In this program Professor Sharp will review the workflow and algorithms most often used to size vessels for stent selection and placement. He will also explain the strategies of using IVUS to optimize stents for optimal PCI results.
I'm really grateful to phillips for supporting this initiative. Um Well, we've already done the first lecture which was the basics of image interpretation. This is the second lecture based format, which is how I personally tackle stent sizing. There isn't one simple way to do it. Um Some people have proposed it, but there isn't one that can do it in a very simple way. And so I'm going to take you through a series of steps that should allow you to be able to handle most different types of vessels. Um When we get to number three of the 10 sessions that we've got planned, that's when we start to produce some live cases in a box. So what we're gonna do is we're gonna record some cases in cardiff and we're going to edit them down and the aim of those cases is to take you through each of the scenarios that you might face when you're looking to use ultrasound to improve your outcomes. So the first one was a zoom type lecture. This is a zoom type lecture. And then from next month onwards until the winter of the end of this year, we're going to be doing monthly sessions with cases. So the aim is to try and get you further of that learning curve with intravascular ultrasound, which we know is is not the easiest to start with. But once you've got this primer and you've done about 50 cases. I think most of you will be very confident with this technology. Once you've got to that point. So how do I do it? So those are my conflicts of interest which includes consultancy and speaker of these from phillips. Okay, I'm just gonna revise normal anatomy. Hopefully many of you were on the last call and we need to be able to identify normal anatomy to be able to size vessels and then work out where to send them. So it's an easy anachronism, anachronism acronym Am I advent isHA media intimate. So the advantage is the bright white circle that goes around the vessel. The media is the jet black circle that sits inside of the advantage in and then the intimate should abut the media and there should be a very thin intimate, so thin that sometimes you can barely see it. Anything between the internet and the media is plaque coronary after roman. Okay. Mhm Konrath Aroma sits between the Internet and the media. Here we see a vessel that has a fair amount of plaque, probably 60% plaque burden. We can see the media, which is the jet black circle that runs around the vessel here. Quite easily we can see the advantage in which is the bright white area that sits outside of the media and then the intimate abuts the blood pool, which is the jet black stuff. Around the ivies catheter, the blood here you can see a wire because this is a rotational ibis causing artifact that goes out towards two o'clock as a, as the iris beam reflects off the wire and what sits between the media and the intimate. It's Konrath aroma. So here we have some very bright white material and yet we can see behind it. So this is fiber optic plaque, but then we get darker material here. So this is fatty plaque and then we have a mixture of fiber fatty plaque for the rest of it. Okay, so we have to understand what normal anatomy is and what abnormal anatomy is to be able to stent size and optimist. So as I said, last time, blood fat and muscle is something that reflects ultrasound poorly and therefore will appear black fibrosis calcium stent will be white calcium will entirely reflect the ultrasound beam. And if you get dropped out behind it, that confirms you have calcium. If you have a bright white segment, if you do not have dropped out behind it, then it's fiber optic material. Okay, so this here at 9:00 is a thick white substance that causes drop out of all material behind. That's important for stent sizing because if you're trying to size a stent in a heavily calcified vessel, you do not see the media to see how this drop out of the medial circle as it runs around the vessel. So you're going to have to infer where that media would be. If you're going to size on that segment. If you have three or four acts of calcium, it can be very difficult to size the vessel because you can't see the media if that's the case, you're better off going upstream or downstream and then being relatively conservative in your sizing for the point at which the circumferential calcification is. And I'll come to that shortly as to why that is okay. So what about our goals of stent optimization? Well, firstly we want to get the largest possible minimum stent area. So that is the strongest determinant of outcome. The smallest bit of the stent is the bit that drives outcomes. So if your minimum stent area is three, Then that stent is much more likely to fail than if the minimum stent area is eight. Now, when we start putting stents in and optimizing them with diverse. Our eyes are drawn a lot to mala position because it's something we can't see on angiography. We think we can see the stents and how big they are. And so we've got to always a feel for how well the stents going up as well as the shape of the balloon during the inflation. But we can't see male opposition on angiography. So when we start doing this we get very focused on that. But actually as the box below shows what we're trying to do in ibises avoid gross smell opposition. There are actually very few studies showing that acute male opposition. E mile opposition at the time you put the stent in is a driver of stent failure. Now there is an RCT study and and a hint in one or two divers observational datasets that if you have significant mile opposition, you get eddy currents behind the stent that become problematic. And there's actually some pre clinical data to support that. So we want to avoid Grossman opposition because it may be a week driver of stent failure. But the other reason to avoid it, which is probably more important to be honest, is that during the course of this procedure or any future procedures, if your stent is hanging off the wall you could wire behind it or you could be bringing a balloon up through and it could catch the roof or the floor of that stent and it could fold that stent in damage. The stent. Now a mangled stent is a driver of stent thrombosis. The beautiful lean, perfectly engineered stents. We have the stent thrombosis rate is very, very low if you make them widely expanded. But if it's hanging off the wall and then you crumple it. So you've got this mash of metal sitting within the vessel then that is a thrombosis risk. So we try and avoid grow small opposition and welcome to the definition of that shortly and how you correct but the reason why a generation of interventional cardiologist grew up worried about my opposition is that the old drug eluting stents aside from the texas, they have toxic polymers on them. So we put the drug eluting stents in and then the polymer started damaging the wall behind the stent. The wall would then shrivel and fibrosis and pull away from the stent. And so you have grossly abnormal wall with free floating stent in the middle of the vessel. And that would occur over 3 to 12 months after the stent had gone in. So that