Abstract
Endovascular treatment of aortic arch aneurysms poses unique problems because of vascularization of the carotid arteries.
Transposition of supra-aortic vessels is becoming an established and accepted strategy for expanding the applicability of stent graft repair. left subclavian artery (LSA) is not usually transposed because its overstenting does not produce relevant complications. Nevertheless, some selected cases need high-pressure revascularization of the LSA, such as in the presence of a patent left internal mammary artery. We present a technique of revascularization of supra-aortic vessels and “balloon protected” embolization of the origin of the LSA.
Surgical transposition of supra-aortic vessels is a reliable and effective solution for the treatment of descending thoracic aortic aneurysms very close to the left subclavian artery (LSA). 1
We began to apply surgical transposition, and, with increasing experience, we extended this technique to the LSA as well as to the left common carotid artery (LCCA) and the brachiocephalic trunk. 2 Our experience, as well as that of others reported in the literature, has shown that this technique has a low morbidity and mortality rate and appears to be superior to standard surgical therapy in high-risk patients. 3
One of our most interesting cases involved a patient suffering from an arch aneurysm who previously underwent aortocoronary bypass with a patent left internal mammary artery (LIMA). In this case, we performed a bypass from the right common carotid artery (RCCA) to the LSA with reimplantation of the LCCA followed by successful endovascular exclusion of the arch aneurysm.
Case Report
The patient was a 77-year-old male who came to our institution owing to symptoms caused by left arm arterial embolization. In 1997, he had undergone surgery for myocardial revascularization using both the saphenous vein and the LIMA as bypass grafts. Chest radiography followed by computed tomography (CT) revealed a large saccular aneurysm involving the aortic arch (Figure 1).
Computed tomographic scan showing a saccular aneurysm of the transverse portion of the aortic arch.
The patient was unsuitable for standard open surgical repair because of severe chronic obstructive pulmonary disease. Considering the limited extension of the disease, he was scheduled for endovascular exclusion. Among routine preoperative examinations, we also recommended angiography, which revealed a patent LIMA.
To obtain a secure proximal fixation, we planned to transpose the LCCA. The LSA also required high-pressure revascularization to prevent myocardial ischemia.
We performed a RCCA-LSA bypass and reimplantation of the LCCA on a Dacron graft (Hemashield Vantage, Boston Scientific Medi-Tech, Wayne, NJ) (Figure 2). The subclavian anastomosis was performed end to side, with the proximal clamp placed distally to the origin of the LIMA. Therefore, we did not change the perfusion of the LIMA, and no myocardial ischemia was observed during the procedure. Three days later, the aortic arch aneurysm was excluded by positioning a Zenith 42 mm thoracic endovascular prosthesis (William Cook Europe –DK-4632-Bjaeverskov, Denmark) via femoral access. At the end of the procedure, angiography showed satisfactory aneurysm exclusion, but the CT scan control revealed a reperfusion endoleak from the LSA, as we expected.
Right common carotid artery—left subclavian artery bypass with reimplantation of the left common carotid artery.
After 1 week, the embolization of the origin of the LSA via the omolateral brachial artery sealed the endoleak. One important technical tip was the use of a ballon (Wanda, 7–20 mm, Boston Scientific Medi-Tech, Natick, MA), which was inflated proximal to the origin of the LIMA to channel and block the coils (Figure 3). In-hospital and 6-month CT scan controls showed optimal aneurysm exclusion (Figure 4).
A, Transbrachial angiography showing a reperfusion endoleak from the left subclavian artery (LSA). B, Embolization of the LSA origin via brachial artery access. C, Final angiographic control shows left internal mammary artery patency after embolization. D, Drawing shows the completed procedure.
Computed tomographic scan control after embolization of the left subclavian artery.
Discussion
The need to revascularize the subclavian artery is still in question, although obstruction with a stent graft does not usually present serious complications. 4,5
During the first part of our experience, we always performed a transposition of the LSA when we expected to cover it. The rationale was the attempt to preserve cerebral and spinal cord supply and to avoid a reperfusion endoleak.
Following other authors, 5 in the second part of our experience, we started to revascularize the LSA only in selected cases, such as extensive covering of the descending thoracic aorta, previous abdominal aortic aneurysm surgery, contralateral vertebral artery occlusion, or, as in this case, in the presence of a patent LIMA graft. In this case, the transposition of supra-aortic vessels followed by LSA embolization gave optimal results, maintaining high blood pressure in the LIMA during the entire procedure.
Furthermore, we believe that an end-to-side anastomosis to the subclavian artery is preferable in any case. An end-to-end anastomosis to the LSA proximal to the origin of the LIMA and the vertebral artery is more demanding because it requires more extensive mobilization of the subclavian artery as both arteries represent fixed points.
In conclusion, the management of the LSA can present some technical problems. This example of revascularization is suitable in the presence of a patent LIMA.
The “balloon-protected” LSA embolization is safe and effective and also represents a technical resource in other cases of LSA reperfusion endoleak.