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BackTable / VI / Article
Below-the-Knee PAD: Device Selection for Calcium Modification, Vessel Expansion & Dissection Repair
Rajat Mohanka • Updated Aug 18, 2025 • 34 hits
Managing below-the-knee calcifications in patients with peripheral artery disease and critical limb ischemia (CLI) remains one of the most technically demanding aspects of lower extremity revascularization. With increasing rates of diabetes, renal disease and aging patient populations contributing to the proliferation of atherosclerotic disease, the utilization of calcium modifying interventions like intravascular lithotripsy (IVL) and atherectomy is increasing as well.
Interventional radiologist Dr. Kumar Madassery shares his preferred tools for different clinical scenarios in below-the-knee peripheral artery disease, emphasizing device selection for calcium modification, vessel expansion, and dissection repair in the tibial arteries. This article includes excerpts from the BackTable Podcast. You can listen to the full episode below.
The BackTable VI Brief
• According to Dr. Madassery, intravascular lithotripsy balloons provide similar vessel compliance to atherectomy but with fewer embolization risks. Current limitations include balloon length and profile size, particularly for smaller tibial vessels.
• IVL can facilitate precise pulse delivery which allows clinicians to focus energy on heavily calcified segments.
• Historical reliance on smaller balloons (e.g. utilizing 2.5 mm balloons for the proximal tibials) often resulted in under-treatment. Current recommendations suggest the use of a 2 mm balloon for pedal arteries and 4-4.5 mm for proximal tibials in most patients.
• IVUS can validate vessel sizing and support appropriate balloon selection but is not always necessary for all segments. Observing calcium patterns on spot imaging can help identify areas requiring treatment and guide balloon expansion efforts.
• Dissections are a common outcome of balloon angioplasty, but their significance depends on hemodynamic impact and flow disruption. Angiography and IVUS are used to evaluate dissections, with angiography often serving as the primary tool for identifying flow-limiting flaps.
• The self-expanding Tack endovascular system (Tacks) provides a flexible option for spot treatment of significant dissections, conforming to vessel size and minimizing unnecessary scaffolding.
• Over-treatment with stents or scaffolds should be avoided to reduce risks of restenosis and long-term vessel complications.
• Selective atherectomy can facilitate vessel expansion; however, it is reserved for areas of high calcium concentration, particularly at entry and re-entry points in chronic total occlusions (CTOs).
Table of Contents
(1) Intravascular Lithotripsy in Tibial Calcification Treatment
(2) Optimizing Tibial Sizing in Below-the-Knee Calcification Treatment
(3) Tibial Artery Dissections: Strategies for Effective Spot Intervention
(4) Navigating CTOs & Calcium: The Selective Use of Atherectomy in Tibial Interventions
Intravascular Lithotripsy in Tibial Calcification Treatment
In treating below-the-knee calcifications, intravascular lithotripsy balloons offer a valuable alternative to traditional atherectomy, reducing concerns about embolization and achieving desired vessel compliance. While limitations exist, such as shorter balloon lengths and challenges with profile sizes in smaller vessels, IVL provides precision by allowing clinicians to focus pulse delivery on the most diseased segments. This targeted approach optimizes calcification destruction while minimizing disruption to less affected areas. As IVL equipment improves – notably providing smaller balloon profiles – its utility for small vessel occlusions is expected to expand significantly.
[Dr. Sabeen Dhand]
…What's your experience of using [IVL] in the tibials?
[Dr. Kumar Madassery]
I think it's been a great addition because we have such a low toolbox in the below-the-knee space. It's nice that you have a balloon that can do the same thing you're trying to do as atherectomy itself with less of the concerns of atherectomy in the sunset, less concern for emboli. You're getting the compliance that you want. There's some limitation in terms of balloon length at the time, but they're working on that, I believe. Again, the profile might be a little bit tough on some lesions because again, it's a little bit more robust than your smallest coronary balloons. Some vessels we're dealing with, you have to take a 1.5 in. Now there's 1.0. You're talking about a hair-sized balloon.
