Preventing Another Stroke: Interventional Approaches
When a person experiences a stroke, not having another one becomes a high priority. There are several things most survivors can start practicing immediately following their stroke to reduce the risk of another one. With the help of their health care team, there are common sense things they can do on their own, such as:
- Eating better
- Controlling high blood pressure
- Controlling high cholesterol
- Maintaining a healthy weight
- Controlling diabetes if you have it
- Taking prescribed medicines as directed
- Getting regular physical activity
- Not smoking!
But some survivors may need more than just these lifestyle changes. Sometimes there is a need for surgical intervention.
Blood flow to the brain
Let’s start with a little vascular anatomy. The carotid arteries are major suppliers of blood to the brain. There are two, one on each side of the neck. They traverse the front of the neck up to the angle of the jaw where they each fork into the internal carotid arteries and the external carotid arteries. “Those arteries are prone to get atherosclerotic plaques, which can cause narrowing,” said Dr. Thomas Brott, professor of neurology at the Mayo Clinic in Jacksonville, Florida. “The plaques usually occur where there is that split to the internal and external carotid, and the narrowing usually involves the region of splitting.” When the arteries narrow, it is easier for a blood clot to become lodged, blocking blood flow to the brain, resulting in a stroke.
In the back of the neck, partly encased in bone, are the vertebral arteries, one on each side. Inside the skull, they join to form the basilar artery that supplies blood to the back of the brain. The right and left vertebral arteries are themselves branches of a larger artery (the right and left subclavian arteries). Joining-points, such as where the vertebral arteries join to form the basilar artery, and where the subclavian arteries join to form the vertebral arteries, are where the plaques tend to form.
Few patients go to the doctor complaining of blockages in their arteries. Most carotid blockages are found when some other issue requires medical imaging — ultrasound, CT scan or MRI — as is done following a stroke or transient ischemic attack (TIA). Using a stethoscope over a carotid artery in your neck, doctors may hear a carotid bruit, an abnormal sound, created by blood flowing through a diseased artery, indicating narrowing in some patients. Further testing is often arranged to confirm that the carotid artery is narrowed.
“Some patients may have neurologic symptoms that aren’t clear-cut, and you can’t always tell what part of the brain they’re coming from. That patient probably would get an ultrasound or MRA or CTA,” Brott said. “Then narrowing could be found in one or both carotid arteries, narrowing that hadn’t been detected before the symptoms developed.”
Endarterectomy & Angioplasty with Stenting
Endarterectomy is a surgical procedure to remove plaque from the carotid. Carotid angioplasty with stent placement is a less invasive procedure to open a narrowed artery. These procedures are typically used to treat or prevent stroke or a transient ischemic attack (TIA). When a patient hasn’t had any signs of a stroke, there is not typically a rush to perform the procedure.
However, when warning signs of a stroke occur, as with TIA, there is a rush. For instance, someone loses speech for 10 to 30 minutes, with some weakness in the right hand in a right-handed person. “In that setting, after the patient is evaluated and other possible causes for the symptoms, like a partial seizure, are eliminated, it’s important that that carotid artery narrowing be fixed quickly,” Brott said. “It’s a bit controversial whether it’s done in the first day or two after the symptoms appear or a little later. Certainly, with patients who have those warning signs and don’t have a serious stroke, the earlier the better. When patients actually have a stroke, then the best time to do the surgery, whether it’s in the first 48 hours compared to the first week, that’s a question that’s not completely answered today.”
If a patient has warning signs, endarterectomy or stenting would usually be recommended if the artery is narrowed by 50 percent or greater. “With patients who don’t have warning signs, a higher standard of 70 percent is usually the consensus among experts as to when one can have benefit from surgery or stenting,” Brott said.
The Endarterectomy Procedure
With a carotid endarterectomy procedure, an incision is made at the site where the plaque has built up; the plaque is then physically removed from the artery walls. Once the plaque has been removed, the incision is cleansed and then closed with sutures.
In the most common form of endarterectomy, blood flow through the carotid artery is temporarily blocked during the operation. An incision is made over the area where the plaque is causing the narrowing. The plaque is peeled off the wall of the artery.
Once the plaque has been removed from the wall, the debris is washed out with a fluid, usually saline. “Then, the blood flow is re-established, so it can go up into the brain, and, following that step, the wound in the neck is closed,” Brott said. “Nine times out of 10, carotid endarterectomy is done under a general anesthetic, so the patient is unconscious, but the operation can be done under regional anesthesia where the patient is actually awake while the procedure is done.”
The Angioplasty with Stent Placement Procedure
Carotid angioplasty with stenting (CAS) involves the insertion of a catheter into the carotid artery where plaque has accumulated. The catheter has a balloon at the end of it which is wrapped by a mesh stent. The balloon is inflated, expanding the stent, which pushes and holds the plaque against the artery walls. The balloon is then deflated and removed, leaving the stent in place permanently.
