Journal of Vascular Surgery
Volume 43, Issue 2, Supplement , Pages A78-A80, February 2006

Managing proximal arch vessels

  • Luis A. Sanchez, MD

      Affiliations

    • Corresponding Author InformationReprint requests: Luis A. Sanchez, MD, Department of Surgery, Section of Vascular Surgery, Washington University School of Medicine, Campus Box 8109—Surgery, 660 S Euclid, St Louis, MO 63110.

Department of Surgery, Section of Vascular Surgery, Washington University School of Medicine, St Louis, Mo.

Received 14 October 2005; accepted 23 October 2005.

Article Outline

 

In the initial trial of the Gore Thoracic Aortic Graft endoprosthesis (W.L. Gore and Associates, Flagstaff, Ariz), a subclavian artery that needed to be covered for stable proximal attachment of the endovascular graft required revascularization. Experience gained over the ensuing years has demonstrated that the subclavian artery can be covered in most patients without the development of any symptoms.1 As we consider endovascular repair for patients with increasingly complex arch anatomy, the management of the proximal arch vessels has moved to the forefront of thoracic endovascular techniques. This chapter reviews the alternatives available currently and future considerations for managing the proximal arch vessels in patients with complex arch anatomy.

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Technique 

Thoracic aneurysms encroaching on or involving the subclavian artery 

The most distal branch of the aortic arch in most patients is the subclavian artery. Thoracic aneurysms often arise within 2 cm of the subclavian artery, a difficult location for securely sealing a thoracic endovascular graft long-term. Patients who have thoracic aneurysms with a short neck (<2 cm) distal to the subclavian artery are best treated with total or partial coverage of the subclavian artery. In many patients, this allows 2 cm or more of proximal attachment, which is sufficient to establish a stable seal zone with a low risk of graft migration and the development of a proximal type I endoleak. Most patients (approximately 90%) tolerate proximal occlusion of the subclavian artery without the development of symptoms, which can include a posterior circulation stroke, subclavian steal syndrome, and left hand claudication.

There are specific anatomic situations in which a subclavian reconstruction should be performed before placement of a thoracic endovascular graft covering the subclavian orifice. These include patients with a single or dominant left vertebral artery, patients with a left vertebral arising directly from the aortic arch, those who have had the left internal mammary artery used for coronary bypass grafting, and patients with severe proximal disease of the left carotid, brachiocephalic trunk, or both. The surgical reconstructions most commonly performed in these situations include a transposition of the left subclavian artery onto the left carotid artery and a carotid-subclavian bypass, often performed with a short prosthetic graft.2 The long-term patency of these reconstructions is excellent in patients with symptomatic subclavian occlusive disease. Less common options include a subclavian-subclavian or an axillary-axillary bypass.2

Covering the orifice of the left carotid artery 

As we consider the endovascular treatment of patients with even more complex arch anatomy, partially or completely covering the orifice of the left carotid artery may be necessary. In selected patients this maneuver would permit stable proximal attachment with a good seal zone (at least 2 cm), thus diminishing the risk of endovascular reconstruction failure secondary to a proximal type I endoleak or graft migration. It is necessary to protect the inflow to the left carotid artery in cases when the endovascular graft has to be placed at the edge of or partially covering the orifice. This can be performed in selected patients by stenting the orifice of the left carotid artery in a prograde or retrograde fashion. Carotid stenting can be performed before endovascular graft placement but is usually safest if accomplished at the time of endovascular graft repair, thus avoiding the potential difficulties of positioning the endovascular graft in the aortic arch with a carotid stent already protruding into the aortic lumen. If complete occlusion is needed to gain an appropriate proximal neck, a variety of carotid reconstructions can be considered. The surgical reconstructions to maintain flow to the left common carotid artery can obtain inflow from the right common carotid, subclavian, axillary, or femoral vessels.3 The simplest reconstruction for this purpose in a patient with good inflow to the right carotid artery is a carotid-carotid bypass; this is most commonly performed through a retropharyngeal approach, but other surgical approaches have been described.2 The right subclavian artery, if healthy, can also be used as inflow to revascularize the left carotid and/or subclavian arteries through an approach at the base of the neck. An axillary-to-axillary artery bypass can also be used to revascularize the left subclavian artery with a sequential carotid bypass.2 Another option that has been described involves obtaining inflow from the left common femoral artery and performing sequential reconstructions to the left subclavian/axillary and carotid arteries.3, 4 This more extensive reconstruction with femoral inflow is likely to have a lower long-term patency rate than a carotid-carotid bypass or other arch reconstructions, but it is a reasonable alternative if the right carotid and subclavian arterial systems are a poor inflow source for an arterial bypass.

