BackTable / VI / Podcast / Transcript #334

Podcast Transcript: New Balloon Technologies for CLI

with Dr. Peter Soukas

In this episode, host Dr. Aaron Fritts interviews Dr. Peter Soukas taking a deep dive into novel balloon technologies, appropriate uses below the knee, and how these new balloons are highly effective in treating patients with critical limb ischemia (CLI). Dr. Soukas explains how new balloon technologies can minimize the risk of dissections (therefore decreasing the need for bailout stents), create effective lumen gain in concentric and eccentric calcified lesions with minimal recoil, and keep pressures low compared to legacy products. You can read the full transcript below and listen to this episode here on BackTable.com.

(1) A Brief History of Cutting Balloon Angioplasty

(2) Lesions Amenable to Serration Angioplasty

(3) Evaluating Quadrants of Calcification

(4) Advantages of Serration Angioplasty in BTK Lesions

(5) Delivery of the Serranator Device

(6) Technical Endpoints of Serranator Balloon Treatment

(7) Major Studies in Serration Angioplasty

(8) Safety Considerations & Suitable Cases for the First-Time Operator

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Ep 334 New Balloon Technologies for CLI with Dr. Peter Soukas

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[Dr. Aaron Fritts]
Hello, everyone, and welcome to the BackTable Podcast. Today we have a very special episode. We're going to be talking about novel balloon technologies and appropriate uses below the knee. Dr. Peter Soukas was recently on the show with Chris Beck as the host. They discussed his algorithm for treating below-the-knee PAD and CLI. It was a very comprehensive discussion, very much A to Z. They covered the challenges of treating CLI, the quality of life impact, as well as a discussion of newer technologies that are being used, including IVL and some of the new balloon technologies. The Serranator balloon was also mentioned during the discussion.
Much like we've done before with newer technologies, we want to take a deeper dive into this, and put out some educational content around it. Welcome Peter, back to the show.

[Dr. Peter Soukas]
Thanks very much, Aaron. It's a pleasure to be back with you.

[Dr. Aaron Fritts]
Peter, just for our audience who may not have listened to the other episode yet, can you just tell us briefly, where you're at and what your practice currently looks like?

[Dr. Peter Soukas]
Sure. I'm currently in Providence, Rhode Island at the Miriam Rhode Island Hospital. We're the teaching hospitals for Brown Medical School, and I've been there now for 13 years. I'm the director of the Vascular and Interventional Peripheral Vascular Lab. I'm also the founder and director of the Vascular Medicine and Endovascular Medicine Fellowship Program, and helping to train the next generation of interventionalists.

[Dr. Aaron Fritts]
How big is your program up there?

[Dr. Peter Soukas]
Our Cardiology Fellowship Program, we have six per year. We have two EP fellows per year, a structural fellow, and a dedicated peripheral vascular fellow.

[Dr. Aaron Fritts]
Oh, wow.

[Dr. Peter Soukas]
We have lots of fellows in our program, and we are very proud of them. They've all gone out and done amazing things in the private arena, as well as in academic medicine. One of the great things about our place is that we're able to do a lot of cutting-edge research, and involved in a number of different clinical trials. I think, for example, right now we actually have 12 clinical trials that we're working on. About four of them, in fact, on this topic that we're going to be discussing today, which is really the treatment of critical limb ischemia, particularly with novel below-the-knee devices.

(1) A Brief History of Cutting Balloon Angioplasty

[Dr. Aaron Fritts]
Let's jump into that, Peter. Today we're going to talk a little bit more about specialty balloons because I think everybody in the audience knows that there's typical scoring or cutting balloons have been around for a while now. You mentioned in the prior episode the Serration Angioplasty, the Serranator. Can you talk to us about how the specialty balloon space has evolved over time? What is the difference between this new balloon and the prior ones that we think of?

[Dr. Peter Soukas]
Traditionally, I think probably the first dedicated Cutting Balloon on the market was the Boston Scientific Cutting Balloon, which was unfortunately fairly limited in terms of lengths that were available. Today, in fact, they're about two centimeters for the peripheral devices, and the coronary devices are even shorter-length balloons. These were basically three surgical balloons that were just glued onto the outer surface of the balloon. When we're talking about below-the-knee disease these are typically long diffuse lesions. It was really not very practical to treat either above the knee or below the knee with these particular devices.

