Key words:

Carotid Artery-This artery originates on the left side from the aorta, and on the right from the brachiocephalic artery. The artery bifurcates (splits) in the neck into the external carotid artery, supplying facial structures, and the internal carotid artery which continues to the brain.

Carotid Endarterectomy- A surgical procedure involving the carotid artery. Plaque is removed, thus re-establishing unobstructed blood flow to the brain.

Cerebral Infarction-Stroke
Approximately 500,000 people suffer from a new stroke each year. Of these patients 200,000 patients die. Of those who survive, up to 20% will have another stroke.

TIA (transient ischemic attack) -A neurological deficit that completely resolves in less than 24 hours. These symptomatic patients are at much greater risk for developing a stroke than their asymptomatic counterparts. Patients may complain of weakness in one of their extremities (usually one sided) or of blindness in one eye that resolves, or of difficulty speaking that resolves.

Amarosis Fugax- Blindness in one eye that resolves. Sometimes described as a “shade” obstructing the vision.

Atherosclerosis-“Hardening of the arteries”- A disease process of the arteries that can lead to a reduction of blood flow, or to debris being released (embolization). This can occur anywhere in the arterial tree.

Vertebrobasilar insufficiency -A process affecting the arteries leading to the posterior brain circulation. Patients can present with complaints including nausea, vomiting, ataxia (unsteadyness), and double vision.

Diseases that Affect the Carotid Arteries

Atherosclerosis
The most common lesion occurring in patients with cerebrovascular disease is atheroscerotic plaque within the carotid artery, or sometimes the vertebral artery, causing obstruction of blood flow. This “blockage” is usually referred to as a stenosis. Although plaques can form anywhere along the carotid artery, it most commonly occurs at the bifurcation of the common carotid artery in the neck. These lesions form due to injury of the intima (inner arterial lining) which leads to the formation of plaque. At times, hemorrhage into a plaque can lead to significant disease. Patients can be completely asymptomatic, and the stenoses are found incidentally, or the patients can present with symptoms including TIAs, amarosis fugax, or stroke.

Risk Factors for the Development of Stroke
The most important risk factor for the development of a stroke is hypertension. This can and should be treated medically. Cigarette smoking is a major risk factor as well. Women who take oral contraceptives have a 5 times higher risk of developing a stroke, especially those women older than 35.  Heavy alcohol use has been implicated in the risk of stroke. Those patients with diabetes mellitus are also at increased risk. Elevated blood lipids (cholesterol and triglycerides) has also been implicated as a risk factor in the development of atherosclerosis in the arterial tree.

Tests Frequently Performed to Assess Carotid Artery Disease

Duplex Ultrasound- Allows for the direct evaluation of arterial disease with no risks to the patient. Lesions within the arteries produce changes in the blood flow patterns which can determine the severity of the stenosis in the artery. This test is done in a vascular laboratory, taking approximately 30 minutes to perform by a skilled registered vascular technologist. It is neither uncomfortable nor painful. It is used as a primary screening test for carotid artery disease and as a follow up study in patients who have already undergone carotid artery surgery.

Magnetic Resonance Imaging (MRI/MRA)- The MR scan is a highly specialized imaging technique which can image the brain and the arteries in the neck. It is safe and painless. Patient movement can hinder the resolution of the study. Those patients who are claustrophobic may not tolerate the test.

Angiography-“X-ray dye test of the arteries”. The angiogram allows for visualization of carotid arteries, the vertebral arteries, and the relationship of the blood vessels in the brain. It is an invasive test involving the placement of a catheter into the arterial system, accessed either from the groin or the arm, and the injection of dye to produce images of the arteries. Although the test is considered the “gold standard” by which all other tests are measured, it does carry some risk. Approximately 0.6% of patients may have a neurological event from the procedure. Rarely, patients can develop bleeding from the puncture site, kidney failure from the dye, and injury to the blood vessels which could lead to operative intervention. Therefore, this test is selectively used in cases that require more in depth evaluation.

Computed Tomographic (CT) Scan -CT plays an important role in the evaluation of cerebral infarction. Although it is a very sensitive test, many strokes are not clearly apparent within the first 24-48 hours after the onset of symptoms.

Surgical Intervention

Asymptomatic patients - Several studies have been performed to study the role of carotid endarterectomy in the asymptomatic patient. The largest study to date, the Asymptomatic Carotid Artery Study, showed that those patients who are operated upon with a morbidity and mortality of less than 3%, the risk reduction of stroke in the surgically treated group was 53% over 5 years. In our published data, the morbidity and mortality is less than 1%. Therefore, we advise that in those patients with hemodynamically significant stenosis of the carotid artery, who are acceptable surgical risks, carotid endarterectomy may be performed safely.

