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Podcast Transcript: Pedal Acceleration Time for Limb Salvage

with Jill Sommerset and Dr. Mary Costantino

Dr. Mary Costantino and Technical Director Jill Sommerset talk technique and utility of using Pedal Acceleration Time for pre- and post-procedure evaluation of CLI patients. They also discuss intra-procedure extravascular ultrasound guidance to aid in safe and effective endovascular interventions. You can read the full transcript below and listen to this episode here on

Table of Contents

(1) The Role of a Vascular Technician

(2) Origins of Pedal Acceleration Time

(3) Using Pedal Acceleration Time in an Office-Based Lab (OBL)

(4) Pedal Acceleration Time Training and Limitations

(5) Pedal Acceleration Time for Foot Ulcers

(6) Starting a Pedal Acceleration Time Program

(7) Pedal Acceleration Time for May-Thurner Syndrome

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Pedal Acceleration Time for Limb Salvage with Jill Sommerset and Dr. Mary Costantino on the BackTable VI Podcast)
Ep 90 Pedal Acceleration Time for Limb Salvage with Jill Sommerset and Dr. Mary Costantino
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[Mary Costantino]
Hello, everyone and welcome to the BackTable Podcast, your source for all things endovascular. You can find all previous episodes of our podcast on iTunes, Spotify, and on

[Speaker 1]
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[Speaker 1]
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[Mary Costantino]
This is Mary Costantino as your guest host this week, and I'm very excited to introduce our guest today, Jill Sommerset. Welcome, Jill.

[Jill Sommerset]
Thank you so much for the invitation to be part of this podcast.

[Mary Costantino]
So, Jill, why don't you tell us a little bit available your background? Who are you? What do you do? Where did you come from? Here you are on BackTable. How did you get here?

[Jill Sommerset]
So, I live in a small town called Hood River, Oregon. I've been doing vascular ultrasound for the last 20 years. I was originally trained in Seattle, Washington, and worked for a company called Pacific Vascular Ultrasound Company. So, we did on-call services, in-patient, and outpatient, and operative coverage for TCD emboli monitoring, for endarterectomies, and open bypass.

Then I transitioned to the University of Washington, where I worked in their research department, mainly on the CREST Chile. Then my family and myself moved down to Oregon, and I've been working at PeaceHealth Thoracic & Vascular Surgery for the last 10 years. More recently, I have the privilege of working with you at Advanced Vascular Centers in your OBL, and that is truly an honor.

[Mary Costantino]
Yeah. So, I ran into Jill at a local meeting and we were really desperate for an ultrasound tech because you never appreciate ultrasound techs until you have one that's maybe not what you're used to. I had seen Jill on LinkedIn in these times and places dealing with some pretty significant PAD cases and limb salvage. So, I just asked her if she knew anybody, anybody who's looking for a job because we were in real need, and she indicated that she might be interested in working in an OBL setting. I consider myself extremely fortunate. Jill comes to my lab on Wednesdays and sometimes on Mondays and we had to do intraoperative cases and we are doing a lot of things with foot perfusion and vessel size. So, that's how Jill and I met. We are having a very enjoyable Wednesday. Wednesdays are my favorite day because it's a Jill Day. Her ability has spread throughout our labs. So, now, my whole staff knows when we see a complex patient we just call it a Jill Patient, and that patient waits until Wednesdays.

So, how did you get into vascular ultrasound? What are your favorite things to do in vascular ultrasound, and what got you so interested in arterial ultrasound?

(1) The Role of a Vascular Technician

[Jill Sommerset]
Well, I think it has a lot to do with the physicians that I worked with in the past who were very supportive and really relied and found a lot of value in the vascular technologists. So, I suppose not only my interest in peripheral arterial launched forward, but I also worked with a vascular surgeon on pelvic congestion syndrome stuff back in 2013, and we developed that transabdominal duplex originally to try to really find more answers for women who were having vulvar varicose veins and needed further testing.

So, I would say that it's the involvement of the physician that has really launched me forward because you are invested in my team and myself. We actually sat down every week for an hour and went over cases and I learned how a vascular surgeon thinks, and I've learned by you, Dr. Costantino, as an interventional radiologist, how you think. That's how I think I've really now got into weeds and have this love of vascular specialty and I suppose that certainly would be a good story.

I also teach the registry for the RPVI. So, when you teach, you also glean more knowledge because you have to educate. So, I do a lot of side consulting as well for pelvic congestion and advanced arterial duplex ultrasound, and now with PAT, it's been really, really enjoyable for me personally in my career.

[Mary Costantino]
Yeah. I mean, as long as I've known you it seems like it's putting together the pieces, the clinical, the surgical/endovascular and the ultrasound is your favorite thing to do. Correct me if I'm wrong on that. Then it seems like that would be a common thing with vascular techs, but I guess not. I feel like ultrasound, it's so critical for the ultrasound techs to be good at what they do and to capture or represent images and to be up-to-date on the disease conditions, but I guess that's not always the case. Is that true? Where are we with that?

