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BackTable / VI / Article
WavelinQ & Ellipsys for EndoAVF Creation
Lauren Fang • Updated Aug 20, 2024 • 1.2k hits
Interventional nephrologist Dr. Neghae Mawla explores the use of the WavelinQ and Ellipsys devices for creating EndoAVFs. The discussion includes pre-procedure preparation, the procedural details for using WavelinQ and Ellipsys, post-procedure care, potential complications, the learning curve, and the future outlook for EndoAVF. These devices assist in endovascular AV fistula creation and anastomosis.
We’ve provided the highlight reel in this article, but you can listen to the full podcast below.
The BackTable Brief
• The Ellipsys EndoAVF procedure device is ultrasound-guided and is used to make a single percutaneous puncture of the deep communicating vein in the proximal forearm and the radial artery. The WavelinQ EndoAVF procedure device requires separate venous and arterial access. Venous access points include the brachial veins, radial, or ulnar veins. Arterial access is obtained through the brachial artery.
• For the Ellipsys device, Dr. Mawla uses a .014” wire and a six French Slender sheath. Depending on if he has to manipulate through valves, Dr. Mawla will use a .018” or .014” wire with the WavelinQ in addition to 5-French sheaths. For both devices, he administers 2500 units of Heparin once arterial access is obtained.
• WavelinQ and Ellipsys EndoAVF creation takes between 15 to 30 minutes on average to complete. The recovery time is 30 to 40 minutes, and patients are sent home with instructions to do exercises with a squeeze ball and weights to help with vessel dilation and fistula maturation.
• Potential EndoAVF complications include hematomas and uncontrolled arterial bleeds.
• On occasion, Dr. Mawla performs an angioplasty post-op if the flows are inadequate.
• Dr. Mawla notes a learning curve for Ellipsys and WavelinQ EndoAVF procedure devices, especially with ultrasound. Having a trained sonographer is essential. For Dr. Mawla, it took about 5 to 10 cases before getting comfortable with the Ellipsys. Educating dialysis unit nursing staff on endofistula positioning, where to cannulate, how to cannulate using a more shallow entry approach, and utilizing a shorter-than-one-inch dialysis needle has been important as well.
Table of Contents
(1) EndoAVF Pre-Procedure Preparation
(2) WavelinQ & Ellipsys EndoAVF Creation
(3) EndoAVF Post-procedure Care
(4) Dealing with EndoAVF Complications
(5) WavelinQ & Ellipsys EndoAVF Procedure Learnings
EndoAVF Pre-Procedure Preparation
Dr. Mawla holds any anticoagulants the day before and the day of the EndoAVF procedure. He does not prescribe any preoperative antibiotics. On the day of the procedure, he performs a regional arm block with conscious sedation.
[Chris Beck]
When the patient has been evaluated and deemed by you to be a candidate, what do you do immediately leading up to the procedure or the day of procedure to get the patient ready?
[Neghae Mawla]
My patient prep is 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. I don't know that it's really needed, it just makes me feel better, because honestly, two doses of Plavix being held is not really going to change much of anything. I don't do pre-operative antibiotics. I do a regional arm block on the morning of the procedure myself. At our ASC, patients can be in and out of the door in three to four hours usually.
[Chris Beck]
As far as anesthesia needs, are your patients getting anything beyond the arm block?
[Neghae Mawla]
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.
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WavelinQ & Ellipsys EndoAVF Creation
The Ellipsys EndoAVF procedure device is ultrasound-guided and is used to make a percutaneous transvenous radial artery puncture. Dr. Mawla brings the Ellipsys device over in a .014” wire into the radial artery. The distal tip is left in the artery, while the proximal end of the device is left in the vein. The Ellipsys uses bursts of heat to clump the vein and artery together, creating an anastomosis. Dr. Mawla’s average procedure time with the Ellipsys is about 15 minutes. The WavelinQ EndoAVF procedure device requires both venous access and arterial access. Venous access points include the brachial, radial, or ulnar veins, and arterial access is obtained through the brachial artery. Dr. Mawla does a fluoroscopic run from the venous network, identifies the perforator, and ensures good superficial outflow. Then, he does an arterial run. Depending on if he has to manipulate through valves, Dr. Mawla will use a .018” or .014” wire. He places the catheters, which are magnetically aligned and positioned. Then, he activates the electrode on the venous catheter to burn from the vein into the artery to create the anastomosis. Dr. Mawla’s last step is deploying a coil on the way out before pulling the sheath. His average procedure time with the WavelinQ is 20 to 30 minutes.
[Neghae Mawla]
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 Wavelike and the Ellipsys device as part of my practice. I'm really excited to be here to talk about it, my experiences, and answer whatever questions you have.
