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Interact CardioVasc Thorac Surg 2008;7:690-697. doi:10.1510/icvts.2008.181222 © 2008 European Association of Cardio-Thoracic Surgery
Is it safe to cover the left subclavian artery when placing an endovascular stent in the descending thoracic aorta?
a Department of Cardiothoracic Surgery, James Cook University Hospital, Middlesbrough, UK Received 7 April 2008; accepted 8 April 2008
1 Present address: Mercy Gilbert and Chandler Hospitals, Phoenix, Arizona, USA.
A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the left subclavian artery may be safely covered with a descending thoracic aortic stent without a prior carotid-subclavian artery bypass or transposition procedure. Altogether 2612 abstracts were identified. Forty-five non-randomized control trials and 213 non-controlled papers were found using the reported search and all these were read in full to search for coverage of the left subclavian artery. From these papers, 20 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. We identified 20 studies with more than 10 cases of left subclavian artery coverage without prior revascularisation. Aggregating the data from all these studies we found 498 covered left subclavian arteries. Complications included 13 strokes (2.6%), 8 cases of paraplegia or paraparesis (1.6%) and 6 endoleaks due to subclavian backflow (1.2%). Of note there were 51 cases of ischaemia or other symptoms attributable to poor blood flow (10%), which resulted in 20 post-procedural revascularisations (4%). In three studies the mean pressure drop in the left arm was between 36 and 48 mmHg after left subclavian occlusion. We conclude that coverage of the left subclavian artery has a low, but not insignificant, incidence of side-effects. This incidence must be balanced with the urgency of the procedure and may be acceptable in emergency or salvage situations. However, in non-emergency cases we recommend that the carotid arteries, the vertebral arteries and the Circle of Willis are fully assessed by tests such as duplex ultrasound, angiography, CT or MRI scanning. An absent right vertebral artery, diseased carotid arteries or an incomplete Circle of Willis is a contraindication to left subclavian artery coverage without prior transposition or bypass grafting of the left subclavian artery.
Key Words: Thoracic aortic stents; Aortic aneurysm; Aortic dissection; Left subclavian artery
A best evidence topic was constructed according to a structured protocol. This is fully described in the ICVTS [1].
In [patients undergoing a descending thoracic aortic stent] does [coverage of the left subclavian artery] cause an unacceptable rate of [vascular complications]?
You are assisting a vascular radiologist with a 77-year-old gentleman who has suffered a contained rupture of his descending thoracic aorta after a road traffic accident 24-h ago. He had been intubated and ventilated immediately on admission to hospital, but on assessment, his age and smoking history persuaded you that his surgical risk was too high. Therefore, you asked your radiologist to place a descending thoracic aortic stent. During the procedure the radiologist who previously thought that he could land the stent below the subclavian now feels that he must place the stent across this artery and asks you if you are happy with this. You say yes, but resolve to check that this is safe in the literature after the case.
Medline, Cochrane CENTRAL, EMBASE, NICE, CADTH, INAHTA databases, MSAS were searched from date of inception to February 2008. [TEVAR.mp OR GORE.mp OR Vanguard.mp OR Braile.mp OR EGS.mp OR TALENT.mp OR Zenith.mp OR Aneurx.mp OR Medtronic.mp OR (endovasc$.mp AND thorac$.mp) OR (stent$.mp AND thorac$.mp)] AND [aneury$.mp OR dissect$.mp OR rupt$.mp OR penetrate$.mp OR intramural.mp OR trauma$.mp)
Two thousand six hundred and twelve abstracts were identified for screening. Forty-five non-randomised control trials and 213 non-controlled papers were found using the reported search and all these were read in full to search for coverage of the left subclavian. Only papers documenting coverage of at least 10 left subclavian arteries without a prior carotid subclavian procedure were included. Also, uncovered stenting across the subclavian was excluded. From these, 20 papers were identified that provided the best evidence to answer the question. These are presented in Table 1.
