Carotid stenosis is a narrowing of one of the main vessels that leads from the chest up to the brain. The brain has two carotid arteries: one on the left and one on the right. Like other arteries, the carotids can be narrowed by fatty build-up and atherosclerosis. The resulting plaque can narrow the artery, reducing blood flow and causing blood clots to form and travel up into the brain where they can cause a stroke or transient ischemic attack.
If the carotid artery stenosis is severe enough, the risk of stroke is about 1% a year. This percentage adds up over time, so in five years such a person would have a 5% chance of having a stroke. These risks are highest in patients who have just had a stroke.
In order to reduce the risks of having a debilitating stroke, physicians recommend surgical management of carotid stenosis when the artery has narrowed by a certain amount. While there is some controversy over when to surgically manage carotid stenosis in a patient who has never had a stroke, the general consensus is that anyone with carotid stenosis who has had a stroke should have stenosis corrected as soon as possible.
The most familiar way of treating carotid stenosis is a surgical procedure called carotid endarterectomy, which is when the artery is cut open and the plaque removed. Such a procedure is not without risks, and many patients prefer that a less invasive method be tried if possible. For some, carotid artery stenting (CAS) may be a better option.
How Carotid Artery Stenting is Done
The goal of the procedure is to place a type of hollow tube (the stent) in the carotid artery at the site of the narrowing, thereby keeping the stent open. Carotid stenting is usually done with the patient awake. Before placing a carotid artery stent, the groin area is cleaned well and a local anesthetic medication is applied. A small cut is made into the femoral artery. After injecting a contrast agent so that the artery can be seen on a monitor using x-rays, a guidewire is passed up the femoral artery into the aorta, and then into arteries of the neck.
A catheter is then threaded over the guidewire in order to place the stent. There are different types of stents available. Usually, an angioplasty is also performed. This involves inflating a kind of balloon inside the blood vessel to crush the plaque and widen the carotid artery.
After the angioplasty is performed and the stent is placed, the wire and catheter are removed. The only thing left is the stent. The incision in the femoral artery may not even need to be stitched in order to heal.
Possible Complications From CAS
There is some controversy about the riskiness of carotid artery stenting compared to the more traditional method of carotid endarterectomy. Early trials seemed to suggest that stenting was more dangerous than endarterectomy. However, that may have been due to less experienced physicians doing the stenting procedure compared to more experienced physicians doing the surgery.
A more recent trial suggests that stenting and endarterectomy have an approximately equal risk overall, but that the type of risk varies. Stenting seems to be more associated with strokes, and endarterectomy seems to be more associated with heart attacks. This may be especially true in the month just following the procedure.
Other risks of carotid artery stenting include bleeding at the site of incision, and puncture or damage to the vessel through which the catheter is threaded.
To Stent or Not to Stent?
The question of who should undergo stenting of the carotid artery instead of carotid endarterectomy is a hotly debated topic among neurologists and neurosurgeons. Unfortunately, it often seems that proponents for a particular technique often stand to profit from that technique being done more often. However, some information seems to be agreed on that transcends such bias.
The skills of whomever is performing the procedure seems very important. If you are considering having a carotid artery stent placed, ensure that the person placing the stent has done so successfully many times in the past. Younger patients (less than 65 to 70 years of age) seem to do better with stenting than older people. Certain anatomical features, such as unusually winding carotid arteries or an especially long plaque, seem to increase the risks of carotid stenting.
There are numerous other possible exceptions for stenting. Because carotid artery stenting is a relatively new procedure, exclusion criteria are still changing and developing. At this time, if you are trying to decide between carotid artery stenting and carotid endarterectomy, it is important to discuss your options with your physicians, and never to hesitate to get a second opinion.
Sources:
Brott, T. G., Hobson, R. W.,2nd, Howard, G., Roubin, G. S., Clark, W. M., Brooks, W., et al. (2010). Stenting versus endarterectomy for treatment of carotid-artery stenosis. The New England Journal of Medicine, 363(1), 11-23
Cohen, D. J., Stolker, J. M., Wang, K., Magnuson, E. A., Clark, W. M., Demaerschalk, B. M., et al. (2011). Health-related quality of life after carotid stenting versus carotid endarterectomy: Results from CREST (carotid revascularization endarterectomy versus stenting trial). Journal of the American College of Cardiology, 58(15), 1557-1565.
Mas JL, Trinquart L, Leys D, Albucher JF, Rousseau H, Viguier A, Bossavy JP,Denis B, Piquet P, Garnier P, Viader F, Touzé E, Julia P, Giroud M, Krause D, Hosseini H, Becquemin JP, Hinzelin G, Houdart E, Hénon H, Neau JP, Bracard S, Onnient Y, Padovani R, Chatellier G; EVA-3S investigators. Endarterectomy Versus Angioplasty in Patients with Symptomatic Severe Carotid Stenosis (EVA-3S) trial: results up to 4 years from a randomised, multicentre trial. Lancet Neurol. 2008 Oct;7(10):885-92. Epub 2008 Sep 5.
