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BackTable / VI / Podcast / Transcript #328
Podcast Transcript: Adrenal Vein Sampling
with Dr. Fritz Angle
In this episode, host Dr. Ally Baheti interviews Dr. Fritz Angle about adrenal vein sampling, including indications, workup, and his technique for accessing the right adrenal vein. You can read the full transcript below and listen to this episode here on BackTable.com.
Table of Contents
(1) Patient Workup for Adrenal Vein Sampling
(2) Pre-Procedure Protocol
(3) One Access Site or Two?
(4) Cannulating the Right Adrenal Vein
(5) Cone-Beam Settings For an Adrenal Vein Run
(6) Confirming Right Adrenal Vein Cannulation on Angiogram
(7) Sampling From the Adrenal Vein
(8) Additional Pearls for Right Adrenal Vein Sampling
(9) Cannulating the Left Adrenal Vein
(10) Interpreting the Results and Patient Follow-up
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[Dr. Aparna Baheti]
I'm your host, Dr. Ally Baheti, coming to you from Tacoma, Washington. My guest today is Dr. Fritz Angle, Director of Interventional Radiology at the University of Virginia. Our topic today is adrenal vein sampling. Dr. Angle, thank you for being on the show.
[Dr. Fritz Angle]
My pleasure. Great to hear your voice again, Ally.
(1) Patient Workup for Adrenal Vein Sampling
[Dr. Aparna Baheti]
Okay let's just get right into it. Adrenal vein sampling. What are some of the indications that you see for this procedure?
[Dr. Fritz Angle]
Almost every referral for adrenal vein sampling is patients have primary hyperaldosteronism, and this is a clinical diagnosis. Patients should come from an endocrinologist. Sometimes you'll get referred by primary care doctor. That's an important distinction, but that's pretty much the only indication is primary hyperaldosteronism.
[Dr. Aparna Baheti]
How common is that disease in the general population?
[Dr. Fritz Angle]
So we're seeing increasing numbers of this. I think finally we're starting to detect more of these. It accounts for less than 5% of hypertension, which doesn't sound like much, but there's a lot of hypertension out there. I mean, worldwide, there's probably a billion people walking around with hypertension. This is a well under-diagnosed disease.
[Dr. Aparna Baheti]
So walk me through your workup for these patients before you start the procedure on them.
[Dr. Fritz Angle]
The most important thing, the easiest thing for you to do is you just need to see the aldosterone-renin ratio, and that should be more than 20. The referring doctor should have figured that out before they send that to you. These people are making too much aldosterone, and it should suppress their renin. Sometimes the renin levels are undetectable, which means you have a very high ratio. If it's less than 20, you may want to send that patient back to that referring doctor for a little bit more in-depth analysis.
[Dr. Aparna Baheti]
Are these labs that you require prior to seeing them in the clinic?
[Dr. Fritz Angle]
That's exactly right. There's really not much I want to see before, but you need to know what their aldosterone and renin levels are, and beyond that, really just list of their medications, allergies, the usual things.
[Dr. Aparna Baheti]
Do you see all these patients for a pre-visit in your clinic?
[Dr. Fritz Angle]
I do. I highly recommend everyone do this. It's a simple procedure. You may say, "Why bring these people through clinic?" So often, there are surprises in the clinic, and usually, the lab work you're looking for isn't available or hasn't been done. CAT scan that you require hasn't been done, or you need to review the medications that are on that can interfere with the test.
(2) Pre-Procedure Protocol
[Dr. Aparna Baheti]
I see. I know we have a list of medications you can look up online, but off the top of your head, can you tell our audience what meds you stop before the procedure and for how long?
[Dr. Fritz Angle]
I think the most important medication class are any of the potassium-sparing diuretics. Most people agree, although it remains a little controversial, that you need to hold those. Traditionally, we said they had to be held for six weeks, but I think there's more and more literature that maybe two weeks is enough. The reason that's important is all these patients, as you know, get into trouble with hypokalemia, and you stop their potassium-sparing diuretics, and it gets more severe.
So look through those medications and try and get those patients off of them. I definitely would not make it your job to stop those medications, because it is tricky management and with endocrinologists is really important.
[Dr. Aparna Baheti]
Got it. Once you've identified those medications and stopped them, are there any other pre-procedure instructions you provide to your patients in regards to this procedure?
[Dr. Fritz Angle]
A lot of these patients are on potassium supplements, oral supplements, and most are instructed not take it on empty stomach. I do try and have them take all their medications that morning of the procedure, whatever blood pressure medications they're on, whatever potassium supplements they are on, because when they get there, a lot of times they have really high blood pressure and really low potassium levels because they stopped their spironolactone.
[Dr. Aparna Baheti]
That's really good to know. I'd like to know a little bit about the CT scan that you get beforehand.
[Dr. Fritz Angle]
Yes. I really recommend you do this. You really learn a lot about where to find that right adrenal vein is really what I'm looking for. Of course, all these patients should be screened for adrenal nodules many times. That's just a noncontrast CT, and I'm fine with that, but if I can, if they've not ordered a CT, then I'm going to order one with contrast, and often I can see pretty clearly where that adrenal vein joins the IVC, which speeds up the procedure, I think a lot.
[Dr. Aparna Baheti]
In researching for this, I read a little bit about the right adrenal vein and variant anatomy for the right adrenal vein, and I read that there was some controversy about whether the right adrenal vein can come off one of the hepatic veins. In your experience, is that something that you see?
