In part two of a two-part interview, Dr. Hady Lichaa continues his discussion with Dr. Nyal Borges (Atrium Health) on the use of microcatheters in interventional cardiology. Here, Dr. Lichaa presents Dr. Borges with several practical everyday scenarios, and Dr. Borges provides his opinion on the best microcatheters on the market to use in the given scenario. Dr. Lichaa described Dr. Borges’ interview as a “tour de force” on microcatheters.
Dr. Hady Lichaa: So, kind of going through practical everyday scenarios, let me put you in a scenario where you have a very tortuous, calcified right coronary artery and you want to cross that with your workhorse wire or with a specialty wire. Give me four or five examples of microcatheters on the market right now that are possibly usable for this scenario and what’s your favorite.
Dr. Nyal Borges: Sure. So I think it depends, as you laid out the scenario, it depends on what you’re trying to achieve. I think in a calcified long segment artery, the main thing you’re overcoming is resistance. And when you encounter resistance in interventional cardiology, pushing in general is the wrong answer in almost every scenario. So what you don’t want then is a microcatheter whose only capability is dependent on push. So there are certain microcatheters that don’t have the ability to torque, and those are ones you would not want to use.
Dr. Hady Lichaa: Tell us about that.
Dr. Nyal Borges: Things like a Caravel or a FineCross, there is a risk of getting them entrapped and breaking tips off that you would not want to encounter. So I would steer towards a bucket of microcatheters that are torqueable. When you think of torqueable microcatheters, you’re talking about, depending on the company you have access to, things like Boston Scientific, MAMBA, or MAMBA Flex, a Corsair family or the Turnpike family.
Beyond that, there are newer microcatheters that are also torqueable and depending on what country you work in, you have access to different things like enhancers, teleports, telemarks, but the general functionality there is you want something that allows you to torque, to minimize resistance and friction, and successfully allow you to cross. My personal favorite of all of those that I currently use right now is a MAMBA or a MAMBA Flex. And the reason is the design of the device actually minimizes the ability of the wire to fuse to the lumen. So a lot of the microcatheters, like the Corsair family and the Turnpike family, have a plastic or a plastic like material at the tip, and it’s two separate actual pieces that are fused together, so the body and the tip are separate pieces. And what ends up happening is due to excessive torque in any particular direction, you can create enough friction and heat to where you end up fusing the wire and the microcatheter and now you have a problem where you have a wire across a microcatheter that’s fused and you have to give up your wire, and that’s called microcatheter fatigue.
It happens in lots of cases, especially CTO cases, and it’s something to be really watchful for. The MAMBA Flex is a single unibody design, and so you can spin it till the cows come home and I’ve never ever had a situation where I fused a MAMBA or a MAMBA Flex to a wire, and it allows you to be more aggressive with trying to not only advance the microcatheter, but really spin the microcatheter and reduce your friction without worrying about this issue of wire fusion.
Dr. Hady Lichaa: So, what do you lose with the MAMBA? What are the things you’re sacrificing?
Dr. Nyal Borges: So, I think depends on which device you use. So the MAMBA comes as a traditional MAMBA or MAMBA red, which it’s considered a larger microcatheter. So the crossing profile is not as good as something that’s a low profile microcatheter. The idea there is you have more muscle or beef behind the push. And so if you’re trying to cross a dense lesion that’s either calcific and really you’re aiming for a focal area, you need to cross, having more push and body to the microcatheter is helpful. What you give up there is trackability. So if you take a MAMBA through a tight lesion that’s calcified, you get across, but the rest of the vessel is making hairpin loops and turns, you’re going to have difficulty encountering that. Because again, there is no perfect device, right? Engineering has limitations. You either pick, I want the ability to get across with rigidity or I want a very flexible, very trackable microcatheter. It’s very difficult to design something that can do everything in every scenario.
Dr. Hady Lichaa: That’s right.
Dr. Nyal Borges: So that’s what you give up with a traditional MAMBA. But they created a MAMBA Flex, which is a lower profile, less rigid, but more trackable microcatheter that still retains the ability to not fuse to a wire because of its unibody design. And I think that drastically is, I would say by far is my favorite microcatheter at this point in time because it’s sort of the sweet spot of both worlds as far as I’m concerned.
Dr. Hady Lichaa: So, another scenario. You have a straight LAD that’s also heavily calcified, but an extreme amount of calcium with a 99% long stenosis and you want to try to get a microcatheter through that. Walk me through, besides obviously the MAMBA, which seems to be obviously a good option for a lot of situations, but walk me through other catheters, choices, and also your personal favorite.
Dr. Nyal Borges: I think in this particular scenario, I would probably err towards using a Corsair or a Turnpike depending on which you have. I think functionality wise they’re very similar. You have to, obviously, remember which direction to torque them because some of them have specifics where you counter to advance it and clock to remove it and vice versa.
