Overview
The two common carotid arteries, one on the right and the other on the left, arise 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. To make sure that there are back-up procedures in case one or more of the arteries gets blocked, the four arteries are all somewhat connected at the base of the brain (circle of Willis). If one of the arteries gets narrowed, the others will attempt to compensate.
Carotid arteries are particularly susceptible to arteriosclerosis. Plaque, or little accumulations of fatty material 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 patients 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. So a vicious cycle begins. Turbulence of 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.
Trouble comes 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 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, 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.
There is still considerable controversy regarding treatment, so patients must consult with their physician. 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 is controversial. Surgery is generally indicated between 60% and 75% 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.
Physician-developed and -monitored.
Original Date of Publication: 01 May 2000
Reviewed by: Under Construction
Last Reviewed:
© 1998-2010 Healthcommunities.com, Inc. All Rights Reserved.
