Carotid Stenosis

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Typography

The carotid arteries are vital blood vessels that supply oxygenated blood to the brain, face, and neck. At about the level of the mid neck, the common carotid artery splits into the internal and external carotid arteries. There is a small bulge at the level of this bifurcation. It is known as the carotid sinus or bulb. The carotid sinus contains vital pressure sensors, called baroreceptors, that help regulate blood pressure. The internal carotid arteries supply blood to the brain and the external carotid arteries supply the face and neck. The carotid arteries may become diseased with atherosclerosis, which causes blood flow-inhibiting plaques which narrow, or stenose, the artery. This often occurs at the level of the carotid sinus. Risk factors for carotid stenosis are age, smoking, diabetes, high cholesterol, and high blood pressure.

Most people with carotid artery stenosis never have symptoms. If a plaque ruptures, pieces of it may travel downstream, usually in the internal artery to the brain causing a stroke. Those at high risk for stroke may have smaller, self-resolving strokes called transient ischemic attacks, or TIAs. If the pieces flow down the external carotid artery, which is rare, they may wind up in the artery to the eye, causing temporary blindness in that eye. That condition is called amaurosis fugax. Carotid artery stenosis may be detected using a simple tool – a stethoscope. Because the diameter of the inside of the artery (called the lumen) may be narrowed by plaque, the blood travelling through it must flow faster, often causing a jet-like blood flow.

As an analogy, a gallon of water flowing through small pipes must travel faster than through large pipes to ensure the same rate of water delivery. The jet-like blood flow in an artery causes a sound called a bruit, which may be heard with a stethoscope. Likewise, the faster rate of blood flow through an artery can be detected by using a duplex ultrasound, or doppler. Carotid artery stenosis may also be detected using CT angiogram (using a CAT scanner) or MR angiogram (using MRI technology).

Those diagnosed with carotid stenosis are usually placed on a statin, aspirin, and medication to control their blood pressure. Stains (i.e. Lipitor) not only lower total cholesterol and HDL, or “bad” cholesterol, they also have an anti-inflammatory side effect that stabilizes plaques, making them less likely to rupture. In addition, lifestyle changes are recommended, for example quitting smoking, losing weight, and controlling diabetes. Current guidelines recommend a vascular surgery evaluation for those who have more than 50% stenosis and symptoms (i.e. TIAs), or more than 70% stenosis and no symptoms.

The preferred method of reopening a stenosed artery is to insert a stent, where a catheter is inserted into the femoral artery at the groin and threaded up to the carotid artery. When stenting is not feasible or contraindicated, a carotid endarterectomy is performed. An incision is made in the neck, the carotid artery is located and dissected free, and then clamped above and below the blocked area. Sometimes a temporary bypass is used to provide blood to the brain. Risks of endarterectomy include stroke, heart attack, and injury to the nerves that control tongue functioning and swallowing.

For more information go to: mayoclinc.org/test-procedures/carotid-endarterectomy/about/pac-20393379

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 By Peter Galvin, MD

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