[Jill Sommerset]
Yeah, I would agree. I don't think it's always true. In fact, I find myself really feeling fortunate everyday that I get to work with a vascular surgeon and interventional radiologist, too, who loves to work with us. Some vascular technologists, they just do their study, they send off their report, and they don't get that constant conversation, that feedback.
So, I think we need more of that. We need more collaboration because vascular techs, if we know what you want, we will give it to you. So, I urge all of the vascular techs and actually physicians, too, to collaborate more and more, especially on these difficult peripheral arterial cases.

[Mary Costantino]
Yeah. I mean, being someone who didn't have the vascular tech I needed for about a year, I started sending all my patients out and I can tell you, I get back these reports from major hospital systems, accredited labs, that are just numbers, they don't really mean anything. Then I've been trying to put the clinical together with the list of numbers on some computers, spread out thing, and the conclusion is always some vague something. Just none of it helps me. It reminds me of this statement from one of my older attendants used to say, "Garbage in, garbage out."

I basically came to rely on these outside ultrasounds as, "Is the femoral artery open or closed?" and that was about it. The tibial work was 50% accurate and definitely, they weren't getting into plantar work. So, if I'm not actually doing the ultrasound in my own lab or you're doing it, and we're talking about it--if they ever end up somewhere else, the furthest amount of information I will accept is basically femoral artery open or closed. The rest of it I definitely count on because we got these reports that are just velocities and then say, "Oh, mild atherosclerotic disease," and it's like, "What is that? That means nothing to me. I don't even know what to do with that."

[Jill Sommerset]
Well, and I think you know me. I like to actually just plan your case for you. So, I like to try to think I am two steps ahead at where you should access and what your-

[Mary Costantino]
Yeah. Jill's like, "Oh, you're so good. You're so good. You are so good at what you do."
I'm like, "Yeah, because when I walk into the room you said, 'Hey, I wouldn't go into that artery here. I would go into here and put a wire through that, and I think you'll open it up.'"
I'm like, "All right. How could you not win?"

I guess that's the point, right? Between what you and I do together, our win of CTO crossings and revascularization and improving perfusion and healing wounds is so good because we are so prepared going into it. Can you talk a little bit about, I know you have strong feelings about what you bring to the table or what any ultrasound tech can bring to the table in terms of preoperative planning?

[Jill Sommerset]
Yeah. I think it's that advanced just education going beyond just being a vascular tech, but really understanding the interventionalist plan. So, I know that you like to do an antegrade access, I'm still going to look at the contralateral up and over access, just in case you need to do that. Then there's some physicians who are just primary pedal. So, if we know your approach, we can be efficient in making sure that we measure those distal pedal vessels for access if there's no groin access, maybe it's radial. So, I think just thinking beyond just the duplex is really helpful.

(2) Origins of Pedal Acceleration Time

[Mary Costantino]
Yeah. The other thing with the pedal is that you often give me this flow direction in the foot. So, if we know the flow to the foot is coming from the AT, maybe we'll go through the PT first just in case I mess it up, which, of course, I'm always hoping not to do. Then I feel we still have that AT forward perfusion. So, knowing the flow dynamics of the foot, how the blood is getting there is really helpful for knowing which vessels are most important, and which vessels if one has to be sacrificed, not that I ever want a vessel to be sacrificed, but if it happens, it's ideally going to happen to the less critical vessel.
So, that leads us right into one of my favorite things, which is plantar acceleration time or pedal acceleration time. I want to say this for the end because it's like the big Christmas gift, but I feel like we should not delay the audience any further of what the real meat of this discussion is about, which is plantar acceleration time or pedal acceleration time. Can you tell us what were you doing when you had that idea? Where were you sitting? How did you figure this out? For the audience, Jill basically invented this technique, and published it, and had to work with physicians to get it out there, but this is her brainchild sitting around playing with her ultrasound machine one day figuring out what information she could give to the interventionalist that we didn't already have. So, Jill, first question, please describe and define PAT.

[Jill Sommerset]
Well, thank you for that good introduction of PAT. So, the story behind it is in 2017, I was fortunate enough to be watching Dr. Howard Feldman down in Roseburg, Oregon. He's an interventional cardiologist. I was down there teaching some of his techs how to image the common femoral artery. So, I watched his case, and he ballooned around the whole pedal arch, and I had never seen that before. I asked him after the case, "Well, how do you know it stays open? What's your follow up like?"
He said, "Oh, I don't. If the wound heals, then it's probably open."

I was so excited and so intrigued at that moment. I had a three-hour drive home, and I didn't even go home. I went straight to my vascular lab, and I scanned my own foot and thought, "Oh, my gosh! I can see my pedal arch."

So, the next day, I started scanning every single patient's foot. I couldn't believe how well we could see these pedal vessels. I worked with four vascular surgeons. I probably drove them crazy because I was just so over the moon about this.

