So, we'll talk briefly about the concept, we'll talk about some overview of options, then I tried to break it down by territory with kind of caveats, case-driven by each one. So, the concept is unlike the coronaries, this is bread and butter in the peripheral world. So, 40 to 50% of patients undergo endo-treatment, they actually have CTO. Despite the fact that it's everywhere, our crossing failure rates are actually pretty high, as high as 30%. And a lot of our complications come from it too, so 15% of all PAD complications come from CTO therapies. So, you've got three broad brush options, wires, escalation, slash wire and catheter, device-based crossing or reentry, and then retrograde or alternative access. Rather than just talking about the broad techniques, we'll make them practical, we'll go by anatomic territory. So, starting with aortic iliac CTO. The most important thing about aortic iliac CTO is you can kill someone trying to do it. You know, perforation may mean death. It's more like coronary in that way than it is like femoral. This is where I started using IVUS in my peripheral practice. You know, angiography just sometimes isn't good enough to make sure that when you're crossing, you're crossing in a safe way. You absolutely can do dissection and reentry with wires, but you need to be a little more thoughtful about it. And this is also where you should really know how to treat your perforations. Covered stents, coils and plugs, know the tools available in your lab. So, what do you do? You know, it's always safer to go from antegrade, from the aorta into the iliac, than backwards because backwards runs the risk of tearing open the aorta when you're trying to reenter. In this case, we went up and over through an IMA coronary guide. We knuckled a wire down into the iliac. We noticed our wire actually crossed into the internal iliac, so then we came up from below. And then when we IVUSed both sides, we found an area where we were true lumen for both. We knew that neither of these areas would risk a perforation. We did a little undersized angioplasty from above, and then we crossed with a stiff-angle glide wire. Made complex fairly simple. We shock-waved it. We ballooned it. We did a self-expanding stent across the external iliac, and it was safe all the way through. We always knew where our devices and our technologies were. You can absolutely use device-based reentry in the aorta-iliac segment. People will. You know, this is the outback catheter, which allows for puncture to reenter, and then a stiff wire to actually cross into the reentered segment. You can do the same thing using Pioneer, where you get some IVUS guidance showing you where the lumen is as you're attempting to puncture back. But the caveat to this in the aorta is that you might know that your quote-unquote reentry site where you're actually poking back in is safe, but you don't know where you've been before. You don't know that when you extend that dissection flap, it's not going to cover the contralateral iliac. It's not going to extend north and hit the renals. It's not going to cause all those things. You also don't necessarily know from that simple IVUS picture where your wire was going. Your dissection pathway might be out and in, and thus your balloon angioplasty path will be out and in, and could cause a just torrential perforation. So be thoughtful about it. You can kill someone very easily in the aorta-iliac segment. FEMPOP. A little bit different. FEMPOPs, we kind of go to war, right? A lot of FEMPOP disease is CTO, as high as 50% in endovascular interventions. This is where we use all of our tools, including using frog-legged SFA sticks for distal SFA retrograde axis. It's cheapest. It's most frequently used to do wire escalation. We've adopted a lot of techniques from the coronary literature in terms of strategies for using coronary techniques. From Peripheral Matters, edited by the good Dr. Sesemsky here, we've got some talks and discussions about using some of these coronary scratch-and-go knuckle wire, mini-star, the things vascular surgeons, you know, don't necessarily use the same acronyms, but are about using both hydrophilic wires or stiff wires for various types of re-entry practices. There are crossing devices, and FEMPOP is the bread and butter for crossing device use. Frontrunner, crosser, wildcat, we'll oftentimes use these for the more complex, longer, maybe more calcified lesions we might expect difficulty in crossing. This was an osteo-SFA occlusion. This is the VEONS catheter, similar to the cross-boss catheter in the coronary space. You rotate the VEONS catheter. The VEONS catheter works to find microchannels in the plaque, and then it actually pulls its way through those microchannels into the distal vasculature. You can see that VEONS microcatheter on the left side there as well, and we can get that maybe playing. If not, we'll keep going. So we found that segment and then worked our way through. The same re-entry devices we talked about, the Outback, the Pioneer re-entry catheter, or the NTR, similar to the Stingray device, can all be used for re-entry in the SFA. Here's an example where we're using that Outback catheter after we've identified wire distal lumen to then re-enter back into the distal SFA space. On the left side here is an area where we're actually SFA frog-legging, sticking a stent in the distal SFA, and using that to get wire access going north to cross. And then on the right side of the picture is where we're doing a true retrograde up the tibia-pedal and allowing that O1-4 wire through an O1-8 microcatheter to work our way all the way up to where we rendezvous in the distal SFA. The short version is in the FEMPOP. You can go to war. You'll find a lot of FEMPOP CTO disease. And whether it's device-mediated re-entry or crossing, or retrograde techniques from the distal SFA or from the tibials, you've got a lot of options to re-enter and cross. Moving our way down to the tibial territory. So in the tibial tech segment, some of our re-entry devices don't work quite as well. We just don't have as much lumen in order to try and cross, either with crossing devices or to re-enter. A lot of this is really wire escalation, and then it's retrograde early and often in our cases. So know your wires, know your pathways, know your algorithms. For me, most commonly, it's a simple 014 wire workhorse knuckle through an 018 microcatheter. If you see a microchannel, treat it like a microchannel on a coronary. You know, if you can see it, a Fielder XT can cross it. If you see a short calcified cap, a Compionza Pro 12, that same CTO 45-degree 1-millimeter tip can work. And be confident in your ability to go retrograde, because oftentimes that's what you have to do. Key points to retrograde crossing in the tibials, the PT tends to be a straight shot. The AT sometimes the easiest access, but you've got to be cautious about that 90-degree bend up proximal, because that's an area where perforations can happen. Perineals require deep sticks, and so on those deep sticks, you've got to be thoughtful. You're staying low on the ankle, because you're not sticking in the calf, or if someone bleeds, you can't compress it, and they can get a compartment syndrome. And then you've got to figure out how to be quick and what your algorithm is. For me, that's the short micropuncture needle, a microwire, the dilator from a pedal sheath. I tend to use V18s through CXI-18s. Then CART, reverse CART, coronary techniques for rendezvous are very commonly used. So in conclusion, you can kill someone in the aortic iliacs, think about perforation being death, and be thoughtful about how you're crossing those lesions, and be thoughtful about what rescue equipment you have. Ibis in the iliacs early and often to make sure you're being safe. The SFA is where you go to war. You shouldn't necessarily be a peripheral operator if you're not feeling confident and comfortable dealing with those cases in an escalating way throughout your practice. Know when and where to use device-based crossing or reentry, and balance the cost of using those devices against their benefit and practice. Knowing that oftentimes they're most effective if you're using them early in your attempts to cross. Retro skill at this point is pretty much mandatory, and the more algorithmic you'll be, the faster you'll be. And know that we as a field, we just have to succeed in CTO in order to be successful in endovascular therapy. So thank you guys all so much.

chronic total occlusions

peripheral vasculature

intravascular ultrasound

wire escalation

CTO treatment