[Chris Beck]
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]
There are two systems available for EndoAVF procedures 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, and so it took me as a nephrologist a little bit because I was not using ultrasound for anything other than an IJ or a femoral vein puncture… 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 I’m at the level of the radial artery, and then I puncture into the radial artery. All of this is under ultrasound, wire goes down, sheath goes down over the wire, and then the device comes over in a .014” wire. Then, you bring it all the way into the radial artery, and then you'll back it up. You leave the distal tip in the artery, the proximal tip of the device is in the vein, then it just clumps together, and it basically uses heat. You activate the device, and it runs through a couple of quick little bursts to create the anastomosis.
[Chris Beck]
Then that's it?
[Neghae Mawla]
That's it. My average procedure time is about 15 minutes. I've gotten down into the 10 minute range and below 10 minutes on the young patients that have great vessels. Then that's it, take the sheath out and hold pressure. I do hepronize them with 2500 units of Heparin once my sheath is placed.
[Chris Beck]
Okay. Let's talk about the other device.
[Neghae Mawla]
The WavelinQ EndoAVF procedure device is dual access, so you need venous access and you need arterial access. I typically will start with venous access first. 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 other 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, depending on the size. If I think the wrist veins are big enough, then I'll come in from the wrist, wire in, sheath in, and then the first step. 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. I make sure I've gotten good superficial outflow, and that's my confirmatory run that I've got a reasonable target zone in terms of size and length. Then I will do arterial access, and the only FDA-indicated arterial access currently is brachial artery, so you'll come from the top down, 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 a .014” wire system. I tend to like using a .018” wire if I'm coming down the brachial vein. Manipulating through the valves it seems to do a little bit easier, so I'll use a .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.
[Chris Beck]
Okay, so it's a lot of ultrasound, some fluoro with the WavelinQ.
[Neghae Mawla]
Once your catheters are in place, then it's just a matter of getting them aligned properly. Sometimes that's actually the tricky part, getting them aligned quickly and properly. The way the WavelinQ device is, the venous catheter component is the active one. Then basically it's hooked up to a bovie pen and a bovie machine. Think of this as an internal bovie. It burns from the vein into the artery, and 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. 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 anastomosis. Once the catheters are aligned and you're good with positioning, then you create the anastomosis. You take it out, and the venous puncture side you just usually typically hold. 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]
How long does this one take roughly?
[Neghae Mawla]
If I'm doing a wrist approach, I can get through quicker as far as the veins. 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 skillset as interventionalists. I’m always using fluoro, wire, catheter to get where I need to. The last step that I forgot to mention about the WavelinQ is 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.
EndoAVF Post-procedure Care
Following a WavelinQ or Ellipsys EndoAVF procedure, Dr. Mawla sends patients home with instructions to exercise with a squeeze ball and later progress to weights and upper arm curls. The purpose of these exercises is to promote vessel dilation and maturation. Dr. Mawla also checks for adequate inflows and outflows, which should match. It can take 6 to 10 weeks for a single outflow endo fistula to mature. Dual outflows tend to take a little longer, around 10 to 12 weeks, before they are ready to cannulate.
[Chris Beck]
Can you talk a little bit about post-procedural care, and how long you keep patients? Do they get any medications, anticoagulations?
[Neghae Mawla]
They both get hepronized. 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, 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, I don't add it to my regimen for them. I see them back in two weeks. The recovery time is about 30 to 40 minutes. Their arm, I send them home with a sling, and I just tell them, "Look, you're going to be back to normal tomorrow." Part of my post-op discharge instructions are really just light activity for the first week, keep 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 at two weeks, and that's when I do the first post-op sonogram. 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 or when I pull back that. I always do one in recovery, and that's what I really use as my baseline.
[Chris Beck]
So there’s a clinic visit after the procedure at two weeks?
[Neghae Mawla]
Correct, and it's really just to make sure my flows are where I want. Everyone has their own number for the brachial artery flow, so the baseline reading is always in the brachial artery. When I bring them back for ultrasound, really I'm measuring the brachial artery flow first, and the idea is inflow equals outflow. Whatever number I get in my brachial artery, I should see that along the venous outflow tracts, and 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 100 my brachial artery flow.
[Chris Beck]
It makes perfect sense. 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]
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… The perforators that communicate to both the medial cubital vein for basilic outflow and the cephalic outflow tend to take a little bit longer, and I try 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. Usually, I can get them up and running inside six to 10 weeks.
[Chris Beck]
Why the squeeze ball and why is exercising with weights an important part of the post-procedural care and instructions?