In more recent years, we had the AngioSculpt balloon, which did have the advantage of coming in 40 and 100-centimeter lengths, but the results were somewhat variable in terms of the acute luminal gain, and the degree of recoil that we typically would see. The newest kid on the block, of course, is the Serranator Balloon, which is really, I think, a fairly unique mechanism of action that uses these serrations, which are able to basically have about a thousand times more focal force than a typical angioplasty balloon.

Why is that an advantage? I think it's able to give us a very predictable and safe expansion of the lumen along these so-called fault lines, and our rates of dissection in recoil are much lower than with the traditional scoring balloons that we've used in the past.

(2) Lesions Amenable to Serration Angioplasty

[Dr. Aaron Fritts]
Okay, perfect. You mentioned that for longer lesions, the prior balloons were kind of disappointing. What specific types of lesions are you seeing serration angioplasty most successful with?

[Dr. Peter Soukas]
I think that the advantages of having 40 and 120-millimeter lengths allows us to expand the types of vessels that perhaps maybe we might have shied away from cutting balloon technology, or focused force angioplasty in the past. The nice thing about it is that it really does seem to be quite effective in the more calcified lesions. I think that's really where some of the older generation devices kind of fell short, was that they really didn't do a very good job or a very effective job on these more calcified lesions.

In our practice, a lot of these patients, particularly our diabetic patients and our patients with chronic kidney disease, we know that the further down you go in the tibial artery, the more likely you're going to encounter more diffuse calcified lesions. I think that's really been the sweet spot for this technology, is not only can it take care of fibrocalcific, but even the more calcified lesions, the more concentrically calcified lesions. It really does seem to do a very nice job addressing those.

As we discussed in the last podcast, we're very big fans of IVL, however, this technology is obviously less expensive, and for most patients, we can typically get a very nice acute luminal gain with minimal recoil with serration technology.

(3) Evaluating Quadrants of Calcification

[Dr. Aaron Fritts]
Another talk I heard you give, you talked a little bit about quadrants of calcification, and you just mentioned it works well with concentric calcification. What about eccentric calcification? Talk to us a little bit about those quadrants of calcification, what you see with serration.

[Dr. Peter Soukas]
Sure. One of the nice things about intravascular ultrasound, it really is so helpful to basically identify the depth and the extent of calcification. We all talk about the now, I think, famous Fanelli paper with micro-CT, which demonstrated unequivocally, that the more quadrants of calcium you had, the lower the likelihood that you'd get a sustained improvement in terms of primary patency with drug-coated balloon technologies. We've certainly seen that in our clinical practice as well.

One of the other things that you just mentioned was eccentric versus concentric. I think we have to acknowledge that one of the potential limitations of IVL, is that it requires more pulses for more eccentric lesions. The nice thing about the Serranator is that we've seen when we have done ultrasound post-PTA, that we can actually see those serrations on ultrasound. They're also apparent on OCT as well. Unless it's 360 degrees of dense calcification, in which case IVL might be the preferred option, but for more eccentric and less heavily calcified or less frequent quadrants of calcium, this seems to be a very nice alternative.

(4) Advantages of Serration Angioplasty in BTK Lesions

[Dr. Aaron Fritts]
You mentioned one of the issues with prior technologies was recoil, especially in BTK lesions, and also the desire not to stent in the setting of CLI. How does Serration angioplasty help solve for those particular problems? I know you mentioned less dissections, for sure.

[Dr. Peter Soukas]
Yes, for sure. In both the PRELUDE above and below the knee studies, we saw really excellent final luminal residual stenosis of less than 23%, and a typically fairly low inflation pressures of only 6 to 8 atmospheres. The dissection rate was really very, very low to the extent that the need for a bailout stent, for example, was less than 2% in the below-knee study and only about 4% in the above-knee study, which I think is pretty remarkable for a balloon technology. It's that predictable response that I think makes it such an attractive tool in our armamentarium, especially for below the knee, where we really, really try to avoid placing stents.