grossly abnormal wall would then be a promoter of thrombosis. And people would come back in with a stent thrombosis and we would see this big male opposition. And so there was a point where we thought my opposition is the thing that causes tends to block, but it actually wasn't what was happening. There was a badly damaged wall by toxic polymer pulling away from a stent. Yes, a free floating stent in the middle of the vessel with the stroke thickness that was there at the beginning of the drug, eluting stent era was not great, but it was a complex multimodal process. So that was late acquired mala position, acute. Myeloid position where where it doesn't quite fully expand and touch the wall when we put it in is a much weaker driver of thrombosis. And the modern stents have so much better polymers or no polymer at all, that we get very little of this later acquired mala position, which is a factor for thrombosis. So what else are we trying to do when we optimize stents. Well, we want to avoid putting in balloons whether they be inside a sense or whether they be preauthorization balloons or post annotation balloons that are too big. If you're believing to archery ratio goes, goes over 1-1 you start to exponentially increase your risk of coronary rupture. So if you have a three millimeter vessel and you take a 2.75 balloon, then the chances of you rupturing that vessel are very, very small indeed. If you take a three millimeter balloon, it goes up a little bit, but it's still very, very low. Once you get above a three millimeter balloon in a three millimeter segment, that's when you start to get the risk of rupture and it goes up exponentially as you take bigger and bigger balloons. So if you have a problem with an under expanded stent within a segment, the solution is higher pressure to release that stunt, not bigger and bigger and bigger balloons. If you take a balloon that's bigger than the vessel, you may break the vessel And there's something very intuitive about that, right? It makes sense if the vessel is meant to be three, don't try and make it four. The final goal of stent optimization is to avoid landing in heavy platform. So if we lend our stents in 30 to 50% plaque, let's call it more than 50%. Like the IPCC guidelines is, let's say 50%. Then what we're going to get is we're going to get a stent that expands as much as possible to the size of the vessel at that point. And then there will be a cliff edge of arthur roman at iva ridge of the stent. There will be injury to that edge either from the stent itself or from balloon overhang from either the stem balloon elongating during inflation. Remember stem balloons or semi compliance. So if you blow them up too much, they will elongate and they will injure this 50% plaque at the edge. Or it may be you post dilate and you accidentally push your balloon slightly too far. And then you've done a plane balloon angioplasty to a 50% accelerometers segment. And you can see how easily that that would promote neo atherosclerosis on neo intimate in that, in that edge segment. And there's also a significantly increased risk of edge dissection. So if you're landing in heavy plaque, you're more likely to dissect, you're more likely to injure that, causing either new internal preparation artery stenosis or near lethal doses down the line. So we're looking for nice clean segments and by that, what what I mean is very little in the way of ath anomalous plaque where we're gonna start our Stanton, we're gonna where we're gonna end now stand and the modern era. Sometimes it's very difficult because we have elderly patients with diffuse disease. It's sometimes extremely difficult to find these clean landing zones and then we have to adapt our strategy. So I'm going to go into that in during this session. Okay so terminology. Um so people will talk about sizing for the vessel and sizing for the lumen. And we do this so often that sometimes we forget that people who are relatively new to ivy's will not quite understand the difference. So the blue line here on the right is the media. So the media, everything inside of it. That's the best I if there was never any disease we would see the internal layer laying on top of the media or inside of the media should I say? And the and the media to to intimate layer would be so thin that we can just size off the media and we'll be okay. Yeah. So that's the vessel. And when plaque starts coming between the media and the intimate then we start to create a difference between the lumen size and the vessel size. So the lumen of the vessel size will be very similar. If there's no country on earth aroma. If there's country after Roma, then what happens is the lumen gets smaller and smaller as the intimate is pushed in by the plaque. And then we end up with a difference. So the yellow here is the Luminal area. And why are they different? Because there's coronary artery Roma between the two. Okay so we want to do vessel sizing with IV's if at all possible. And I'll take you through that. You sometimes hear people talking about E. M. Or E. L. And that's just a slightly different terminology. I tend not to use it. I tend to stick with media because it's very simple, very easy to identify. And this does not need that desperate extra however many microns. But you know cT talks you'll hear that people talk a lot about the external lasting membrane. And that's because it used to be the O. C. T. With undersize stents compared to us. And so people have looked for mechanisms of just expanding the extent of it further when you size on the basis of O. C. T. I've already gives you a nice big stents if you size on the media. So what is the excellent lasted 11 or external elastic membrane? It is a layer of tissue that sits on the outside of the media. And just to emphasize just how little difference there is. When you're talking about sizing on ideas if you size for the far side of the media, that's where the external examiner is and it's extremely thin. It's microns thick. So I personally think it's just an unnecessary complicating factor because people wonder where is the internal where's the external which one am I sizing. So when I talk about sizing I talked media to media. Okay because my aim is to try and make things as understandable as possible. And again you can see here that in terms of the sizing you get on I this it's really not so different. This is going to make a vast difference compared to angio guided stenting whichever way you choose it. Either the one on the left where you choose the external stick laminate on the outside of the media or whether you just find the jet black circle and draw from one side to the other. A media to media. Okay, so on the right we find the jet black circle. We draw through the middle of the vessel to the other side of the vessel. And that is media to media sizing of the vessel. The lumen would be the inside of the plaque to the inside of the plaque. Okay, what else do we talk about in terms of terminology? So you'll hear people talk about landing zones. What we mean by that is where the stent starts and where it will end within the vessel. So what we're looking for is nice healthy segments with very minimal plaque. You'll also hear people talking about reference segments. So this is the