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BackTable / VI / Podcast / Transcript #77
Podcast Transcript: Endovascular AV Fistula Creation
with Dr. Neghae Mawla
Interventional Nephrologist Neghae Mawla from Dallas Nephrology Associates walks us through his experiences with endovascular AV Fistula creation, including devices, patient prep, procedure steps and post procedure care. You can read the full transcript below and listen to this episode here on BackTable.com.
Table of Contents
(1) The Need for Fistula Creation
(2) Candidates for AV Fistula Creation
(3) EndoAVF Pre-Procedural Steps
(4) EndoAVF Procedure
(5) EndoAVF Post-Procedural Care
(6) EndoAVF Complications
(7) Differences Between EndoAVF and Surgically Created Fistulas
(8) EndoAVF Education in Dialysis Centers
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[Chris Beck]
Ladies and gentlemen, welcome to the BackTable Podcast, if you are a new listener, welcome, for all of our regular listeners, welcome back and thank you for listening. BackTable is a podcast committed to all things IR and endovascular. I'm Chris Beck, and I'll be your host today. I'm a private practice interventional radiologist based out of New Orleans, Louisiana. Today, we have an exciting episode lined up.
Before we get to that topic I would like to take a moment to recognize our sponsor, BD. Using two thin, flexible, magnetic catheters via an endovascular approach, and a burst of radio frequency energy, the WavelinQ EndoAVF Systems creates a unique forearm split-low AV fistula, with multiple cannulation zones for hemodialysis treatment. The Wavelinq EndoAVF procedure leverages fluoroscopic guidance to help easily, and clearly visualize the catheters, and confirm the AV fistula. The WavelinQ EndoAVF System is not for all patients, to learn more, including patient eligibility visit bd.com/wavelinq, and consult product labels and instructions for use for indications, contraindications, hazards, warnings, and precautions. Again, thank you to BD. Our guest today is Neghae Mawla. Neghae, would you take a moment to introduce yourself, and tell us a little bit about your practice?
[Neghae Mawla]
Yeah, thank you again for having me. My name is Neghae Mawla, I'm an interventional nephrologist, I practice in the Dallas area up in North Dallas, in Plano. I'm one of the physicians at Dallas Nephrology Associates, and I'm one of their interventional nephrologist. We have five interventionalists in the practice, and I'm the one that picked up the EndoAVF part of the practice here. I'm using both devices, the WavelinQ and the Ellipsys device as part of my practice. I'm really excited to be here to talk about it, talk about my experiences, and whatever questions you have.
[Chris Beck]
Excellent. Just for those of us, for our listeners who may not know, will you talk a little bit about the training process for interventional nephrology, and where you are at, like how long you've been out, and how has your practice shaped up so far?
[Neghae Mawla]
The training for me was in Saint Louis University, the interventional program was part of our core curriculum. It was two years of nephrology fellowship, and within that two years was part of my intervention training. Then I came out into the Dallas practice, and when I joined Dallas Nephrology I was doing a little general nephrology, and a little interventional, and then over the years I've tweaked it and become solely interventional. My Monday through Fridays are purely into access centers, and all I'm doing are dialysis patients, and dialysis cases. There are a few programs now that will offer interventional nephrology as a subspecialty after general nephrology fellowship. I'm not sure where all they are, but I've heard that there are a few out there now.
(1) The Need for Fistula Creation
[Chris Beck]
Okay, fantastic. All right, so jumping into the topic, can you just provide our listeners the broad view of dialysis, and need for fistula creation? Give us broad scope so we can frame what we're going to jump into in a little bit.
[Neghae Mawla]
The thing about vascular access or dialysis access in particular, these patients are hooked at the machine, and the machine is running at about, on average 400 ml per minute, and so you've got to have a large caliber access--something that will support pulling the blood at 400, running it through, and returning it all back, and that's where just a plain, old access doesn't work. This is, I explain to my patients, "Put an IV in, it's not going to run fast enough." So that's really where the concept of vascular access came in, and if I remember correctly in the early days they were doing femoral artery puncture, and a femoral vein puncture, and they were using the arterial blood pressure to actually pump through the entire circuit. We're now 50, 60 years out now from the original Cimino fistula, where it was the arteriovenous fistula that allowed us to use venous access for both needles instead of an arterial access and a venous access.
So that's been the standard for all these years up until this EndoAVF, your catheter and shunts have been there along the way, but really the first innovation has been this EndoAVF in terms of, at least how to create the anastomosis in a simpler way.
[Chris Beck]
Maybe for some of the uninitiated, we have a lot of trainees who are listeners, can you talk about what we mean or what people mean whenever people say Fistula First, and why fistula creation is so important for the dialysis population? Why not just put catheters in everybody? You know what I mean?
[Neghae Mawla]
It's all about outcomes in terms of infection rates and quality. The quality of dialysis with a catheter is always lower, and the only reason catheters are still around is because of immediate use. Even then immediate use graft still takes two or three days to let the soft tissue swelling to calm down before you can access it. The graft is immediate use, but the tissue may not allow immediate use, and a lot of times that's okay, but the infection rates for catheters are higher. The outcomes with catheters at the dialysis level, and those patients are clearly lower, so that's why we made a big push to avoid catheters. The outcomes for fistulas are better than grafts in terms of lifespan, and infection, so that's why this initiative came out with Fistula First, to really try to get a fistula in someone who's a candidate because that's where the better outcomes were.
Now, the newest guidelines have gone away from a Fistula First on everybody to more of a right access for the right patient at the right time, recognizing that a 90-year old patient who starts on dialysis, whose lifespan is a year and a half or two years may not need a fistula, or go through the hassle of getting a fistula in, and struggling to get mature, that maybe a graft is better for a patient, or maybe the catheter is better for a patient. Now the algorithm is starting to change, and the question of where does EndoAVF come into this algorithm is also unclear at this time. The idea behind the Fistula First initiative was really based off the fact that a mature fistula is better than a mature graft, is better than a catheter.