[Neghae Mawla]
It just helps with vessel dilation and maturation. When we make a fistula, we want that vein to 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, on several patients you'll see that the deep veins in the forearm actually increase 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 buys. The squeeze ball helps particularly in the forearm. I think upper arm weights in curling helps for upper arm, and then there's a pneumatic tourniquet device that also may help. In my opinion it doesn't hurt. I just ask them to do it. The squeeze ball I start for about the first month, and then I really tell them to focus on upper arm weights. Really, it's to help enhance vessel dilation.
[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 as soon as you clear it's ready to go, 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. The cephalics are the simplest and the quickest. I don't know why, but they mature very quickly, so if I've got an endocephalic, they are usually ready to go inside four to six weeks. But, I only see them at the six week mark. The endobasilics 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.
Dealing with EndoAVF Complications
Minor complications of EndoAVF include hematomas. The potential major complication with both devices is an uncontrolled arterial bleed. This can be managed with balloon tamponade. On occasion, Dr. Mawla performs an angioplasty if the flows are not adequate.
[Chris Beck]
In your practice what are the most common, either minor or major, complications that you've seen? Whether or not you've seen it, 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, but 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 a hematoma form sometimes right after. Usually for that, since it's under fluoro, I'll just do a couple of subsequent runs, and I'll see that it almost looks like an extravasation, and that will resolve.
[Chris Beck]
Okay.
[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. If 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 EndoVAF procedure, then I always have the radial artery at the wrist prepped just in case I need to get quick arterial access. Then, I just put a sheath in the radial artery at the wrist, take a three millimeter balloon up, and tamponade it from that standpoint.
[Chris Beck]
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 do an angioplasty at the two week visit. Most of the time I don’t have to do that. It’s rarely the case where they come in, and their brachial artery flow may be 200, 250, and I say that's just really isn't going to cut it in terms of development. 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, 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. For Ellipsys, it is a radial artery approach at the wrist, and I use distal radial access in the snuff box for all of my maturation procedures. For the Ellipsys device, it's usually just a matter of doing an anastomosis, an angioplasty at the anastomosis and perforating vein, and I will come in with a six millimeter balloon at that point.
[Chris Beck]
And for WavelinQ?
[Neghae Mawla]
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. 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. For the WavelinQ, on the ulnar side, the same. I do wrist ulnar artery access to make sure that I can get in. For 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. 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.
WavelinQ & Ellipsys EndoAVF Procedure Learnings
Prior to using the Ellipsys and WavelinQ EndoAVF procedure devices, Dr. Mawla and his sonographer were trained. Having very little ultrasound experience, Dr. Mawla did about five to 10 cases before getting comfortable with the Ellipsys. Challenges in learning the WavelinQ came down to the many variations of approaching from the radial side or going to the ulnar side and proceeding with wrist or brachial vein access. Educating dialysis unit nursing staff on endovascularly created AV fistulas has been important as well. Dr. Mawla has had great success with calling the device companies and getting them to send an educator to a patient’s dialysis unit. They can help explain the different positioning of an endo fistula compared to a surgical fistula, where to cannulate, and how to cannulate using a more shallow entry approach along the cubital fossa.
[Chris Beck]
As far as your evaluation to look at these patients, it's all with an office ultrasound. Was there some training and some learning curve to understand what you were looking for or how to look for sizes of vessels, the perforating vein, and things like this?
[Neghae Mawla]
Correct, there is. Both devices, Avenu and BD, are actually very good about getting you and your sonographer trained in terms of what to see, so a lot of it was getting the sonographers educated. My experience came from being with one of the sites with the FDA Pivotal Trial for Ellipsys. I had the experience several years ago, and so I learned it then, and I've maintained it. If you talk to a regular sonographer 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. 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]
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 procedure, 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 procedure as well, the challenges were the 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, and 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?"
[Chris Beck]
One of the roadblocks or potential roadblocks for the procedure is dialysis unit nursing staff education on endovascularly created AV fistulas. What are those hurdles, and how can you overcome some of those?
[Neghae Mawla]
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 sites are a couple of inches above the anastomosis, which for a surgical fistula is fine. But, for standard cannulation sites on an endo fistula, it 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. 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. 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 to 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 say, "Okay, an endo anastomosis, I have to approach a little bit differently than a surgical anastomosis." Both devices have given 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 draw a roadmap on the patient's arm, where the cannulation zones are. 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, and both companies have been very supportive of me in doing this.
[Chris Beck]
Some dialysis units have algorithms and protocols in place to help everyone be safe, and they have standard operating procedures, but has there been some difficulty in breaking down some of those walls and re-education of these units?
[Neghae Mawla]
There's been a lot of movement to re-educate these clinics, saying "Look, an EndoAVF is a little bit different, it's not your standard fistula cannulation techniques or 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 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--having the shorter needles.
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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