Carotid and Intracranial Atherosclerosis and Angioplasty and Stenting

Figure 1. 74 y.o. experienced dizziness before right-Carotid endarterectomy

This is commonly referred to as "hardening of the arteries". It is actually a complex process of deposition of cholesterol and inflammation that leads to narrowing of a blood vessel (Figure 1) and/or a predisposition to blood clot formation. The main risk factors for development of atherosclerosis are elevated cholesterol, high blood pressure, smoking, diabetes, and genetics. This can occur anywhere in the body's blood vessels. If commonly occurs in the main arteries of the neck going to the brain, which are called the carotid arteries. It can also occur in the blood vessels of the brain itself, and then it is called intracranial atherosclerosis. In both locations, strokes and TIAs can occur.

Figure 2. 64 year-old-man with aphasia, right hemiplegia

Figure 3. MRI Perfusion sequence, whiter area on right hand of each image indicates the area lacking blood flow, which is not functioning and will go on to die if blood flow is not restored.

Figure 4. After opening blocked carotid artery in neck, then distal blood clot in brain vessel removed.

When there is damage to the brain by rupture of a vessel, it is called a hemorrhagic (bleeding) stroke (see aneurysm). When it is caused by a blood clot or atherosclerotic narrowing, then it is called an ischemic (lack of blood flow) stroke. A stroke is an injury to the brain that causes a permanent loss of function (Figure 2). Typical ischemic stroke symptoms are loss of sensation or strength, typically on one side (face, arm and/or leg), loss of vision on one side, garbled speech or inability to understand speech, or loss of balance. If these symptoms are short lived (less than a few minutes), it is called a transient ischemic attack (TIA). These are both emergencies, as the TIA may signal that a major stroke is about to occur, and even some severe stroke symptoms can be reversed if treated in the first few hours after onset (Figure 3 and 4).

Before a stroke has occurred, we can open up the artery that is narrowed by angioplasty and stenting, open it up by surgery, and/or give medications to reduce the risk of stroke. If the stroke is not very severe, and with TIAs, treatment may prevent a subsequent stroke. We also have methods of treating acute strokes using drugs and devices if the patient comes to the hospital in the first few hours after the stroke.

In the carotid vessel, carotid endarterectomy has been the gold standard for atherosclerotic disease. This involves opening up the vessel and removing the plaque that is causing the narrowing and/or blood clotting. Recently, angioplasty and stenting has been used successfully in the carotid artery, especially in patients who have some medical or anatomical reasons to be at higher risk for surgery. These higher risks include significant heart disease, prior neck surgery or radiation therapy, lung disease, or narrowing in a difficult to get to location for the surgeon.

Figure 5. Example of a filter

Figure 6. Filter Protection

The angioplasty and stenting is done through the artery in the groin, guiding up the devices inside the blood vessels to the neck. First, a filter device (Figures 5 and 6)is placed through the narrowed area to capture any debris loosened by the procedure. Then a balloon in placed and inflated (Figure 7) to open up the artery partway. Then an expandable metallic cage (stent) is placed across the narrowed area. This expands to further open the blood vessel. Finally, an additional balloon is inflated inside the stent to maximally open the artery. The filter, with whatever material may have been captured, is removed and typically a device uis used to close up the hole in the groin artery. It is usually a 24 hour hospital admission, and the procedure does not involved general anesthesia. It is necessary to take medication to prevent clot formation for some time around the procedure.
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Figure 7. Balloon expands the stent while the filter catches any plaque debris

Beyond the surgically higher risk patients, the angioplasty and stenting procedure is currently being studied under the CREST protocol in a randomized trial in normal risk patients.

For Intracranial angioplasty and stenting, currently there is no alternative surgical procedure, and so the only alternative therapy is medicines. This procedure is similar to the carotid stenting, but deals with much smaller vessels inside the brain. Therefore this procedure is reserved only for patients who are having symptoms while already on medical therapy. Those symptoms would also be similar as those for carotid disease.

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Images of ischemic stroke

CAROTID ANGIOPLASTY AND STENTING

INTRACRANIAL CLOT RETRIEVAL
GOBIN ET AL.

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What research is being done?

The National Institute of Neurological Disorders and Stroke (NINDS) conducts research in its laboratories at the National Institutes of Health (NIH) and also supports additional research through grants to major medical institutions across the country. The NINDS supports a broad range of basic and clinical research aimed at finding better ways to prevent and treat cerebrovascular disorders such as cerebral aneurysms.