vessel adjacent to the edges of where the stent is or will be. They're very similar things. But the former landing zones is a sort of description. We're looking up and down the vessels trying to find where we start and stop referenced segments. We tend to associate dimensions within the measurements, but really they're talking about the same thing. The vessel where we're going to start and stop the stent. Okay, and what is messa. So you'll hear people talk about this a lot. It's the minimum extent area and this is important because it's the most important determinant of outcome. If you can get your minimum certain area above five millimeters squared, you start to get an exponential fall in the chances of stent failure. And when you're getting up to 89 10 millimeter squared, it's quite unusual for those steps to fail unless there is a problem with it. Like you've mashed it with your guide catheter or has been disrupted by a bifurcation procedure or this is somebody who's grossly growth robotic for whatever reason. Mhm And this is how we measure the minimum stent area in this case 8.6 millimeters squared. We just draw around the inside of the stent metal and that's our minimum stent area. So we would go up and down our service. And at the moment it's done visually, there are algorithms coming that calculated automatically for you. But for drivers at the moment we are doing it manually. So we go up and down the vessel. We look for our smallest bit of the stent and then we measured and we need that smallest bit to be more than five Or greater than 90% of the distal reference area. I'm going to come to that to explain that in great detail. The other thing you may hear about, We've just heard about M. S. A minimum stent area, you might hear about. M. L. A. M. L. A. Is minimum Luminal area. So that's the narrowest point of the lumen by area. So that's important for a number of reasons. But the most common reason why people use this terminology is to try and decide whether something is so tight that it needs fixing. So there is a rough rule of thumb and it is rough. This is not the best way of determining ischemia physiology is better at that. But if your minimum level area in a proximal epic cardinal vessel, like the led the circum flex, the right coronary, If it is greater than four squared And you probably are going to have a negative ischemia test. Now there are exceptions to that. If you've got gross left ventricular hypertrophy and its approximate led you can get a schema a minimal Luminal area 5.5. But for most cases if your minimum Luminal area which looks like this Is greater than four, then you are probably going to have a negative ischemia test in that in that vessel. If it's less than 22.5 usually it's ischemic. Unless you're dealing with some tiny little septal branch or branch of the diagonal. If you're talking about an epic cardio vessel it will usually be a skeptic. And then in the middle we were not so sure that's what coronary physiology is designed to tell us. But minimum bluemel area will be talked about a lot in the left main we say that a minimum level area over six is typically associated with the negative ischemia test? The minimum Luminal area less than 4.5 is usually ischemic And then 4.5-6 is somewhere in the middle. And we're not quite sure whether it's ischemic or not. Some people will just stent within that zone. Some people will look for a second test like a pressure wire or take them off the table for a non invasive test. Okay so extensive using algorithms. So many have been tried. The only algorithm tested in a randomized trial of all comers. All patients we might put sense in is the ultimate trial. All the other are CTS in inter Connery imaging have looked at success whether it be cto long lesions beatifications. In ultimate They took over 1400 patients who are having PC in stenting with any type of anatomy and they randomize people to endure guided or I was guided and they showed a significant benefit with IV's guidance using a particular protocol. And so I teach to that protocol because it's simple it's proven and see it applies to all comers. So it's not just a protocol that's been designed for specific lesions and there's one modification to that protocol I will come to and that's for very long lesions where I think it doesn't work. And but there's a very simple way to solve that and I'll talk you through it. So what was ultimate well it's the most important trial in the history of ISIS. In my view, it looked to see whether Andrew are guided P. C. I. In all comes versus Ivan's guided pc. I have different outcomes and the primary outcome was target vessel failure. So whether that you had stent failure requiring revascularization, thrombosis, semi or death. And it included patients with silent, ischemia, stable or unstable angina or am I Okay? So again abroad lesion population subset and it was randomized 1 to 1. And what were the what was the criteria they used? I mean they didn't pull this out of thin air. This was based on a lot of prior work from all around the world from observational datasets and from some of the previous randomized trials in lesion subsets. And what they, what they asked their operators to do was achieved a minimum Luminal area. Exodus cross sectional area, minimum Luminal area Within the standard segment of more than five Or 90% of the distal reference Lumen area. So your distal reference area is the first bit of the unstinted segment downstream from the stem. You then measure your reference lumen. And if that Luminal area was five, They asked you to get at least 90% of that value for the smallest bit of your stand. And now in that case that I've just shown you The two numbers are roughly the same. Greater than five or 90%. If you're stunting the proxy led the exit of your stent a normal lumen. At that point We'll have an area of 11 1213. So aiming for a minimum level area within approx-led east end of only five. He's not good enough. So you would switch to the second part of the requirement which is 90% of the distal reference area. I'm going to go through all of this with some nice examples and drawings to show you how to explain what this means. The second part of the requirement, which was the one that they found most difficult to achieve because there's so much diffuse disease around at the moment Is that they ask you to look for an area where the stem starts and stops that has less than 50% plaque burden. So you think that's easy. Right? So I will just go back to this diagram I've got at the beginning because plaque burden is an important thing to understand. So the green area here is the platform. Now you might think that's the same as stenosis, but it isn't because the first response to Konrath aroma is for the vessel to stretch, glide off, remodeling. And so we don't know for sure what the area upstream and downstream is and we don't know what the size of the vessel was meant to be at that point because it will have stretched to accommodate the plaque in the first instance when the vessel can no longer stretch, it can no longer perform Gallagher free modeling. Then the plaque starts to come in words and narrow down the vessel. And so plaque burden can be very high. Even though you've got a decent, decent Luminal size, I