Endovascular treatment of the subclavian artery aneurysm in high-risk patients – A single-center experience

Background/Aim. Subclavian artery aneurysm (SAA) is a rare disease, but with serious complications. Recently, besides open surgical procedure, appearance of the stent-grafts enables endovascular reconstruction. We presented our first experience with endovascular treatment of 6 SAA occurring in five male and one female patient. Methods. All the patients, in our studies, according to ASA classification were at high risk of open repair of SAA. The etiology of all aneurysms was atherosclerotic degeneration of the artery. Two aneurysms were at intrathoracic location, and the other ones were extrathoracic. Symptoms related to SAA were present in two of the patients, compression and chest pain in one, and hemorrhage shock in another one. Other patients were asymptomatic. We preferred the Viabhan endoprosthesis for endovascular repair in 5 cases. In one patient with rupture of SAA, who was at high risk of open repair we performed a combined endovascular procedure. First of all, we covered the origin of the left subclavian artery with thoracic stent graft and after that put two coils in a proximal part of the subclavian artery. Results. There was no operative mortality, and the early patency rate was 100%. The follow-up period was from 3 months to 3 years. During this period, one patient died of heart failure and another one required endovascular reoperation due to endoleak type I. Conclusion. Endovascular treatment is recommended for all patients with SAA whenever it is possible due to anatomical reasons especially in high-risk patients with intrathoracic localization of aneurysm, to prevent potential complications.

SAA, who was at high risk of open repair we performed a combined endovascular procedure.First of all, we covered the origin of the left subclavian artery with thoracic stent graft and after that put two coils in a proximal part of the subclavian artery.Results.There was no operative mortality, and the early patency rate was 100%.The follow-up period was from 3 months to 3 years.During this period, one patient died of heart failure and another one required endovascular reoperation due to endoleak type I. Conclusion.Endovascular treatment is recommended for all patients with SAA whenever it is possible due to anatomical reasons especially in high-risk patients with intrathoracic localization of aneurysm, to prevent potential complications.
Correspondence to: Ivan Marjanović, Clinic for Vascular and Endovascular Surgery, Military Medical Academy, Crnotravska 17, 11 000, Belgrade, Serbia.Fax: +381 11 3608 560.E-mail: sofijaivan@gmail.comIntroduction Subclavian artery aneurysm (SAA) is a rare disease, thus it represents only 0.1% in relation to all other aneurysms of the aorta or peripheral arteries 1,2 .Possible complications of SAA are rupture, distal embolization, compression and thrombosis, and therefore should be considered for surgical treatment 3 .Atherosclerosis is the most common cause of these aneurysms.Other causes that can lead to SAA are: thoracic outlet syndrome, degenerative connective tissue disorders, infection and trauma.The only way to treat SAA was open, surgical aneurysm reconstruction, until the appearance of stent-grafts and endovascular reconstruction.Open surgical procedure in the treatment of SAA depends on whether aneurysm affects the intrathoracic or extrathoracic segment of the artery 4 .For endovascular reconstruction of SAA localization of aneurysm is not so important but it is very important that aneurysm has adequate anatomical characteristics for the endovascular procedure.That means that SAA has adequate proximal and distal zone for stent-graft fixation.

Methods
We reported our single-center experience with endovascular treatment of 6 SAAs in the period January 2009 -December 2013.Four aneurysms were at extrathoracic location, while two of them were intrathoracic.Most of them were asymptomatic.Symptoms were present in two patients, compression and chest pain in one, and massive hemorrhage and chest pain in another one (Figure 1).
We preferred the Viabahn endoprosthesis (W.L. Gore, Flagstaff, USA) for endovascular repair in 5 cases.In one case, we covered the origin of the left subclavian artery with thoracic stent graft (TAG 3110, W.L. Gore, Flagstaff, USA) and after that we put two coils (Azur 35 Helical Hydrocoil 10 mm, Terumo, Tokyo, Japan) in the proximal part of the subclavian artery because the aneurysm did not have enough proximal neck (Figures 2 a and 2 b).
Under the local anesthesia we combined the transfemoral approach to endovascular treatment with the transbrachial approach to put the diagnostic catheter.
The follow-up period was from 3 months to 3 years.The patients were monitored postoperatively by physical examination, doppler ultrasonography at 3-, 6-and 12-month intervals, and once yearly thereafter.Control computed tomography (CT) angiography was performed in the patients after the first year of operation or more often if there was a need.

