Introduction
A build-up of plaque in the carotid artery can lead to atherosclerosis, narrowing of the artery, stenosis, and subsequent carotid artery disease. Carotid artery disease increases a person’s risk for cerebrovascular disease or stroke. This disease can be asymptomatic or symptomatic. Carotid endarterectomy (CEA) is a surgery performed to decrease the risk of stroke. The procedure entails removing plaque from the common carotid artery and internal carotid artery to improve blood flow and remove embolic material. Carotid artery reconstructions began in the early 1950s, and techniques for carotid endarterectomy procedures, as well as indications to perform them, have evolved.
Anatomy
Within the superior mediastinum, the arch of the aorta can be found at the level of the sternal angle. Three large vessels originate from the aorta. This includes the brachiocephalic trunk, the left common carotid artery, and left subclavian artery. On the right side, the common carotid artery stems off as the first branch the brachiocephalic trunk. Both the left and right common carotids will bifurcate into an internal and external carotid artery. This division occurs around the fourth cervical vertebrae (C4) along the superior border of the thyroid cartilage. There is a deep cervical fascia that forms the carotid sheath. This surrounds the carotid arteries, internal jugular vein, and vagus nerve. They are found medially to the sternocleidomastoid muscle. The internal carotid artery will continue into the skull to form part of the Circle of Willis and supply blood to the brain and eyes. Branches of the external carotid artery supply blood to the neck and face.
Indications
In 1987 the North American Symptomatic Carotid Endarterectomy Trials (NASCET) began. Patients with moderate carotid stenosis (less than 70%) and severe carotid stenosis (greater than 70%) were randomly assigned to treatment groups, which included antithrombotic medication for a majority of patients. The study found that the benefit of surgery was great for those who had severe carotid stenosis, and patients with less than 50% stenosis were found to have no benefit. Patients who have 50% or more narrowing of the carotid artery and history of ipsilateral stroke or TIA are recommended to have carotid endarterectomy surgery. Symptoms of TIA can include amaurosis fugax, a painless temporary loss of vision in one or both eyes, hemiparesis, and speech loss episode.
Asymptomatic patients with 70% or more narrowing, also are encouraged to undertake the surgery. In the Asymptomatic Carotid Artery Stenosis (ACAS) trials for endarterectomy, it was shown that after the procedure there is a significant 5-year reduction in stroke risk in asymptomatic patients. As medical therapy has improved since the 1980s, the CREST-2 trial is currently underway. The trial will provide data about best medical therapy versus surgery in patients with asymptomatic, high grade internal carotid stenosis.
It is possible to screen asymptomatic patients with the use of carotid duplex ultrasonography (CDU). It can assess the degree of carotid stenosis. The severity of the obstruction correlates to carotid velocity. Inaccuracies can be shown if there are blood vessel kinks and bends which may cause elevated velocities. Although it is a great tool for detecting hemodynamically significant stenosis, it has relatively low specificity for those patients with 50% to 60% stenosis. Other forms of screening include computed tomography angiography (CTA), and contrast-enhanced magnetic resonance angiography (CE-MRA). They help to assess other variables that can impact an individuals risk including plaque morphology, intracranial collateralization, and brain perfusion. CTA or CE-MRA information can be used alongside CDU to help put into perspective a patient’s need for surgery.