hope that makes sense. That if this thing just keeps expanding with accelerometers, plaque, you might have an area in the middle of this example of eight squared, which is excellent. But when you measure plaque burden at this point, the difference between blue and yellow in terms of the area, it might be 60%. Okay, but that's not a 60% stenosis because upstream maybe nine millimeter square downstream, maybe seven millimeters squared. You've got eight in the middle. And yet you've got Blackburn at that point because there's all this plaque that stretched the media out and at that focal point, I hope that makes sense. All right, we'll get back to our roles. Mhm. I was talking about this. Okay. So what did ultimate show? Well, it's a slightly busy graphs. So I've tried with some cartoons to improve it. So this was the angio guided arm. So for three years It showed an event rate of 10.7%. Okay, that's actually not that bad. It's reasonable angioplasty and that's because they were mandated To postulate all these steps up to 20 atmospheres. So it wasn't like the angio and got bad angioplasty and then the I've disallowed good angioplasty the Andrew arm a good angioplasty and the ivory salon. Excellent angioplasty and that's actually reflected in these values. 10% of three years is not a catastrophe. But look how much better the Iverson was 6.6%. So we had a 40% reduction in hard events at three years. So imagine we had a drug that could reduce hard events three years by 40%. Do you think we'd be allowed not to use it? I mean, unless it was, You know, $100,000 a year for that drug. We'd be forced to use it. I mean we'd be sued. We'd have guidelines mandating it. And yet here we have a randomized trials showing an outcome benefit of 40 and it's not like it's a trivial endpoint. This is target vessel failure. Very good employment. But they then did a secondary analysis where they looked at optimal versus suboptimal PCO. So if you got randomized to ibis and you couldn't achieve those three criteria that I showed you on the previous page, which were to get your stem big. And the numbers don't matter so much. But the numbers I told you about, you've got to get your scent big. You've got to make sure that you landed in an area where there isn't 50% or more plaque burden and you have no dissections at the edge. I didn't dwell on that on the previous page, but you, you know know dissections. And if you were able to achieve that big stent healthy edges. No dissections, then you had optimal piece here. If you could not achieve that, then you had suboptimal even though you used iris. And so how did that work out? Suboptimal PCR you couldn't achieve what they asked you to 9.2%. Not far off what we're doing with the angio guided. What about if you could do what what we asked you to Incredibly low event rate 4% at three years. That's not far off statins in primary prevention. You know, we're talking about if you're the same age as this group with the same clinical parameters and you've never been diagnosed with ischemic heart disease. You're on a statin you're probably going to have a similar cardiovascular event rate And three years. Is this? So it's almost like if you can restore normality to that segment, you're restoring the patient back to as though they've never had coronary disease. So this is a very alluring prospect. Of course, if you couldn't do optimal pC despite I visit maybe that that lesson can't be restored. And no matter how hard you try with IV's you're going to have a patient who's at risk because there's a lot of plaque all them down this vessel. And the reason we did suboptimal pc is, we couldn't find nice healthy places to start and end our step and that's what medical therapies for. But if we can make sure that our stents are landing healthy too healthy, expanding nicely and we don't dissect either end. Then we can offer our patients an incredibly low event rate 4% three years. And again the question is what comes next. So we've had the three year data look at how in suboptimal pc. I I know I'm probably stretching it a bit almost literally in the case of this graph. But you can see how you get a sense that with suboptimal pc I it's gonna keep getting worse. An optimal PCI. Maybe it's flattened out and so I can't wait to see the five year data. If the five year data continue to show a flattening of the optimal pC. I curve. Whereas the suboptimal pcr curve keeps getting worse. I really think it's going to become difficult to justify not using iris to try and restore this vessel. I mean it's difficult already on the basis of the primary endpoint. But it makes sense, doesn't it? That if you can do a really good job, take as much of the placards needs taking that you can almost return them to values as though they haven't been diagnosed with heart disease before. That is an attractive hope. Okay, so let's get on with optimizing stents. So first you take you through some cartoons to describe how we handle a simple lesion with iris. Okay, I've changed the colors so we don't have the same old cliche coronary colors. So here we have 2023 millimeter long lesion. This is the lumen in yellow and blue. Is the plaque. Okay. And the media, he's here. The edge of the cartoon. So if we look on the left at this, I this image here and we have a very healthy looking landing zone. There's virtually no plaque. We have the bright white advent isHA. On the outside. We take a step in and we see the jet black media. So if we wanted to measure media to media, we measured from jet black to jet black across the middle. And then the intimacy is a little bit thickened here, but it's thin all the way around. Okay. So there's very little coronary plaque, if any at all. Similarly downstream researched on the isle of us and we found a healthy segment just beyond where the stenosis is again, looks very healthy. So this is a perfect pair of landing zones. It's not too far from the lesions. So we're not doing excessive standing in order to accommodate all the plaque. But equally we wouldn't want to move into here where there's probably 50% plaque burden and we wouldn't want to move in here where again, there's 50% plaque burden. So where I've dropped my arrows. This is where we're looking for to start and begin to begin and end our stents. Okay. Less than 50% blackbird. And that's how we would measure it in this case it's 3 mm across one dimension. And in the long access 3.2. Okay, now some people do this. They draw diameters two diameters and they accept that I think that's okay. But with modern IV's particularly when you control it yourself at the table like you do with the intra site where there's a swipe pad on the other side of the table where the operator can just draw dots around the media. Getting this sort of circle. It will then give you an automated minimum and maximum diameter to the vessel. We can then average that out and we stepped down in ivy's which will come to in a second. Similarly here is 2.5 diameter distantly three proximately and we would average out the minimum and the maximum and then downstairs. But personally I usually draw around the media because then we get that automated minimum and maximum diameter. And I would encourage you all to do that if at all possible. So what do we do with this