So, over time, they got onboard and we started tracking our data. We looked at waveform analysis. We looked at velocity. We were trying to figure out what is the best way to assess perfusion in the pedal vessels, now that we can see it.

Ultimately, it ended up being acceleration time, and we've used acceleration time in other beds of the body, and the distal renal arteries, the common femoral artery, the carotid arteries. Now, we just applied acceleration time to the foot. So, we started just tracking. I would journal entry every single day with the patient's ABI and TBI and clinical symptoms. Gosh! We just started seeing this incredible correlation and started just tracking all of our data.

So, that was the beginning of plantar acceleration time. Now, it's called plantar acceleration time initially because we knew where to look at the lateral plantar artery in our datasets. Then, now fast forward and we looked at the entire pedal arch, and that's why the name was changed and there's more papers coming out to reflect that. So, that first initial paper was just looking at the lateral plantar artery, comparing that to ABIs. These patients were nondiabetic, non-renal failure patients. So, ABI was reliable, but not only does PAT correlate with ABIs, but also really correlates with clinical symptoms.
So, that's the backstory of how PAT was born, and it's just taken off like wildfire. To be honest, it has created so much joy, and it's so amazing to scan these patients' feet and help them in decision making. I think I'm really excited, especially working with you, Dr. Costantino. We can see the changes of PAT intraoperatively and postoperatively. So, there's a lot of value to PAT.

[Mary Costantino]
Yeah. As you're talking, I'm thinking, well, two things. First of all, you're like the Alexander Fleming of foot perfusion--trying it on yourself, journaling it, and making big discoveries. The other thing I'm thinking is all the exciting ways we could use it, and I'm trying not to be so exuberant because there's so many fun times that we use this. Oh, we need to talk about class, PAT class. Can you describe the actual numbers and how you classify PAT?

[Jill Sommerset]
Yeah. So, the original criteria, we retrospectively evaluated 499 limbs. Again, all of those patients were nondiabetic, non-renal failure patients. We correlated PAT to ABIs and we found a statistical significance that broke into four classifications. So, PAT class goes from class I being normal and that's equivalent to a normal ABI to class II, which is mild disease. So, that would be equivalent to a 0.7 ABI, all the way to class III, and then IV being the worst. So, class IV PAT, which is an acceleration time of greater than 225 milliseconds, that is consistent with rest pain and tissue loss.

So, if you remember any two numbers out of the PAT classification, 120 milliseconds or less is normal, and 225 milliseconds or greater is abnormal. Basically, what that is is we're measuring the onset of systole to the peak of systole of the arterial waveform, and we can gather that acceleration time and apply it to the criteria.

(3) Using Pedal Acceleration Time in an Office-Based Lab (OBL)

[Mary Costantino]
So, I have a couple of ways in mind that we use it, but let's talk. Why don't you tell the audience how you and I use this on a typical day in the OBL.

[Jill Sommerset]
So, we scan all of our patients in Dr. Costantino's lab in an outpatient setting, and we do pedal acceleration time on every single arterial patient. It can be for a foot pain, for claudication and, of course, for tissue loss and rest pain. This is just an extension of the arterial duplex. We can do a limited arterial duplex, and that's billable for PAT. It's the 93926 CPT code. So, it's all billable. So, we use PAT in the preoperative ultrasound, and then when she does her case, I like to mark on the patient's foot where the vessel is if it's right next to a lute. We'll do a PAT right before the patient rolls into the cath lab. Then I know exactly where to place my probe when she's delivering therapy.

We're oftentimes the only ones in the cath lab to jump up and down and be so excited when we see that dramatic change, especially in the antegrade access. It is instant. Once she does atherectomy and does balloon angioplasty, that PAT changes on the table, and then we use it postoperatively as well for wound surveillance.

[Mary Costantino]
Yeah. So, we just had a case last week where the guy had an occluded femoral artery, an occluded PTFE, fem-pop graft, and an occluded fem-tib venous graft. Started having grafts in 1984, had surgical groins bilaterally, and reported a seven-hour surgery for some leg aneurysm from his previous surgeries that "didn't work". So, we knew his groins were a nightmare. He had scars all over his legs.

Jill mapped him. He had a profunda that had elevated velocities, and then branches going into his AT. His contralateral groin was heavily calcified, about 60%-70%, bulky calcification, so it's unfavorable. He was on Plavix for coronary stents and he was obese with a large panis. So, Jill hands me that ultrasound. So, I did this radially, and that's not the interesting part because I think a lot of us could do that. I just went down into the profunda, atherectomized the profunda, ballooned the profunda, and what I used Jill for was she went on down to that foot and he had a class IV PAT. I didn't know if I was making any difference in this foot.

After I pushed the intervention as far as I could from the profunda, she looked at the PAT, and it was a class III, which is not exactly where we want it, but much improved. So, I knew that I had actually reestablished flow down to his foot. He has an ulcer and a pretty ischemic foot.

