Podcast Transcript: Percutaneous Transmural Arterial Bypass (PTAB) as a Treatment Option for CTOs

[Dr. Sabeen Dhand]
We've already talked about some of the selection criteria, but what would be the ideal patient, and then what are some key contraindications that you guys looked for?

[Dr. Sean Lyden]
For the trial allowed severe claudicants, people with rest pain, even with ischemic ulcers, so Rutherford 3, 4, and 5, the amazing thing was we really wanted to be using this in complex lesions, so the lesion had to be at least 20 centimeters in length. It could be a CTO, it could be diffuse stenosis, it could be in-stent restenosis, because of the size of the stent graft, the reference vessel that you're treating had to be bigger than 4½ millimeters and it had to be less than or equal to 6.7 millimeters.

We talked about you had to be able to get in or access the origin of SFA and you had to have a adequate landing zone at least 3 centimeters above the tibial plateau with one tibial vessel runoff, and then the femoral vein had to be at least 10 millimeters or duplicate. In terms of contraindications, if the patient could not tolerate [unintelligible 00:13:33] therapy, if they had an infectious issue, a connective tissue issue, if they'd had a prior DVT or pulmonary embolism, so very standard exclusion criteria for other trials.

[Dr. Sabeen Dhand]
Of the patients you included in the trial and also moving forward, how many patients had already endovascular treatment done on the primary lesion? Almost like a failed endovascular intervention.

[Dr. Sean Lyden]
If we look at the patients that had prior treatment, just about a third had had prior stents. To me, the most impressive thing of the trials, if you look at the treatment length of the lesions, the lesion length normal to normal was 32 centimeters, and so where most SFA fem-pop trials are 4, 6, 8-

[Dr. Sabeen Dhand]
This is huge.

[Dr. Sean Lyden]
-10 centimeters long, this one was 32, and to me, that's really the one thing that really stood out the most where the average CTO length was 220, and so these were patients that had pretty significant lesions and very aggressive. I've treated these patients endo, I've retreated them endo, but I think if you have that CTO that's densely calcified or in-stent reocclusion that you might spend hours and hours on, I think this is going to really add to what we can offer them.

[Dr. Sabeen Dhand]
Yes, I'm just imagining some of those patients that we've had where you just see all that calcium, right, on that fem-pop and you're just like, "Oh, how am I going to do this?" A lot of times those patients don't have great tibial runoffs though, but in that patient that just has a total fem-pop disease, like a brick of calcium, this just seems like an amazing option. Where is Detour going to fit in your algorithm now? Do you think it's going to take a bulk of your femoral popliteal disease? Is that going to be your first option, or is it going to be reserved for a specific subset?

[Dr. Sean Lyden]
I think it's still going to be reserved for a subset. If you look at both the BASIL trial and if you look at the BEST trial, we know that vein bypass works. My practice has always been in someone that I'm going to take to the lab for an intervention. I've always got vein mapping. Then I always try to understand what their heart's like. Do they have coronary disease? Is it symptomatic? What's their EF like? I always tell patients endo works, but it sometimes doesn't last. It may last, it may not last, and depending on how complex it is, it will be how it lasts. I generally do endovascular first, but I also sit there and say, depending on how sick the patient is or how good their vein is, how long I'm going to try doing it.

If it's a short calcified lesion, 100% of the time endo. Moderately long lesion, moderately calcified, 90% of the time endo. If it was a 40-centimeter long occlusion and they had good vein, I probably would do a vein bypass, but before I ever again do a prosthetic bypass, I would do this all day, every day. Those times when I spent three or four hours trying from above or below, poking through stents to try and redo an endovascular intervention, I got to admit, going to do this instead. I think after I get to play with the device the way I want, now that the trial's done, I'll get a better understanding of how I can push this technology and how it might grow in what I do.

[Dr. Sabeen Dhand]
How steep was the learning curve when you first started from the beginning?

