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Conventional Surgical and Endovascular Treatment of Innominate Artery Atherosclerosis
The arterial blood supply to the upper extremities and brain is based on the supra-aortic trunk vessels, which include the innominate, left common carotid, and left subclavian arteries. The innominate artery is unique in that it is solely responsible for the circulation to the right arm and entire right hemisphere of the brain. Although a variety of pathologic disease processes are known to affect the innominate artery, atherosclerotic occlusive disease is the most common. Typically, atherosclerotic involvement represents spillover from a diseased aortic arch and is generally isolated to the ostium of the vessel.
Clinical Presentation
Patients with significant innominate arterial occlusive disease may be free of symptoms or can present with right-sided cerebrovascular and upper extremity symptoms. With a significant innominate artery stenosis in a right-handed patient, complaints of early-onset arm fatigue may be evident, as well as vertebrobasilar insufficiency. Alternatively, plaque rupture of an innominate artery lesion and distal embolization can lead to a clinical presentation of right upper extremity ischemia and/or a stroke, transient ischemic attack (TIA), or amaurosis fugax.
Diagnosis
The diagnosis of an innominate artery stenosis or occlusion is best achieved using noninvasive radiographic imaging. Duplex ultrasound can provide indirect evidence of an innominate arterial lesion by detecting reduced flow velocities in the right common carotid and subclavian arteries, but direct assessment is best achieved with either contrast-enhanced computed tomography angiography (CTA) or magnetic resonance angiography (MRA). Duplex ultrasound is hampered by the inability to directly image the innominate artery in the chest, whereas CTA and MRA provide cross-sectional, sagittal, coronal, and three-dimensional views of the innominate artery. Moreover, CTA and MRA provide additional detail of the plaque morphology and characteristics of the atherosclerotic lesion. Contraindications to CTA are the risk of radiation exposure and sequelae of intravenous iodinated contrast administration. MRA is generally avoided in cases of claustrophobia and preexisting ferromagnetic elements such as a pacemaker. If noninvasive imaging is not feasible, then conventional angiography can be used to accurately assess the innominate artery.
Treatment
Medical therapy remains a cornerstone for atherosclerotic innominate artery disease. In certain instances, additional surgical or endovascular treatment is advocated. Although this particular disease has not been as well studied as extracranial carotid artery disease with randomized studies, the guidelines for proceeding with surgical or endovascular treatment are similar: symptomatic disease with at least 50% stenosis or asymptomatic disease with at least 80% stenosis.
Surgical Techniques
Traditional open surgical treatment of atherosclerotic innominate artery disease is typically divided into transthoracic bypass, transthoracic endarterectomy, or extra-anatomic cervical bypass. The transthoracic bypass is considered the gold standard, but all three are effective and durable therapies. An extra-anatomic bypass is generally reserved for patients deemed unable to undergo a median sternotomy for definitive treatment owing to a prior sternotomy, severe cardiopulmonary disease, or extensive ascending or aortic arch disease. The primary risks associated with these approaches are cranial nerve injuries, stroke, and myocardial infarction.
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