Debranching procedures 

Patients with arch aneurysms that involve the portion of the arch adjacent to the brachiocephalic artery require total aortic arch debranching to obtain an adequate proximal attachment and seal zone in the ascending aorta and across the orifice of the brachiocephalic artery. The potential sources of inflow in these cases include the femoral arteries or the proximal ascending arch distal to the coronary arteries. Femoral-to-axillary bypasses (unilateral or bilateral), in combination with some of the previously mentioned supraclavicular arterial reconstructions (carotid-carotid, subclavian-carotid, and subclavian-subclavian bypasses), can be used to reconstruct the critical aortic arch branches in these patients.3, 4 In selected patients the ascending aorta can be used as an inflow source. Patients with a healthy, noncalcified, normally sized ascending aorta can undergo a median sternotomy (or a right thoracotomy in redo patients) to access the ascending aorta or old graft in that position. A bypass using a bifurcated graft (usually a 12-mm or 14-mm polyester bifurcated graft) or tube graft (usually an 8- or 10-mm polyester graft) can be anastomosed to the ascending aorta after partial cross-clamping of the inflow vessel.4 This technique is well tolerated by even marginal patients from a cardiovascular standpoint and can provide inflow for a variety of arterial bypasses to aortic arch branches in patients with complex arch anatomy who are being considered for endovascular aneurysm exclusion.

Combined ascending and descending arch aneurysms 

The most complex cases involve patients with combined ascending and descending arch aneurysms. These patients have been treated in a limited fashion with combined open and endovascular techniques. If the patient is a suitable candidate for hypothermic cardiac arrest and ascending arch reconstruction with an elephant trunk technique, a one- or two-stage procedure can be used. The descending thoracic aneurysm repair can be performed with an endovascular graft if the patient has a good distal landing zone and an appropriate proximal landing zone in the distal elephant trunk.5 The creation of a long elephant trunk (at least 5 cm) is recommended for stable attachment of the distal endovascular graft. The graft used should be of a size (preferably between 23 and 35 mm in diameter) to accommodate one of the available thoracic endovascular graft components. The access into the elephant trunk may be difficult because the polyester graft is free floating in the descending thoracic aorta. Some investigators have suggested the use of marker clips at the end of the graft, and other methods are being considered to stiffen that graft portion to avoid infolding of the material during manipulation and endovascular graft deployment. These include the use of stents and other supportive materials. If a one-stage procedure is planned, the site of endovascular graft introduction into the new ascending arch graft needs to be in line with the distal arch. Investigators have used a graft side arm, often used for temporary bypass during the arch reconstruction, for this purpose. The side arm needs to be at least 10 mm in diameter to fit all potential thoracic endovascular grafts and should be in line with the distal anastomosis of the elephant trunk to allow easy endovascular manipulation and deployment of the thoracic graft. These combined open and endovascular procedures have the potential to decrease the morbidity and mortality associated with such extensive arch and thoracic aneurysm repairs.

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Conclusion 

There are not enough data available to clearly establish these techniques as the treatment of choice for patients with complex anatomy, but the existing pool of information is rapidly growing. The data from the Thoracic Aortic Graft trial6 clearly define, for the first time in a prospective evaluation, the morbidity and mortality associated with endovascular and open techniques used for the treatment of thoracic aneurysms. Extrapolation of these data suggests that patients with good aortic anatomy and a higher risk of perioperative morbidity and mortality are also likely to benefit from these developing techniques. Currently, surgical groups in Europe have reported their adoption of combined open branch revascularizations and aortic exclusion for patients with thoracoabdominal aneurysms, in an effort to decrease the periprocedural morbidity and mortality.7 These combined techniques are likely to continue to flourish.

In the not-so-distant future, branch devices will simplify the exclusion of aortic aneurysms in the aortic arch and the visceral abdominal aorta. Early precursors of branch devices have already been used for the treatment of arch aneurysms either alone8 or in combination with extra-anatomic reconstructions of some of the aortic arch branches.9, 10

The use of endovascular grafts for the treatment of thoracic aneurysms and other lesions continues to grow, on the basis of the increasing body of evidence available. Prospective series6 and single-center experiences1 with encouraging short- and mid-term results associated with low periprocedural morbidity and mortality continue to be published. The treatment of more complex aortic arch and thoracic aneurysms is evolving rapidly with the use of extra-anatomic arterial reconstructions to maintain the patency of important aortic arch branches and lower-risk endovascular exclusion of complex aneurysms. As branched reconstructions evolve to the point where they are relatively easy and safe to use, endovascular techniques will likely be applied to a growing number of patients with complex aortic anatomy. We still await data on the long-term durability of these devices before considering endovascular techniques the treatment of choice for thoracic aortic lesions, where the anatomy allows it.

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References 

  1. Criado FJ , Clark NS , Barnatan MF . Stent graft repair in the aortic arch and descending thoracic aorta (4-year experience) . J Vasc Surg . 2002;36:1121–1128
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  8. Inoue K , Hosokawa H , Iwase T , et al.   Aortic arch reconstruction by transluminally placed endovascular branched stent graft . Circulation . 1999;100(19 Suppl):II316–II321
  9. Chuter TA , Buck DG , Schneider DB , et al.   Development of a branched stent graft for endovascular repair of aortic arch aneurysms . J Endovasc Ther . 2003;10:940–945
  10. Schneider DB , Curry TK , Reilly LM , et al.   Branched endovascular repair of aortic arch aneurysm with a modular stent-graft system . J Vasc Surg . 2003;38:855

 Competition of interest: none.

PII: S0741-5214(05)01857-4

doi:10.1016/j.jvs.2005.10.042

Journal of Vascular Surgery
Volume 43, Issue 2, Supplement , Pages A78-A80, February 2006

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