Ann Thorac Surg 2006;81:1502-1505
© 2006 The Society of Thoracic Surgeons
Case report
Dislocation of a Stent-Graft Into the Aortic Arch During Endovascular Repair of a Descending Thoracic Aortic Aneurysm
Norbert Augustin, MD
a
,
*
,
Robert Bauernschmitt, MD
a
,
Jörg Hausleiter, MD
b
,
Rüdiger Lange, MD
a
a Department of Cardiovascular Surgery, German Heart Center Munich, Clinic at the Technical University, Munich, Germany
b Institute for Radiology and Nuclear Medicine, German Heart Center Munich, Clinic at the Technical University, Munich, Germany
Accepted for publication May 9, 2005.
* Address correspondence to Dr Augustin, Department of Cardiovascular Surgery, German Heart Center Munich, Clinic at the Technical University Munich, Lazarettstraße 36, München, D-80636 Germany (Email: augustin{at}dhm.mhn.de).
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Abstract
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A 59-year-old man showed a saccular aneurysm due to a penetrating atherosclerotic ulcer, as well as a small type B aortic dissection located in the proximal descending aorta. The lesion was treated by the implantation of a stent-graft. On release, the stent-graft dislocated into the aortic arch. Intraoperative angiogram showed free perfusion of the brachiocephalic trunk and left common carotid artery; however, an overstenting of the carotid artery was apparent. Computed tomographic scan exhibited a complete covering of the supra-aortic vessels, and conventional, open aortic arch surgery was inevitable. A partial resection of the proximal part of the stent-graft was performed.
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Introduction
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Open surgical graft replacement of the descending aorta is still associated with high perioperative morbidity and mortality. Even in large series, complication rates of 1.5% to 19%, as well as mortality rates of 3% to 26% are reported [1, 2]. Endovascular stent-graft placement has emerged as a promising, less invasive alternative to open surgery of thoracic aortic aneurysms and dissections [3–4]. Despite such encouraging reports, early and late complications still occur.
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Technique
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A 59-year-old man with a history of hypertension was admitted to an urban hospital with acute chest pain and nausea. A computed tomographic scan showed a saccular aneurysm of the proximal descending aorta caused by a penetrating atherosclerotic ulcer. A small thrombus adhering to the aortic wall was also detected (Fig 1). Furthermore, ensuing magnetic resonance imaging revealed a dissection of 5 cm extension. The patient was in stable cardiopulmonary condition, with a sinus rhythm of 70 beats/min, and his blood pressure was 150/80 mm Hg. During hospitalization, symptoms completely disappeared due to successful antihypertensive treatment.
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Fig 1. Oblique sagittal reconstruction of computed tomographic angiogram demonstrating preoperative aneurysm in the proximal descending aorta (volume rendering technique).
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The patient was transferred to our center for interventional endovascular stent-graft placement. This procedure was performed in the operating room under general anaesthesia after surgical exposure of the right femoral artery. A 24/22 mm Talent-Stent (Medtronic) was guided into the proximal descending aorta and the distal transverse aortic arch under fluoroscopic control. The bare springs were positioned proximal to the origin of the left subclavian artery.
On release, the stent-graft dislocated into the proximal aortic arch, possibly due to an accidental movement at the operating table. Retraction of the stent-graft was not possible. The immediately performed intraoperative angiogram showed unimpaired perfusion of the brachiocephalic trunk and left common carotid artery, however an overstenting of the carotid artery by the covered part of the stent was apparent. To aid with operative planning, a spiral computed tomographic scan was performed. Complete covering of the supraaortic vessels was evident, but opacification of the brachiocephalic trunk, left common carotid artery, left subclavian artery, and the aneurysm was also demonstrated (Fig 2). To avoid potential further complications, open surgical repair of the aortic arch was considered to be mandatory. As the aneurysm was perfectly excluded, complete extraction of the stent and replacement of the descending aorta through a left lateral thoracotomy was not necessary.
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Fig 2. Computed tomographic reconstruction after implantation of the stent-graft shows complete covering of the supra-aortic vessels, but with opacification of the brachiocephalic trunk, left common carotid artery, left subclavian artery, and aneurysm.