(2) Candidates for AV Fistula Creation
[Chris Beck]
In broad a stroke--and I get that, like the pendulum has swung from Fistula First, fistula two, now appropriate access for appropriate patient--with that being said it is now a good time as any to jump in to the actual topic which is the endo AV fistula. Can you talk about, first, who is a candidate, and what does the pre-procedure or evaluation look like to tease apart who, and who is not a candidate for the EndoAVF?
[Neghae Mawla]
Everything is done with ultrasound screening for me in my center. The first question is to figure out, "Are they an upper arm fistula candidate or not?" So your EndoAVFs are an upper arm fistula either utilizing the cephalic vein or the basilic vein. There's no forearm EndoAVF options. The first question is, "Are they an upper arm fistula candidate?" Then if they are, then it's a matter of additional screening of the perforating vein to figure out, "Are they an endo candidate?" A lot of patients are not an endo candidate, but can be a surgical brachiocephalic or a brachiobasilic fistula for example. It really boils down to the anatomy of the perforating vein, which is typically antecubital fossa, and really identifying where that perforating vein goes. The perforating vein really just communicates the deep veins and the surface veins, and so if you look at your surface veins, meaning the cephalic and the basilic as your fistula outflow for cannulation for dialysis, if that perforating vein will communicate between one of those, or both of those, everybody got different anatomy, down to the radial veins and/or ulnar veins, then that gives you an EndoAVF option.
[Chris Beck]
Okay, and as far as your evaluation to look at these patients, it's all with an office ultrasound. You clearly have a command of the anatomy, but was there some training, and some learning curve to understand what you were looking for, and how to look for, basically sizes of vessels, the perforating vein, and things like this?
[Neghae Mawla]
Correct, there is, and both devices, Avenu and BD are actually very good about getting you, and your xenographer trained in terms of what to see, so a lot of it was getting the xenographers educated. I was one of the sites with the FDA pivotal trial for Ellipsys, and I had the experience several years ago, and so I learned it then, and I've maintained it. I utilize them in addition to having my xenographer trained, because if you talk to a regular xenographer and say, "Hey, where does this perforating vein go?" A lot of them don't know. it's not something that's routine anatomy that they look for, and so it's just a matter of getting somebody on board. It is not a lot of effort, and it's not that hard to do, it's just a new place for them to look, and new details for them to look at.
[Chris Beck]
Okay. One of the things I wanted to touch on, it seems like whether or not you have a perforating vein, and maybe the position or connection of that perforating vein is very important, but is there anything else regarding vessel diameter or arterial inflow that you look for on the preprocedural ultrasound?
[Neghae Mawla]
The general rule of thumb is a cephalic or basilic outflow of two and half millimeters, which is your general criteria for a surgical fistula. Although, this 2 to 2.5 range is a maybe, but the general consensus has always been, "Okay, is cephalic or basilic of 2.5?" So that's where I start with. In addition to just the basilic, I also look at the median cubital vein, because that comes into play for the EndoAVF. I look at a 2.0 for a median cubital vein or the cubital cephalic, perforating veins are 2.0, and then the artery dimensions are all at the minimum of 2.0. So really it's two and half at the outflow, and 2.0 everywhere else is really the threshold in terms of your vessel criteria. If you're looking at Ellipsys, it's really looking at radial, proximal radial artery perforating vein, and your outflow. If you're looking at a WavelinQ, you're looking at ulnar artery, in addition you're looking at your ulnar veins in that proximal territory, and your radial veins in that proximal territory as well for your anastomosis.
[Chris Beck]
For those who don't know, or may not have any experience with this, when you say proximal territory, will you just clarify that?
[Neghae Mawla]
Sure. Everything is at the proximal forearm, so we're looking right at the bifurcation of the brachial artery into the radial and the ulnar, and typically right around the range of the recurrent radial artery is where that perforator comes down, and communicates just adjacent to the radial artery. On the ulnar side, we look to keep it in the common ulnar artery before the interosseous take off.
[Chris Beck]
Okay. In your experience, what are the most common things that you're evaluating for in EndoAVF? What are the most common veins you see that exclude them from being a candidate for the procedure?
[Neghae Mawla]
It all boils down to vessel anatomy, things that I've tended to notice, patients that have a high bifurcation of the brachial artery in the upper arm sometimes don't have a perforator, and sometimes it doesn't communicate very well because it just seems like their superficial outflows are not that good, and they stay small. Some people have large cephalic, basilic drainage. Some people have very large brachial vein drainage naturally, because if you don't need it for dialysis I don't know that it really matters. It's a matter of which highway am I going to take home, but for dialysis I need that large cephalic and basilic drainage, and I've noticed that high bifurcations tend to have very big radial veins, and very big ulnar veins, and their superficial veins are not that big, or they just don't communicate well into the deep level.
It's not that I haven't done any, but it feels like they are less common of a catch, and then it's just those variants where everything grains into the brachial veins, and they have no cephalic or basilic outflow. A lot of people don't have perforators, but my capture rate is right around 50% I think, in terms of my screenings to those that are a candidate for EndoAVF.
[Chris Beck]
Okay. We talked about who might be excluded from being a candidate, in your mind who is the patient that comes in that is an ideal candidate for the procedures, completely based on the anatomy that you find on the ultrasound?
[Neghae Mawla]
It is. It is all based on anatomy really, then it's just a matter of talking to the patient and say, "Okay, which way do you want to go?" In general, the dilemma is not so much when it's an endo versus an open option. If it's a square-cut option patient, and you tell them, "Look, we can do this endo or we can do it open." Most of them choose the endo option. The dilemma of terms of discussions are if they have a forearm radial cephalic option, and they also have an endo upper arm option, then what's the right access for them? I don't know if there is an answer, a good answer, or a standard answer yet because our standard algorithms always say to really start in the forearm, and then work your way up for surgical fistula. But now, this endo anastomosis is at the deep level, and if an endo fistula doesn't take or goes down, it usually goes down at the deep level near at the anastomosis or at the perforating vein.
I've had a couple of patients that failed my EndoAVF, that went back later and got a radial cephalic fistula surgically, and they're doing fine. Those are the ones that I have discussions with the patients to say, "Hey, which way do you want to go? Do you want to start with the forearm, or do you want to start with the upper arm?" The question is, if an EndoAVF takes, and lasts them five years, then can you go back and do a radial cephalic fistula when that goes down? It depends on, again where it fails.