vessel? We have a three millimeter diameter proximal reference by the healthy get where we're going to start our state And we have a 2.5 millim pistol reference, healthy bit where we're gonna end up dead. So what we do is we size for the distal reference i where the stand is going to end we take the diameter there If it is 2.6 we downsized to 2.5 because we want to avoid a balloon that's bigger than the natural diameter of the vessel. And I've also over size is a little bit over sizes by about 6% to 12%, depending on which brand you're using. So just remember that 2.6 might be 2.7, And so you're better off to go down a bit to make sure you account for that. Okay, So if you're between stent sizes and then the one you take off the shelf is the size below. Okay. And then just put it in a nominal if you've got a 2.5 millimeter vessel receiving a 2.5 millimeter stem. If you've got a healthy landing zone, you can take 1-1. Okay. So if your measurement is 2.5 and it's healthy, you can take a 2.5 mm stent If you've got bigger than 2.5 and what you're doing is you're stretching that digital reference segment bigger than it's designed to go. There is a greater risk of rupture or or of dissection. Although it has to be said in very healthy vessels, there is a degree of gift. But nevertheless we want to avoid overstretching that digital reference segment because very few segments are completely normal. Like the example, I just showed you there's usually a bit of plaque and therefore we risk splitting the intimate splitting the plaque and getting tracking into the media of dissection plane. And that's how you end up with a cute closure of the vessel. So we put our 2.5 mm stent in. But the problem is that's going to be too small for the proximal edge. It's going to be mala post. So what we do is we post dilate with graded balloons at varying pressures In order to get what we think is the right size. So remember, if you take a 275 n. c At 24 atmospheres, that would typically be 2.9 to 2.95, depending on the brand. If we take a three millimeter balloon At 12, it will be about three. If we take it at 20 it will be 3.2. So the choice events, the post annotation bloom will depend on a few things and I'm going to come to that in the moment. But again, you can always make stents bigger. You can never make them smaller. So if in doubt go down a quarter size and then dilate. If you think it's too small, you can go to higher pressure and the and the balloon will expand a bit more even and then see balloon and then you'll get a little bit more diameter pressure is to release. Constricted vessel and diameter is to size where the stent is okay. Mhm. And what we're aiming for is the smallest area of the stent. So the essay, It needs to be more than 90 of the distal state reference. And if that cannot be achieved, aim for five. So if the smallest bit of your stent You trace it around and the area at that point is 6.5 and then you go to the exit of the stent and you measure the area and it's nine then your stand isn't big enough Because 6.5. Abaria I said, he's not 90% or more of the area of the exit of the stunt. So we want to make that bigger. We want to get it up to 8.2. Okay, if you can't achieve that Then you can bail out to five squared. And why is that? Because in studies either studies if you have a minimum stent area of greater than five, you start to get an exponential fall off in event rates. But as I've mentioned before, five is not good enough for a proximal major epic arial vessel. So I think that's the second place criteria. We want to get more than 90% of the distal reference area. Okay, so what about a longer lesion? So this is the classic LED. It's a tapering vessel diffuse disease. How do we handle this? Well, again we're looking for reference areas where we start and where we stop our status. So in this case with the healthy bit is the near the Austrian of the LED and the healthy bit is disability. So we've got a long segment extend him and you can just dropped something in the middle just to show that there's tapering that. Okay, so here we have a three millimeter landing zone distantly that he's healthy. He's got very little plaque burden. So there's a low likelihood of dissecting that landing zone as long as we don't oversize the stem. But there is a large size disparity as we come back up the lady Approximately 4.25. So if we're going to do a single stent, we need a stent that can be sized for the distal reference. So that's the three stent And it also needs to be stretchable. One of a better phrase. We need to be able to stretch it up to 4.25 approx. Now you would imagine that they can all do that. But actually that's not the case. Some stents have got very limited over sizing capabilities. And so you need to understand your sense if you're going to do these long segments, that taper. So this is from our jay Carney, it's available on his twitter feed if you go back to about three months ago, that's the last time he dropped it in there with some of the more contemporary stents. But all he's doing is he's reporting what the engineers are saying from each company. So they're saying that yes, you get the solid bar for a three millimeter synergy out to from if it's a three millimeter century goes up to 3.5. But if you want to post related, it will go up to 4.25. Okay, But if you look at a 2.75 onyx, the labeling is that it only goes up to 3.75. Now, in fact, you can make the onyx bigger, just like you make a lot of these stents bigger. But the engineers are telling us that the architecture of the polymer, everything else, It's designed to go up to 4.25 with the synergy but it's not designed to do that with the Onix. Okay, so you can make it go bigger. And so a lot of people get fooled into thinking, okay, this will be fine. I'll just over expand it. But actually when you do electron microscopy on the polymer and the stent, it isn't quite as good as it would have been if it would have been within it's engineering limits. So, I actually have these on my wall. I have RJ's posters on my wall in my cover so that I can just go and look at it. I also have a little bit of extra on the side showing where the stent marker is. I. The balloon to the edge of the stent. So I know is the stent inside of the balloon market, is it halfway or is it on the outside of the balloon market and it just allows me to have many stents on the shelf without making mistakes. So I would suggest you get that from RJ's feed. So synergy a three millimeter stent sized for the distal landing zone will be post relatable to 4.25 without disrupting the stent. So we're gonna we're gonna put that in. I'm gonna make sure that the stent balloon doesn't damage the front of that. Standards were taken out and then I'm going to post dilate. So the distal half for that segment might need one type of NC balloon and the proximal half will need a bigger one. And we want to size RNC balloons according to the media to media diameter at various points along that stent. So should you do another IV's run ideally. But it's the real world. I think it's reasonable to just have measured it before you put the stent in and then take your N. C. Balloon in the second half of the stent. I would probably use a three N. C. Or 3.25. Making sure I stay inside