of the moderator and getting to talk about something that is a little bit provocative and a little bit out there. And I remember a couple of years ago having a discussion with Bill about, gee, wouldn't it be great if we could have a device and think about using IVL for these calcified lesions. And I think at the time you looked at me like I had three heads. But be that as it may, I'm going to still try to provide a rationale for why I think it might be reasonable to consider IVL or the future use of IVL in carotids. Well we know that heavily calcified carotid arteries, for the most part, have been excluded from carotid artery stenting, so we really don't have any pertinent data. Severe calcium in the carotid, just like in other parts of the body, can result in a higher risk of complications such as dissections, perforations, and distal embolization. And in the case of carotid stenting in particular, not being able to get an adequate expansion of the artery logically would lead to a suboptimal stent expansion, which in turn of course could lead to a greater risk of restenosis, potentially even stent fracture or stent thrombosis. For IVL, one of the great potential benefits is that we could prevent these nasty situations where you have a 50% residual after putting in a stent and it just looks terrible because the vessel's been under-expanded because of the deep wall calcification. And then of course, are there patients who are maybe not great candidates for, say for example, an endarterectomy or a T-CAR, and they really need a transformal carotid stent? How about using the potential of IVL to try to make that a better and safer patient experience, but also maybe increase the pool of patients that potentially could be treated with a lesser invasive option? Now, there have been a few case reports. This was Nelson Bernardo's group from the Washington Hospital Center from a few years back. This particular patient that they did actually had an embolus to the ophthalmic artery that they treated with TPA. We published a paper looking at our experience using IVL for these larger brachiocephalic vessels with 100% procedural success with no complications. And especially now that the larger IVL balloons are available, people are using them for innominates and subclavians, for example, and common carotid. This was a fun paper that we participated in. Aaron Armstrong's fellow, Stephanos Gianopoulos, basically went to Shockwave and said, hey, we know that people are using this. Can you just tell us anybody who is doing it? And he took the initiative to contact all these people so that we could sort of pool all of our data. And the results were really pretty remarkable, the 100% success rate, and there was a single patient who had re-stenosis but didn't require a TLR. Dr. Malas' group, he alluded to this in his talk, but in the VQI registry, CAST registry, that patients with a greater than 50% calcification tended to be older, had more comorbidities, and more contralateral occlusions, and not surprisingly, they had a higher likelihood of having a neurologic event. Aburama reported a stroke rate of 6.3% after transfemoral CAST of heavily calcified lesions versus 1.2% in those without heavy calcification, and another VQI registry paper from Catano reported a stroke and death rate of 12.5% with patients with severe calcified plaque versus 2.3% without. So this is, I think, a nice example of why we're even thinking about this. So this was a 57-year-old patient of mine, had a lot of comorbidities, coronary disease, a slew panvascular path, and he had a slew of peripheral procedures, and was referred for an iliofemoral bypass. And then I got a frantic phone call from my referring vascular surgeon, saying as they were inducing him to do the operation after he had just made the incision, the anesthesiologist noted that he had tombstone ST elevation, so he immediately was brought down to the cath lab where I put a couple of drug-moving stents in his right coronary artery. And then about three days later, he presented with episodes of amaurosis to the left eye and was noted to have a greater than 90% stenosis. So it actually ended up being a very kind of boring, typical case. Unfortunately, during our institution's conversion to Epic, the original films never got transferred, so I can't show you the index procedure, but you'll just have to trust me that it looked like a regular, normal carotid. Unfortunately, he developed asymptomatic resynosis, and you can see on fluoroscopy, even before we inject the contrast, that there's quite a bit of calcium there, and that this is seriously under-expanded stent, undoubtedly related to this deep wall calcification. And on selective angiography, again, I tried to outline as best I could the contour of that stented segment, and you can appreciate those dense nodules there. So we had to actually use a buddy wire to deliver embolic protection device. We ballooned it with a five-millimeter balloon. Didn't do anything. Tried a six-millimeter balloon. Really not much better. And I even hemmed and hawed and went to a low-pressure seven-millimeter balloon, and at that point, I had Gary Rubin on my shoulder