[Chris Beck]
Sure. Is the converse available to the patient in that if they go just on radial cephalic fistula, that fails, can you do Endo AV fistula subsequently?
[Neghae Mawla]
Yes, you can.
[Neghae Mawla]
So that becomes the option. So typically what my patients have been choosing, I've noticed the trend again, there's almost the bimodal curve towards EndoAVF. The elderly patients, even if they have a radial cephalic option will choose an EndoAVF just to avoid the surgical open, just to avoid anesthesia, just to avoid all of that, and this maybe the only access that they need. Someone who's 75--we'll look at lifespan--if you get them one good access that maybe the only one they need to get their access for the reminder of their time on dialysis. So the elderly patients will preferentially choose an upper arm EndoAVF over a radial cephalic fistula. The young patients who are in their 20s and 30s will do the same, choosing upper arm for cosmetic reasons more than a lifespan reason. But the patients who are in their middle age, that are more in their 40s, 50s, and even early 60s, it's a 50-50 split, a lot of them say, "I want to preserve all the access choices I can." I say, "Okay, then start with the Cimino." Some of them say, "No, let's go ahead and start up here."
[Chris Beck]
Okay, that's interesting, about the bimodal distribution, and the reason for the elderly I understand, I wasn't expecting the cosmetic thought process for younger patients.
[Neghae Mawla]
I have one patient who I put their EndoAVF in before they were on dialysis, and then he got a preemptive transplant, and he's done great, so he didn't need dialysis at all. So he came for his six month visit and he said, "I completely forgot about this," and I said, "What do you mean?" He says, "I look down I don't see it," he says, "So I forgot it's there." So I scanned him. At first, I got worried because I thought maybe it went down, I scanned him, it looks great, sizes are great, then I said, "No, it's there. It's functioning." He says, "Okay, so it's there when I need it," I said, "Exactly." This is my little byline for the EndoAVF, it's there when you need it, but it's forgotten when you don't. He completely forgot it's there because he can't tell.
[Chris Beck]
Sure, that's great. I think now is a good time as any to jump into how do patients end up in your clinic for the pre-procedural evaluation? Basically the line of thought is what are the referral patterns for this procedure?
[Neghae Mawla]
I'm unique in the sense because my practice, Dallas Nephrology Associates, has 90 plus, 95 nephrologist, and so most of my referrals are internal, and I didn't have to do a lot of effort into the marketing side of it, not all of my partners refer to me because the geography is obviously so big. I'm in North Dallas, and so the patients from the South, it's a waste for them to get up to me, so not all of them are able to, some of the patients still will make that drive up there just for the screening, but really I've kept it all internal. I do have some patients that come from other physicians, and other practices, and I think part of that is driven by dialysis clinics, because the dialysis clinics are also taking care of these patients.
So if they get a patient that initiates on dialysis they say, "What's your access plan?" Then the dialysis clinics will send them over for the vein mapping as well. They obviously check with the referring physician, but if the referring physician says, "Yeah, that's fine, I don't have preference. I don't have ... Send it to whoever you want." Then the dialysis clinics will send them over. So a lot of education is also spent at the dialysis clinic level for the referral practice, in addition to your nephrologist that would be referring to you.
[Chris Beck]
Okay, are there any nephrologists in your group, or I guess, were there any reluctant referers, even within your group, who-- imagine you guys are all colleagues, it's a big group so maybe you don't know everyone on a super personal level, but were there any people who were reluctant or had some reservations about sending patients for this procedure?
[Neghae Mawla]
There are. I think it's really mainly they just want to see how it develop and how it goes, and they want to provide the best care for their patients, and they want to make sure EndoAVF is a good option, not only in terms of the anastomosis, but you gotta see it through all the way to cannulation and catheter removal. A lot of them are waiting to see this whole process, and how it goes before they really start sending all their patients over.
(3) EndoAVF Pre-Procedural Steps
[Chris Beck]
Okay. All right, so switching gears a little bit, and back on the pre-procedure, so now the patient has been evaluated, they're deemed by you to be a candidate, that they're set for their procedure date on either ... What do you do immediately leading up to the procedure or the day of procedure to get the patient ready? What I'm driving at here is do you premedicate them with anything, either any coagulation-wise? Do they take antibiotics beforehand, or you have a pre-procedure antibiotic? Those kind of things that for someone like getting off the ground, how do you get your patient prepped and ready to go?
[Neghae Mawla]
My patient prep is really I just look at their anticoagulant list, and I hold it the day before, and the day of the procedure, Plavix, aspirin, Coumadin, Eliquis, those are the main ones. It's really just the day before, and the day of, and then assuming everything went well, then they can resume their anticoagulation that night, so they really only miss a dose. I don't know that it's really needed, it just makes me feel better, because honestly, two doses of Plavix being withheld is not really going to change much of anything. So that's the only thing, I don't do pre-operative antibiotics. I do a regional arm block on the morning of the procedure myself, and then my turn around time for the patient for door to door at our ASC is usually around three to four hours. So they can be in and out of door in three to four hours usually.
[Chris Beck]
That's great. As far as anesthesia needs, anything beyond the arm block?
[Neghae Mawla]
Conscious sedation. I'll give them conscious sedation, and I do the arm block. I think the arm block also helps vasodilate, which helps everything along the way, but there are plenty of providers who are doing this all under conscious sedation, both with the Ellipsys and the WavelinQ. It's not absolutely necessary because I know providers that are doing both without, and they are only doing under conscious, but the arm block makes it much more comfortable for me. In general, everybody has done really well with that.
[Chris Beck]
Can we take a quick detour, and talk about the nerve block? I would assume maybe you did know how to do nerve blocks before, and maybe you didn't. I haven't done one personally, but I just maybe thought I would learn a little bit about your process, and how difficult was it to learn it, and what exactly do you do?