of the stent And I post dilated upgraded pressures to make it wider. Higher the pressure, the wide records and it's only a couple of you know 9.2 mm or something. But it nevertheless it's extra amateur. And then I would take a bigger balloon for the proximal segment. So maybe a four millimeter balloon in this case. And I'd again grade the pressure to make sure I didn't excessively expanding even an NCB. And what we're trying to do is get a minimum content area more than 90% of the distal reference. Okay, the problem with that is that. And I'll show you this in a minute when you've got a very long stent. Sometimes the distal reference is actually quite small and you can't really apply that rule to the proximity. And I'll show you an example here. So this is an example of different 15 millimeters, approximately 2.5 millimeters asleep. We've all seen this in the L A D. It's a very long 48 millimeters sensor. So the area Of the vessel here is 19 at the proximal edge 11 at the middle and 4.9 distantly. Now, 90% of the distal reference area Here is going to be 4.3 whatever it is, it's clearly inappropriate to say that you've done a good job in the proxy lady if you leave that 19 millimeter squared vessel at 4.4. And so this is where the ultimate rule falls out And neither is getting it more than five squared any good? It's just not. Those two rules together are not good enough for a very long standing second. And so how do you deal with this? You segmented? So you take the first half of the vessel. And you apply the rules to that. So you want to be either the minimum, the smallest bit of the stent needs to be 90% or more of the distal reference area, which in this case you draw here Where the 2nd Red Arrow is And 90% of 11 mm square to 9.9. So you need the proximal half of your stent to be 9.9 or more. Okay, 10 square. And then you take the second half of your stent and you apply the rules again. So in this case we want more than 90% of the distal reference 4.9, which is 4.4. We've got this other rule. Can you get the stent to more than five millimeters squared at it's smallest point in the second half of the long led east end. I would try and get to that other rule as well. So proximal half I'm going to use only the distal reference The digital half. I'll say well I'll try and get to five but if I can't I'll definitely try and get to 90% of that digital reference area of 4.4. So I try and aim for the higher of the two as long as it's safe to do so. And I'm not excessively expanding. And this is how you deal particularly with the LED which has an issue with tapering because of all the branches that come off it. I hope that's clear. Okay, case three Unhealthy distal landing zones. So what do you do if you can't find a healthy bit to start and finish extent. Now that actually happened a fair amount in ultimate because diffuse disease is more and more common as people get older. So in this example we got 3.75 approximately 2.75 distantly as our media to media diameter. So that's the vessel diameter. The problem is while the lumen and the vessel are very similar here. Remember the luminous the area inside the intimate because there's no plaque here. We can't find anywhere without plaque. And so whilst we have a 2.75 millimeter immediately media We've got more than 50% black Burton and the lumen is a lot smaller. So if we stand here, we're going to get a cliff edge a plaque at the edge of our stent, which is bad. So what do we do size for the looming on the media? What we do in this situation is we try and find a better place because This is 2- 753. The Lumen is 2.25. We've got too big a difference here too much plaque. So 2.75 millimeter vessel at the distal landing zone that we've seen in the last case, but it's unhealthy. So there's a higher likelihood of dissecting at that point. If we size media to media. So the suggestion is look elsewhere. And if that means extending your stent by 5-10 mm then so be it obviously you have to make a judgment call then if extending your stent by 5 to 10 millimeters means going into a highly torture segment or across branches or into an area you really don't want to be involved in. And you never subjugate your clinical judgment to any rule. You just gotta do what you think is right. But some people are afraid of extending stents and I don't think we should be if it means going from a bad landing zone to a good one because what happens if you put in a bad landing zone, you might get dissection there and then so you put the second stent in anyone or you end up with a vulnerable area that may be prone to target vessel failure in the coming 123 years. So it's better to extend the stent and accept the small penalty with modern drug. Eluting sense of having longer sense. Used to be that long stents were terrible in the modern Eder adding an extra bit of stent length on is not a disaster compared to stenting in a bad area, of course we don't want to put it in excessively unless we have a good reason. And this is a good reason finding a healthy landing song. So if you can't find areas with plaque burden less than 50%,, you've got a size for the lumen, not the vessel. So in this case we managed to shuffle around and find a slightly better distal landing zone here. I mean, although it doesn't look very much that will probably work out 30-40% plaque at least. I wouldn't be surprised to this a bit more. In this case it's 2.5. If it measures out of more than 50% plaque burden, I would size for the lumen here at 2.5 rather than 2.75. And then again, just pick your sent most of them will be able to cope with this sort of thing. So two point 5,000,008 science will go to 3.75. We post isolate from the distal edge of the stem back being very careful with this plaque at the exit that we don't accidentally posted late beyond the edge of that stent. And then we graded up with RNC balloons sized according to what the ivies tells us is the media media within the body of the stent. Now, when you do size for the lumen, it's important that you're careful. A lot of people will shy away from the dis legend extent, which is understandable because its platform. If you get too far away from the distal edge of the stent, you get what's called candy wrapping where you balloon the stent and then the distal edges folding. And I just sort of created an image of that here. So where what happens is as you balloon slightly back from the edge, it folds the distal edge of the stent in stem boost is very good for spotting that If you have that in your cath lab, do a stem boost as you're doing that. Distal balloon, N. C. Positioning and then you'll know that you're you're close to but not beyond the edge of the stent and try and get it within about half a millimeter at the edge of the stent. Don't come too far back. Okay, mala position, correcting my position is pretty straightforward if you have an image first, the stent needs to be able to go to that size to correct if we knew it was a four millimeter vessel. Hopefully we haven't put 2.5 millimeters stent in. And then the rules are, if you've got more than no 0.4 millimeters of mala position, you should try and correct. In reality, if we're seeing mala position on ibis, we should probably just have a goal of correcting it in a judicious way. So