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Scott Webb: As the number five cause of death in the US and the leading cause of serious longterm disability, stroke affects hundreds of thousands of Americans each year. But for many patients with the most common kind of stroke, the ischemic type involving a vessel blockage, recanalization requires a procedure called a mechanical thrombectomy in which the clot must be physically removed. And I'm joined today by Dr. Daniel Sahlein, He's a brain and spine interventional neuroradiologist practicing at Franciscan health. And he's here today to tell us about mechanical thrombectomies and so much more.

Scott Webb: This is the Franciscan Health Doc Pod. I'm Scott Webb. So doctor, thanks so much for your time today. We were talking off the air and I mentioned that, you know, folks during COVID maybe have not been going to the hospital for signs and symptoms of stroke and heart attack and things like that. But today, our focus is going to be specifically on how you treat stroke, or the different types of stroke and so on. So as we get rolling here, what is an ischemic stroke?

Daniel Sahlein: So an ischemic stroke refers to injury to the brain from lack of nutrient supply. The nutrients to the brain are coming through the arteries. So there is oxygen-rich blood that's being pumped through the arteries under pressure from the heart, being delivered to the tissue of the brain. And in an ischemic stroke specifically, the injury to the brain is from blockage of that nutrient-rich flow.

Scott Webb: Yeah. And I think that's good to kind of set the stage here as we roll on. So what's meant by the term large vessel occlusion?

Daniel Sahlein: So large vessel occlusion refers specifically to blockage of one of the larger arteries in the head. The arterial supply is like a tree, in that you have a large trunk coming out of the heart, going out to smaller and smaller branches the farther away from the heart you get. And there are arteries. in the base of the skull that are fairly large, they're large for us, probably three to four millimeters in size, so not large overall, but large for us, and those supply large portions of the brain. One of them, for example, called the middle cerebral artery, supplies about 75% of the cerebral hemisphere, so the half of the brain that it's going to.

And so in a large vessel occlusion, one of these larger branches is blocked. Now, here's where this gets crazy, large vessel occlusions only account for about one-third of all ischemic stroke, but because they lead to more devastating clinical injury and more devastating functional deficit, they actually account for about 60% of all deficit related to stroke.

Scott Webb: Interesting, yeah, and the disparity there between the incidence of large vessel occlusions and the consequences. Yeah, that's really interesting. And I mentioned in my intro that we're going to speak specifically about mechanical thrombectomies. So let's talk about stroke treatment, specifically endovascular stroke treatment.

Daniel Sahlein: This is fairly recent. It was only in 2015 that there were five trials published in the New England Journal of Medicine, sort of the most prestigious journal of medicine that showed that endovascular stroke treatment or the kind of strokes we were about to describe was substantially better than the best medical therapy or noninvasive treatment.

And so here's how this works. We take a catheter, a long, skinny plastic tube, up through one of the larger arteries in the body, typically the big artery in the leg, sometimes the artery in the wrist. We thread those catheters through the vessels in the body until we get to the neck. From there, we inject contrast agent or x-ray dye and visualize with high resolution the vascular tree in the head to identify the site of the occlusion or obstruction. And from there, we take smaller catheters through that catheter. So it's a series of telescoping catheters all the way up into the head and we do a number of different things to pull a blood clot, a little plug out of the artery in the head to restore normal blood flow to that tissue in the brain. And so those tools include a little rake-like device, a little self-expanding stent that we can push through a microcatheter, a tiny little catheter, and then gets up into the head and expands because it's made of metal that wants to expand, and it's connected to a wire, so it acts as kind of a rake. It gets enmeshed with the clot. And then when we pull out the wire, it pulls out the whole clot. And we also take catheters that are almost the size of the vessels in the head. And we actually apply vacuum to those catheters to literally vacuum or aspirate the clot out of the head. And oftentimes, we use sort of a combination of those two, which has been extremely successful for us.

Scott Webb: It's really amazing. And I'm sure prospective patients would want to know what are the risks associated with these types of procedures.

Daniel Sahlein: So, you know, the risk is really fairly minimal, Scott. There's always a potential risk of injury to the vessel in the leg or the vessel in the wrist where we go in. We can cause what's called a dissection where one layer of artery gets peeled off another. The artery wall is like an onion skin, it has multiple layers. And it's possible to perforate a vessel in the head and cause a bleed. It's possible to break the clot up or pull the clot even more proximally and then have it become stuck and not be able to move it to cause a worsening stroke. But, you know, what the study shows, what the data shows is that patients do much better with this procedure than without. And Goodman Campbell Brain and Spine has been one of the largest practices in the United States doing this type of work for the last five years. We have a database of over a thousand of these cases that we've done. So we study our outcomes carefully and are constantly refining our technique and our craft.

And when we look at that database, we see actually very, very few complications and many, many more good outcomes. Our capacity to open the vessel and have a good recanalization, meaning open it really nicely, is about 95%. So the procedures are overwhelmingly technically successful. And, at this point, the procedures only take about 20 minutes. So it's actually a fairly quick procedure for a group that has done this many of these. This is not the same everywhere. And in fact, when you look at our data over about a seven-year span, we became much quicker at the procedure just from doing hundreds and hundreds of these. So smaller practices definitely don't have the same type of success that larger, more experienced practices have. But we are one of those larger, more experienced practices and we've seen the impact of that kind of volume in our own work.