[Neghae Mawla]
The nerve block is pretty straightforward, it's under ultrasound guidance. It is a supraclavicular nerve block that I do. I use a combination of lidocaine and dibucaine, and that gives me quick enough onset, and lasts me long enough to get through the case, especially in the early days when the cases will take a little bit longer. I tried lidocaine only in the beginning, and towards the end of some of my longer cases it was starting to wear off. So I do a combination of lidocaine and dibucaine, it is the total of 20 ccs. It's all under ultrasound, you identify the subclavian artery, and the nerve bundle is very easily visualized right there. It actually looks hypoechoic, it almost looks like vessels, so I'll usually turn on color because sometimes they branch off. The subclavian artery will course through it so just have to identify it.
I went and observed somebody doing a nerve block once, and then there was a course I went through, and then I had some people guide me as well, so the learning curve for that was actually very quick and simple. It is not hard to do, in a free-standing ASC, it's easy to add-on. In a hospital base there are more protocols you may have to go through if you want to do it yourself.
(4) EndoAVF Procedure
[Chris Beck]
All right, so let's jump into the meat of the topic, which is the procedure. Can you talk a little bit about the two systems available of EndoAVF first, and then just a 10,000 foot view of both of them?
[Neghae Mawla]
Sure. There are two systems available for EndoAVF right now, the first is the Avenu Ellipsys device, and this is the one that I was part of their initial pivotal trial for. This is all ultrasound-guided procedure, and so it took me as a nephrologist a little bit of time because I was not using ultrasound for anything other than an IJ or an femoral vein puncture for a perm cath. So learning the anatomy was a little bit there, learning to manipulate down, but the idea is basically it's a percutaneous transvenous radial artery puncture. So I take my needle into the cubital vein, usually on the cephalic side, needle down the perforating vein until you're at the level of the radial artery, and then puncture into the radial artery.
So all of these is under ultrasound, wire goes down, sheath goes down over the wire, and then the device comes over in .014 wire, and then you bring it all the way into the radial artery, and then you'll back it up. Then you leave the distal tip in the artery, the proximal tip of the device is in the vein, then it just clumps together, and then it basically uses heat. I forgot their technical terms on how each device works. Then when you activate the device, it runs through a couple of quick little burst to create the anastomosis.
[Chris Beck]
Then that's it?
[Neghae Mawla]
That's it.
[Chris Beck]
Wow. How long does that take?
[Neghae Mawla]
My average procedure time is about 15 minutes. I've gotten down into the 10 minute range, and below 10 minute on some very large vessels that belong these young patients that have great vessels, it's quick and easy to get in and out. Then that's it, take the sheath out, hold pressure, I do hepronize them with 2500 units of Heparin once my sheath is placed, sheath out, hold pressure, and that's it. 30 minute recovery.
[Chris Beck]
Okay. All right, let's talk about the other device.
[Neghae Mawla]
The WavelinQ device is dual access, so you need venous access, and you need arterial access. I typically will start with venous access first, and so the WavelinQ can be a little more tricky because you have two options, you got a radial side you could use, or you could use the ulnar side, so it's always a matter of deciding which way you want to go. Your access points can be the brachial veins, or the radial or ulnar veins. So it depending on the size, if I think the wrist veins are big enough, then I'll come in from the wrist vein up, wire in, sheath in. This is all under fluoro, but I do use a lot of ultrasound to guide my wire positioning, because sometimes these brachial veins are more than one, and it's a matter of identifying which one communicates to the anastomosis side you want.
First step is doing a fluoroscopic run from the venous network for me, then identifying the perforator, making sure I've gotten good superficial outflow, then that's my confirmatory run. This way, I've got a reasonable target zone in terms of size and length. Then I will have arterial access, and the only FDA-indicated arterial access currently is brachial artery, so you'll come from the top down, and just do a quick arterial run, and then get the wires down. Once the wires are in place then it's just the catheters coming in over the wire, again, this is an .014 wire system. I tend to like using an .018 wire if I'm coming down the brachial vein. I think manipulating through the valves seems to be a little bit easier, so I'll use an .018 wire for that. But if I'm coming up from the wrist, and not having to fight the valves then it's just the .014 wire.
Once your catheters are in place, then it's just a matter of getting them aligned properly. Sometimes that's actually the tricky part, is getting them aligned quickly and properly. The in the WavelinQ device, the venous catheter component is the active one, then basically it's hooked up to a bovie pen and a bovie machine. So think of this as an internal bovie, and it burns from the vein into the artery, so there is an active electrode on the WavelinQ catheter. The arterial catheter is just a backstop so you don't burn through and through, and it's just a capture device. So really it's just the magnetic alignment is just to make sure everything is positioned appropriately, your venous catheter is your active electrode, and that's what burns through, and creates your double slit anastomosis.
Once the catheters are aligned, you're good with positioning, then you create the anastomosis, you take it out, the venous puncture side you just usually typically hold, and then the arterial side is also being held in a routine protocol there--20 minutes of pressure for the brachial artery. Recovery is about the same actually, about 30, 40 minutes after that.
[Chris Beck]
This also sounds fairly straightforward, and how long does this one take roughly?
Neghae Mawla:
So this one ... If I'm doing a wrist approach I can get through quicker as far as the veins, because it's just a quick image and the wire goes up. My fastest was about 13 minutes, but average time probably is about 20 to 30 minutes. If I'm doing a brachial vein approach, and I have to manipulate the valves and everything, and get down, then sometimes it takes a little bit longer, but this is probably a 20, 30 in my case on average once you're comfortable. The initial cases were very long, but a lot of it was manipulating territory I was not familiar with. But yes, this is the same skill set, as interventionalists, we're always using to get where I need to. The last step that I forgot to mention about the WavelinQ is that I usually drop a coil. Since I've got access already on the brachial vein, just drop a coil on the way out before you pull the sheath.
[Chris Beck]
Okay. Maybe this is hard to gauge, but what you're describing is not new skill sets that you have to learn, it's a lot of ultrasound, some fluoro with the WavelinQ. In terms of level of difficulty, how many cases did it take for you to get comfortable with the procedure? How would you gauge the level of difficulty compared to what you do on just your standard dialysis maintenance and treatment?