According to the National Institutes of Health, carotid angioplasty and stenting (CAS) is done using a small surgical cut in the groin after using some numbing medicine. The patient is also given medicine to relax.
The surgeon places a catheter (a flexible tube) through the cut into an artery. The catheter is carefully moved up to the neck to the blockage in the carotid artery. Moving x-ray pictures (fluoroscopy) are used to see the artery and guide the catheter to the correct position.
Next, the surgeon will move a wire through the catheter to the blockage. Another catheter with a very small balloon on the end will be pushed over this wire and into the blockage. Then the balloon is inflated.
The balloon presses against the inside wall of the artery. This opens the artery and allows more blood flow to the brain. A stent (a wire mesh tube) may also be placed in the blocked area. The stent is inserted at the same time as the balloon catheter and it expands with the balloon. The stent is left in place to help keep the artery open. The surgeon then removes the balloon.
The major risk of endarterectomy is a stroke, either during or shortly after the procedure. The danger is that a blood clot may develop inside the artery at the surgical site, then break off and travel up to the brain. The likelihood of this is reduced during endarterectomy by careful dissection of the plaque, removal of plaque debris from the artery before re-establishing blood flow and meticulous closure of the wound site.
In carotid stenting, the risk is reduced by putting in an umbrella-like device beyond the narrowing to capture debris that may be freed both when the balloon widens the narrowing and when the stent is put in place to maintain the widening. Because endarterectomy injures the artery wall, strokes can also occur in the days afterward. “Arteries have linings, like an overcoat has a lining that allows you to slip that overcoat over your sport coat and the sleeve slides right in,” Brott said. “That lining prevents clots from forming on the wall of the artery and going north into the brain. When you’ve taken the plaque off the artery, it takes a little while for the surface of the artery to remodel so that it’s as smooth and slippery as it is under normal circumstances. During that time, particularly for the first few days, clots may form on the surface of the vessel that’s been operated on and those clots may go upward into the brain.”
While invasive, endarterectomy is well tolerated by patients and recovery is generally quick and with limited pain. “With general anesthesia, patients often don’t have a great appetite when they wake up,” Brott said. “There could be pain from the incision in the neck. With head and neck movement, things can be uncomfortable for a few days. Rarely, there can be some injury to the nerves where the operation was done. In general, the symptoms after the surgery are mild, pain is not severe and the patient can often go home the next day or the day after.”
Stents are almost always done under local anesthesia in the groin where the catheter is inserted. “The patient may be mildly sedated as part of the procedure, but generally speaking, within a few hours, the patient’s back to normal and can go home the same day, certainly the next day. Sometimes, there can be some leg pain because the catheter is introduced through the groin; sometimes, some neck discomfort but not too often. The stenting is less invasive, the surgery more invasive. But ironically, the surgery appears to be a little better than the stenting in older patients, and this less-invasive stent procedure appears to be a little better for the younger patients.”
Dr. Thomas Brott
Following either procedure, patients require blood thinning medication indefinitely. “We’re getting new medicines all the time, but for the time being, patients who have had carotid surgery, being on aspirin is the standard of care. Some patients don’t tolerate aspirin, and there are other medicines that inhibit platelet function and those medicines can be substituted for aspirin,” Brott said. “With the stents, most interventionists recommend that patients continue with aspirin and clopidogrel for a few months to a year, and then the aspirin is continued lifelong, unless there are problems with the aspirin.”
Both procedures are “durable,” meaning they don’t have to be repeated. “Only about one in 15 patients develop significant narrowing after the operation, and that’s over a two- to three-year period,” Brott said. “Both procedures are durable with regard to keeping the artery open and with regard to protecting the patient. So, once the patient has gone through the risk of getting either the operation or the stent, the risk for subsequent stroke from the carotid artery is very, very low.”
Control what you can
Whether or not an endarterectomy or stenting is recommended, reducing risk factors if you have them is paramount to preventing another stroke. “The treatment would be to get your bad cholesterol down, ideally under 70 for patients with carotid disease, get your blood pressure under 120. And, if it’s greater than 120, make lifestyle changes to try to get it to 120,” Brott said. “If it’s greater than 130, then you need to be on medicine to reduce it below 130. Of course, no cigarettes. If you’re diabetic, try to control your blood sugar. Get plenty of exercise.
“With carotid narrowing, you need to be on an antiplatelet medicine, usually aspirin. Stenting requires the patient to be on both aspirin and another antiplatelet medicine, usually clopidogrel. Different medicines, the anticoagulants, prevent stroke in patients with atrial fibrillation, an abnormal heart rhythm. There is some evidence that the new anticoagulants, the ones advertised on TV, may also prevent stroke in the setting of carotid narrowing. However, the studies are limited, and these drugs are much more expensive than aspirin and probably a little bit more dangerous.
“Aspirin is still the gold standard for patients with carotid narrowing. If you have warning signs, aspirin is not sufficient, nor is treating your LDL and your blood pressure. You need that narrowing fixed.”