this is gross mala position here where we have no 0.8 millimeters amal opposition. So that's way beyond the A. P. C. I roll If if it's greater than 0.4 millimeters corrected. So here we have grossly proposition so we size For diameter and we do not need pressure here. There's nothing stopping the stent expanding. We just need a bigger balloon to make it expand. So we don't need to be going to 24 atmospheres. We don't need to even necessarily take an NC balloon. An ordinary compliant balloon will inflate this. In reality I use an N. C. Balloon to make sure it doesn't elongate out at the end of the stent but you can use either and I tend not to I tend to only go to go to a nominal in this situation. And here I take a 4.5 millimeter balloon to my 3.5 millimeter stent and get this thing onto the wall. So how how much can do we post a late so we want to go 1-1 sizing at the edge of the stent. As long as there's healthy edges. Okay, so if it's 4.25 approximately, we want to use a balloon that goes up to about 4.24 point 25. Okay. If distantly. If it's three, we want to have a balloon at the distal edge. That's three. So what about in the middle? So within the body of the stent. Remember there's all this plaque behind it So I've, this oversized is slightly. Okay, so we've just got to be careful to go slightly down on ivy's measurements when we're choosing a balloon. If the Ibis is 3.25, you're better off taking a three and then blowing it up a bit more to make it wider. Okay and remember the plaque has to go somewhere and we've got to be cautious about negative and positive remodeling. So what do I mean by the plaque has to go somewhere. This is the body of the lesion. Okay, here's a four millimeter media to media. And he has all this plaque going around within the vessel. When we put a stent in, that plaque has to go somewhere. What is he going to do? It's going to stretch the plaque out and therefore stretch the media. And what is it that causes rupture. It's excessive stretch of the true vessel size. So we do have to be a little cognizant to the fact that we are going to make this vessel probably bigger than it's designed to go. And remember it's already undergoing remodeling and stretched a bit. So that's what it looked like. If we were to take 1 to 1 sizing in a plaque segment. So if this said it was four and we took a four millimeter balloon, we're going to stretch that plaque out and it's going to push the media out a lot of the time we get away with that. But if ever you're wondering how have I ruptured this vessel, It's usually a mixture of the things I'm going to tell you about now. Either we haven't accommodated for the plaque to stretch the vessel or there's something abnormal about the vessel wall at that point or we've got our sizing wrong. So what do we do about this? We downsize RNC balloon by .25, on the media to media diameter. So it was four at this point no more than a 375 and sometimes use a 35 if I want to go to high pressure. If I see calcium and fibrosis, I need high pressure to get that stunt up. So I'll go down to 3.5 of them at that point and blow it up to 24-26 atmospheres. The balloon will go up to about 3.753.8. And that that atmospheric pressure. And then I know that I'm pushing my plaque out and not excessively stretching the vessel at that point. If it's a soft plaque like this, I might go for a 3.75. Okay, so remodeling coming towards me and I think we've got about five minutes. So remember that within the body of a long lesion there could be focal negative like this 2.3 millimeter segment here or positive like this 4.25 millimeter segment within the body of that lesion. So you've got to be really careful about about over interpreting a single point of remodeling and then interpreting that to your whole stent size and balloon science negative. Remodeling will mean they'll be within that lesion. An area where the media to media has been shrunken usually by a process of fibrosis. So this is smaller than the distal segment which isn't what it should be, it should taper down gradually. Okay. And because it's fiber optic, It's actually sometimes very difficult to release and it can behave unpredictably if you take a balloon sized distantly or proximal. Okay, so I've seen people measure distal landing zone, approximate landing zone and say, okay, 275 will be fine. It's very rare. But if ever you wonder why that weird rupture happened last year, it may be that there was a segment of negative remodeling in the middle and that this 2.3 millimeter vessel. Yes, it was designed to be 2.75 but this is a highly fiber optic abnormal wall. And so if I see that I'll just be a little more cautious in that segment. Remember we're aiming for 90% of the distal reference. We're not aiming to restore entire normality to the disease segment would be lovely if we could but we have to use our judgment and protect the patient similarly with those positive remodel segments. If you took a full balloon And it's 3.5 upstream And two and 2.3 downstream. That's the stuff of madness. Stay away from that decision making. So sweep up and down your ibis. Make sure you don't size on a single positive remodel segment. Okay, so what do we do at the end of our procedure? We check we've covered the stenosis, we put it in the right place, we got healthy edges. We check that there's no dissection. So it's meant to be if it involves the media runs from more than three. But neither is if you're seeing a dissection and there's little cost to covering it would usually just say cover it otherwise people just get down into the weeds and spend ages trying to work out whether to do it or not. It's different with L. C. T. Where you see all sorts of dissections that are of dubious meaning looking for thrombosis, tissue protrusion is a big debate about what to do about that. I talked about the selection I want donald We want to try and correct my opposition. I mean .3.4, you know, I don't think it's so important if you can see my opposition on either try and correct it as long as it's not a cost to doing so. But I've seen people go with four or five balloons going for half an hour trying to correct .25 mm of my opposition. It's not worth it. The reason you're trying all these different balloons and techniques, it's probably because the stent can't get any bigger. So if we buy this upfront, we hopefully won't get into this situation where we end up with gross smell opposition and crucially the thing that decides the outcome of your procedure more than anything else. Extension expansion. We want to get the smallest bit of the stent, more than 90% of the additional reference area or over five millimeters squared with the caveats that I've banged on about this entire thing. So to close, we're looking for healthy landing zones, that will accept 1-1. Media media sizing decided on the distal reference and then we post dilate to smooth that stent to appropriate sizing for the rest of the body. Unhealthy landing zones. If you can't find any healthy landing zones, you've gotta size on the loop on the loom and not the vessel. So instead immediate, immediate. You do intimate, intimate and that's to avoid edged a section. You've got to be very careful postulating that when you are postulating within the body of the lesion