[Neghae Mawla]
With the Ellipsys having no ultrasound experience, probably five to 10 cases to really understand, "Okay, this is what's happening, this is what I need to do." For the WavelinQ as well, the challenges for the WavelinQ were a little more just because they're so many variations in terms of coming down to the radial side, or coming to the ulnar side, and whether I'm going to do wrist access, or whether I'm going to do brachial vein access. But now I've got it down, so my preference is always wrist access in terms of the veins, and I always really look for that. Sometimes I'll get probably a third of the way up the forearm, away from the wrist if I think the vessels are good enough for venous access. That still gives me enough length with the sheath in there to get my device, and the catheter in there to activate. But it's really trying to figure out, "Okay, what's the streamline approach to really get in there and get going?" There were more variabilities in the WavelinQ, but once you figure those out everything goes really quick and smooth.
[Chris Beck]
Okay. All right, if we could, let's take a break real quick, and we'll have another word from our sponsor, who we appreciate their sponsorship for this podcast, and then we'll jump right back into the material, okay?
Chris Beck:
BD is focused on partnering with physicians to deliver minimally invasive solutions to some of health care's biggest challenges. When BD introduced the WavelinQ EndoAVF System they did more than just introduce an AV fistula product. They provided expert training, clinical training, and reimbursement guidance to help ensure success from patient selection through cannulation. The WavelinQ EndoAVF System is not for all patients, to learn more, including patient eligibility visit bd.com/wavelinq, and consult product labels and instructions for use, for indications, contraindications, hazards, warnings, and precautions. All right, easy, ready to jump back into it?
(5) EndoAVF Post-Procedural Care
[Chris Beck]
All right, so we've talked about the preprocedure and the procedure. Can you talk a little bit about post-procedural care, and how long you keep patients? Do they get any medications, anticoagulants?
[Neghae Mawla]
They all get heparinized, both devices I use, the 2500 units of Heparin once I have arterial access. The Ellipsys, I may not have mentioned, was a six French Slender Sheath, the WavelinQ devices are five French sheaths that I use, so sizing is about the same. Then that's it, I don't send them home on anything additional. If they're not on anticoagulants, Plavix, I don't add it to my regimen for them, and then I see them back in two weeks. The recovery time is about 30, 40 minutes. I send them home with a sling, and I just tell them, "Look, you'll be back to normal tomorrow." So part of my post-op discharge instructions are really just light activity for the first week, like keeping them under about five pounds or so. Most of them do really well with that.
They start exercising a couple of days after with the squeeze ball, and then really I think it's a matter of getting the weights, and upper arm curls to really develop the upper arm vessels. So that, I instruct them to start after a week, and I usually start with somewhere in two to five pounds, but I tell them if they want to go higher I have no problems with that. I see everybody back in two weeks, and that's when I do the first post-op sono. In discharge I will do a sonogram also, and I'll just get a baseline brachial artery flow for that particular fistula.
[Chris Beck]
Do you do that immediately after the procedure is done to establish the baseline?
[Neghae Mawla]
Correct, so in recovery I'll do that. I will do one intraoperatively just to make sure I'm happy with it, but then I've noticed that the sheath being in there tends to slow things down a little bit, particularly on the Ellipsys, because that sheath is right in that perforator sometimes. I always do one in recovery, and that's what I really use as my baseline.
[Chris Beck]
Okay. One concept I wanted to go back and drill down on, because some people may not be familiar with fistula creation in general, but can you talk a little bit more why the squeeze ball, and exercising with weights is an important part of the post-procedural care?
[Neghae Mawla]
It just helps with vessel dilation and maturation, so when we make a fistula what we want that vein to do is increase in size. Now, there's debate over whether they really work or not, but if you put a sono on an arm that doesn't have a tourniquet, and ask them to pump their fist a little bit and look at the deep veins in the forearm, on several patients you'll see that it actually increases in size while they're pumping. That's the idea behind this in terms of how we help mature these vessels to grow appropriately. Although not everybody is on board with it, the squeeze ball helps particularly in the forearm. I think upper arm weights in curling helps for the upper arm, and then there's a pneumatic tourniquet device that also may help as well that's being looked into. In my opinion it doesn't hurt.
[Neghae Mawla]
So whether it helps or not I just ask them to do it, but the squeezable I start for about the first month, and then I really tell them to focus on upper arm weights, and the heavier they want to go on I'm fine with that, but really it's to help enhance vessel dilation.
(6) EndoAVF Complications
[Chris Beck]
Okay. Talking a little bit about complications, can you talk about, in your practice what are the most common, either minor or major complications that you've seen? Then subsequently, whether or not you've seen it or not, what's the feared complication that everyone is worried about?
[Neghae Mawla]
Minor complications are just hematomas on both devices, and there's nothing to worry about. Sometimes I'll see the hematoma on the follow up visit, at the surface level. Most of the time, for example the Ellipsys, under ultrasound you can see a quick little extravasation right at the time of creation or right after, it usually self-resolves. On the WavelinQ device as well you can see hematoma form sometimes right after, and usually for that, since it's under fluoro, I'll just do a couple of subsequent runs. I'll see that extravasation, it almost looks like an extravasation, and that will resolve.
[Neghae Mawla]
The concern on both devices is obviously an uncontrolled arterial bleed, and how you would manage that, because you're basically creating a hole into the artery one way or the other. It's just a matter of is there an outflow into a vein to capture that? Iif there's not it's just going to go into the tissue, and that's the worst kind of consequence to think about in terms of, "Okay, if there's an arterial bleed how am I going to manage it? What's my line of course?" If you've got arterial access already because of the WavelinQ device it's easy to do, you can throw a balloon down there, and tamponade it off if you need to. If you're doing an Ellipsys then I always have the radial artery at the wrist prepped just in case I need to get quick arterial access, and just put a sheath in the radial artery at the wrist, and take a three millimeter balloon up, and just tamponade it from that standpoint.
[Chris Beck]
So we touched on it briefly, you said, I think I remember that the clinic visit is after the procedure two weeks?