Dr. Hady Lichaa: Tell us about that. That’s a very, very important detail. So tell us the details about the torque direction for someone who has not used these devices.
Dr. Nyal Borges: So, in general, for the Corsair family, you’re counter clocking to advance and then when you clock you can remove them. And for Turnpike it’s the opposite, but less important and you can actually advance in either direction and remove in either direction. Where it becomes even more important is when you have something like a turnpike spiral or a turnpike gold because those have what we joke around as called front wheel drive where they have spiraling on the catheter itself, where if you torque it in a clockwise direction, you’re actually allowing the catheter to move and antegrade because it’s with the spiral, the direction of the rotation of the spiral. And so that facilitates crossing the lesion and they also modify plaque. So it is important to know and be familiar with your specific device, and the information again, is easily available when you look at the device in the packaging on which direction to go.
But for your particular lesion though, I would use either a Turnpike or a Corsair and try to cross that lesion and then exchange for atherectomy wires and whatever else you might need. There are scenarios though where you’re not going to be able to get the microcatheter across, and that is true of all cases. That’s true regardless of what microcatheter you use. And I think when you get into a situation that is a device uncrossable lesion, you then have to go down that algorithm, which most of the time involves of small balloon, or 1.0 balloon, or a 1.5 balloon gently modify the proximal part of that lesion, which then in a large majority of cases will facilitate entry of a microcatheter and successful lesion cross.
Dr. Hady Lichaa: Excellent. So from a practical standpoint, you have now the Corsair between your hands and you’re literally trying to spin it. Describe the technical tips of how to be successful at doing so. What’s the speed of spinning? How do you hold the wire, et cetera?
Dr. Nyal Borges: Right. So I think there are several different ways to do it. I don’t know that there truly is a right way like most things in intervention, but-
Dr. Hady Lichaa: How do you do it?
Dr. Nyal Borges: What works and what’s practical is, for me, it starts with a guide. So trying to spin a microcatheter through a tight lesion with a guide that’s floating in the breeze is a recipe for failure. So I make sure first that I have my guide in a very supportive position, depending on the guide you’re using. I gently advance the microcatheter to the occlusion, that I think is going to give me resistance and then I personally use a two hand technique. So I’m spinning with my right hand at the actual hub of the microcatheter, which usually has a plastic type material coating to it to allow you to have some grip. And then I use my left hand to advance the microcatheter with a two finger, so thumb and index finger technique to slide the microcatheter forward as I’m simultaneously spinning. So it looks something like this.
Dr. Nyal Borges: I think the faster you spin, the better off you are because, at the end of the day, it’s a question of friction it’s a question of resistance, and the faster you rotate, the less friction, the less resistance. Similar to rotational antherectomy, right? Having a bur at a higher speed, it always crosses easier. In terms of holding the wire. I actually don’t pin the wire when I’m advancing a microcatheter. I think for the most part, as long as you’re not using something like a Confianza Pro 12 or a Miracle 12, something that has a very high penetration power and it’s parked in a small distal vessel, I tend to leave the wire free and just watch it under fluro. Most of the time, the wire does not freely advance with a microcatheter in a very tight lesion. Once you start to cross the lesion though, I usually will use my pinky finger to keep track of the wire in case it’s moving, just pin it to the table gently.
But the beauty of the type lesions is things don’t cross and they tend to hold wires. So you will feel a lot of resistance on the wire when you’re crossing the lesion, which also tends to serve in your favor by holding the wire when you’re trying to advance a microcatheter through. Once I’ve gotten through, I will exchange the wire for whatever your need is, whether it’s a supportive wire or atherectomy wire, and I personally trap out all of my microcatheters so I will counter the direction of torque that I applied to remove it. And one really important point there is when you’re taking the microcatheter out, your guide is going to get sucked in. And so you have to be very, very mindful of that because I’ve seen vessels dissect from guides getting deep throated while taking out microcatheters that had a lot of friction to them.
So spinning the microcatheter on the way out allows you to overcome some of that resistance, which protects the ostium of the vessel or the proximal vessel from guide dissection. And then once you back the microcatheter out on, certainly on a one 90 centimeter wire, I use a trapper balloon or a 2.5 or 3.0 balloon depending on the size of your guide to be able to safely exchange it. There are other ways you can get the catheters out if you’re using short wires, and I would encourage everybody to use short wires, but those are outside of using something like a trap liner, which is similar to a trapper balloon just with a guide extension. All of the other techniques are less reliable and more prone to wire loss, wire retraction, other modes of failure. So I would stick to either a trapping balloon or a trap liner by and large.
Dr. Hady Lichaa: Perfect. So third scenario and final scenario. You want to cross from the LAD through a nice very small septal into a PDA, back to the proximal RCA. That huge kind of course with a lot of, not too many calcifications, but a lot of twists and turns and ups and downs. What catheter do you pick and why?