Then the decision was: do I need to do an attempt at any tibial revascularization? You had occluded AT and PT and you just had a single peroneal. So, complex case, and knowing that I had improved the flow to the foot with just the atherectomy and angioplasty, the peroneal allowed me to stop then to see how he was doing over the next couple of days. That was really critical information because had I gone down to this guy's AT and PT, I don't know that he had enough flow in them to really keep them open if I had put a sheath in. I think I would have given myself just about 15 minutes to do the case because I was worried about occluding one of his tibials.

So, really critical information that allowed me to make a decision I was pretty confident about. The other way I used Jill in that case was that he did have a small aneurysm in the common femoral artery right before the profunda, and I didn't want to atherectomize in the aneurysm. So, I had the wire down the profunda, and I was envisioning the orbital atherectomy device flying around in the aneurysm. So, I wanted to start right at the origin of the calcification, and I had marked it with IVIS, but he had moved and all this. I mean, we're talking millimeters of difference. So, I had her ultrasound over the orch and the profunda. I lined up the atherectomy device exactly where the calcium started, and I knew exactly how far I had to go. So, it was a completely visualized atherectomy, which helped because of the proximal aneurysm.

So, you can gain a lot of confidence in these procedures when you have a tech that can actually direct you. I think anytime we can actually see what we're doing and have some less subjective and more objective data, that's valuable.

[Jill Sommerset]
So, one of the common questions, too, is do you have a dedicated vascular technologist in the cath lab, and my answer is yes because not only can we monitor PAT, but we can also be really valuable for just what you spoke about, which is extravascular ultrasound, where a new set of eyes that we can get right at the CTO cap with wires or catheters or help place balloons or stents extravascular. So, I think that in itself is an extra tool that can be really helpful.

[Mary Costantino]
Yeah. Can you describe how you do that? Can you describe just the flow of the case? Let's say I have a CTO and it's on a Jill Day, which, of course, they always will be. Describe your role in the cath lab. You don't just sit there the whole time. I mean, you're out working and coming in and out. So, describe for the audience how the flow of that work goes.

[Jill Sommerset]
So, in my opinion, we always have to plan. I did the preoperative duplex ultrasound prior to the case, so I should know that patient's perfusion and occlusions, and CTO caps better than you. So, when I do the preop marking, I mark on the patient's leg where the CTO caps are, so I know the length of occlusion and I know exactly where to place my probe during the case. I also mark on the patient's foot, so I know where if I'm going to look at their arcuate artery, their dorsal metatarsal artery or the lateral plantar, I know exactly where to go.

So, then when the patient rolls in, I'm prepped and ready to go because the physician is always asking questions like, "Oh, how far do I have left to go?" or "Where's the cap?" or "What does this look like?" So, I always want to be two steps ahead of you and my time, as we know, well, time in the cath lab is precious. We have to be quick and efficient. So, as a vascular tech, we get into precarious positions to reach under the drape or go over at their folded prep, but while you're holding a balloon for a prolonged inflation, I'm going to get my ultrasound ready. I know exactly what the setting should be. Therefore, when the balloon is deflated and you pull it out, I can go straight to the patient's area that we need to look at and be really efficient. So, I think that there's a lot of prep that goes into these cases. So, the ultrasound tech can be very efficient.

[Mary Costantino]
Yeah. So, Jill will do the ultrasound of the patient preoperatively. Like she said, she knows the patient better than I do at that point. We also are doing a lot of patients with kidney disease as most of us doing a lot of PAD are. So, I have dilute contrast. I'm usually trying to use between 20 and 30 cc of contrast at most. So, these big beautiful runs that I use to get in the hospital when you power inject through the pigtail within the aorta. In the aorta, you get these beautiful images. They just don't happen because I'm trying to use a dilute metacontrast.

So, I can sometimes see the distal reconstituted vessels and sometimes not, but it actually doesn't matter. So, I just reduce the contrast dose between IVIS. Jill, I actually have done full CTOs with under 5 cc of contrast, and that's pretty incredible. We love to do that. So, Jill will usually be outside of the lab, and I'll be working away, and she'll be doing stuff out there.

I anticipate I'm getting the sheath up and over, going antegrade. I usually like to go antegrade, getting the lay of the land, figuring out what I want to do. If I anticipate I'm going to need Jill, I'll have my nurse or somebody go out and get here, and it takes her I would say under five minutes--probably under three. The machines are in the room. The machine is positioned. It's turned on, and the patient's name is inputted in there. The patient's marked. She knows exactly where she's going.

She just comes in. I don't think she keeps lead on, but she just gets her lead on, cap and mask and everything. She gets sterile and pops around and starts ultrasounding. That takes I would say under two minutes. So, we have no delay. Doing this adds zero delay. In fact, it saves a ton of time, contrast and runs.

