Carotid artery stenoses, both symptomatic and asymptomatic, increase the risk for ischemic cerebrovascular events. The long-standing gold standard for invasive treatment of these lesions has been surgical carotid endarterectomy (CEA). CEA reduces the risk of stroke for both severe asymptomatic carotid stenosis1-4 and moderate or severe symptomatic stenosis5-7 when compared with medical management alone.
Surgery, however, is not without limitations. The risk of stroke associated with CEA ranges from 2.9% to 10.7% in major trials.1-3,5-7 Additionally, the coronary artery disease (CAD) that frequently accompanies carotid atherosclerosis increases the risk of perioperative myocardial infarction (MI), complicating even further the management of these patients. Moreover, several groups of patients have a prohibitively high surgical risk for CEA due to comorbid conditions such as severe coronary atherosclerotic disease, severe left ventricular dysfunction, severe aortic stenosis, a history of head or neck radiation, previous ipsilateral CEA, or contralateral carotid occlusion.
Because of these factors, along with the inherent invasiveness and recovery time associated with surgery, nonsurgical alternatives are an important tool in the management of carotid artery stenosis.
In most individuals, the right common carotid artery (CCA) originates from the innominate (brachiocephalic) artery, which is typically the first branch of aortic arch, and the left CCA arises as the second branch of the arch. There are, however, many anatomic variants. Up to one fourth of patients have a common origin of the left common carotid and innominate arteries, and in one-fifth of patients, the left CCA arises directly from the innominate artery.8 Although historically referred to as bovine arch configurations, these two variants do not actually resemble the arch of cattle.9
Elongation of the aorta with aging, atherosclerosis, and different shapes of the chest cavity all impart tortuosity to arch vessels and alter the relationship of their origins to descending aorta. These changes are important for an interventionalist to recognize because they determine the accessibility of these vessels for percutaneous interventions. Figure 108–1 demonstrates the commonly used anatomic classification of the origins of the great vessels. Aortic arch classification is based on the relationship of the innominate artery to the top of the arch. In the type I arch, all three great vessels originate from the same horizontal plane (Fig. 108–1A); the origin of the innominate artery lies between the horizontal planes of the inner and outer curvature of the aortic arch in the type II arch (Fig. 108–1B); and in the type III arch, the innominate artery arises inferior to the horizontal plane of the inner curvature of the aortic arch (Fig. 108–1C).10
Aortic arch classification. A. Type I arch. B. Type II arch. C. Type III arch. The arch type is dependent on the relationship of the innominate artery to the outer and inner curvatures of the ...