We know that you can successfully implant coronary drug-coated stents, but that's really limited to the proximal third of the tibial artery. What do you do when you're down near the ankle? You can't put a balloon expandable stent there because it'll get crushed. The ability to avoid the need for a scaffold, particularly in the distal two thirds of the tibial artery, I think is a real potential advantage for serration technology, as opposed to just plain-old balloon angioplasty.

[Dr. Aaron Fritts]
You brought up a good point. I heard a talk by Edward Gifford at the recent sharing cross talking about, there was maybe a study released recently about using it below the ankle. Is that right?

[Dr. Peter Soukas]
Yes, that's true. One of the nice things about the technology is that because it's not rigid, stainless steel blades, it has the flexibility that you can take it around the corner into the common plantar, and in fact, into the dorsalis pedis or the medial or lateral plantar vessel. That's again, I think an advantage compared to the older focused force angioplasty technologies.

(5) Delivery of the Serranator Device

[Dr. Aaron Fritts]
That brings up my next question was specialty technology tends to have a reputation for being challenging to deliver, or bulky. You just kind of demonstrated with that, that it seems not to be, but anything else you can comment on there? How's it typically delivered? How well does the balloon track in heavily calcified vessels?

[Dr. Peter Soukas]
Overall, I think it tracks quite well. Once in a great while, if we encounter a difficulty in terms of delivering the device, and that typically is more likely to occur when we're trying to deliver the longer 120-millimeter length balloon versus the 40-millimeter balloon. Serration Balloons, like IVL balloons, occasionally you may need to pre-dilate with a smaller caliber balloon just to make a little bit of room in there, so that you can then deliver what will hopefully be the definitive treatment to that vessel segment.

[Dr. Aaron Fritts]
How do you decide the size of the balloon? Is it different from your standard balloon?

[Dr. Peter Soukas]
Not really. We are very big fans of IVUS, and we like to IVUS things ideally at baseline and then after each iterative technology that we're using, and then of course, a final ultrasound at the end. In general, if you can pass the ultrasound catheter, you should be able to deliver the balloon. One of the things that we've learned from the DCB trials, particularly for below the knee, as you know, they were pretty disappointing, the IN.PACT DEEP Study and the BIOLUX Study. One of the explanations, I think, primary explanations, in fact, is that we were likely undersizing our balloons significantly.

The other nice thing about a serration technology is that you're not needing to go to high pressure, so your likelihood of causing a type C or greater flow limiting dissection is much, much less. That does allow you to be a bit more aggressive, and so much like an IVL balloon, we're looking more at like a 1.1 to 1.2 to 1 ratio. If I've IVUS ahead of time, then I know exactly what size the vessel is, and I can pick an appropriately sized balloon. I think we've been perhaps a bit too timid in our balloon sizing below the knee.

If we're using specialty balloons like IVL balloons or serration technology, that does allow us to be a bit more aggressive. I think that greater luminal gain will hopefully translate into a better clinical response for the patient, particularly for the CLTI patients, where keeping that vessel open for at least three months is really something that we need in order to be able to achieve wound healing.

(6) Technical Endpoints of Serranator Balloon Treatment

[Dr. Aaron Fritts]
You kind of answered my next question, but what's your primary technical goal with this serration angioplasty?

[Dr. Peter Soukas]
Ideally, at least three months. Of course, we'd like to have better patency rates than that for all of our technologies, but if we look at, for example, the PRELUDE BTK study that we referenced a few minutes ago, that paper was published in JEVT back in November of 2021. They had a nearly 98% freedom from TLR at six months, which is really quite remarkable. That particular study included patients with Rutherford 5 disease. That was a pretty remarkable result, and we're certainly seeing similar results in our day-to-day clinical practice as well.

[Dr. Aaron Fritts]
It's that red gold that you're looking for with your podiatry and wound care colleagues? Are you getting any comments back from them?

