Hybrid Repair With Endovascular Debranching of the Aberrant Right Subclavian Artery for Complicated Type B Aortic Dissection in Patients With Kommerell’s Diverticulum

Introduction

Aberrant right subclavian artery (ARSA) with Kommerell’s diverticulum (KD) is the most common congenital variant in a left-sided aortic arch. ¹ KD exclusion with preservation of bilateral subclavian arteries (SCAs) is indicated for symptomatic patients with aneurysmal formation, type B aortic dissection (TBAD) and rupture. ² Various techniques, including open surgical repair, hybrid repair, and total endovascular repair, ³ have been described without consensus on a standard treatment. In the present case, we performed a novel hybrid approach in a complicated TBAD patient with KD and ARSA, including a left common carotid artery (LCCA) to left subclavian artery (LSA) interposition graft, an endovascular debranching stent-graft between the bilateral SCAs, and thoracic endovascular aortic repair (TEVAR).

Technique

This hybrid repair was performed on a 50-year-old symptomatic man presenting with progressive aneurysmal formation of KD with ARSA after chronic TBAD. Preoperative computed tomography revealed face to face orientation of the LSA and ARSA origins, aneurysmal formation of KD for more than 5 cm, and TBAD originating from the ARSA (Figure 1A and B), which mandates the indication for endovascular aortic repair. The diameters of the distal aortic arch and the bilateral SCAs measured 28 mm and 11 mm, respectively, and the proximal landing zone (PLZ) was 2 cm in length if zone 1 landing was planned according to the modified Hishimaru classification. ¹ A 3-step technique, namely cervical debranching with a LCCA to LSA bypass, TEVAR, and an LSA to ARSA endovascular debranching, was planned for 1-stage repair. This procedure was performed under general anesthesia with open right common femoral artery and left supraclavicular approach. After the LSA and the LCCA were exposed, a 6-mm Dacron conduit (InterGard; InterVascular, La Ciotat, France) was then anastomosed to the LSA in an end-to-side manner. An endovascular snare wire (EnSnare, Merit Medical, South Jordan, UT, USA) was inserted into the proximal descending thoracic aorta (DTA) through the interposition graft. The right brachial artery was accessed percutaneously and a 0.035-inch hydrophilic wire (Radifocus Glidewire, Boston Scientific, Marlborough, MA, USA) was advanced to the proximal DTA through the ARSA. A through-and-through wire access was achieved by pulling the 0.035-inch guidewire through the interposition conduit with the endovascular snare. A 12 French Cook Flexor sheath was advanced from the LSA to the ARSA via the wire with the sizing catheter in place for the length measurement (Figure 2A). A 31 mm × 150 mm Gore C-TAG endograft (W.L. Gore & Associates, Flagstaff, AZ, USA) was successfully deployed at zone 1 from the right groin, covering both SCAs and the primary tear distal to the ARSA. A 13 mm × 100 mm Viabahn stent-graft (W.L. Gore & Associates) was positioned with a minimum landing length of 2 cm in both the ARSA and LSA. It was then deployed proximally to both vertebral arteries (Figure 2B). Simultaneous balloon dilation was done because of the TBAD. After removing the 12 French Flexor sheath and the through-and-through wire, the other end of the 6-mm Dacron graft was anastomosed to the LCCA. The final angiogram showed patent endovascular debranching stent-graft, LCCA to LSA bypass, exclusion of the aortic aneurysm, and coverage of the primary intimal tear of TBAD. The postoperative course was uneventful and without complications. A 1-year follow-up computed tomography scan revealed a patent LSA to ARSA endovascular debranching stent-graft, complete false lumen thrombosis, and KD aneurysm exclusion (Figure 2C) (Supplementary material is available in the online version of the article).

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Figure 1.

Contrast-enhanced computed tomographic images of a 50-year-old man with chronic type B aortic dissection associated with aneurysmal formation in Kommerell’s diverticulum and an aberrant right subclavian artery (ARSA). (A) Three-dimensional reconstruction. Axial section (B) revealed an ARSA (arrow).

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Figure 2.

(A) An angiogram shows through-and-through wire access with a sizing catheter in place for the endovascular debranching stent-graft length measurement (arrow) from the aberrant right subclavian artery (ARSA) to the left subclavian artery (LSA). (B) The Viabahn stent-graft was positioned with a minimum landing length of 2 cm in both the ARSA and LSA and proximally to the right vertebral artery (arrow) and the left vertebral artery (asterisk). (C) Three-dimensional contrast-enhanced computed tomography obtained at 1-year follow-up revealed complete aneurysm exclusion, false lumen thrombosis, patent left common carotid to LSA bypass (asterisk), and LSA to ARSA endovascular bypass graft (arrow).

Discussion

For decades, conventional open surgical repair has been the standard treatment; however, various reports indicate a mortality rate ranging from 9% to 23.5%.^4–8 In recent years, treatment has shifted toward hybrid or total endovascular repair due to their minimal invasiveness.

In hybrid or total endovascular repair, the availability of a suitable PLZ is the key factor. Due to the normal anatomic proximity of the ARSA to the LSA orifice in KD, endograft coverage of both vessels as well as revascularization of one or both is often required. Traditional bilateral CCA to SA bypass through double cervicotomy potentially increases the risk of complications, such as stroke, hoarseness, and phrenic nerve palsy. Thus, a staged approach with extra-anatomic revascularization and thoracic endografting is usually preferred.^1,4 In this technique, the ARSA was preserved through the endovascular debranching conduit from the LSA, which was revascularized by the unilateral LCCA-LSA bypass. This lowers the risk of complications from bilateral cervicotomy and can be performed in a 1-stage operation. Unilateral CCA to LSA bypass with axillo-axillary bypass grafting is an alternative choice, however, the patency of the axillo-axillary bypass is less durable. Total endovascular repair with periscope or chimney grafts carries the risk of gutter endoleaks and incomplete pathology exclusion. Unlike the classical chimney procedure, in this novel technique, thoracic endografting was deployed at the PLZ without parallel grafting from the LSA because the endovascular debranching conduit was positioned distally to the PLZ between the orifices of the LSA and the ARSA to prevent the gutter endoleak. In this case, the small true lumen may complicate parallel deployment of the periscope graft from the ARSA as well as thoracic endografting. The oversizing of the aortic endograft in chimney procedure was usually by 20% to 30%.^9–12 In TBAD, the suggested oversizing was between 0% and 10% due to the risk of retrograde type A dissection. ¹³ Therefore in this technique, the thoracic endograft is oversized by 10%, the endovascular debranching stent graft is 1 to 2 mm larger than the ARSA or LSA at its intended landing zone and is ≥2 cm inside the ARSA and LSA branches without covering either vertebral artery. Due to the lengthy course and the “U” shape orientation of the endovascular debranching graft, the Viabahn stent-graft was chosen.

Conclusion

We believe that this new hybrid approach is a safe and effective strategy for treating TBAD in patients with KD and ARSA.