Overview of Carotid Artery Disease
The two common carotid arteriesone on the right and the other on the leftarise from aorta or branches of the aorta in the chest. The carotids, along with the right and left vertebral arteries, supply the oxygen-hungry brain. In case one or more of the arteries gets blocked, the four arteries are all somewhat connected at the base of the brain (the circle of Willis). If one of the arteries gets narrowed, the others attempt to compensate.
Carotid arteries are particularly susceptible to arteriosclerosis. Plaque, or little accumulations of fatty material, can start to build up near areas where the blood flow is a little turbulent, such as the where the carotid arteries divide in the neck—the carotid bifurcation.
Blood flows calmly through the straight common carotid arteries, but when the flowing blood encounters the carotid bifurcation, the flow suddenly becomes turbulent. In people who are prone to plaque build-up, one of the affected areas is the carotid bulb, the upper most part of the common carotid artery just before it divides. The other location is the start of the internal carotid artery.
In carotid artery disease, a damaging cycle begins. Turbulence of blood flow (perhaps exaggerated by high blood pressure) may slightly damage the wall of the internal carotid artery, causing some plaque to build up at the site of damage. Consequently, this build-up further increases turbulence. More plaque, more turbulence, more plaque, and so on.
Problems come from two directions. First, the build-up physically narrows the channel and may start diminishing flow. Fortunately, the other carotid artery and the vertebral arteries may be poised to take over if the situation deteriorates too much.
Second, not only does fatty plaque accumulate on the walls of the arteries, but small blood clots may start accumulating on damaged sections of the wall and on the plaque itself. If these clots get dislodged by turbulently flowing blood, they go directly into the internal carotid artery and on to the brain. Tiny clots may cause little damage, but if they are large enough and/or end up in critical end arteries, they can cause a damaging stroke.
When the plaque build-up in the artery narrows the channel significantly, blood flow diminishes to a serious degree and, depending upon clinical circumstances, surgical treatment may be necessary. This surgery, which is called endarterectomy is usually performed by a vascular surgeon or neurosurgeon. Such surgery is not to be taken lightly, but is lifesaving in many circumstances.
It's important for people with carotid artery disease to consult with their health care provider about treatment. Generally, until the narrowing is severe, patients are treated with "blood thinning" medications to prevent the red blood cells from forming clots. The cut-off point of the narrowingthe point at which surgery is recommendedis somewhat controversial. Surgery is generally indicated between 60 and 75 percent narrowing. Completely blocked arteries are not generally considered candidates for reconstruction. Before surgery is considered, the patient's general health and ability to tolerate major surgery are considered.