[Neghae Mawla]
Correct. So the first follow-up visit is two weeks, and it's really just to make sure my flows are where I want. So everyone has their own number in terms of what the brachial artery flows want, so the baseline reading is always in the brachial artery. So when I bring them back for ultrasound, really I'm measuring the brachial artery flow first, and the idea is inflow equals outflow. So whatever number I get in my brachial artery I should see that along the venous outflow tracts. Because an EndoAVF is a side to side anastomosis it gives me multiple venous outflow tracts.
The majority of it that I want is in the superficial veins, so the cephalic and, or the basilic vein. But because it's a deep anastomosis, I will also get flow into the brachial veins. So what I measure is brachial artery flow, and let's assume I get 500, that's the target. I'm going to measure cephalic vein flow, basilic vein flow, and brachial vein flow, all of those should equal pretty close to plus or minus a 100 my brachial artery flow.
[Chris Beck]
No, it makes perfect sense. So you mentioned the minimum of what you're looking for in the brachial artery, what is the minimum that you're looking for in your coronary venous drainage?
[Neghae Mawla]
So usually 400, if I'm going to run them at 400 then I want it to be 400, but I've noticed that if the brachial artery flow is 500, and it's all primarily superficial, then they have been okay. So the challenge becomes in your venous drainage for your dialysis is whether it's a single outflow or a double outflow. Some perforating veins will communicate only to the cephalic, or only to the basilic, and so then you have to plan accordingly in terms of cannulation, but also maturation for those tends to be a little bit faster, and requires a little less slow. The perforators that communicate to both the cubital, meeting cubital vein for basilic outflow, and the cephalic outflow tend to take a little bit longer, and I tried to keep those flows a little bit higher at 700. I've noticed that those vessels take a little bit longer to mature. They actually may take a little bit more than three months versus a single outflow, which usually I can get them up and running inside six weeks to 10 weeks.
[Chris Beck]
Okay. Two questions, one, how long do you wait for maturation in somebody who is not progressing as well as you would expect? Is there anything you can do about it to either redirect flow or improve flow to your primary venous drainage?
[Neghae Mawla]
So the two week flow check is really just to make sure everything's patent, everything's settled down. On occasion, I will angioplasty at the two week visit, but most of the time I'd not have to do that, that's very rarely the exception where they come in, and their brachial artery flow maybe 200, 250, and I say that's just really isn't going to cut it in terms of development. But usually I look at the six week sizing, and if the flows are still below 500 at the six week margin then I say, "Okay, let's go in and do an angioplasty for single vessels." If the flows are below 700, then I say, "Okay, let's go do an angioplasty and take a look."
So for the Ellipsys, and these are on dialysis patients, if they're not on dialysis and on CKD then I usually will say, "If we don't need it right now, why go in there and try to rush it?" I give it another four weeks, and I let them come back. I basically see them once a month after that initial two week visit. So for Ellipsys it is a radial artery approach at the wrist, and all of minor distal radial access in the snuff box for my maturation procedures for actually, for both devices I do distal radial artery access. For the Ellipsys device it's usually just a matter of doing an angioplasty at the anastomosis and perforating vein, and I will come in with a six millimeter balloon at that point.
For the WavelinQ device, it’s a lot of times the radial vein in between the anastomosis and the perforating takeoff that needs to get angioplasty, so I'll go in there, same with the five or six--I usually start with a five--and then I'll follow with a six millimeter balloon, and open up that superficial outflow. While I'm in there if I feel like the brachial veins are very competitive, I can usually get a wire into the brachial vein and drop a coil, if not, I will just do a brachial vein stick and drop a coil that way.
[Neghae Mawla]
For the WavelinQ on the ulnar side, the same, I do wrist ulnar artery access to make sure that I can get in, both devices, if they develop a stenosis it's almost a juxta-anastomotic stenosis that we're typically seeing with a surgical fistula. It's usually the ulnar vein right above the anastomosis on the WavelinQ, or the radial vein just above the anastomosis. Then on the Ellipsys it's that perforating vein because that happens to be right above the anastomosis. Those are the main places where I do the angioplasty.
[Chris Beck]
Got you. Got you. That was going to be my next question, is where are the common places that you actually get the stenosis? In your experience, has it been near, about 90%, that's where you get the juxta-anastomotic segment you're going to find the narrowing?
[Neghae Mawla]
It's right there, that juxta-anastomotic segment.
[Chris Beck]
On average, when will the fistula be ready to use? Then also, when do you clear it for use? Let's say you have a patient who's on dialysis, and soon as you clear it's ready to go, and how fast are they to develop from there?
[Neghae Mawla]
Most of my accesses I target, especially for the dialysis patients, in that six to 10 week window. If it's a single outflow six weeks is usually good enough, and the cephalics are the simplest and the quickest. I don't know why, but they mature very quickly, so if I've got an endo cephalic they are usually ready to go inside four to six weeks, but I only see them at the six week mark, when they come back they're ready to go. The endo basilics are similar, sometimes that median cubital vein takes a little bit longer to dilate up, and so I usually wait for that. My threshold is five millimeters in diameter for cannulation, and so it's a matter of getting a flow above 500 and vessels a diameter of five millimeters to cannulate. My dual outflows tend to take a little bit longer, and so those perforators that are fairly feeding both the cephalic and the median cubital for the basilic are the ones that I'm probably waiting 10 weeks, 12 weeks before they're ready to cannulate.
[Chris Beck]
Okay. One question, with the dual outflows, are both outflows available for access?
[Neghae Mawla]
Yes. So that's typically my approach, is cannulating one into each vessel.
(7) Differences Between EndoAVF and Surgically Created Fistulas
[Chris Beck]
Okay, single sticks into those vessels. For some people who don't know anything about this procedure, can you talk about the difference between what a standard surgically created fistula looks like versus an EndoAVF?
[Neghae Mawla]
So if you look at an upper arm fistula the surgical fistula is usually anastomosed to the brachial artery above the cubital fossa, and so you've got a cephalic alpha, and it's an end-to-side anastomosis, and so either you will have a cephalic outflow or you will have a basilic outflow. Basilic thing gets transposed and elevated as well because as it travels up the arm it tends to dive in underneath the bicep's muscle, and just the way it courses, it's hard for the patient to sit there on dialysis with the needles on the inside of the arm. So the surgeon will elevate it, and transpose it, bringing it more to the front, so the dialysis nurses can access it.
