Stenting of the carotid artery. Ken U. Ekechukwu, MD, MPH, FACP.

What is stenting of the carotid artery?
The carotid artery carries fresh blood from the heart to the neck, the face, and the head including the anterior brain. Two carotid arteries arise from the aorta, the large artery in the chest that comes directly from the left heart; one runs through the right neck, while the other runs through the left. Somewhere close to the angle of the jaw the arteries divide into two unequal branches that carry blood to the front of the brain (the larger artery) and the neck and face (the smaller branch), respectively.

These arteries, like all arteries in the body, can be narrowed or obstructed by cholesterol-rich material (called atheromatous plaque or, simply, a plaque) that grows in their walls due to conditions like hypertension, diabetes, high cholesterol, and smoking. This narrowing, when severe or complete, slows or shuts off blood flow to the brain causing stoke-like symptoms or actual stroke. Sometimes tiny particles of the plaque break off and travel with blood into the brain to cause stroke. Stroke can be prevented from occurring in some patients by doing surgery on the narrowed artery (Endartherectomy) to repair it or by widening it with a stent. A stent is cylindrical tube made from metal into whose walls are cut numerous small holes that turn the walls into a mesh. A stent placed across a narrowed or blocked artery keeps it open and reduces the chance of particles of atheroma breaking off to cause a stroke.

How does one prepare for stenting of the carotid artery?
You must prepare yourself emotionally for the procedure and gather as much information as you can. Your health care provider will tell you what the procedure entails and discus its benefits and risks with you. Expect to be asked to take Aspirin and clopidogrel (Plavix) for 3 to 5 days (if you are not already taking them) before the procedure. After the procedure you will take Aspirin for life and Plavix for 3 to 6 months. These medications reduce the chance of clot formation in the arteries or the stent during and after the procedure. You will not be placed under general anesthesia because staying awake during the procedure allows your physician to know when a complication of the procedure occurs, but you may receive light sedation. You will be asked to refrain from eating food or drinking water after the midnight preceding the morning of your procedure and are likely to be advised not to take your antihypertensive medications on the morning of the procedure, if you take any.

How is the carotid artery stented?
Carotid artery stenting is usually performed in an interventional radiology suit (or similar suit) because the operators need x-ray images to guide them during the procedure. After applying a local anesthetic to your groin (or arm if the groins are not suitable), small tubes (the size of unboiled spaghetti) and wires will be used to place the stent across the diseased artery. The procedure is tricky and complicated, requiring great care and attention to prevent or minimize complications; so do not expect a hurried departure from the hospital.  In the absence of major complications most people will go home the next day.

What are the complications of stenting of the carotid artery?
The complications of carotid artery stenting are several but occur relatively infrequently in expert hands; operators who have mastered the skills of the procedure have fewer complications than those who have not. The most feared complication is stroke, the loss of neurological function that may be brief with full recovery of lost function within 24 hours (transient ischemic attack or TIA); or it may be minor, requiring less than 7 days for incomplete neurological recovery or is associated with a less than four-point increase in the NIHSS (National Institute of Health Stroke Scale) score; or major in which the deficit stays longer than 7 days or is associated with a greater than four-point increase in the NIHSS score. Stroke can occur from plaques travelling downstream into the brain to block arteries or from bleeding into the brain. Other complications of the procedure include the following:
1. Bleeding at the puncture site in the groin or the arm or into the back of the abdomen (retroperitoneal hemorrhage).
2. Injury to the punctured artery called dissection, transection or thrombosis that may lead to limb loss.
3. Dissection of the carotid artery during the procedure.
4. Contrast-induced neurotoxicity, which presents as a brief loss of vision and is due to crossing of the blood-brain barrier by the radiocontrast (dye) used for the procedure. Its risk is minimized by the use of less concentrated radiocontrast.
5. Contrast-induced nephropathy, which is renal injury caused by the radiocontrast.

These complications, though remediable, are avoidable by due diligence and care during the procedure, but sometimes even with meticulous attention to detail things go wrong.