Dr. Nyal Borges: Sure. I think this is the good scenario because septals are different than most other vessels. And the reason I say that is you don’t really need torque in a septal, right? Your resistance is from myocardial contraction and the size of the septal you’re using, it’s not a friction related resistance. And so you generally want to use something that is small, something that is soft and something as minimally traumatic as possible. So I think the three best options are a Turnpike LP or low profile, a MAMBA Flex, which can, again, for most of these you would be using 150 centimeter microcatheter because you need the length to get all the way to the proximal right. Or in a lot of scenarios, something like a Caravel, which is very soft, very low profile, and very atraumatic. And again, a Caravel is a non torqueable microcatheter, but you don’t really need the torque.
There are cases where when you get into the bottom of the septal where it turn makes the corner into a distal right, it becomes very difficult to make that turn. And in that case, you sometimes need torque or a small predilation balloon, but that’s a scenario where a Caravel might struggle and you exchange the microcatheter out for something torqueable and then maybe put the Caravel back in if that’s what you want to use for the rest of the case. So I think crossing septals for CTOs is a unique scenario where you want to use as atraumatic and as flexible of a microcatheter to be able to make multiples as possible. Very similar to what you would use in an epicardial collateral. Something that’s not going to damage the collateral you’re using is the number one priority of retrograde crossing of collaterals.
Dr. Hady Lichaa: Excellent. So final kind of stage of this discussion is complications. So what could go wrong? What are the things that are red flags when you’re using microcatheters and how do you technically try to avoid them and solve them?
Dr. Nyal Borges: Sure. So I think the first and most common complication, it’s not really a complication, but issue with microcatheters that I mentioned is fatigue. So you can have device related malfunction long before you create a complication, and I think some of that comes from aggressively trying to torque microcatheters through lesions. What that feels like is you start to feel the microcatheter sticking. When you try and pull it back, it doesn’t come back. The wire and the microcatheter move as a unit. The second you start to feel that, that is only going to progressively get worse. As you torque it more, you’re going to run into more issues that my [inaudible 00:14:32] to everybody having fused more than my fair share of microcatheters over time is as soon as I start to worry about fatigue, if I’m using a microcatheter prone to fatigue, I immediately remove it in exchange it for a brand new microcatheter.
There is no technical solution to that other than exchanging the actual equipment. Okay. The next complication, let’s say you torque the microcatheter, you’re getting through the lesion. There are certain microcatheters that can get stuck in the lesion, and when you try and counter the torque, you actually broke tip off. And again, retain foreign bodies and foreign objects in tight lesions can be well tolerated they can be really poorly tolerated. The workaround for that is multiple things. So if you have a tip of a microcatheter stuck in a lesion, you can wire alongside it, balloon that area to create some flow, if you’ve lost flow. Often when you do that, the tip of the microcatheter will go further down the first wire and leaving a tip of a microcatheter embedded in an artery at a distal bed of a small vessel is okay. Again, it’s not ideal, but it tends to be reasonably well tolerated and not cause thrombosis.
If you’re not able to wire around microcatheter, we have had to do this in the past where you have a tip of a microcatheter on a wire, you can actually advance a second microcatheter over the same wire and wedge it into the tip, and then through both microcatheter and the broken tip advance a rota floppy wire and then actually rotablate the microcatheter tip out of the way.
Dr. Hady Lichaa: Wow.
Dr. Nyal Borges: So that is way to get a stuck and trapped microcatheter tip out of the way. Outside of that just pushing the microcatheter will often allow it to pass through the lesion and float downstream, but it ends up being a retained microcatheter tip. The other complication that I’ve seen is you can actually fuse microcatheters and other equipments to each other so it really only comes up in CTOPCI. But when you have a microcatheter on an externalized wire, you have to be careful to make sure you don’t kiss the tips of two pieces of equipment because they will sometimes get fused and that becomes a very difficult problem to solve because now you have an externalized wire that has equipment from either side that has fused inside the body. And really the only way to fix that outside of pulling and really very uncomfortable luck is surgically to remove all of that equipment. There isn’t a clean and easy way to do that.
The final thing is I’ve seen people do cases where they protect wires with a microcatheter and a rotablate alongside for left main bifurcations and things like that. That it’s not free of risk. I know there’s been a lot of cases published where people have done it and it’s worked out fine, but we’ve also seen microcatheters coming out damaged, including having perforations in the side of them, shaving off tips, shaving off material that then causes slow flow down the side branch. So I think being really mindful of what equipment is alongside the microcatheter and what’s in contact with what is really important when you’re using a microcatheter. But by and large, they tend to be safe devices.
Dr. Hady Lichaa: So, that was literally a tour de force on microcatheters and, obviously, all what you described can be also applied in the peripheral vasculature, and a lot of things have been taken from the coronary world and applied elsewhere. So thank you so much for this fantastic talk. You are a fountain of knowledge and I appreciate all this information you’ve shared with our viewers. Hope to get you next time.