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June 2010
Isolated Innominate Artery Aneurysm
An endovascular approach to treat this rare presentation.
By Kuldeep Singh, MD; Mohummed Khani, MD; Johnathan Scheiner, MD; Martin Zomaya, BS; and Gary Giangola, MD, FACS
Isolated innominate artery aneurysms (IAAs) are uncommon, and causes may include trauma, infection, or atherosclerotic degeneration. Atherosclerosis generally causes occlusion of the brachiocephalic vessels in up to 4.8% of patients;1 however, approximately 4% of all innominate artery surgeries are for aneurysmal disease. 2 The aneurysm is usually asymptomatic and is detected as an incidental finding of a mass on a chest xray. A large aneurysm may also present with symptoms of compression on mediastinal structures.3 The IAA may rupture, enlarge, thrombose, or embolize and should therefore be treated. Conventional treatment has largely been a surgical approach via a thoracotomy or median sternotomy with or without cardiopulmonary bypass;4,5 however, an open approach has a significant morbidity rate associated with the procedure. We report a case of a large, isolated IAA causing compression and probable erosion into the trachea, which we treated endovascularly.
CASE REPORT
A 77-year-old man presented with a cough, fever, and
shortness of breath. A chest x-ray showed an elliptical density
in the right upper lobe. He was subsequently treated for
presumed pneumonia. The patient began to develop worsening
shortness of breath and hemoptysis. A computed
tomography (CT) scan of the chest revealed an anterior
mediastinal mass that we suspected could be a brachiocephalic
artery aneurysm. A dedicated CT angiogram
showed a multilobulated aneurysm measuring 5 X 5 cm
arising from the lateral aspect of the innominate artery. The
right common carotid and subclavian arteries were noted to
arise from the aneurysm sac. The right vertebral artery was
patent and came off 2 cm beyond the origin of the subclavian
arteries (Figures 1 and 2). The aneurysm abutted the
trachea, causing compression and left shift, which accounted
for the patient's symptoms (Figure 3). An open repair
was considered, but given the history of cardiomyopathy
with an ejection fraction of 20% and pulmonary hypertension,
the patient was deemed to be extremely high risk for
an open procedure. Therefore, an endovascular approach
was chosen.
The patient was taken to the surgical suite, and the right femoral artery was accessed percutaneously. An angiogram was obtained confirming the large aneurysm (Figure 4). The carotid and subclavian arteries were patent bilaterally. A VTK catheter (Cook Medical, Bloomington, IN) was then introduced into the aneurysm and advanced into the external carotid artery. A 9- X 59-mm iCast covered stent (Atrium Medical Corporation, Hudson, NH) was first placed into the common carotid artery, and then a 10- X 38-mm iCast covered stent was placed within the first stent, landing partially into the aorta. The stent was balloon dilated to 12 mm (Figure 5), and the aneurysm was filled with coils through a right brachial artery approach (Figure 6). An endoleak was noted from the subclavian artery into the aneurysm sac. A plug was not readily available in the institution at the time. Therefore, coils were placed into the origin of the subclavian artery percutaneously via the brachial artery, and the endoleak was subsequently resolved (Figures 7 and 8).
On postoperative day 3, the coils were noted to have migrated to the axillary artery, and the patient was taken back to the operating suite. An aortogram showed a patent subclavian and vertebral artery and flow in the axillary artery. A 12-mm Amplatzer plug (AGA Medical Corporation, Plymouth, MN) was then placed into the origin of the artery percutaneously via the brachial artery. This maintained the position of the previously placed coils and occluded the subclavian artery. A subsequent thoracic angiogram revealed a proximal leak around the covered stent; a 14-mm dilatation balloon angioplasty sealed the leak.
DISCUSSION
Isolated true IAAs are rare; they represent approximately
3% of all aneurysm incidents.3 Bower et al found only six
cases in a retrospective survey of the Mayo Clinic records
spanning 40 years.6 Traditionally, these aneurysms were
encountered secondary to infection with syphilis
(Treponema pallidum); however, with advances in medical
treatment, syphilitic arthritis has virtually disappeared. The
majority of IAAs encountered today are associated with a
coexisting ascending or thoracoabdominal aortic
aneurysm.7 Other causes include connective tissue disorders,
vasculitis, or an associated trauma.8 An isolated IAA, as
we presented here, is exceedingly rare.5 The clinical picture
ranges from an incidental finding to a catastrophic event.