[Dr. Sabeen Dhand]
Yes, and you can't get that step off to go through anything.
[Dr. Kumar Madassery]
I like the fact that you can use that. The IVL balloon, you can use it for up to 10 centimeters of length because you deliver the pulses and you can also determine where you want to apply the most of those pulses in terms of the segment of the vessel. If you know that one area has far more disease, you know by your passing of your catheters and wires and the imaging, then you can actually deliver more pulses there and deliver more of it there. It's nice that you can specifically treat what you want to with it in a sense. I think there's value there.
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Optimizing Tibial Sizing in Below-the-Knee Calcification Treatment
Tibial sizing refers to the selection of appropriately sized balloons or stents for interventions in the tibial arteries; this process is critical for optimal vessel expansion and the restoration of blood flow. Advances in imaging technologies, such as intravascular ultrasound (IVUS), have influenced a shift toward larger balloon sizes to achieve better results. Historically, smaller balloons were favored, particularly in the pedal vessels. However, IVUS data and clinical experience have shown that many interventions were likely undersized. Current practices now favor using 2.0 mm balloons for pedal vessels and 4.0-4.5 mm balloons for the proximal tibial segment. This change reflects a more accurate understanding of vessel anatomy, challenging previous assumptions about tapering, particularly in heavily calcified vessels. By addressing calcification more aggressively, clinicians can achieve better vessel expansion and improved patient outcomes.
[Dr. Sabeen Dhand]
Everyone always likes to talk about sizing of tibials. We've talked about IVUS. You're not putting IVUS all the way down, not usually all the way down to the pedal. How are you sizing, when you're talking about all these devices, whether it's conventional or scoring or this or that, how are you sizing your tibials?
[Dr. Kumar Madassery]
The beauty of this, and I think we know this amongst our CLI friends, friends who do a lot of lithotripsies, everybody's a purist when it comes to talking. We have people who say 100% IVUS every single time, which is great, and that's something you can do and utilize. That's great. I think what it's helped us understand is maybe we've been undertreating in the past.
The way I look at it is maybe five, six, seven years ago, I was using-- in the beginning, I was using probably very small balloons from the mid tibial down because all these are small vessels. The proximal tibial, you use like a two, five and you pat yourself on the back. In my mind mentally now, after we've done enough and we've used IVUS to learn and others, far smarter people have shown me, I'd say from nowadays, I say, I want a 2 millimeter at least in the pedal. Then I want to get up to about a 4 or 4.5 in the proximal tib in most patients.
Now, you may have to say some caveats for elderly females, some of the other patient demographics that may have smaller vessels. But I think in general, as we go, if there's a question, you look at your angio, you look at your other vessels, you can look at the contralateral side or IVUS if you need to really confirm what you're doing.
[Dr. Sabeen Dhand]
Yeah. I just want to repeat that for our listeners. That is 4 to 4.5 approximately in the tibial. People will think they won't even go above 3 or 3.5. That is definitely larger.
[Dr. Kumar Madassery]
Well think about it. We say pop used to be all. Mentally we say 4.5 to 5.5 somewhere that people are considering 5 on average for pop. To consider that you go from your P2, P3 to down to like a 2.5 in the proximal tib.
[Dr. Sabeen Dhand]
It doesn't make sense.
[Dr. Kumar Madassery]
It's a crazy taper. That's probably not what it was like. If you always look at those calcium on your-- when you're doing the ballooning, you see the circle threshold calcium on your spot image, you can always see the balloon is always so small compared to the calcium itself, your underside. You always can see that and you're like, man, I'm really going wall to wall. Remember the wall was built with calcium. So if you can treat some of the calcium, you could expand that better. It's not elastic at that point yet.