So, if I have a CTO, I'll get positioned right in that cap. Of course, I'll try the old school way. I'll try to open it just through angio, but if this thing is heavily calcified, which I know because we've talked about it before. Maybe it's got a big calcified cap, but the rest of it is soft versus a 10 cm heavily calcified just pile of rocks segment versus all soft.

So, I'll give a little college try, try to poke a wire through there, but if it doesn't go or it's budding or it's going into that horrible little collateral that is coming off right where the cap is, I'm already calling for Jill. That allows me to position my catheter right up against the cap, and it allows me to do what I call really dangerous things. I'll say, "I'm about to do a really dangerous thing," but I don't really say that out loud because you can't say that out loud with an awake patient, but I'll get the backend. It's all stuff that we know how to do, but we don't like to do that much, like reversed ends.

I've used the reversed end of a weighted wire. Man, that thing is sharp as heck, but if I know I'm intraluminal and I'm right next to that cap and I'm watching, I can see where my catheter is, maybe I have a trailblazer down there, maybe I just have a regular Kumpe catheter, it doesn't matter. You got the catheter poked right in there and you can take that wire and you can shove really hard. I mean, I actually want to get a needle, that's my next thing because I just need to pop through that cap. If I know I'm intraluminal and I'm watching with ultrasound, you can be really aggressive.

We've gotten through some really incredible CTOs that way, and just the heavily calcified one we just march down. I'll ask Jill 14 times, "Am I intraluminal? Am I intraluminal? Am I intraluminal?" These are the cases where by angio the wire is making a little curvy twist and turn. You don't really know, "Am I going around the calcification or am I going subintimal or am I out of the vessel entirely?"

I like to say intraluminal because I do because I went subintimal once and have always regretted it. So, I like to say intraluminal. So, Jill will come in and out on those cases. When we're trying to get across a CTO, she's going to stay there the whole time, and I'm going to do basically the whole CTO by ultrasound.

The only time you can't do it is when that calcium shadows and we miss a centimeter. Sometimes you gotta watch that under angio. Then we always have the moment of celebration of when we actually get through, and then we move along with the rest of the case, and Jill's done until the PAT time. So, Jill, where is PAT being used? How are you seeing it used nationally and worldwide?

(4) Pedal Acceleration Time Training and Limitations

[Jill Sommerset]
So, I think we have to remember that this technique is still pretty young. It's only three years in the making. So, just trying to get publications out. We have so much great data that we're trying to get published and trying to teach at a lot of or speak at a lot of national and international meetings. The Society for Vascular Ultrasound is a place where a lot of vascular techs attend that meeting. So, we'll do hands-on training there, and a number of lectures.

So, the information is getting out. I think where we're at now is that a lot of people want to learn. So, we're trying to develop that platform of how to teach them. Right now, they can learn at the Society for Vascular Ultrasound annual meeting or just me personally. So, what the training entails is four hours of Zoom conferencing and lecture, and then the techs will go out and scan 10 limbs and then report back to me, so I can validate all 10 of those limbs.

So, that's how we're doing it right now. So, if you're anybody listening, if you're interested in having your tech trained, I would encourage it to be physician and tech because everyone has to understand how to utilize this information. I guess I would just say to call me and we can set up some sort of training, which would be really fantastic.

Then it's also going internationally. There's some really great research that's going to get underway in Australia, in New Zealand, in Italy, in Mexico. So, that's really exciting to see these projects start and we'll see the collaboration at the end when we get our data back.

[Mary Costantino]
Yeah. Working side by side with Jill I'm always seeing her on some international webinar with some doctor in Argentina. That's what's so cool about medicine these days. You can teach people remotely and they can start to gather information. I do think working with you, it's important that it's not just the tech, not just the physician. This is something that if you want to start, it really needs to be collaborative. You want to handpick your best vascular tech and your person who's most excited about limb salvage, and then pick your physician who's most excited about limb salvage and start there. Wouldn't you say? I feel like if a tech just showed up, be able to do it or a physician wanted to do this without a tech that was that interested it might be a little more difficult.

[Jill Sommerset]
Yes. I couldn't agree more. We have to have an open mind. This is a new concept, and so perhaps there's some people that maybe a little bit more resistive to a new technique. I think that the thing to remember is PAT is not the end all be all. This is a new additional data point that just helps you in your clinical decision making. We also know that PAT has limitations. It has these fake outs. So, we should know that. So, if you don't mind me telling you what those limitations are.

[Mary Costantino]
Definitely, please.

[Jill Sommerset]
So, the first limitation or fake out can be isolated inflow disease. So, if a patient has an occluded common iliac artery and then patent in for inguinal, in for popliteal arteries, the PAT is going to present as normal in the foot, but the velocity will be really low. So, if the velocity is less than 5 cm per second in a foot, that is, number one, very abnormal, but number two, we just cannot rely on PAT. We're pushing the boundaries of our ultrasound system.

