Occlusive lesions of the innominate artery are rare and may present with right upper-extremity weakness and fatigue, transient ischemic attack (TIA), or vertebrobasilar insufficiency. The majority of patients present with cerebral atheroembolic events, such as amaurosis fugax, TIA, or stroke. Vertebrobasilar insufficiency, or posterior circulation symptomology, is associated with the development of a subclavian steal syndrome. Suggested criteria for “classic” vertebrobasilar insufficiency or posterior circulation symptoms were suggested by Ouriel et al. in a study to predict the success of carotid endarterectomy for nonhemispheric symptoms (Table 34-1). Patients not meeting the criteria are referred to as “nonclassic” and represent a more global hypoperfusion state. Lesions of the innominate artery increase the risk of embolism or hypoperfusion for both the anterior and posterior circulations. The clinical presentation of innominate artery lesions is varied: 20% are asymptomatic and present simply with unequal pulses or blood pressures during routine physical examination. Despite a severe stenosis or even a total occlusion, upper-extremity symptoms are uncommon, except that digital necrosis may present as a manifestation of an embolism.

The initial consideration of innominate artery stenosis or occlusion is often based on clinical findings. A differential upper-extremity pulse, palpation, or a blood pressure differential between arms suggests the diagnosis. Hemodynamically significant stenoses are demonstrated by brachial artery pressures differing more than 20 mm Hg or unequal radial pulse wave amplitude. Standard duplex ultrasonographic techniques provide indirect data in the evaluation of the innominate, common carotid, and subclavian arteries. Low flow in the suspect artery with normal or augmented contralateral flow should suggest the presence of a proximal lesion. Patients with diffuse disease of multiple aortic arch vessels may require more definitive studies, which are always employed before any planned intervention. Standard contrast angiography remains the most common diagnostic modality, but alternative imaging techniques such as computed tomography angiography and magnetic resonance angiography (MRA) provide alternatives with less risk of procedural embolism.

Maintenance of cerebral and upper-extremity blood flow along with the elimination of atheroembolism risk are the treatment objectives in patients with upper-extremity arterial disease. Surgical options for lesions of the innominate artery include indirect (extra-anatomic) and direct approaches. Indirect repairs were developed to avoid the morbidity and mortality of a median sternotomy, especially in high-risk patients. Extra-anatomic approaches are suboptimal for several reasons: the bony sternum is not favorable for graft configuration; the questionable ability of a donor arch vessel to provide adequate blood flow to both arms and the vertebral arteries; the potential difficulty of graft kinking from external compression; and poor long-term results. The direct approach is considered to have superior long-term results, and the preferred approach to an innominate arterial lesion is via median sternotomy. The choice of direct reconstructive procedure is influenced by the extent of disease and other technical factors. Innominate endarterectomy is a suitable procedure for innominate artery disease located away from the aortic wall. Diffuse atherosclerotic disease extending into the aortic arch does not allow safe clamping and endarterectomy, and it is thus an absolute contraindication. In addition, the origin of the left common carotid artery must be at least 1.5 cm from the takeoff of the innominate artery to allow for clamping without threatening the flow in the left carotid artery. The conversion to a direct innominate artery bypass is necessary if the arterial wall is not amenable to endarterectomy or clamping. The most common procedure for orificial innominate disease is an end-to-side bypass from the ascending aorta and end-to-end to the innominate bifurcation, using an 8 to 10 mm Dacron graft. Absence of calcification of the aorta in the intrapericardial location is a prerequisite to permit safe placement of a side-biting clamp on the aorta.

Endovascular treatment of the innominate artery is not well described in the literature, and there are no large series establishing the safety or efficacy of the approach. Similarity in wall composition, branching anatomy, and the hemodynamic milieu between the innominate artery and the common iliac artery suggests successful endovascular treatment. Case reports describe excellent initial technical success with minimal morbidity and mortality; however, long-term follow-up data is not available.

Endovascular therapy is ideal for focal stenotic lesions less than 3 cm. Vascular access is obtained via the common femoral artery. A good arch aortogram in the LAO position is the first step. The arch must be “maximally unwound” to prevent overlap of the orifices of the supraaortic trunks. The innominate lesion is first crossed with a guidewire. The catheter and wires selection entirely depends on the type of aortic arch (types I to III, further described under carotid stenting). Some interventionists start treatment with balloon angioplasty alone, treating suboptimal angioplasty results with stent placement. Indications for stenting include a persistent hemodynamic pressure gradient, residual visual stenosis of greater than 30%, or an occlusive dissection of the arterial wall. Our practice with all supra-aortic trunk disease is to use primary stenting with a balloon-expandable stent whenever possible in order to decrease the risk of embolization.

Balloons and stents are oversized by approximately 20% to that of the innominate artery just beyond the lesion. Usual balloon diameters are 9 to 12 mm, with a length to approximate the diseased arterial segment, usually 2 or 4 cm. It is likely that embolization protection devices will be developed and increasingly used. Predilation with a smaller balloon may be needed when technical difficulty in traversing the lesion with a larger balloon is encountered.

A retrograde approach via the right brachial artery is an alternative. The advantages are less working length and greater pushability across the lesion. Disadvantages include a higher access complication rate, more difficulty in achieving access in the nonpalpable brachial artery, and difficulty in defining the proximal end of the lesion due to high aortic flow.

Cerebral brain stem and upper-extremity embolism are possible complications of innominate artery angioplasty. Described methods to decrease the risk of embolism include external compression of the right carotid artery during dilation and routine placement of a second (occluding) balloon in the common carotid. A risk factor for embolism is antegrade flow through the right vertebral artery. A postprocedure angiogram is required not only to confirm a satisfactory radiographic result but also to exclude embolism to the cerebral circulation. Reported complications include cerebral infarction (2%), TIA (6%), and mortality (0.2%).