Tibial Artery Dissections: Strategies for Effective Spot Intervention
Tibial artery dissections, which can occur as a complication after extended interventions for calcified lesions, pose a significant challenge in below-the-knee revascularization. Although every ballooning procedure causes some degree of dissection, the critical factor is determining its relevance to flow dynamics. Unlike larger vessels, tibial arteries offer less tolerance for untreated dissections due to their thin walls and high calcification burden. When deciding how to intervene, clinicians may rely on visual and IVUS-guided evaluations of flaps and contrast density. Spot interventions, like the Tack endovascular system, allow for targeted corrections without overextending scaffold placement. With the use of a targetable scaffold system, prolonged balloon angioplasty and strategic stent placement risk of dissection can be effectively minimized.
[Dr. Sabeen Dhand]
When you do the- post-plasty, what is your end point? Say, okay, fine, of course the vessel looks great and clean. You've got more flow. You've got wound blush. What if you have, and especially in these calcific lesions, a little dissection angiographically or on IVUS, how do you approach those?
[Dr. Kumar Madassery]
A little dissection is like a little pregnant, right? You have it, you have it. I think every ballooning you do causes dissection. How relevant is it to your flow, to your hemodynamics in your vessel? That's kind of the question. I don't think we have an excellent predictor. I think everybody can do the eyeball test and say, ah, that's fine. A lot of that's based on what time it is of the day, what you got left. You're like, oh, that's not significant. That's not flow limiting. I don't know how many people have decided what exactly contributes to flow limiting in some scientific sense.
[Dr. Sabeen Dhand]
Yeah, exactly.
[Dr. Kumar Madassery]
It seems to be like a gestalt, like the ocular reflex, oh, okay, I got another case. I got a meeting to go to. That's pretty good. No, but I think when you see a dissection, you know a dissection. To me in the tibials, you have a lot less wiggle room to leave a dissection because that's your outflow from everything else. When you have dissections in the SFA, you can't necessarily leave those alone. Unless it's a major one, you have a lot more pressure head coming in. You have a larger vessel, you have more room for that.
A tibial, that's literally you just spent an hour and a half fixing a 25 centimeter occlusion and then leaving a dissection if you can avoid it. When your eyeball shows you the flow, you can see the contrast and a differential flow or you throw an IVUS in there and you see the flap actually in the lumen. I think that's something that warrants treatment if you feel like you're actually trying to reduce the number of times a patient comes back.
[Dr. Sabeen Dhand]
Yeah, I think also the density, if you see the density of the contrast significantly different. You might be catching the flap on FOSS, not perpendicular. That's significant.
[Dr. Kumar Madassery]
You'll see the flap, it'll either be a spiral or you'll see the top and bottom if you had a CTO that you went, entry, re-entry.
[Dr. Sabeen Dhand]
You said it too, you just spent an hour and a half, this is what I tell all my younger guys too who are doing PAD in my practice, it's just, you spend all this time, you went retrograde, you did all this and you have this result and you're like, ah, should I treat this? I'm like, that's the thing that's going to take this down by the time a patient leaves the recovery. Treat it. If you have devices to treat it now.
[Dr. Kumar Madassery]
The question is there a system to tell you this is significant? I don't think we have nailed it down yet. IVUS really can have you proof of why you did something else, but you know when you know. You see the dissection and if you can't see it, then you should get some more experience looking at angiograms, but you can always see it in these vessels. There's people who are saying if I see any dissection, that's going to–
We have Brian Fisher, fantastic friend of ours, amazing surgeon. He'll say if you don't stop that dissection, you're doing a disservice. That's to each their own. Using prolonged balloon angioplasty, if you feel that's your best bet, using the balloon expandable stents, which is the current marketing stents that we have that are not meant for it, but we use it or Tack depending on it. I think we have ways to treat it. We don't have enough drug coated balloons to maybe say that might help the dissection not become significant. I don't think that's the right way to go yet.
[Dr. Sabeen Dhand]
Anyone doing atherectomy for a dissection? I think I've heard people throwing that out there. I've never tried that.
[Dr. Kumar Madassery]
I've never tried it. I feel like once you have a dissection, then you try to be more aggressive with that dissection, you may get into that epitaxial problem, just personal fear.