We also see that 5 cm per second velocity in low cardiac output. I just scanned a patient the other day with an EF of 15%, and the velocity was two. So, of course, he needs to get that fixed, but there are these fake outs that we have to be aware of.
Another one is bypass surveillance. So, remember PAT is capturing all of the blood flow that goes down to the foot. That branches off the profunda, off the geniculate. So, you're going to have an occluded SFA and the patient can walk a mile, and they have normal PAT. It's because PAT captures all of that collateral flow.

So, if you have a patient with a fem-pop bypass graft, we recommend that you actually do duplex surveillance because you could have a high grade distal anastomosis stenosis and the PAT will present as normal, but that's really bad because if the mid-graft velocity is 20, that is looking at perhaps graft failure. So, PAT may miss that because it's capturing all of that other collateral flow.

So, those are some things we have to address and publish and let people know where the pitfalls are. I think where PAT is really going to find its niche is in the CLTI patient, in the diabetic foot wound or even just pure ischemia. When there's a wound involved, PAT does this really amazing job at capturing what the perfusion is like. Is it enough to heal the wound?
We look at the entire pedal arch. So, we look at the arcuate, the dorsal metatarsal artery, mediolateral and deep plantar. However, we can also look beyond that and look at the medial or lateral tarsal artery. We can look at that calcaneal vessels going to the heel. So, there's a lot of value in those wound patients.

[Mary Costantino]
That is a perfect segue to one of my favorite ways, another one of my favorite ways that we use plantar ultrasound, maybe less so PAT, but can you describe what you do for me with the foot ulcers? It's the most amazing thing ever, and it really helps understand flow to the foot and, of course, what I'm talking about is the dorsal metatarsal and how you approach ultrasound in a patient with a foot ulcer.

(5) Pedal Acceleration Time for Foot Ulcers

[Jill Sommerset]
So, PAT not only stands for pedal acceleration time, but actually what it really stands for is perfusion, anatomy, and transducer, which is flow direction. So, we now have this really incredible insight to a patient's foot, especially in the setting of a wound where I can tell you, Dr. Costantino, that maybe this patient has an anatomical variation on the top of the foot, and they do not have a dorsal metatarsal artery. In fact, they have a huge lateral tarsal artery with no flow going to the great toe. Or I can tell you that the arcuate artery is retrograde or the lateral plantar is retrograde, and the perfusion is class IV.
So, when we can tell you the anatomy, the perfusion, and flow direction, it provides incredible insight to, number one, is the wound getting enough flow, but also in decision of surgical treatments. So, will this patient heal just a toe amputation? Or, do they truly need a transmetatarsal amputation? Or, if the pedal arch is not intact, maybe they need to be thoughtful of where they do their amputation.

[Mary Costantino]
Yeah. That's one thing I think that the people referred to us really like is that we'll take the ulcer and do an ultrasound right at the ulcer bed. Jill will be able to say how much flow is getting to that ulcer. Usually, we're doing an intervention regardless if there's an ulcer, and then we're looking at: Did we change the flow to the ulcer?

So, we just had a similar guy--I keep reopening his tibials and they keep shutting down. So, the debate that they're having on the surgical side between podiatry and orthopedics is: are they going to amputate a toe or are they going to amputate a midfoot? We were able to bring him in, and Jill did his ultrasound and showed that he had great arcuate arch flow. He just was lacking flow through his second dorsal metatarsal. That convinced them to just take the toe and not the midfoot.

So, Jill, actually, that's a great segue into the case you did this morning. So, it's Sunday afternoon. It's a beautiful day in Oregon. We just survived wildfires and we're in the midst of COVID, and it's a beautiful day outside. So, everybody wants to go outside and hang out, and what is Jill Sommerset doing? Jill, tell the audience what you did this morning.

[Jill Sommerset]
Oh, I just can't resist. So, I was on my way to the hospital to scan a patient. He presented with a diabetic foot, first toe ulcer, and the patient had a huge infection. So, a couple of days ago, they did source control and did just the first toe amputation or first ray amputation, and then I was called to assess perfusion in the foot. This patient has class IV PAT. Class IV is consistent with tissue loss and rest pain.

So, what PAT can provide is we can expedite care right to vascular surgery for intervention. We're not sitting on things versus I've gotten the same call for a patient with a diabetic foot ulcer with normal perfusion, and that is not a vascular intervention. That would be more orthopedic or podiatry to take care of that patient. So, I think the inpatient diabetic foot program can gain a lot of value by having a vascular tech to do these PAT studies on all patients with foot wounds.

[Mary Costantino]
Yeah. I'm laughing at the visual, the cartoon of a patient, diabetic foot wound heading the door. The old way is all these people in coats throttling each other and battling each other out like old school about who has to admit the patient, and then you come in. For those of you who have never seen Jill's picture, she's a gymnast, and she's got this long blonde hair, and I can see her floating in and just ultrasounding and just having to decide everything. I feel like all the wars, all the battles would just stop when Jill just floats in and tells people, "This needs revascularization," or "This needs amputation." You're like a superhero putting out fires across ERs all over the world.