[Dr. Sean Lyden]
It's really not. One of the things we did, because you need to have both arterial access and venous access and we're a big department, we said that we would have more than one physician doing the case, even though we're a training institution and you have trainees, sometimes having a staff physician who knows what they're doing is much, much easier. Our very first case took an hour and 20 minutes. I think the two things that provide a little issue for some people is if you don't do a lot of venous interventions or you're not used to using ultrasound guided access yourself, the hardest part, I think the learning curve of the trial for many of the investigators was getting a percutaneous posterior tibial vein stick, and so that took longer than most of the case for everybody.

[Dr. Sabeen Dhand]
What about how fast does the case now on average take you? The first one, an hour and a half, what are the–

[Dr. Sean Lyden]
They basically took about that period of time. The trial required a complete leg runoff before the procedure, after the procedure. It also required treatment of inflow of iliacs, which was okay. If you look at total procedural time, I don't think it reflects what it's going to take now it's FDA approved and commercial because I typically would get a CT scan ahead of time, and if their inflow is good, I'm not going to treat it at the time, I'm not going to get all those extra pictures because we don't get paid for it, and if you already have some other way of imaging it, it's completely unnecessary.

I can imagine that once it's commercial approved that it's probably going to take people somewhere between an hour or two. Probably most of the patients were done with local anesthesia, but some were done with general anesthesia. At our institution, the very first one we did it under general anesthesia, not because the patient needed it, but I always find when you're doing a new device and it's a new trial, you want to be perfect and you want to be able to talk openly amongst the team-

[Dr. Sabeen Dhand]
Exactly right.

[Dr. Sean Lyden]
-about your plan so it goes best for the patient. Whereas sometimes it's a little harder with an awake patient who's asking what's going on while you're doing it. They don't understand.

[Dr. Sabeen Dhand]
They're like, "Why are you asking how to do this?" [laughs]

[Dr. Sean Lyden]
Exactly. With the crossing device, all crossing devices where it's the commercial Outback or the Pioneer or this crossing device, the EndoCross, they'll have their hieroglyphic you have to look at to know which direction the crossing device is aiming at, and so in the room, we'd have these big posters of what it looks like everybody agreeing that, "Okay, we all agree this is the direction we're pointing," because I sort of look, it's like carpentry, can measure a bunch of times, but you only get cut once, and so if you're firing the crossing device, you ideally want to make sure everybody's on the same page. "We're heading where we think we are and get it across the first fire every time."

[Dr. Sabeen Dhand]
Speaking of the crossing device, it must have a longer needle than Outback or Pioneer, right?

[Dr. Sean Lyden]
It does, and it's also spring-loaded.

[Dr. Sabeen Dhand]
Spring-loaded, it's a very like quick jab.

[Dr. Sean Lyden]
Yes. You basically, you cock load the spring and it throws out, don't quote me on this, but I think it's 15 millimeters. I always tell people, when you play with the device, be very, very careful because when they're showing it to you and we showed it to sites and we had training, if someone were to push the fire, it'll go right through your entire finger. Yes. It will cross a stent. It'll cross calcium. I have to tell you, I'm excited for it to be approved because I can see all the other anatomies that I'm now going to want to use this device because for Iliacs-

[Dr. Sabeen Dhand]
It sounds awesome. That's exactly what I was saying. I was like, okay.

[Dr. Sean Lyden]
-venus interventions. I've already thought about all the different anatomies that because this thing, the Outback, you're pushing really hard with your finger, and if you can't push hard enough, it doesn't cross, same way with the Pioneer, where this thing just, it's like a gun, it comes out so fast.

[Dr. Sabeen Dhand]
That's amazing. You said that the device now it's FDA approved as of last month or a month and a half ago. Is it now available? Any site can get it?

[Dr. Sean Lyden]
It should be soon. From what I am told by Endologix, I think we will be the first US case. The trial we did in the United States was called the Detour 2 trial. It was preceded by in Europe, the Detour 1 trial. In Poland and Latvia, they had the most experience and they've been using this device as part of their practice for three and five years now at some of the sites.

[Dr. Sabeen Dhand]
That's amazing.

[Dr. Sean Lyden]
US, it's ready now, but I don't think anybody's gotten to use it yet.