The Eurostar registry [2] in 2007 collected data from 58 institutions with 606 thoracic endovascular aortic stent procedures (TEVAR) in total. They reported 119 cases of coverage of the left subclavian artery (LSA), with an additional 40 having prior revascularisation. While there were only 15 cases of spinal cord injury on their database, they identified non-revascularised LSA as being a risk factor for this complication with an odds ratio of 3.9 which was significant (P=0.027). The incidence of stroke was not increased in this group. Riesenman et al. [3] reported a cohort of 112 patients, of whom 24 had LSA coverage. One of these patients required LSA stenting due to rest pain in the arm and a further three had mild upper limb symptoms. Gorich et al. [4] documented the patency of both vertebral arteries prior to coverage of the LSA in 23 patients. There were no serious complications, although five patients had a pressure drop of more than 60 mmHg in the left arm and three patients had some mild arm symptoms. Criado et al. [5] documented 186 patients having TEVAR of either an aneurysmal or dissected aorta. Forty-four patients had intentional coverage of the left subclavian without revascularisation. One patient had significant backflow from the LSA to cause an endoleak which required embolisation. In addition, one patient died as they were later found to have had absent vertebral arteries and suffered a bilateral cerebellar infarct. In addition, 15 patients suffered from left arm claudication but did not require any intervention. The TALENT Registry [6] contained 457 patients up to 2004 and of these 32 had coverage of the left subclavian artery. They reported that 17 of all 457 patients suffered a stroke and that this was significantly associated with occlusion of the LSA without prior revascularisation (P=0.004). Unfortunately, they did not give the exact number of strokes that these 32 patients suffered. Khoynezhad et al. [7] covered the left subclavian in 41 patients. Two of these suffered a stroke and two suffered paraplegia, but this incidence was no higher than in the total cohort of 153 patients. The Eurostar registry combined with the UK thoracic endovascular stenting registry to report their results [8]. They reported that 42 patients had the subclavian artery covered without prior revascularisation and a further 37 had coverage but with prior revascularisation. They also report that 22 patients had complications relating to sidebranch occlusion but this category included mesenteric and renal ischaemia as well as limb ischaemia. Also, they did not report how many of these complications occurred in the uncovered LSA stented group. Orend et al. [9] reported their experience with 34 emergency stenting procedures for traumatic descending aortic injuries. They covered the left subclavian on 23 occasions and only one patient required revascularisation for arm hypoperfusion (4%). They also stated in their discussion that they have now covered the left subclavian in over 100 cases in their practice without any further complications, although these data have not been published. Three studies specifically looked at the issue of left subclavian artery coverage: Peterson et al. [11] reported their experience in 30 patients. Eight had coverage without revascularisation but four of these patients had a stroke. CT confirmed that three of these were posterior circulation strokes and two patients had absent contralateral vertebral arteries. A fifth patient suffered subclavian-steal, requiring revascularisation seven months later. Reece et al. [12] documented 20 patients who underwent coverage of the left subclavian artery without prior revascularisation. Four patients required subclavian bypass for arm claudication or steal syndrome. Furthermore, of the seven patients that were revascularised preoperatively, all were due to preoperative CT-scan findings, including three aberrant right subclavian arteries, one dominant left vertebral artery, and two incomplete circle of Willis'. Rehders et al. [13] also specifically looked at this issue and reported that there were no significant complications in 22 patients who had left subclavian artery occlusion, other than four patients who had minor sensations of cold in the outdoors in the months following the procedure. However, their preoperative evaluation was meticulous, including not only TOE, angiography and CT or MRI but also a 30-min balloon occlusion test of the left subclavian while the patient was awake and unanaesthetised. Sunder-Plassmann et al. [15] found a mean blood pressure drop of 48 mmHg in the left radial artery after left subclavian artery coverage. Twelve patients underwent this procedure with only one requiring subsequent subclavian transposition.
Aggregating the data from all these 20 studies we found 498 covered left subclavian arteries (Table 2). Complications included 13 strokes (2.6%), 8 cases of paraplegia/paraparesis (1.6%) and 6 endoleaks due to subclavian backflow (1.2%). Of note there were 51 cases of ischaemia or other symptoms attributable to poor blood flow (10%), which resulted in 20 post-procedural revascularisations (4%). In three studies the mean pressure drop in the left arm was between 36 and 48 mmHg after left subclavian occlusion.
We conclude that coverage of the left subclavian artery has a low, but not insignificant, incidence of side-effects. This incidence must be balanced with the urgency of the procedure and may be acceptable in emergency or salvage situations. However, in non-emergency cases we recommend that the carotid arteries, the vertebral arteries and the Circle of Willis are fully assessed by tests such as duplex ultrasound, angiography, CT or MRI scanning. An absent right vertebral artery, diseased carotid arteries or an incomplete Circle of Willis is a contraindication to left subclavian artery coverage without prior transposition or bypass grafting of the left subclavian artery.
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Abstract
1. Introduction