So, that's a really interesting way of helping an admit of directing patient care. I mean, think about how huge that is if it comes down to just figuring out the ultrasound and figuring out where the patient is best admitted. I wish more of those patients were admitted to interventional radiology, but right now, vascular surgery is the dumping ground of everybody and I think in some hospitals around here that I've worked with, vascular surgery has stood up to be the dumping ground, which has made internal medicine the dumping ground of every diabetic foot ulcer.

So, I know that it's different in every hospital, but it would just seem like gathering information so that no one group feels too put upon will be really helpful. Jill talks about driving into the hospital. She lives three hours from the hospital. She lives near Mount Hood. So, when she drives in real fast to go check on a wound, it's really out of true dedication to her craft. She's doing it because it's not down the street.

So, Jill, tell me if you have, I know you talked about if anybody listening wants to start doing this in their practice, is there any place that you think this can't work. I mean, you work in an OBL, you work in a hospital. Personally, I think this could work anywhere. It can work in a clinic. I mean, you just need an ultrasound and a Jill and you could make this happen. What's your ideal scenario to work in, but answer that question after you answer how would any listener start this program. It sounds like they would find a physician and a tech, and they'd contact you. So, who would you say should not implement a program like this, if anybody?

(6) Starting a Pedal Acceleration Time Program

[Jill Sommerset]
I think PAT can be implemented into any program. They just have to have an updated ultrasound system because we now know that if the scale of the ultrasound system does not drop below 10 cm per second, that is a limitation. So, you need to have a current ultrasound system, and then also a skilled vascular technologist.

So, like anything, we have to learn anatomy. So, in the protocol that's published in the Journal For Vascular Ultrasound, there's a proper way to put the indicator of the probe towards a certain direction for the top of the foot and the bottom of the foot. So, there's a developed protocol and developed technique.

So, with that, I would say right now it is just me training, but what we're working on is a center for excellence of training for advanced arterial duplex ultrasound. I think that, in combination with having a physician, and a tech to hold a program like that could be very valuable.

[Mary Costantino]
Do you want to tell the audience what your favorite equipment is, and I should note that you have no corporate relationships, right? Nobody pays you to do anything. Is that right?

[Jill Sommerset]
I deliver educational content to Philips, but I do use a Philips EPIQ ultrasound system, but I'm not biased. You and I have a Siemens ultrasound system that does fantastic work. Again, it just needs to be a current model of ultrasound. So, I'm not biased.

[Mary Costantino]
Yeah. I've never detected any bias in you at all. In fact, I'm trying to make you more bias. I'm trying to monetize you, Jill. I can make money off of you somehow. I'm kidding. Oh, we have so much fun working together.

[Jill Sommerset]
I know. As far as probe selection, you don't need anything special. You need your standard linear probe that we use for carotid duplex or arterial studies, and then a high frequency probe like a hockey stick probe or a 15-18 megahertz probe also works. We only use it really for the top of the foot because some of these patients' feet are so thin that they need a little higher frequency probe, but for the most part, I use a linear probe. So, nothing fancy.

(7) Pedal Acceleration Time for May-Thurner Syndrome

[Mary Costantino]
Jumping straight to the venous disease because I know we're going to have to wrap up soon, but I really want the world to know. How do you use ultrasound in the detection of May-Thurner and trying to differentiate between venous nutcracker, May-Thurner, ovarian vein reflux, and peripheral venous disease?

[Jill Sommerset]
So, a colleague of mine named Brian Sap out of Georgia developed this incredible way to evaluate a waveform in the groin. His work hasn't been published yet, but I have gleaned a lot of information from him. So, we can now detect if the waveform in a common femoral vein is abnormal to indirectly suggest that there's more proximal obstruction in the iliac veins. I think for you and I, that technique really has been pretty right on.

So, when we talk about new techniques in vascular ultrasound, PAT, looking at venous waveforms in the groin, the techs are on the frontline. We scan these patients all day long. So, when we start to look at things from a different perspective, new techniques come out and I think as long as we have the data to back it, this will just benefit all of the patients that we scan on a daily basis.

So, I love pelvic venous disease as you know. So, that study is a big comprehensive study. We look at left renal vein compression. We look at ovarian vein reflux and iliac vein reflux. Looking far beyond just venous reflux of the lower extremities, but really how to help these patients with chronic pelvis venous insufficiency. Of course, you do a great job by treating them. I think it's a good combination.

[Mary Costantino]
Well, I'm laughing because I see these patients and they've got all the symptoms. I'm just an undertreater. I'm just so conservative. I'm in a really conservative phase right now with the venous stents. Some of these pictures, these images we see on LinkedIn where it looks pretty open to me, they get stented, and I just have gotten more and more conservative not because of any bad outcome. These stents are going to be staying in these thin women for so long. I probably have between five and 10 outstanding patients right now that I feel like need stents, but I'm just not really wanting to put them in. So, I send them to Jill and then find something inevitably.

She says, "It's May-Thurner."