Scott Webb: Really amazing. I'm sort of shaking my head, 20 minutes, 95% effectiveness. That's truly amazing and you can really get a sense of why, you know, going to you and your partners would be the right choice. And, you know, I know they say time is brain when we think about strokes. So what happens to the brain during a large vessel occlusion and really how much time does the patient have after symptom onset to receive stroke treatment?

Daniel Sahlein: That's a great question, Scott. So here's what happens, you know, if there is no supply to the brain with a blockage of a large vessel, that is no blood supply, then you would only have about five minutes to save the brain. And we know this because in the cardiac arrest literature, when the heart stops completely, you only have about five minutes to save the brain in those patients, because you really have no blood flow going to the head, and that's why he put defibrillators in malls. But we have much more time than that, or this just wouldn't work because there's no way to get a patient into the hospital within five minutes.

When you have a blockage of a large vessel in the brain, there are detour vessels from other areas of supply to the brain that fill that territory in around the blockage. Those detour vessels are good, but not great. If they were great, you wouldn't have any symptoms at all. But typically what happens, overwhelmingly what happens, is that patients start to have symptoms because that territory of brain is what we call ischemic, meaning it's not getting enough nutrients to function normally, but it is in a stunned, but salvageable state. So the tissue can still be rescued if you restore normal blood flow. And what the aggregates studies from 2015 tell us is that most patients have about six hours after last known well to restore blood flow and salvage enough brain that that patient will be living independently at three months.

But that time window that we call the therapeutic window is really dependent on how good those detour vessels are. And those detour vessels happen to be very, very variable from person to person. Now, they tend to be much better in younger patients than older, but even within each age group, there's tremendous variability. And so what we found later on a few years later is that, in some patients, we actually had up to 24 hours to treat. Now, in order to figure out how much of that tissue was viable versus how much of that tissue was dead and unsalvageable, we have to do a special type of CAT scan called a CT perfusion study. And that CT perfusion study literally gives us a map of what volume of the brain is unsalvageable versus the volume of the brain that's at risk but is still salvageable. And Franciscan has this software, and so we're able to work up patients up to 24 hours to determine whether or not they are candidates for this procedure.

Scott Webb: Yeah, right. So we'll go back to, you know, time is going to continue to be brain, but 24 hours, that's pretty amazing. And we think about the work that all are doing it's already amazing and you've already, you know, done so many of these. Is there anything else? Is there anything in the pipeline? Is there any other, you know, breakthrough sort of treatment options that might be on the way?

Daniel Sahlein: Our tools are always getting better, Scott. We have larger catheters that we can get through all the twists and turns into the head and the larger the lumen of the catheter, the inner diameter of the catheter, the more flow we can establish. So the better we can extract clots with those, there are, you know, next generation little rakes coming out and these kinds of things.

I think actually though that right here, right now, we are doing what is the true next big step in stroke, which is to educate the public on the signs and symptoms of stroke and get more people to come to the hospital earlier so that they are still candidates for this function-sparing kind of procedure. The majority of patients still are not getting to the hospital on time. And so we're where cardiology was in the 1970s before cardiologists did a big education effort to educate people on the signs and symptoms of heart attacks, so they understood that it might not just be pain in the chest, sometimes it's pressure or shortness of breath, or even some, you know, discomfort in the stomach or shoulder pain or jaw pain or what we call claudication. So we need to get the word out on the signs and symptoms of strokes that people come in earlier.

I'll make one more point about the time is brain issue. Yes, the average patient, we can treat up to six hours, we can treat some patients up to 24 hours, but every single person does better if they come to the hospital earlier. So for an individual person, their outcome will be better if they're treated earlier. And so it's always a race with the clock. We are always available 24/7, 365 days a year, and we are ready to rush into the lab, get that workup done quickly to see if this patient is a candidate and go to our specialized operating suite where we can catheterize the patient and get the clot out very, very quickly. That's an important point with respect to time is brain.

I think the biggest leap right now is just the hard work of getting out there, doing podcasts like yours, so thank you, having platforms to educate the public, getting into various public spaces. I actually just did a little halftime event with Boomer, the Pacers mascot at a Pacers game. I was able to bring my children to that, so that was fun, and I educated Boomer on the signs and symptoms of stroke. We went into a number of high schools in central Indiana and educated high school students. And my theory on that was while high school students may not listen to their parents, their parents and grandparents definitely listen to high school students. So if we teach a rising generation of hoosiers about the signs and symptoms of stroke, they'll educate their parents and grandparents, so they're a great vector for education. And then about a month or two later after we did this event, there was a write up in the local Bloomington newspaper that a student who had been at that event had recognized the symptom of a stroke and brought her grandmother into a local hospital and had treatment. So, you know, it worked at least in that one case that made it to the press. So, you know, we're trying to touch individuals one patient at a time and save people's function one patient at a time and educate people in the best way that we can.

Scott Webb: Yeah, we definitely are. And of course, as you've said today and emphasized, earlier is better. So at the first signs and symptoms of stroke, call 911. Don't drive yourself, call 911. You know, be fast, time is brain. As you say, it's a race against the clock. So this has been so educational. Great to have you on and you stay well.

Daniel Sahlein: Great. Thank you, Scott. Thanks so much for having me.

Scott Webb (Host): And for more information, go to Franciscan health.org and search stroke.

Scott Webb: And if you found this podcast helpful, please share it on your social channels and be sure to check out the full podcast library for additional topics of interest.

This is the Franciscan Health Doc Pod. I'm Scott Webb. Stay well, and we'll talk again next time.