Signs and symptoms include supraclavicular pulsatile masses, chest pain, dysphagia, dyspnea, tracheal compression, and hoarseness.9 Although neurological manifestations due to embolism or thrombosis are by far the most frequent devastating events associated with these aneurysms, rupture has also been reported. For example, Kieffer et al reported such a case in the Journal of Vascular Surgery.5 IAA rupture is more commonly seen in conjunction with posttraumatic aneurysms and in patients with hereditary connective tissue disease.5 Posttraumatic aneurysm may also present with thrombosis. An IAA is usually detected as an asymptomatic mass on chest x-ray, and CT scan or angiography can confirm the diagnosis.8,10
Surgical treatment is always necessary in symptomatic cases and should be considered in asymptomatic patients to prevent complications, which include cerebral embolization if thrombus is noted lining the aneurysm wall.6 However, surgical treatment comes with considerable morbidity and mortality rates, and although these rates have improved, they remain significant. Hadjipetrou et al report rates of 3%, 2%, and 16% for death, stroke, and complications, respectively,11 for patients undergoing surgery to treat IAAs. Kieffer et al reported a perioperative mortality rate of 11% in 27 patients who were treated for IAAs over 3 decades.5 Schumacher et al3< quote a mortality rate of 41.7% in 47 patients treated for nontraumatic IAAs. Endovascular treatment of IAAs is desirable because of the difficulty in approaching these aneurysms and the considerable mortality rates. Endovascular graft repair is also an option for patients who cannot tolerate general anesthesia due to severe pulmonary disease. Endografts can be delivered by either a femoral approach or via a brachial approach; however, it may be unusual to find IAAs with a proximal neck. Only aneurysms with an adequate proximal and distal neck (> 1 cm) are suitable for endografting.
If the patient is not a candidate for endovascular repair, a surgical approach through a median sternotomy and bypass grafting from the ascending aorta to the subclavian and carotid arteries can be performed and has good long-term patency2,10 rates around 94% + 3% and 88% + 6% at 5 and 10 years, respectively.12 Various surgical approaches have been devised to treat IAAs and include ligation alone,10 patch angioplasty, resection with end-to-end anastomosis, and bypass with either saphenous vein or prosthetic grafts. The surgical approach depends on the extent of the aneurysm, which is classified into three groups: group A does not involve the origin of the innominate artery; group B involves the origin but not the aorta; and group C involves the origin and the aorta and requires cardiopulmonary bypass for repair.5
Kieffer et al noted that patients with isolated asymptomatic aneurysms who are at high surgical risk should undergo surgery when the aneurysms are saccular or when their maximum transverse diameter is > 3 cm.5 In an elective setting, the mortality risk is 4% to 5% and increases up to 50% in cases of emergency surgery for a ruptured aneurysm.10
CONCLUSION
A surgical approach has largely been the conventional
treatment via a thoracotomy or median sternotomy with or
without cardiopulmonary bypass;4,5 however, an open
approach has a significant morbidity rate associated with it.
An endovascular approach offers the advantage of being
minimally invasive and having a decreased morbidity rate,
although long-term follow-up and evaluation of the durability
are still to be determined.
Kuldeep Singh, MD, is with the Division of Vascular Surgery, Staten Island University Hospital in Staten Island, New York. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Singh may be reached at kgoraya@yahoo.com.
Mohummed Khani, MD, is with the Division of General Surgery, Staten Island University Hospital in Staten Island, New York. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein.
Johnathan Scheiner, MD, is with the Division of Interventional Radiology, Staten Island University Hospital in Staten Island, New York. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein.
Martin Zomaya, BS, is with the American University of the Caribbean School of Medicine in St. Maarten, Netherlands Antilles. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Mr. Zomaya may be reached at (501) 319-5319; martin.zomaya@gmail.com.
Gary Giangola, MD, FACS, is with the Division of Vascular Surgery, Staten Island University Hospital in Staten Island, New York. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein.
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