Carotid Artery Narrowing Due To Plaque Formation

By Dr Harold Gunatillake Health Writer

Plaque is heaps of debris, cellular components, calcium deposits and cholesterol crystal build ups, causing obstruction to the flow of arterial blood. They are found mainly in certain sites of the arterial system, including bifurcation of vessels. Plaque causes oxygen insufficiency, resulting in ischaemic symptoms. Heart attacks are due to plaque build-up in the coronary vessels, blocking the free flow of oxygenated blood to the cardiac muscles. Some strokes are due to emboli (freely running detachable elements) from plaque in the carotid arteries, or clots from cardiac valvular insufficiency, and releases from ulcerating plaque in the carotids.

These plaque build-ups may be silent for a long time, and the progress of narrowing of the vessels causing obstruction may be very slow.

Some doctors seem to think that there is not enough evidence from contemporary clinical trials to make firm recommendations for interventional approaches, such as stenting and endarterectomy, in asymptomatic carotid stenosis.

The review, published in the May 7 issue of the Annals of Internal Medicine, was conducted by a group led by Gowri Raman, MD, MS, from Tufts Medical Center, Boston, Massachusetts.
"The medical management of patients with asymptomatic carotid stenosis has improved significantly over the past 20 years, with stroke rates having come down markedly," co-author David E. Thaler, MD, PhD, commented to Medscape Medical News. "While there may be a role for invasive approaches such as stenting and endarterectomy in high-risk patients, it is not clear if these interventions are superior to medical therapy in the modern era; more work is needed to better identify high-risk patients and to test the interventional approaches in this group."
While carotid stenosis is a known risk factor for stroke, Dr Thaler noted that routine screening is not part of recommended clinical practice in the United States at present. However, carotid artery imaging of asymptomatic individuals is on the rise.

Medical treatment entails emphasizing good primary prevention measures, such as control of cholesterol, blood pressure, diabetes, smoking cessation, exercise, and diet. In addition, therapy with an antiplatelet drug and a statin is recommended, or in some cases an interventional approach with stenting or endarterectomy can be pursued.

Dr Thaler noted that interventional approaches do run the risk for periprocedural strokes due to emboli breaking off and causing a blockage downstream.

"We must ensure that the procedural related stroke is less than the overall expected stroke risk. There are guidelines on this. There probably are symptomatic patients who are at higher risk of stroke in whom intervention may be a better option than medical therapy but they have not been clearly identified as yet."

He continued: "Strokes generally occur from carotid stenosis caused by an embolus. They are not normally related to reduce flow. The degree of narrowing of the carotid is therefore not the main measurement of interest. It is more a proxy of the degree of plaque which could break off and form a blockage downstream. Some people may have high grades of narrowing but a low risk of stroke. The risk of stroke is more to do with the morphology of the plaque. Is it ulcerated, thin capped or calcified? We need to be more able to quantify these things and understand how they relate to risk in order defining a population of patients who may benefit from stenting or endarterectomy."

In most situations, the silent plaque build-ups do not give symptoms. In any case, doctors would not suspect carotid artery stenosis unless an emergency arose as in Transient Ischaemic Attacks (TIA), causing fitting and temporary stroke. Patients are investigated and put on anticoagulant therapy for a while and interventional procedures will be contemplated if the blockage is over 60% of the lumen.

The stenosis of carotid arteries occurs progressively with age. Only one percent of adults age 50 to 59 have significantly narrowed carotid arteries, but 10 percent of adults age 80 to 89 have this problem.

Most plaque build-ups are hard, but some deposits are soft and prone to cracking or forming roughened, irregular areas inside the artery. If this happens, your body will respond as if you were injured and flood the cracked and irregular areas with blood-clotting cells called platelets. A large blood clot may then form in your carotid artery or one of its branches. If the clot blocks the artery enough to slow or stop blood and oxygen flow to your brain, it could cause a stroke. More commonly, a piece of the plaque itself, or a clot, breaks off from the plaque deposit and travels through your bloodstream. This particle can then lodge in a smaller artery in your brain and cause a stroke by blocking the artery.

If you are diagnosed with an asymptomatic carotid stenosis, you could prevent further progress by: Exercising regularly, eating healthy food and maintaining a healthy weight, on anticoagulant therapy, and statins.

One simple way to suspect carotid artery stenosis by the doctor is by placing his stethoscope on the side of the neck to hear a bruit or a murmur. If there is any suspicion, further investigations will be done. Next time you visit your doctor, mention to check for bruits in the neck, in case he omits.

Unfortunately, the first sign of carotid artery stenosis could be a stroke as mentioned earlier.

The symptoms could be:

•Feeling weakness, numbness, or a tingling sensation on one side of your body, for example: in an arm or a leg.
•Being unable to control the movement of an arm or a leg
•Losing vision in one eye (many people describe this sensation as a window shade coming down)
•Being unable to speak clearly

In most situations, these symptoms may go away within 24 hours. You should go to the emergency department of your closest hospital and seek treatment, without ignoring the situation.
The first investigation that will be done will be a carotid duplex ultrasound. Carotid duplex ultrasound detects most cases of carotid artery disease. Therefore, your physician usually may not need to perform other tests. However, if ultrasound does not provide enough information, your physician may order one or more of the following: CT scan and CT Angiography. MRI angiography or angiography using a contrast dye through a catheter that is threaded into your arteries and then x-ray pictures are taken.

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