[Dr. Peter Soukas]
Yes, they're very, very happy that we will go to great lengths. If it takes 2, 3, 4, 5, 6 hours, we'll do whatever it takes to try to get as much red gold down to the foot as we can, because we all know that when a patient loses a limb, their life is in jeopardy. Patients with CLTI have a 50% five-year mortality, and that mortality will be hastened if they lose a limb. Not to mention all the devastating psychological and economic fallout from a patient being a functioning member of society to then perhaps even being required to be living in a nursing home. Anything that we can do to avert that disastrous conclusion is a very good thing.

(7) Major Studies in Serration Angioplasty

[Dr. Aaron Fritts]
Peter, any other studies that you recommend the audience look at that can help them learn more about this newer technology, and anything else that we left out? You've mentioned a couple, but anything else that would be interesting to the audience around this technology?

[Dr. Peter Soukas]
With regards specifically to the Serranator device, The PRELUDE First in Human was published by Andrew Holman in JEVT, and then the formal BETK study, as I mentioned, was published in November 2021 in JEVT. There is also a PRELUDE-BTK subanalysis, which Marianne Brodmann was the primary author on. That particular sub-study looked at standard balloon angioplasty, versus serration balloon angioplasty, and we're very much looking forward to those results as well.

(8) Safety Considerations & Suitable Cases for the First-Time Operator

[Dr. Aaron Fritts]
Peter, one thing I forgot to ask earlier, we talked about the decrease in dissection and recoil and spasm even. What about embolization, which is obviously a concern with atherectomy devices?

[Dr. Peter Soukas]
That's a great question. One of the things that can really sync your procedure is distal embolization, particularly, for example, if a patient has single vessel runoff and you send debris downstream, you've now taken that CLI patient and converted them to an ALI patient. Distal embolization and perforations below the knee are absolutely catastrophic. Anything you can do to minimize that risk, I think is really important.

I think that's another reason why we've sort of shied away from atherectomy devices below the knee, is that the consequences of distal embolization are so dire. I think one of the advantages of this particular technology is that we just really don't see it. Honestly, I can't think of a single case that I've ever had where we had distal embolization. These alternative technologies, I think really not only are they better in terms of acute luminal gain, but the safety profile is, I think, much more favorable as compared to atherectomy.

[Dr. Aaron Fritts]
Great. Anybody in our audience who's looking to maybe try this, what's a good first case to start with?

[Dr. Peter Soukas]
I think for patients who have more sort of fibrotic lesions that are not densely, densely calcified, I think that's probably a very good place to start with serration technology. The balloon, as I mentioned, does really track quite well, and if you have areas where you really don't want to have to bail out with a stent, for example, at the pop TP trunk bifurcation or at the pop to 80 AT bifurcation. We know that atherectomy in that location is particularly problematic in terms of the risk of a dissection or perforation.

Areas where you don't have horrific amounts of calcium, but you have fibrofatty plaque or fibrotic lesions or lesions that are even moderately calcified, I think folks will be pleasantly surprised at how well the device tracks, and the acute luminal gain that you'll gain.

[Dr. Aaron Fritts]
Great. Any other dos and don'ts before we finish up?

[Dr. Peter Soukas]
Again, realizing that you may need to pre-dilate, the devices do go through a 5-French sheath and it's just really important to make sure you prep the balloons very well, and give them time to deflate before you take them out because it can be a little bit snug in a 5-French sheath. If you do a really good job in terms of giving it time to rewrap, then it's usually not an issue.

[Dr. Aaron Fritts]
Perfect. Peter, thank you so much for your time and hopefully, we'll see you at a conference one day.

[Dr. Peter Soukas]
All right. That sounds great. I appreciate it. Thanks so much for the time.

Podcast Contributors

Dr. Peter Soukas

Dr. Peter Soukas is the director of Vascular Medicine and Interventional PV Lab at Lifespan.

Dr. Aaron Fritts

Dr. Aaron Fritts is a Co-Founder of BackTable and a practicing interventional radiologist in Dallas, Texas.

Cite This Podcast

BackTable, LLC (Producer). (2023, June 19). Ep. 334 – New Balloon Technologies for CLI [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.