I'm like, "Yeah, but don't you think I can do the ovarian first or the legs periphery?"

"No. It's May-Thurner."

Then we go back and forth. Inevitably, I ended up IVIS-ing them and Jill's always right about all this stuff, but you've actually made my job more challenging, my debate of when the right perfect time to put a venous stent in, which is always, I wish I can answer that question. Your ability to detect May-Thurner by a simple ultrasound is unmatchable than anybody I've ever seen, which is supposed to make my job easier, except for if it's the answers I have to do something I don't really feel like I want to do, but it definitely helps patients.

So, final question. I think everybody should know about these great socks. I just find this so funny, Jill's socks. I'm sock obsessed because I talk about compression all day long, having developed venous insufficiency after pregnancy and coming from before this pregnancy thinking that venous insufficiency was all made up and it was just ridiculous and we needed to be spending our time doing real things like treating cancer.

So, of course, I got pregnant and developed venous disease, and I haven't been treated. So, I have to wear compression all the time for myself. Over the years, we have a company in Portland called Sock It To Me, which makes great socks. I'm talking about socks and looking at socks all day long.
Well, then these amazing flow socks. I saw these flow socks that mapped out the arteries and veins. They're my favorite pairs, and I actually use them in clinic. Mondays is my clinic day and I always wear my flow socks, so that when I'm talking about tibials, I just show the patient my socks. That's the artery that we have to open up, which I think is so cool. So, tell me about the flow socks. Where did it come from and who buys these things? Where do you sell them? What do you use them for? How did you think of that?

[Jill Sommerset]
The socks, yes. So, I run our multidisciplinary limb salvage program at PeaceHealth. Gosh! We've had it now for three years. So, when I wanted to celebrate our one year anniversary, I wanted to develop something that brought a sense of community and people to be proud to be part of this multidisciplinary program to save limbs. So, I work with a company called the SockGuy down in California, and I just thought about putting vessels out on a sock, and that's how it started out. I just gave them away for free, and then people's friends saw the socks and wanted to buy them, and they just took a life of their own.

Then I started to see the joy that socks brought to people. So, gosh, I think I've done eight different iterations of colors and adding disease and half of them I give away for free because, truly, what we all do makes a difference in people's lives. If those socks can bring a smile to a surgeon's face or an interventionalist's face, I mean, I just wanted something to bring continuity to people in this fight against amputation.

[Mary Costantino]
That's the most amazing thing about you and why it is so fun to work with you is I feel like your goal is always to spread disease awareness, save limbs. You're just using your brain and your knowledge and your skillset and you're just advancing medicine. I feel like that's number one through 99, and figuring out how to monetize anything is not even on your radar. When you lead with passion and knowledge and skill and ability and willingness to work hard, the rest of it all follows. You're just such an amazing example of that.

We all need to get back to that and be that medicine. I feel like it used to be a lot more like that. It's so refreshing to be able to work with you and we just get to geek out on this stuff, and then I get to wear your cool socks.

[Jill Sommerset]
Well, I was going to say likewise. I mean, I truly am very lucky to work with not only four great vascular surgeons, but you, Dr. Costantino, who brings that passion and energy to work every single day. You care about your patients so much and you put in a lot of value and you allow me to be part of your team and your daily practice. So, I thank you for that because that's the reason why I come to your office every single day.

[Mary Costantino]
Wow! I am hoping to steal you away from that other place soon and have you full-time. Do you have any final words? Anything you'd like to add that I've missed out on?

[Jill Sommerset]
Well, the only thing that I would add is there's some excitement of pre-DVA mapping coming in the future. I know that that's becoming more of a common technique. Pedal ultrasound can be very helpful to map out those not only arteries, but also veins to help with the preoperative mapping for DVA. So, that's an exciting place to discover as well.

[Mary Costantino]
Right. Well, thank you so much. I just cannot wait to see you at work. We have so much fun together. Jill and I always talk about how we need to actually meet up outside of work, but all of us, we just are home with families and jobs, and she's running all over saving limbs. So, we never get to hang out. So, it's really awesome spending Sunday afternoon with you.

Podcast Contributors

Jill Sommerset, RVT, FSVU discusses Pedal Acceleration Time for Limb Salvage on the BackTable 90 Podcast

Jill Sommerset, RVT, FSVU

Jill Sommerset, RVT, FSVU performs outpatient and intraoperative Advanced Vascular Ultrasound at Advanced Vascular Centers in Portland, OR.

Dr. Mary Costantino discusses Pedal Acceleration Time for Limb Salvage on the BackTable 90 Podcast

Dr. Mary Costantino

Dr. Mary Costantino is a practicing interventional radiologist with Advanced Vascular Centers in Portland, OR.

Cite This Podcast

BackTable, LLC (Producer). (2020, October 19). Ep. 90 – Pedal Acceleration Time for Limb Salvage [Audio podcast]. Retrieved from

Disclaimer: The Materials available on 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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