Carotid Artery Disease

The blood supply to the brain comes from four arteries. The carotid arteries are found in the front of the neck and the smaller vertebral arteries are in the back of the neck. Through these arteries we receive blood and oxygen to the brain and any significant interruption of this blood flow can cause serious problems. The carotid arteries arise from the major vessels of the heart starting as the common carotid artery. This vessel splits into two branches, the internal carotid and external carotid just below the level of the jaw. The external carotid artery goes to the face and the internal carotid artery supplies the brain. Once in the brain the internal carotid artery connects with an intricate system called the Circle of Willis and at the back of the brain the vertebral arteries connect to this same system. One could consider this as Interstate 285 as it circles Atlanta with the other highways joining in from the North and South. As you might expect, the “flow” of traffic on this route can sometimes cause trouble.

All of our blood vessels are subject to disease. Advancing age, cholesterol and other chemicals can result in the formation of fat deposits inside arteries which can develop into obstructions of plaque. This is what is commonly called atherosclerotic disease or “hardening of the arteries.” There are multiple factors that can contribute to this process including gender (male>female), family history, diabetes, cholesterol levels and smoking. As these deposits increase in size they begin to significantly obstruct the flow of blood and can cause increasing turbulence. The surface of the plaque becomes very irregular and rough and can collect clumps of cells called platelets. These clumps of platelets may suddenly break free and travel with the flow of blood. If these cells or a piece of the actual plaque breaks loose and flows into the circulation of the brain for a brief period of time a Transient Ischemic Attack or TIA can occur. This may cause a temporary loss of function to a part of the body. An individual may experience some weakness or clumsiness in an arm or leg. They might notice difficulty speaking and a family member may notice that there is a weakness on one side of the face. In some instances a temporary episode of blindness in one eye may occur. This could be described as if a window shade was being pulled partially over the eye obscuring vision, either from the top down or the bottom up. These episodes typically improve over time with a return to normal function. However, it must be understood that even a brief episode of only a few minutes could be a warning sign of an impending stroke. These events should not be taken lightly and individuals who experience them should seek medical attention. When episodes like this occur and do not improve resulting in a permanent loss of function, even a small loss, then an individual has had a Cerebral Vascular Attack (CVA) also known as a stroke. Some strokes can also be the result of other types of problems and not necessarily caused by carotid artery disease, but emergency medical attention is required to determine the cause and extent of the problem and begin treatment immediately.

One of the screening tests used to detect possible plaque inside the carotid artery is a Carotid Duplex Scan. This non-invasive test is performed by placing ultrasound gel on the neck and transmitting sound waves onto the artery. Similar to sonar on a boat, the sound waves bounce back giving an image of the artery and actually can determine the speed of the blood flowing in the vessel. The velocity of the blood can indicate the degree of narrowing or stenosis in the artery. Just as if you narrow the nozzle on a garden hose to make the water come out faster, we can measure the speed of the blood and calculate the amount of narrowing that has built up in the vessel. When the amount of narrowing increases significantly, then the risk of possible stroke begins to rise. Unfortunately many patients do not have any warning signs to tip them off that the carotid artery is in danger and their first hint of trouble is an actual stroke. The goal is to detect these potential time bombs and treat the problem before a stroke can occur.

In some instances other imaging studies are used to visualize the blood flow to the brain. These tests may include a Magnetic Resonance Arteriogram (MRA) which is a non-invasive test which involves using a large magnetic scanner. A dye test called a carotid arteriogram can also be done. This invasive test requires a small catheter to be placed within the artery and dye is injected so xray pictures can be taken. Fortunately with the increasing accuracy of carotid duplex scanning these other tests are not as common.

When the buildup of plaque in an artery begins to increase certain aspects of our health maintenance may need adjusting. Since we cannot control our family history or other inherited characteristics, we should make every effort to control the other risk factors as much as possible. First, if you smoke, STOP! This is the most powerful risk factor we place on ourselves. Without going into the other health issues of lung disease and cancer, smoking will harden your arteries more than any other problem you may have. If you have diabetes, then strict blood sugar control is needed. Elevated blood sugars can cause rapid progression of disease, especially in the very small arteries. Elevated cholesterol and triglyceride levels also lead to buildup of plaque so a low fat diet and possibly medication may be necessary. Since we know that clumps of cells called platelets can break free from the plaque medications that prevent these cells from clumpimg together can also be helpful. Medications such as aspirin and clopidogrel (Plavix) are commonly utilized. Unfortunately, despite all our efforts to control these risk factors plaque can still build up and more mechanical treatments are necessary. Carotid artery intervention by open surgery or stenting has been performed for many years. The safety and durability of this operation has held up to the test of time. In the hands of an experienced vascular surgeon, the risk of serious complication is less than one percent.