plaque behind the stem has to go somewhere and remember it's abnormal. By definition you're putting a stent in it so it may have calcification, fibrosis, it may be negative remodel. Just be a little careful and downsized by at least 0.25 off the media, the media diameter. And if you blow your balloon up to very high pressures, It will be going 1-1 and potentially more than 1-1 if there's negative remodeling within that segment. So just be a little aware of that. We want to put the stent on the wall, that's what it's designed for. But don't get too bogged down in it. If you either before you put your stent in, you'll find that this is not a major factor in how you're doing your cases anymore. If you go on angiography. Put your stent in either so you'll find loads of our position and then you're gonna spend a lot of time sorting that out vibrating and calcified diseases. Less forgiving, especially when negative remodeled. And you need to tell a sensitizing post allocation according to all the information that includes clear clinical information. If you've got a patient who might struggle with Jolanda playlists, you don't want to be covering the big long 48 millimeter segment. You want you want a nice short fat stent if that's the area where the critical lesion is. Do the critical lesion. Now you could argue that applies to every case. But again there's lots of things to consider over and above what we see on an intravascular ultrasound. So I'm going to finish their, I've slightly overran but let's see if there's any questions. So salome. Did did you acquire any questions if you've got any questions? I should have said this at the beginning and put them in the chat and I'll try and answer them now. Um So looking at the chat here stent sizing for the left main Luminal vessel but it's the same consequence if you've got a healthy a proximal edge, you're not going to size on the proximal edge. You're going to size on the distal landing zone. So if you're standing left, main, two left main fine. You know, you want healthy too healthy. But most of the time you're going from left made into LED or sir complex. So you try and pick the bigger of the vessels if it's appropriate to do so so that you've got less size disparity between your distal reference in your approximate reference. So if your circuits 2.75 and your L E D S four and your left Mainz five, it's much easier to get a four millimeter stand up to five in a nice geometric way Than it is to get a 2.75 mm. Stand up to five some of the morning. So try and when you're standing, the left main size for the landing zone, that is the most appropriate to receive that stent where the dominance dominance that reflects sometimes it's the other way around. But it depends whether using one or two stents. If you've got a smaller Cyprus. So let's say the circus 2.75 melodies four. And you're doing a two stent as if you're doing a DK crush. That's easy. So you're going to crush the 2.75 and then you're going to do the LED four millimeter one because then your final stent is nice and big and smooth and tailored accordingly. Okay, so if you have any other questions, drop them in the chat and I'd be delighted to answer them. But otherwise we're coming up towards the end. So here we got one. So when measuring diameter, do you aim for intermedia middle or outer practice seems to vary a lot. Yeah. So this is this. So the media is a pretty small structure. Point 1.2 mm. There's a lot of focus amongst RCT users on where the media is, where the external collaborators. Because RCT registers a bit small and you see a bit more of the wall and so they measure E L T E L. That's fine. You know, they need a little bit more for the media. If you're if you're in a mid proximal led, right? Whatever it is, it's a very miniscule difference. The hard .05 or .1 mm. So I tend to measure towards the outside of the black circle. So if this is the circle, I'll try and get it. My measurement to start on the outside of the circle, to the outside of the circle, which is effectively E L. T. Okay. But I honestly don't mind that much if you're starting your learning curve, just measured black circle, the black circle and I don't mind so much how you do it because your stents will be so much bigger than they would have been with angio guided that you're going to end up with much better results. The important thing is that you either skied your procedure and as long as you can do it right. These minor differences are not going to make a massive difference, outcome a little bit. Maybe if you make it you'd be surprised, you know, 0.1 millimeter can make a difference in small vessels, but in your average proximity circuit and so on. It's not going to make that much difference. Okay, so we're now at three o'clock, I'll just give it 10 seconds more to see if anyone wants to drop a question in the chat. But otherwise we've covered in section one the basics of identifying what you're looking at in session to a set of rules to guide stent sizing. Again, you've got to be adaptive because vessels can be very different. They can go from 5-3. They can go from 5 to 4.5. They can also different geometry depending on whether you're going across certifications certifications, but that's a rough primer to allow you to start sizing and optimizing extents don't overdo it. You know, there is a signal from an observation registry a long time ago that when people start doing this, they start seeing these massive vessels and they start going crazy. So they see a four millimeter positive remodel segment. So they take a four millimeter balloon. They blow it up to 24 atmospheres, which makes the balloon 4.3 And either side of it is a 3.25 vessel. So do be just a little bit conscious of that. Bit cautious if in doubt go down. You can always take a bigger balloon and go up and on that safety. First notice I'm going to finish there. So thanks for coming everybody. Session three, which will be about a month from now. We're going to record a case of a relatively simple lesion, maybe a 30 millimeter lesion, something like that. And we're going to show how we we assess that vessel with ultrasound, we put the stent in, we postulate and optimize it and we checked we've done a good job so it's not going to be a heroic um you know, to our angioplasty, it's going to be a nice simple case and then we're going to take you through all the different types of cases that we're going to be doing subsequently. And these will be cases in a box. So hopefully they'll be edited down for maximal education and then we'll have a Q and A at the end of each of these life cases that we're doing that with my colleague. Sean Gallagher, so look forward to seeing you for that. Keep an eye on my twitter feed if you want to know when it's going to come and keep in touch with your local phillips or a pool also know and get on with your office. Now we've just got a hand up at the end there. I don't know whether if you've got a question everyone's on mute. So if you want to drop it in the chat, then the countdown is almost done but otherwise feel free to get in touch with me afterwards either via my twitter feed, which is Doctor Andrew sharp at twitter or you can email me and my emails out there. Okay? Thanks for coming, everybody. Have a good day.