Because the endo-anastomosis is actually in the proximal forearm you get a little bit more real estate in terms of cannulation zone. So your cephalic outflow, you have the cubital cephalic vein in addition. Your basilic outflow, or your dual outflows, you also get the median cubital vein. So for dialysis I actually utilize the median cubital vein for my cannulation site. So if I've got an endo basilic, meaning that there's no cephalic outflow, I will plan on cannulating across the median cubital vein, and I have been able to get most of my patients cannulated without a basilic elevation or transposition. One of the, I think really nice advantages of an endo option is if that patient only has a basilic vein, then it doesn't absolutely require an elevation and transposition because that's actually a pretty big surgery sometimes, especially on these elderly patients.
[Chris Beck]
There is an option though in terms if you did need a basilic vein transposition to collaborate with, maybe vascular surgeons on this procedure, in which you could still do the endo AV fistula, and then they could participate in the transposition portion of the procedure.
[Neghae Mawla]
Absolutely, and I've done that. The patients that have required an elevation, I reached out to my surgeon and said, "Look, I've got enough. Fistula's great, the vessels sizes are great, flows are great, I just don't have enough room for two needles. I can get one needle in if I needed to, but that second one it's just not going to take, these median cubital vein just dives down really steep as it crosses over.” So I've had one of my surgeons elevate that.
Another patient actually came to me because the surgeon saw the patient and said, "We're going to do a two-stage basilic transposition." The basilic vein is of a marginal size, the surgeon may opt to do it as a two-stage procedure, one, just to create the anastomosis, wait for it to develop, and then after it's matured then do the basilic elevation. So the patient was a little apprehensive about two surgeries, went back and told the nephrologist, "Hey, he says I'm good to go, but he wants to do it in two stages," and this was a non-dialysis patient. The nephrologist, who was my partner, says, "Maybe we could do stage one endovascular, send them to me." He said, "Yeah, you're right, we can." So I did stage one, created the anastomosis, once it was matured and good to go then the surgeon did the full transposition in the end.
So there is a lot of inter-specialty correlation that I think is a great option for these patients, especially the ones that are apprehensive about two surgeries, even though it may not necessarily be a big surgery to do stage one. Yeah, a stage one endo basilic anastomosis followed by a surgical elevation I think is a great option for some of these patients.
[Chris Beck]
Going back to, now, the end user of these fistulas, and actually, of course it's all for the patient, but we talked about one of the roadblocks or potential roadblocks for the procedure is dialysis unit nursing staff education on endovascularly created AV fistulas. Can you talk a little bit about that topic in overcoming some of ... what those hurdles are, and then how you overcome some of those?
[Neghae Mawla]
So the challenge is because the anastomosis is a proximal forearm anastomosis, most of the flow comes across the cubital fossa into the superficial outflow. The dialysis clinics are used to the anastomosis just above the elbow, and so their cannulation sides are a couple of inches above the anastomosis, which for a surgical fistula is fine, but standard cannulation sites on an endo fistula is really too far away. It's not that they go away, it's just not strong enough there to really allow cannulation in the mid upper arm, so most of my cannulation has been cubital fossa-ish cannulations, much lower than they're used to. So that's one hurdle is to say, "Okay, we're going to stick you somewhere new."
The second thing is the vessels across the cubital fossa are much more superficial than where they normally cannulate, than higher up into the arm, so the entry angle is not that steep. So they are used to this 45 degree entry, and to get down into the vessel, and if you do that in the cubital fossa you're typically going to go through and through. It's really a matter of getting them rethink this approach almost like a phlebotomist, and to go very shallow with the entry along the cubital fossa. That's really where the mindset changes to be, "Okay, an endo anastomosis, I have to approach a little bit differently than a surgical anastomosis." Both devices have been giving me very good support in terms of getting an educator and a trainer out to the dialysis clinics.
Once I clear the patient the next thing I'm going to do is I'm going to draw a roadmap on their patient's arm, and basically where the cannulation zones are, and then I stick a Tegaderm on it and I say, "Okay, go to dialysis, let them know this is where we're going to stick." Then I call the company, and then they send an educator out to that patient's dialysis center, and both companies have been very supportive of me in doing this. That educator has a picture of that arm, because I'll take a picture of the arm after I've marked it. I'll let the patient take a picture of the markings so that they have their own permanent record, and they go and educate the staff on that patient's arm, and the tips and tricks for the cannulation site. This includes both staying in the cubital fossa, and the entry angle, and that has been very successful in terms of getting these patients up.
I've noticed it takes about probably four or five patients at each clinic before they're completely confident and comfortable, where I can just draw on the arm and send the patient to the clinic, and then they can say, "Yeah, okay, we got it." But the initial patients are always educated, and I've done a lot of them myself, where I will go out and say, "This is where we are. This is where we go," and I guide them to the cannulation.
(8) EndoAVF Education in Dialysis Centers
[Chris Beck]
Okay, that's great. I kind of know the answer to this, but there must be some inertia in some of these places that have been doing something for a long time a certain way, and then changing them or getting off their routine, and their standard of practice. Some dialysis units have algorithms and protocols in place to help everyone be safe and they have standard operating procedure. Have there been some difficulties in breaking down some of those walls, and re-education of these units?
[Neghae Mawla]
There has, and there's been a lot of movement to re-educate these clinics, and to say that, "Look, an EndoAVF is a little bit different, it's not your standard fistula cannulation techniques that you're used to, protocols that you're used to." Actually because it's so superficial there is a shorter needle, the average needle for dialysis clinics is a one inch needle in terms of length, but there is a shorter ⅗ inch needle that I typically start my EndoAVF cannulations with. So I'll get the clinic to order that ahead of time saying, "All right, this patient's maturing, can you order these needles so when we need them, you're ready to go?" That's made cannulation problems a little bit easier by having the shorter needles.