[Dr. Fritz Angle]
Yes. The hardest part of the whole procedure is finding that right adrenal vein, and there are a lot of caudate lobe branches, small hepatic vein branches joining the IVC. You need to learn to differentiate, "Okay is this a hepatic vein I'm looking at, or is this the gland?" Then the second problem we have is that sometimes that adrenal vein dumps into the IVC right at the site of the right or an accessory right hepatic vein.
I think this variant is a lot more common that's in the literature, because I feel about 1 out of 10 patients, I am putting some reverse curve catheter in the right hepatic vein and twerking it to find that adrenal vein. It's very close or even within that hepatic vein in my experience.
[Dr. Aparna Baheti]
I don't want to get ahead of ourselves with the procedure, but yes, that is awesome. I'm glad that we're going to talk about some of the intricacies of selecting that right adrenal vein. What labs do you get the morning of the procedure?
[Dr. Fritz Angle]
Well I get a stat potassium level. There is some thought that low potassium levels will mask the aldosterone gradient, and so if they're well below normal, I'd give them some potassium supplements, inter-procedural pre-procedural. Of course, extreme hypokalemia can be dangerous so I'll get a stat potassium level. That's really the main thing I look for that day. Otherwise, it's a venous procedure so whatever your standard is for any other central line placement you do, which probably not too much. A good history usually avoids getting a lot of unnecessary labs.
(3) One Access Site or Two?
[Dr. Aparna Baheti]
All right, let's get into the nitty-gritty and the nuts and bolts about how you do the procedure. Can I just personally say that I love the way we do them at UVA, and I hope you get into some of the quirkiness about how we do the procedure there.
[Dr. Fritz Angle]
I'll take that as a compliment. It is quirky. Things work, and you just hold onto them. You're like, "Why change it?"
[Dr. Aparna Baheti]
If it works, it works.
[Dr. Fritz Angle]
One of the controversies, if there can be controversy in such a procedure as adrenal vein sampling, is do you do one access site or two? The reason is, because a lot of practices switch to starting an ACTH drip, and then they put one catheter in there, and they do the right and the left, and the peripheral, and then they're done. It's beautiful because it really simplifies the procedure.
You start that ACTH drip, have it going for at least a good 20-30 minutes before you do the sampling so it can get done even in the prep area, and then you do your sampling and you're done. I continue to do non-stimulated and stimulated samples, which means I can't give the ACTH before they get in the room. Maybe this is just a thing for referral centers because some of the cases I get have had the one catheter method, and they didn't show a gradient, but the endocrinologist really thinks there's something going on there so we do it over.
Once in a great while, I'll find somebody where you do the sampling without and then with ACTH, and you only see the gradient, the left-right difference that we're looking for on the non-stim samples. Most people, though, it's fine, you're going to see it on the stimulated samples, and you can go back and redo them without stimulated samples later if necessary. We do dual femoral access to finally answer your question and put catheters into the right and left simultaneously for the purpose of getting non-stimulated samples. I'm not going to say you have to do that or even recommend that you should do that, but that's what we do. Working with a really world-famous group of endocrinologists that's an expectation we have here for our practice.
[Dr. Aparna Baheti]
Absolutely. Yeah, and you get cases where they have tried on the outside, couldn't get it, or got false results, and then they come to see you. It's kind of a no-holes-barred type of thing.
[Dr. Fritz Angle]
The other reason that the two-catheter technique is a little bit helpful is the right gland is really hard to find. I've got that all done, I don't have a clock sort of ticking. You got time to figure that out. Once I've got it, I'm like, "Okay, let's get some non-stimulated samples. All right, let's get the ACTH then we'll get some stimulated samples." It does take a little bit of the pressure off. Your usual single catheter technique is you give this single dose over drip. You can dilute it out and give it over an hour, but sometimes getting that right adrenal gland can take 20, 30, 40 minutes. It can be really challenging.
(4) Cannulating the Right Adrenal Vein
[Dr. Aparna Baheti]
Well, let's get into that because that's what our audience wants to know. Is that right adrenal vein. Walk me through the Fritz Angle algorithm for how you get into that right adrenal vein.
[Dr. Fritz Angle]
Okay, well, first off, I do always do the left side first because it's easier and the catheter is really stable, but we could talk about that in a minute because you're right. The hard one is, what do you do with the right? I think most experienced operators agree that the C2 is the go-to catheter for this. That works probably 80% of the time.
[Dr. Aparna Baheti]
Just to interrupt you for a second, you're talking about a C2 that has the extra side holes in it, correct?
[Dr. Fritz Angle]
Yeah. Real important point, and we'll put a side hole, and I put that really close to the tip, like 2 mm from the tip because I want that side hole to be literally in that adrenal vein if I can. We'll punch a little side hole used to be the cook side hole punch set, which we used forever, but it is no longer available.
[Dr. Aparna Baheti]
Did it accidentally get tossed and can't reorder it?
[Dr. Fritz Angle]
That's right. You can't reorder it. Restaterilized the same set of punches, probably for a decade, and finally, they got bent or dull or lost or whatever. But fortunately, you can use a biopsy that's used actually for skin so you can use a dermatologic biopsy, and this device, you get the 0.3-millimeter ones, really small, and you can punch a hole that's just the right size. It does almost always go through both sides, by the way, but don't worry about it. That's fine. We just double-wall it. I usually do it on the bottom of a plastic bowl so I don't ruin my sterile field. If it goes through both sides of the catheter and down into the bowl, that's fine. Just don't use the bowl because it'll leak all over.
[Dr. