Mahmoud Malas, MD, MHS, RPVI, FACS, Professor In Residence, Vice Chair of Surgery For Clinical Research, and Chief Division Vascular and Endovascular Surgery at the University of California in San Diego, talks about a new way to treat and prevent strokes by reversing one’s own blood flow.
Talk to me about your carotid and stroke.
MALAS: A stroke is the fourth leading cause of death in the United States. And despite dramatic improvement in medical management over the last two decades, it’s still now about the fifth leading cause of death. It is also the leading cause of disability in the Western Hemisphere and costs us over $50 billion a year mainly because of the rehabilitation. And, what happens after the stroke? The medical management dramatically improves with aspirin and platelet therapy and statin drugs. But we still have about 10 to 20 percent of stroke happen from carotid artery disease. The carotid arteries are the two main arteries that run in the neck and profuse to the front of the brain. And, just like you can have a blockage in any artery in your heart or your legs, you can also have a blockage in these carotid arteries. The risk factors are usually the same – smoking, aging, diabetes, high blood pressure, and high cholesterol. The problem with this blockage is that little pieces of plaque break off and go to the brain and cause an embolic stroke. Traditionally, the best treatment, which is still the gold standard, is to do carotid endarterectomy. It’s an operation that usually requires general anesthesia. It’s made through an incision in the neck where we remove the plaque, carve it out of the artery, and then put a little patch on the artery to keep it open. We dramatically improved the outcome of that procedure, but it still has about a stroke rate of 2 percent if the plaque is stable and patients are asymptomatic. If the patient already had a stroke and we do want it to prevent a second stroke, the risk from the surgery could be as high as five percent. A lot of these patients are high-risk for surgery whether they have severe heart disease, had prior surgery on their neck, radiation, cancer, or they could have severe COPD that cannot withstand anesthesia. The newer technology that developed about 15 years ago is to perform carotid stenting. Stenting is basically a cylinder that you put into the carotid artery. Traditionally, the way we did it is we went from the femoral artery in the groin up through the aortic arch into the carotid artery. The stent stabilizes the plaque and does not remove any plaque. What we learned over the last 10 years is as we’re going up, we can break little pieces of plaque from the aorta near the heart and cause a stroke while we’re doing the procedure. Despite dramatic improvement of this technology using filters like a little basket that you put at the end of the artery to capture the plaque, the risk of stroke is twice as much with transfemoral stenting compared to carotid endarterectomy.
So, now we’re at a 4 percent risk?
MALAS: Yes, with stenting. The newer technology, called transcarotid artery revascularization, eliminates going through the arch from the femoral artery. It goes directly into the carotid artery bypassing this long pathway and bypassing all these potential areas of debris and stroke. By making a small incision at the base of the neck, we can directly deliver the stent into the carotid artery. It’s also a hybrid procedure that combines the best of both worlds because when we do the small incision, we clamp the carotid, so stuff doesn’t go up in the brain. It’s also combined with dynamic cerebral flow reversal. So, we actually reverse the blood flow in the brain temporarily as we’re delivering the stent. That’s probably one of the coolest things we do today in vascular surgery. Let’s say we are delivering a stent in the left carotid artery, the blood will reverse temporarily, go from the right carotid right brain across the brain, and then in the wrong direction temporally out of that little plastic tube. Instead of debris going up to the brain to cause a stroke, it gets out of the patient filtered and then back into the patient. By reversing the blood flow and clamping the carotid artery by avoiding the arch, we were able to reduce the stroke rate to as low as 1 percent or less. This technology now has been available for a few years and is disseminated in the country. So about 2 to 3 years ago there were only maybe 100 done in the U.S., and today there’s over 7,500 TCAR procedures done. Despite disseminating this technology to a much larger cohort of surgeons and patients who are high-risk, the stroke rate is holding about one and a half percent.
Are there any risks to doing this?
MALAS: Of course. There is obviously the risk of stroke that is still there, but it’s dramatically reduced. There is a small risk with any incision and risk of small bleeding. Also, a very small risk of wound infection, and maybe a minimized risk of injury to the nerve. So, there are a lot of nerves that run around the carotid artery and with carotid endarterectomy, the risk of cranial nerve injury could be as high as five to six percent. With TCAR, it is about 1 percent or less.
How many of these are you performing now a week?
MALAS: We’re doing a lot more than we did in the past. We could do one to two depending on the patients who it comes in. It’s not steady. Some weeks might be more than others.
Would you ever go through the chest anymore?
MALAS: There are very few situations that we will have to go through the chest. If there is a lot of calcium where we need to deliver the stent and the artery is very hard and not healthy, we cannot put the stent through the carotid artery. These are the situations where I go from the groin.
Can you explain the video?
MALAS: This is an example of carotid endarterectomy. You can see here the artery is clamped. And then the yellow part is the plaque that is being removed with carotid endarterectomy. The other technology is to go from the groin, deliver a catheter in a wire, and those little debris are breaking off and going to the brain until you put a filter. The filter is still not perfect. So, instead of putting a filter and going from the groin, you’re going directly through the carotid artery and then reversing the blood flow. The blood is going out through the sheath. Here’s the small incision in the neck. Here is the axis through the carotid artery in the neck. I’m putting a small needle and wire and then advancing the sheath which is a plastic tube that allows us to deliver the stents. When we’re ready to deploy the stents, we clamp the carotid artery right here and reverse the blood flow. So, the blood will go from the other side of the carotid and get filtered through that filter and then back into the femoral vein, so the patient does not lose any blood. Essentially, no debris can go up into the brain. We were able to minimize the risk of stroke by cutting it by half comparing to transfemoral stenting. So far, we’re showing similar stroke and death compared to the surgical procedure carotid endarterectomy, but almost 90 percent reduction in the risk of injury to the nerve creating, the cranial nerve injury.
Interview conducted by Ivanhoe Broadcast News.
END OF INTERVIEW
This information is intended for additional research purposes only. It is not to be used as a prescription or advice from Ivanhoe Broadcast News, Inc. or any medical professional interviewed. Ivanhoe Broadcast News, Inc. assumes no responsibility for the depth or accuracy of physician statements. Procedures or medicines apply to different people and medical factors; always consult your physician on medical matters.
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