[Dr. Sabeen Dhand]
You mentioned Tacks too. We've been trying them out. They're IFU, they're meant to go all the way down to the ankle, if I'm correct. I haven't done that yet. My experience with that is limited.
[Dr. Kumar Madassery]
Interestingly enough, I think most of the dissections that you see that are seen to be pertinent are the ones you in that proximal to mid-tibial arteries. The nice thing about the Tack, I think, is that you can spot stent, your spot treating, just like we talked about in trials with the SFA bailouts. We have a long lesion. Can you treat the lesion but spot stent where you need to? To me, this is like a patchwork and fix only what you need to fix. Because otherwise, you're unnecessarily putting scaffold where you don’t really need it.
Being able to put something that conforms to whatever the vessel size is, that seems to make more sense, which is why we're waiting for the self-expanding tibial stents rather than what we have now. These Tacks are self-expanding, so they should go to the size of the vessel that you treated. Then also places like the AT bend, that's not a great area for-- sometimes stenting is a little tough, but the Tacks is going to lay down well there.
If I see flaps that have-- you can see the segments that you actually need to Tack, it's nice to be able to spot treat it rather than cover or treat unnecessary segments because you know that when you stent something it's not like a one and done, this is going to be great. We know this from every part of the body we do it in, especially the tibials. Putting more and more stuff in there is not going to be the answer.
Navigating CTOs & Calcium: The Selective Use of Atherectomy in Tibial Interventions
Chronic total vascular occlusions – particularly in heavily calcified tibial arteries – are deceptively risky to treat.While the subintimal approach is often favored when crossing a heavily calcified vessel, atherectomy still holds value in specific cases, especially at the entry and re-entry points. These areas tend to resist full vessel expansion due to calcium buildup, and targeted atherectomy may help ensure proper opening and long-term patency. However, performing atherectomy along the entire subintimal segment is typically considered high risk, because it can destabilize the vessel. Balancing the risk of destabilization with the urgency of limb revascularization makes any intervention more challenging, but Dr. Madassery advocates for consideration of spot treatments in most cases.
[Dr. Sabeen Dhand]
We've been talking about severely stenotic lesions, but all of this stuff really applies to both CTOs after you cross and plasty and treat then you get into this same discussion. For a totally occluded calcific lesion, and you're obviously not going luminal. If anyone says that they're going luminal, then more power to you. Obviously a sub-intimal, it would, not extra luminal, but do you avoid atherectomy then, as far as the algorithm we just discussed, everything else the same, but avoid atherectomy, or you still do it?
[Dr. Kumar Madassery]
I don’t think there is a hard and fast rule to avoid it completely. I think when you go through a long CTO that you have an entry and re-entry, I think those entry and re-entries might be areas that if you haven’t experienced, you might want to consider some atherectomy because those areas may be the hardest to get a vessel complete expansion.
The subintimal space, it's a great space. We know this from the SFA pop area when you have a heavy calcified occluded vessel the subintimal space will expand nicely, it may not stay open unless it gets enough pressure through it, but where you enter and re-enter especially if I have to use a re-entry device into to the tibial, that's going to be a tough spot of calcium. You're going to have an entry calcium ring around it. I think in those areas are the ones I may consider atherectomy just because I know I need the vessel to be open there, just like when you do a DVA, you need that connection to be open, to stay open, not just from the blood pressure alone.
Yes, I don’t ever advocate and I don’t think you should long segments subintimal atherectomy, I think that’s maybe a little bit hazardous, more power to you. I think directional that could be a very dangerous, that entire space, but if you need to spot treat just to get your final treatment there, I think that's where the value goes.
Podcast Contributors
Dr. Kumar Madassery
Dr. Kumar Madassery is a practicing interventional radiologist with Rush University in Chicago.
Dr. Sabeen Dhand
Dr. Sabeen Dhand is a practicing interventional radiologist with PIH Health in Los Angeles.
Cite This Podcast
BackTable, LLC (Producer). (2021, December 27). Ep. 175 – Treating Below the Knee Calcium [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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