephant trunk (FET) device (Terumo Aortic) is a single-use medical device combining a Gelweave polyester graft with a nitinol self-expanding stent graft used for open surgical repair of the aortic arch and descending aorta. 4To the best of our knowledge, no studies have reported on ISLF of the Thoraflex Hybrid device.In this report, we describe a case of ISLF of a Thoraflex stent graft to achieve immediate LSA revascularization, demonstrating the feasibility and technical success of using ISLF in this setting.The patient provided written informed consent for the report of his case details and imaging studies.

DISCUSSION
For patients requiring extensive aortic and LSA coverage, LSA revascularization can be vital for spinal cord perfusion.Our initial plan to reconstruct the LSA during the FET procedure was altered due to inaccessibility.Relying on retrograde LSA perfusion and staging the procedure proved inadequate due to sac thrombosis at the LSA, indicating that earlier LSA revascularization would have been a better approach.
Extra-anatomic bypass remains the benchmark for LSA revascularization but can sometimes be unsuitable in the emergency setting and carries the risk of complications, such as thoracic duct injury, phrenic nerve injury, and stroke. 5Thus, interest has increased toward endovascular preservation of the LSA.Endovascular options include branched and fenestrated devices, which have limited off-the-shelf availability, especially in the European market. 6Parallel graft technology, such as snorkels or chimneys, is available in the emergency setting but is limited by its vulnerability to gutter leakage. 7,8SLF represents a valuable off-the-shelf solution for aortic arch endovascular repair in the acute setting when a short window of opportunity exists for vascular reconstruction and for patients considered at high risk for conventional open management or who present with anatomic characteristics that do not permit application of custom-made solutions.ISLF technology, being energy-based, raises concerns of fabric fraying during balloon dilation, and limited data are available on the long-term durability and the frequency of endoleaks.Hence, ISLF is not primarily used in elective situations.Accumulating data, however, support its safety and feasibility with Dacron stent grafts in the short and medium term. 3,9,10A systematic review by Houérou et al 11 indicated ISLF feasibility in treating aortic arch pathologies, with an incidence of type III endoleak of 3.5%, without further definition of whether these endoleaks were related to fabric tears or disconnection of the modules.
Although the focus of this case report was the feasibility of ISLF with the Thoraflex stent graft, the complex course of the present case also illustrates other applications of ISLF, such as creating a fenestration for temporary perfusion of the aneurysm sac.Kasprzak et al 12 highlighted the potential of temporary aneurysm sac perfusion in maintaining spinal cord perfusion and possibly reducing spinal cord ischemia.Nevertheless, the level of evidence for its value remains weak, and the risk of aneurysm rupture must be considered.Given the high mortality and morbidity associated with paraparesis, and the elective nature of the repair, extending aneurysm sac perfusion for a few weeks was deemed a justified approach.
This case report demonstrates the feasibility of ISLF with the Thoraflex stent graft, which did not require any modifications compared with ISLF with other Dacron stent grafts.The case further shows the possibility of urgent innovative measures with the technology.

CONCLUSIONS
This case report indicates that ISLF of the Thoraflex stent graft is technically feasible and can be considered as an alternative to standard surgical revascularization in the acute setting or for patients unfit for surgery.However, we cannot yet draw conclusions regarding the longterm durability of this nonreinforced fenestration.

A
75-year-old man presented with an 85-mm Crawford classification type II aortic aneurysm and a 57-mm ascending aortic aneurysm, with the largest diameter in the descending aortic aneurysm (Fig 1).A staged aneurysmal repair was planned to reduce the risk of paraplegia.The first stage included ascending aortic repair with aortic valve replacement (23 mm; Magna Ease; Edwards Lifesciences) and FET, using a 28 Â 30 Â 180-mm Thoraflex Hybrid prosthesis.The distal anastomosis was performed at Ishimaru zone 2, with reimplantation of the brachiocephalic trunk and left carotid artery.The LSA was inaccessible and, therefore, left unreconstructed.The immediate postoperative course was complicated by acute mesenteric ischemia, and the patient underwent thrombectomy of the superior mesenteric artery and stenting of the celiac artery with partial bowel resection.In addition, he developed a posterior cerebral infarction on the left side without residual symptoms.A follow-up computed tomography scan during the same admission depicted perfusion of the LSA from the nonsealed aneurysmal sac and a patent left vertebral artery.

From
the Division of Vascular Surgery, Department of Surgical Sciences, Uppsala University, Uppsala a ; and the Division of Surgery, Department of Surgical and Perioperative Sciences, Umeå University, Umeå.b Correspondence: Maysam Shehab, MD, Division of Vascular Surgery, Department of Surgical Sciences, Uppsala University, Uppsala 75185, Sweden (e-mail: shehabmaysam@gmail.com).The editors and reviewers of this article have no relevant financial relationships to disclose per the Journal policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest.2468-4287 Ó 2024 The Author(s).Published by Elsevier Inc. on behalf of Society for Vascular Surgery.This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).https://doi.org/10.1016/j.jvscit.2024.101426

Fig 1 .
Fig 1. Three-dimensional reconstruction of preoperative computed tomography angiogram showing a Crawford type II aortic aneurysm.

Fig 2 .
Fig 2. In situ laser fenestration (ISLF) of the Thoraflex stent graft.a, Diagnostic angiography showing flow in the left subclavian artery (LSA; arrow) and left vertebral artery (dashed arrow).b, The 0.018-in.wire was advanced into the Thoraflex and ascending aorta, and a 4 Â 40-mm balloon (Armada 18; Abbott; arrow) was used to predilatate the fenestrated orifice.Dashed arrow indicates the Thoraflex stent graft.c, Completion angiogram showing a patent LSA and left vertebral artery.

Fig 3 .
Fig 3. a, Distal extension with aortic tube graft and landing in the distal aorta (arrow).b, Completion angiogram showing no endoleak.

Fig 4 .
Fig 4. In situ laser fenestration (ISLF) to the thoracic stent graft was performed, and a stent was inserted for temporary aneurysm sac perfusion, highlighted in blue (arrow).

Fig 5 .
Fig 5. Three weeks after the last procedure, the patient had a follow-up computed tomography angiogram showing a patent left subclavian artery (LSA) stent (arrow) and no endoleak.Dashed arrow indicates the Thoraflex stent graft.