Then there's the mindset to say, "All right, look, this is something not just new for everybody, but this is something that's better for the patients in terms of how it was done, maybe even the outcomes compared to surgical fistula." Because if you think about it, not only is this a multi-outflow, but this is a lower flow fistula so maybe some of these long-term issues that we manage in terms of stenosis and cephalic arch stenosis, who knows, maybe an endo cephalic fistula will never develop that cephalic arch stenosis because that flow is never high and turbulent enough to have an issue down the line.
So it's not just a cosmetic thing that I think about for the patients, I actually think there may be a physiological flow benefit that only time will tell. I can't say that for confidence, but to explain to them that, "Look, this is not something that is a challenge because I want it to be a challenge or just because it's cool. I think this is actually better for the patient, and by doing this, and learning this we're actually taking better care of the patients." So that is usually what gets people on board.
[Chris Beck]
So you're pioneering, you're tracking through new ground, but hopefully people who are early adopters of this procedure will do some of the heavy-lifting, and then as it becomes more mainline then some of these barriers have been broken down it won't be so difficult. Not to say that it's super difficult, but I realized that whenever you roll out something new that there's some inertia that you have to overcome in terms of your own staff, and then the end users, which are the dialysis units.
[Neghae Mawla]
The biggest rollers and movers of this inertia are the patients. If you look back at the history of laparoscopic cholecystectomy, there was a lot of resistance from some surgeons along the way. I grew up in a small town in Texas, but I still know some of the surgeons back there, and I asked one of them, I said,, "Hey, do you remember when the lap chole started?" He says, "Oh, yeah, I remember." I said, "And?" He said, "Yeah, I assisted on the very first lap chole in town." I said, "How did it go?" He said, "It took us five and a half hours. Two surgeons, five and half hours," and I said, "And what happened in that first interim window?" He said, "I watched complications. I watched lap choles get converted to open." He said, "I watched patients end up in the ICU. I saw patients die," he says, "and I never did it." I said, "But you're a big laparoscopic surgeon now," I said, "What changed? How did that change?"
He said, "I went six months, and I would not offer a lap chole." He says, "Patients would come to me in the office," and this was back in 1990, before Twitter, and things went viral, everything like that. He said, "Patients would come see me in the office, and when I told them I would only do an open, they left me." He said, "So I knew that in order to stay relevant, I had to adopt this technology," and this is how I see the EndoAVF movement. It's not going to be driven by the doctors, it's going to be driven by the patients, and it's the patients who I see on followup that are loving it.
One of my patients and his wife are both in the healthcare field, and she is an ER nurse, and she cannulates him at home, and he is doing home dialysis now. But I remember their faces when I told them that, "Yeah, your fistula's mature, and ready, and done." Because they both know in their head what a fistula is supposed to look like, and they said, "You're kidding, that's it?" If you could have seen the smiles on their faces, and now that they've been dialysing for four, five months now, and how it looks, and they've got great buttonholes, and they're young, and otherwise they're healthy, and they walk around, and nobody knows. They don't have to explain, "What is this in your arm? What are the bumps? What's going on? Why does this vessels stick out?" He lives a normal life, and nobody knows. These are the people that are driving this movement, it's not me or you, or the dialysis nurses and technicians. Yeah, we're a big part of it, but the ones that are driving it are the patients.
I now have patients that are coming only because they've seen another patient in that clinic, and they say, "That's what I want, can I get it too?" This is where the success of EndoAVF is going to come from. It's the patients, it's not the operators or the providers, it's the patients.
[Chris Beck]
I think there's also something to be said for that, dialysis patients spend time with each other as a community within a community, and they talk, and they discuss different doctors, techniques, and things like this, and you're right, there can very much be a grassroots movement amongst dialysis units in terms of them marketing different things for each other. So that's really neat, and it makes you feel like when the patients are driving the direction that it feels like we're going into the right direction.
[Neghae Mawla]
Right.
[Chris Beck]
Yeah. So, Neghae, we got a lot of interventional listeners, we have vascular surgery listeners, interventional nephrology listeners, for people who are interested in getting in this procedure, and they're just starting to dip their toes in the water, are there any resources that you would recommend or things that would maybe make this process seem less daunting, or easier to approach?
[Neghae Mawla]
It's going to sound weird, but YouTube is actually a great reference because if you Google this there's actually live cases, I think of both devices where somebody has recorded and put up there in terms of watching what a live case looks like. I think every society has videos as well, whether it be the IR or the vascular surgery, or the Interventional Nephrology Society has videos, and libraries as well for you to go research and review. There have been several now. The pivotal articles were great, but I think there's a couple of articles now that are really showing up in the journals in terms of short-term, long-term, two, three year outcomes with these patients, that is very encouraging. Then it's just a matter of reaching out to the reps, and they can get you educated.
I think everybody has something that is a BD product, and so it's just starting with a BD rep, and then finding the Avenu rep for your area to contact. If you're unsure then they can contact me, and I can get them hooked up with either one of the representatives from either device, at least the contact name or to say, "Hey, go find this doctor, they're interested." So anything that I can do to help I'd be glad to do. I think this is a great thing for the patients in the long run.
[Chris Beck]
All right, that's awesome. We'll make sure that we have a link to your email for anyone who wants to get in touch. So that about wraps things up, to our audience, thank you for listening. We covered an important topic today, an exciting topic, if you enjoyed the podcast, and want to support the show, here are two easy ways, first, take a second and press the Subscribe button on whatever platform you're listening in on. This helps platforms like iTunes and Spotify know that you, our audience, value what we're doing, and you're interested in getting our latest content as we're producing it. Second, if you're getting a lot of value from this podcast, please go to iTunes and leave us a short review, it helps us in so many different ways. We love the feedback. That will wrap things up, we'll see you next time in the BackTable Podcast. Thanks.
Podcast Contributors
Dr. Neghae Mawla
Dr. Neghae Mawla is an Interventional Nephrologist with Dallas Nephrology Associates in Texas.
Dr. Christopher Beck
Dr. Chris Beck is a practicing interventional radiologist with Regional Radiology Group in New Orleans.
Cite This Podcast
BackTable, LLC (Producer). (2020, August 17). Ep. 77 – Endovascular AV Fistula Creation [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.
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