Fenestrated Thoracic Endovascular Repair for Acute Type B Aortic Dissection with Isolated Left Vertebral Artery: A Case Report

Thoracic endovascular aortic repair (TEVAR) of acute uncomplicated type B aortic dissection (uTBAD) has been discussed for its potential to prevent future aortic events. We present a fenestrated TEVAR in the case of an 86-year-old man with acute uTBAD with an isolated left vertebral artery (ILVA). The ILVA originated from the distal side of the left subclavian artery, the left subclavian artery, and the intramural hematoma with an ulcer-like projection extended close to the left subclavian artery. We selected a fenestrated stent graft to achieve a proximal healthy landing. This case demonstrates that a fenestrated stent graft for acute uTBAD is useful for preserving arch vessels.


Introduction
Thoracic endovascular aortic repair (TEVAR) has recently been discussed in treating acute uncomplicated type B aortic dissection (uTBAD) if the aorta enlarges rapidly. 1,2)owever, surgeons must consider the preservation of cervical branches when the dissection extends into the aortic arch.Here, we report the treatment of uTBAD with an isolated left vertebral artery (ILVA) arising directly from the aortic arch adjacent to the left subclavian artery (LSA) using a semi-custom-made fenestrated stent graft.true lumen to the detached orifice of the CA via the false lumen to close the distal tear.An angiography image after implantation showed that the Viabahn stent was bridging the CA, and the contrast leakage into the false lumen was almost lost (Figs. 2B and 2C).Conformable Gore TAG (CTAG; W. L. Gore & Associates, Inc.) was placed in the descending aorta.A guidewire was then advanced from the right brachial artery to the right femoral artery.Then, the Najuta stent graft was placed in zone 2, however it migrated distally, and LSA and ILVA blood flow were preserved by only proximal fenestration.Completion angiography showed no entry flow and blood flow preservation in the LSA and ILVA (Figs. 2D and 2E).A CT scan performed two weeks after the operation revealed that the ILVA was preserved, and the descending aortic diameter decreased from 48 mm to 40 mm (Fig. 3).The patient's postoperative course was uneventful.

Discussion
][5] Here, the patient had an anomaly of Adachi and Williams' classification type BE, 3,4) an extremely rarely reported form of ILVA combined with a bovine arch.Generally, debranching bypass, branched stent graft, the chimney technique, and retrograde in situ branched stent are effective methods for preserving cervical branches, as demonstrated by several studies. 6,7)These   techniques have been used successfully in the treatment of patients with Adachi and Williams type C aortic arch anomalies, which are defined as cases in which the left vertebral artery arises from the proximal side of the left LSA.In some cases, ILVA reconstruction via transposition and the chimney technique has been used. 3,4,8,9)However, in the present case, surgical exposure of the ILVA was expected to be difficult and highly invasive, and endovascular treatment was selected as the preferred approach.Herein, we report a case in which the ILVA was preserved using a custom-made fenestrated stent graft.The Najuta stent graft has a structure in which an ePTFE graft is located outside the Z-stent and is largely unattached to the stent (Fig. 3).This feature allows the graft to expand with blood flow, thereby functioning like a windsock and creating an active seal.For this reason, the radial force of the Najuta is minimized and, therefore, may contribute to the prevention of new entries proximally and distally. 10)It is regrettable that the stent graft migrated distally in this case.Due to its design, Najuta directly receives cardiac output during deployment, requiring careful attention.It has been reported that the administration of drugs, such as adenosine, and the use of rapid pacing during deployment can effectively aid in the precise positioning of the stent graft by inducing hypotension in the patient. 11,12)We should consider employing these methods.Furthermore, in the present case, bridging covered stent placement was effective for large tears in the CA.

Conclusion
We performed fenestrated TEVAR with ILVA preservation using the Najuta stent graft to treat uTBAD in a patient with the extremely rare Adachi and Williams aortic arch type BE.This case indicates that fenestrated TEVAR is a useful option for preserving the cervical branches, including the ILVA.

Informed Consent
The patient provided informed consent for case details and imaging studies to be reported.

Fig. 1
Fig. 1 Preoperative computed tomography.(A) Computed tomography on the day of admission reveals a tear in the aortic dissection at the origin of the celiac artery.(B) Computed tomography shows the shared origin of brachiocephalic and left common carotid arteries.The left vertebral artery arising directly from the aortic arch on the distal side of the left subclavian artery is indicated with an arrow.(C) Computed tomography performed on the 11th day post-admission indicates dilation of the false lumen.(D) Computed tomography performed on the day of admission and the 11th day post-admission (left to right) indicates enlargement of the descending aorta from 43 to 48 mm.(E) Computed tomography performed on the 11th day post-admission reveals an ulcer-like projection in the descending aorta.(F) Computed tomography performed on the 11th day post-admission reveals that the intramural hematoma with ulcer-like projection extended close to the left subclavian artery and isolated left vertebral artery.

Fig. 2
Fig. 2 Angiography during endovascular repair on the 31st day after aortic dissection onset.(A) Najuta stent graft with two fenestrations is shown.Fenestrations were designed to preserve blood flow through the left subclavian and isolated left vertebral arteries.The custom-made device required a few weeks to create.Note the fact that the graft material is largely unattached to the stent thereby allowing for active seal.(B) An angiographic image shows the true lumen (white arrow), false lumen (blue arrow) and the orifice of the celiac artery tear (red arrow).(C) Angiography after implantation of the Viabahn-covered stent (yellow arrow) reveals the absence of blood flow in the false lumen and the preservation of the celiac artery circulation.(D) Angiography indicates an isolated left vertebral artery (arrowhead) arising directly from the aortic arch just distal to the left subclavian artery.(E) Angiography after implantation of Najuta stent graft indicates the preservation of the isolated left vertebral artery (arrowhead) blood flow is shown.

Fig. 3
Fig. 3 Postoperative computed tomography.A postoperative computed tomography shows preserved isolated left vertebral artery blood flow (arrow, A); good aortic remodeling and descending aorta diameter reduction to 40 mm (B); and the absence of an ulcer-like projection in the descending aorta (C).