Carotid artery stenosis, or carotid artery disease, is a narrowing of one or both of the two major arteries that run up the neck and carry a large blood supply to the brain. The narrowing is caused by a build-up of plaque on the inside lining of the blood vessel. Plaque build-up (atherosclerosis) is caused when cholesterol, fat and other substances collect in the artery, thereby decreasing the amount of blood flow. When blood flow is decreased, a transient ischemic attack (TIA) or ischemic stroke can occur.
Signs and Symptoms
Signs and symptoms of carotid stenosis include:
- past history of ischemic stroke
- weakness, numbness or tingling in the face, arm or leg
- vision changes
- slurred speech
- drooping face
Testing for carotid stenosis includes a doppler ultrasound of the neck, computed tomography angiogram (CTA) scan of the neck, or magnetic resonance angiography (MRA).
The doppler ultrasound is a noninvasive test that reveals the carotid arteries, the amount of blood flowing through them, and how much blockage is present.
A CTA is a noninvasive test that uses contrast dye to illuminate the vessels of the neck. It can also be used to visualize the narrowed artery and to measure the extent to which an artery has narrowed.
An MRA of the neck is similar to the CTA. It uses contrast dye injected through an IV to illuminate the vessels in the neck.
How carotid stenosis is treated will depend on the extent of arterial blockage, the patient’s symptoms, and his or her medical history. Depending on the severity, carotid stenosis can be treated medically or surgically.
Medical treatment is suitable for patients who have a low percentage of stenosis (below 70 percent), are asymptomatic (without symptoms), or have medical conditions that increase the risk of a surgical procedure.
Medical treatment for carotid stenosis consists of antiplatelet therapy with aspirin as prescribed by a physician. Aspirin is a blood-thinning, antiplatelet medication that prevents clotting in the narrowed arteries and allows blood to pass more easily. The major side effect to aspirin therapy is increased risk of bleeding. Therefore, care should be taken to prevent injury.
If aspirin therapy is not well tolerated, another antiplatelet drug, such as ticlopidine or clopidogrel, may be used.
Additional medical therapies include regular blood pressure screenings and blood pressure lowering medications, smoking cessation, cholesterol monitoring and cholesterol-lowering medications, and limited alcohol consumption.
Carotid artery bypass is a surgical procedure that reroutes the blood supply around the plaque-blocked area. A length of artery or vein is harvested from somewhere else in the body, usually the saphenous vein in the leg or the ulnar or radial arteries in the arm. The vessel graft is connected above and below the blockage so that blood flow is rerouted (bypassed) through the graft. A bypass is typically used only when the carotid is 100 percent blocked. A complete blockage is also known as carotid occlusion.
Carotid endarterectomy is a surgical procedure that removes the plaque build-up from the inner lining of the carotid artery. This procedure improves blood flow through the artery into the brain and prevents future ischemic strokes. A carotid endarterectomy is typically indicated for patients who are symptomatic (have experienced a previous ischemic stoke or TIA) and have greater than 70 percent vessel stenosis. Surgery reduces the five-year risk of stroke by 6.5 percent for patients with 50 to 69 percent stenosis, compared to an 80 percent risk reduction for patients with greater than 70 percent stenosis. Patients with 50 percent stenosis or lower do not show enough benefit from endarterectomy to outweigh the risks of the procedure.
Cartoid endarterectomy requires general anesthesia. An incision is made in the neck, and tissues are retracted until the carotid artery is visualized. The artery is clamped above and below the area of stenosis. The artery is opened, the plaque is removed, and the artery is closed again.
After a carotid endarterectomy it is extremely important to monitor blood pressure and take medications as directed. It is equally important to quit smoking, limit alcohol consumption and check cholesterol levels regularly.
Carotid angioplasty is an endovascular procedure performed by a neuro-radiologist during an angiogram of the affected carotid vessel. The procedure takes place in the interventional radiology suite.
During the cerebral angiogram, a catheter is inserted in the groin and threaded up to the carotid vessels. A special catheter with a balloon surrounding the outside is used. The balloon is inflated over the plaque, compressing the plaque down and creating a larger diameter for increased blood flow to the brain. A stent is placed over the plaque to keep the plaque compressed and the vessel opened.
This treatment for carotid stenosis is typically indicated for symptomatic patients who are 75 or older, are at increased risk for general anesthesia and surgery, have recurrent stenosis, or have stenosis caused by previous radiation therapy.
Prior to a carotid angioplasty, certain medications (such as aspirin) are administered at least two days prior to the procedure and on the day of the procedure. Plavix is also administered the day of the procedure.
These medications are blood-thinning antiplatelet agents that protect against stroke during the procedure and maintain free-flowing blood over the stent. Long-term antiplatelet therapy is necessary, and patients receiving this endovascular treatment will be discharged home on these medications.