Carotid Angioplasty/Stenting

The two common carotid arteries bring oxygenated blood from the heart to each side of the head. The internal carotid arteries, which run deep within the neck and behind the cheeks, supply blood to the brain. The external carotid arteries branch out into smaller arteries that supply blood to the face and scalp.

As people age, cholesterol or other lipids (fats), calcium, and fibrous scar tissue combine to form plaque inside the arteries. Over time, these plaques collect on the walls of the arteries as cholesterol circulates in the blood. The arteries become narrow and stiffened, a process known as atherosclerosis, or hardening of the arteries. When atherosclerosis interferes with blood flow to the brain through the carotid arteries, it is called carotid artery disease. Atherosclerotic plaques in the carotid arteries can cause stroke by increasing a person's risk of an arterial embolism, or the sudden blocking of an artery.

Carotid artery stenting is a procedure in which a tiny, slender metal-mesh tube is fitted inside a carotid artery to increase blood flow in areas blocked by plaques. The stent is inserted following a procedure called percutaneous transluminal angioplasty (PTA, commonly known as angioplasty), in which the physician guides a balloon-tipped catheter into the blocked artery. The balloon is inflated and presses against the plaque, flattening it and re-opening the artery. The stent acts as scaffolding to prevent the artery from collapsing or being closed by plaque after the procedure.

WHEN IS IT INDICATED?

Carotid artery stenting is indicated in patients who have significant stenoses of the internal or common carotid artery. Patients have either had symptoms (TIA or stroke) or had no symptoms (asymptomatic). Indications in each group are somewhat different.

Patients who have symptoms and have internal carotid arteries that are narrowed by more than 50 percent are candidates. In patients who are asymptomatic, physicians may also order carotid stenting if the internal carotid artery is narrowed by more than 80 percent or the external carotid artery is narrowed.

Stenting is often recommended for people who are unable to undergo an endarterectomy, the surgical removal of plaque from inside an artery.

PRE-TREATMENT GUIDELINES

To reduce the risk of stroke, the patient will take aspirin and prescription medications before undergoing carotid artery stenting. These medications inhibit the ability of platelets to stick together, so that blood clots are less likely to form.

The physician may also order one or more imaging tests prior to the procedure. These tests help assess the degree of carotid stenosis and reveal any anatomical conditions that increase the difficulty or risk of complications of the procedure.

WHO IS ELIGIBLE?

As with all procedures, the success of carotid stenting relies upon meeting certain criteria for eligibility. Certain conditions may exclude patients from this procedure, including arrhythmia, evolving stroke, and a life expectancy of fewer than 5 years.

RISK FACTORS FOR POSSIBLE COMPLICATIONS

Physicians have identified several risk factors for complications during carotid stenting, including hypertension (high blood pressure), allergy to contrast dye, and complex anatomy making catheterization difficult.

WHAT TO EXPECT

Patients are admitted to the hospital the day of the procedure. Physicians give patients medications such as heparin or other anticoagulants to help prevent clots from forming during the procedure and atropine to reduce the risk of a slowed heartbeat.

Patients having carotid artery stenting might not receive any other medications. They may need to remain alert during the procedure to follow instructions and describe sensations to the physician.

Carotid stenting requires several steps: Initial angiography: Once the physician has identified the narrowed carotid artery and can see the extent of the blockage, the procedure can begin.

Placing the access instruments: A series of wires and catheters (thin tubes) are inserted to allow the physician to place the stent.

Once an incision has been made, a guide wire is inserted into the artery. A catheter sheath, essentially a short, hollow tube, is guided over the wire. Using a type of x ray imaging, called fluoroscopy, the physician steers the guide wire or guide catheter to the point of the blockage in the carotid artery.

At this point, the physician may insert an embolic protection device--a tiny balloon, basket, or filter--into the artery that is designed to protect the brain from plaque particles that may be dislodged during the placement of the stent. Trapping these particles is important so they cannot travel to the brain and cause a stroke.

Widening the carotid artery with angioplasty: Next, a deflated and folded balloon is carried on the tip of the catheter into the area affected by plaque buildup. Gas or air sent through the catheter inflates the balloon, so that it can compress the plaque deposits and expand the carotid artery.

Stenting: Using a different catheter guided to the same spot, the physician places a stent inside the artery under the compressed plaque deposits. The stent acts as scaffolding to prevent the artery from collapsing or being closed off by plaque so that blood can flow to the brain.

POST-PROCEDURE GUIDELINES AND CARE

Immediately following the procedure, pressure is typically applied on the insertion site to allow the puncture area to close and prevent bleeding. Other techniques may be used to seal the puncture site, including a cork-like device inserted into the wound, or stitching with sutures that may eventually dissolve.

POSSIBLE COMPLICATIONS

The most serious potential risk involved with carotid stenting is the risk of embolism, or a disrupted plaque particle that breaks free from the stenting site and blocks an artery in the brain, causing a stroke. Other risks of the procedure include re-narrowing of the artery, blood clots that form along the stent, short periods of reduced blood pressure and heart rate, and sudden increased blood flow through a previously blocked carotid artery that can cause a hemorrhagic stroke.

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