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After a median sternotomy, routine cardiopulmonary bypass with cardioplegic arrest of the heart was instituted for profound hypothermic total circulatory arrest. In the Trendelenburg position, the previously placed cross clamp was removed. A longitudinal incision was made in the middle part of the ascending aorta extending to the stent-graft, and the inside of the aortic arch could be examined. The stent-graft had not completely unfolded; therefore, flow to the supra-aortic vessels through a gap between the aortic wall and the stent-graft was preserved, even though a perigraft thrombus formation was already present. Antegrade cerebral perfusion was established. After cutting the wires, partial resection of the stent-graft was performed by fenestrating the wall below the origin of the brachiocephalic trunk and the left common carotid artery. The stent-graft was then fixed to the aortic wall between the left carotid and left subclavian artery by a running suture to avoid migration or disintegration of the stent-graft. The aorta was closed and cardiopulmonary bypass was re-established. The intraoperative and postoperative course was uneventful. Postprocedure spiral computed tomography revealed correct stent-graft position and normal opacification of the supra-aortic vessels, except for the still covered left subclavian artery, as well as exclusion of the aneurysm (Fig 3). The patient could be extubated the next morning and transferred to the urban hospital 5 days after the operation. Over a 3-month follow-up, the patient continues to do well without neurologic or vascular events.
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Fig 3. Postoperative reconstruction of computed tomographic angiogram showing correct stent-graft position, normal opacification of the supra-aortic vessels, except a covered left subclavian artery and complete exclusion of the aneurysm.
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Comment
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Aneurysms and dissections of the thoracic descending aorta are life-threatening conditions and represent an exceptional challenge to the surgeon. Because of high perioperative mortality and morbitity of open surgical treatment, the endovascular stent-graft procedure is considered to be a promising, less invasive alternative. Glade and colleagues [5] published a multicenter study, as well as a meta-analysis of a cumulative cohort of more than 1,000 patients treated for descending thoracic aneurysm by endovascular or open repair. Combining their results with pooled data from the literature, the perioperative mortality and paraplegia rate was significantly lower in patients treated with an endovascular stent. In spite of this encouraging report, evaluation of long-term durability is still awaited. Although endoleaks are the most frequent complications [3, 6, 7], acute stent-graft dislocation rarely occurs either into a distal or proximal direction. Proximal dislocation into the aortic arch is more likely if overstenting of the left subclavian artery is inevitable to extend the length of neck. The necessity for transposition to the left common carotid artery in such cases is controversially discussed. Several authors favor this operation as a routine procedure, whereas others performed extra-anatomic revascularization only in a few cases [3, 7]. Impairment of the flow into the left carotid orifice is less frequent, but potentially life-threatening, and should be corrected without time delay. Recently, Orend and colleagues [7] reported a similar case as the one presented here regarding dislocation proximal to the left common carotid artery, which was treated by extraanatomic carotid-carotid crossover bypass. Our patient, however, had an overstenting of all three supra-aortic arteries due to acute dislocation; therefore an open surgical repair was considered superior to aorto-bicarotid bypass surgery.
If severe proximal dislocation of a stent-graft compromises the flow to all supraaortic vessels, we suggest extra-anatomic bypass procedures should not to be performed, but instead to open the arch during a short period of hypothermic circulatory arrest and re-establish physiologic flow patterns by partial resection of the stent-graft. This procedure offers the possibility to secure the stent-graft to the inner aortic wall, thus preventing proximal endoleaks and further migration of the graft. Perigraft thrombus formation can be safely excluded, so the risk of cerebral embolization is minimized. The risk of the procedure compared with extraction of the stent and replacement of the descending aorta is low if antegrade cerebral perfusion is established.
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References
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- Nienaber CA, Fattori R, Lund G, et al. Non-surgical reconstruction of thoracic aorta dissection by stent-graft placement N Engl J Med 1999;340:1539-1545.[Abstract/Free Full Text]
- Glade GJ, Vahl AC, Wisselink W, et al. Mid-term survival and costs of treatment of patients with descending thoracic aortic aneurysm; endovascular vs. open repaira case-control study. Eur J Vasc Endovasc Surg 2005;29:28-34.[Medline]
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Abstract
Introduction