Results
Six presented patients were between 72 and 84 years old (five males and one female).All aneurysms were athero-  The most common comorbid conditions in the presented patients were: arterial hypertension, coronary artery disease, cerebrovascular insult, chronic cardiomyopathy, diabetes mellitus, peripheral arterial occlusive disease and chronic obstructive pulmonary disease.All the patients in our group were active smokers.It is interesting that none of the patients in our group had no medical history of aneurysmal aortic disease, nor a peripheral artery aneurysm.Medical history of the patients showed no chest injury, nor other types of trauma in the subclavian artery region (Table 1).
There was no operative mortality, and the early patency rate during the first tree months was 100%.During this follow-up period there was no need for open reconstruction of SAA and there were no complications such as stent graft thrombosis or distal embolization and ishemia.
During follow-up period of 3 years, one patient died of heart failure and another one required endovascular reoperation due to endoleak type I (Figures 3a and 3b).

Discussion
Elective surgical repair is mandatory for subclavian aneurysms, even when asymptomatic, because they tend to increase in size with increased risk of rupture, thrombosis, distal embolization and compression of surrounding structures.
Although aneurysms of SAA are rare, potential risk of rupture and secondary ischemic complications are complications which require surgical treatment.Open repair of SAA, especially of the intrathoracic segment in patients with previous median sternotomy or lateral thoracotomy, is a technical challenge with a lot of postoperative complications.Davidović et al. 3 reported a series of 14 patients with SAA treated with the supraclavicular or trans-sternal approach, depending on aneurysm location.No mortality occurred and the postoperative complication rate was 21%.During the follow-up period one patient required reoperation because he developed aneurysmal degeneration of a saphenous vein graft.
Endovascular techniques offer a minimally invasive option especially in high risk patients.Endovascular repair of SAA have been reported in a small series 5 .MacSweeney et al. 6  subclavian artery aneurysm in larger series of patients.Preoperative duplex ultrasonography and CT angiography are always mandatory for diagnostic and planning the endovascular treatment of SAA 7,8 .These diagnostic procedures are necessary to determine the proximal and distal neck diameter and proximal and distal landing zone, as well as to determine approprite the length of the stent-graft.
We preferred a Viabahn stent-graft for endovascular repair of SAA.It is a flexible nitinol stent frame covered internally with polytetrafluoroethylene (PTFE) graft.The flexibility of the Viabahn adapted well to the tortuosity of the subclavian artery, with minimal alteration in the native vessel curvature.
In our series, we successfully treated SAA in five patients with Viabhan stent-graft.All the patients were treated with Viabhan stent-graft placed endovasculary as an elective operation, but there are studies that present emergency stentgraft repair of SAA with Viabhan due to rupture 9 .In one patient with ruptured giant intrathoracic SAA who did not have an adequate proximal lending zone of the aneurysmal neck, we placed emergently thoracic stent-graft to cover the origin of subclavian artery, and after that we put two coils in the proximal part of the subclavian artery to prevent endoleak type II.Amiridze et al. 10 have already described the use of coils for treatment of the subclavian artery pseudoaneurysm and arteriovenous fistula.But it seems that endovascular treatment only with coils is reserved for pseudo-aneurysm and small saccular aneurysm.

Conclusion
Endovascular treatment of subclavian artery aneurysm may be a valuable, less invasive alternative to open surgical approach.This treatment is especially good for high risk patients with aneurysm of the intrathoracic part of the subclavian artery.However, long-term results of this technique have not yet been established.
Fig. 3 -A) Aneurysm of the subclavian artery above the previously placed stent-graft with endoleak type I one year after the first reconstruction; B) Endovascular reoperation with one more placed stent-graft.