Symptomatic patients - Several prospective studies have been performed that concluded that carotid endarterectomy is highly beneficial in reducing the risk of stroke in patients treated surgically compared to those treated medically. We therefore advise that those patients who are not completely disabled by a major stroke, or who are not surgical candidates for other medical reasons, and who have carotid lesions demonstrated by ultrasound, MRI, or  angiography ispilateral to the affected side should undergo carotid endarterectomy. The timing of surgery is chosen on an individual basis.

Technical Aspects of Surgery - Traditionally, surgery is performed with the patient under general anesthesia, using a longitudinal arteriotomy (incision of the artery). The plaque is then removed, and the artery is sometimes closed primarily, or patched with either vein or a synthetic patch. At the Vascular Institute, we have performed over 4000 carotid endarterectomies with a morbidity and mortality of less than 1%.  Our patients undergo regional anesthesia. This enables our team to continually assess the patient during surgery. We perform the eversion technique which allows the plaque to be removed cleanly with a good visualization of the plaque endpoint. This also decreases the chances of recurrent stenosis compared to the longitudinal technique. Rarely, if the patient develops neurological changes, the placement of a shunt is performed to allow for continued blood flow to the brain while the procedure continues.

Post-operative Care - Our patients are monitored for 24 hours on a vascular surgery floor, with nurses trained and dedicated to the treatment of patients with vascular diseases. Most patients are discharged home the day following surgery. All patients are followed up by home visiting nurses for blood pressure monitoring.

Combined Carotid Endarterectomy and Coronary Artery Bypass Grafting (CABG) - We have published data that shows that concurrent carotid endarterectomy and CABG is safe and effective in certain patient populations. (see bibliography)

Carotid Artery Angioplasty and Stent Placement - A new technique which is done only as a part of a multi-center trials. We participate in these trials. Only high risk patients are considered, including those patients with very high surgical risk, previous surgery of the head and neck, and patients who have undergone radiation of the head and neck.

Other diseases Effecting the Carotid and Vertebral Arteries

Fibromuscular Dysplasia is an arterial disease that can effect the carotid and vertebral arteries as well. It can lead to stenoses (blockages) of the arteries involved. There is an association with intracerebral aneurysms. It seems to occur more often in women, and seems to have a genetic component was well. Although the spectrum of symptoms may be very similar to those patients with atherosclerotic disease of the carotid artery, patients can also present with pain, blurry vision, facial numbness, headaches, vertigo and tinnitus (ringing in the ears). Although the treatment of these patients has been mostly been medical management with antiplatelet therapy, some patients with stenoses are amenable to percutaneous transluminal angioplasty.

The etiology of vertebral artery insufficiency is either thromboembolic or hemodynamic in nature. Thromboembolic vertebral insufficiency can be caused by atherosclerosis, trauma, arterial dissections and aneurysms. Surgical intervention is considered in those patients with transient neurological problems or patients with small residual deficits. Those patients with hemodynamic vertebrobasilar ischemia should be individually accessed for carotid disease and vertebral artery disease with treatment and surgical reconstrution tailored to the specific lesions found.

Extracaranial carotid artery aneurysms can be caused by atherosclerosis, fibrodysplasia, trauma and infection (mycotic aneurysms). Management is individualized. Theraputic intervention depends on the etiology of the aneurysm, the presence or absence of symptoms and the patient’s overall medical condition.

Carotid artery or vertebral artery dissection is  usually caused by a tear in the wall of the artery, creating a false passage which can lead to occlusion of the artery. Generally, these patients are treated with anticoagulation therapy. Follow-up studies are done to further guide therapy. Those patients who develop recurrent neurological symptoms may require surgical intervention.

Carotid body tumors are uncommon neoplasms of the paraganglion (nerve) cells of the carotid body. Although these tumors are rarely malignant, up to 5% can present with metastases. These tumors are slow growing, usually presenting as a mass in the neck.  Five percent of patients have the tumors bilaterally. The tumors seem to occur is families. These tumors are treated surgical excision.

Takayasu’s arteritis is an inflammatory process of the aorta and proximal arteries usually in young patients. Initially the treatment of choice is medical therapy. Some patients who are symptomatic are treated surgically with reconstruction of the affected vessels.

Giant cell arteritis or temporal arteritis is a systemic vasculitis usually occuring in patients over the age of 50. Biopsy can be helpful in making the diagnosis, however medical therapy with the use of steroids is the treatment of choice

Radiation induced arteritis is a segmental lesion in arteries that course through a radiated field. For example, those patients who have undergone radiation to treat headn and neck cancers are at increased risk. Some patients can be treated with endarterectomy, sometimes they require bypass. Percutaneous techniques are presently being studied.