saying, Peter, for God's sakes, what are you doing there? Stop. So I stopped at a seven, and I got an okay result. But despite all of that work, you can still see we have that dreaded hourglass, and this was super frustrating, and I think is a nice example of why there potentially might be some use of this technology in carotids. This was my second case was an obscenely calcified carotid. So this was another case where one of my vascular surgeons was actually in the operating room doing an endarterectomy, but aborted because it was such prohibitive calcification that precluded his ability to cross clamp. And so he quit, stopped, and said, maybe you could do something with that fancy shockwave balloon of yours. And you can see this dense calcification here. I mean, it's pretty remarkable. So we ended up bringing him to the lab, and he actually had TC2 flow here because of this huge nut of calcium that was in the distal CCA. These were his AP and lateral intracerebral angiograms, and I was able to get a 300, actually should be a 315-centimeter bare wire, but I could not get the NAV6 to go because of that dense calcification. So I gently predilated with a 2.5 balloon. Still didn't go, so I threw a buddy wire up there, again, taking a page from our coronary playbook, and I was finally able to deliver the NAV6. And we initially utilized a 4-millimeter S4 device, which is typically used for below-knee tibial vessels, and we were able to make a little bit of room in there. And I thought, well, heck, if I'm going to do this, I might as well go all the way and use the 7-millimeter device at two atmospheres. And yes, the patient, as you might expect, was a little bit unstable, and that had to give him some atropine and a little bit of Neo, but he turned around very promptly. And then we ended up putting a micro-net, closed-cell, open-cell micro-net stent, and you can see here we ended up with really a very nice result with the full expansion, and more importantly, no evidence of distal embolization. That patient actually did very well, and this was a follow-up stent. So a good stent design and the utility of IVL, I think, really made this technically feasible. My third case is a patient who presented with ISR. Not surprisingly, all the usual risk factors. They already had a CABG, multiple lower extremity interventions, and he had presented originally with an asymptomatic high-grade lesion, and in 2017, this was his baseline duplex ultrasound velocity of about 400, and you can see on his pre-procedural CTA, very dense, severe calcific disease. And on real-time angiography, again, I think you can appreciate this very severe lesion here at the origin of the ICA. And so after predilatation and deployed the stent post-dilatation, we went ahead and put in a closed-cell exact stent, actually had a pretty nice angiographic result. But to my dismay and surprise, he returned to the lab, and 10 months later, he had on duplex what really looked like a very grossly under-expanded stent, which we presumed was secondary to deep wall calcification. And on selective carotid angiography, again, you can appreciate this high-grade lesion. And this time, really to try to figure out the mechanism of failure here, we decided to maybe do something a little different here. So we actually used OCT, and what we found was really interesting, that the patient really had this incredible calcified chunk that was really preventing the stent from fully expanding, and had a baseline area there of only about 4 millimeters squared. So in this particular case, we went ahead and treated this with a 6-millimeter IVL balloon, and we did, I think, a total of two cycles here. And this was the OCT post-lithotripsy, dramatic improvement in the cross-sectional area, with more than doubling, in fact, from 4.2 to 9.8. And then since I was completely off-label, I figured, what the heck, let me just throw a DCB in there just for fun. And our final images really showed a great luminal expansion, and the fact that the majority of the gain was, in fact, from the IVL. So in the end, we went to an area of over 10 millimeters squared, a very nice angiographic result, but more importantly, this patient is now at least three or four years out, and you can see that he has a nice, well-expanded stent that remains patent. So peripheral IVL devices have been used off-label to treat calcified brachiocephalic and carotid vessels, for the most part, safely and effectively. I do think that IVL prep may reduce the likelihood of suboptimal stent expansion, and hopefully that in turn will lead to lower likelihood of patients developing stent fractures, stent thrombosis, and instant restenosis. It may potentially increase the pool of patients who perhaps might not be candidates for more traditional therapies. And there, of course, has been a lot of discussion about carotid IVL trials, and this may expand the number of patients eligible for, and likely improve, the procedural success of transformal stenting and TCAR in these heavily calcified carotid arteries. So thank you for that.

intra-vascular lithotripsy

calcified carotid arteries

carotid artery stenting

procedural success

treatment options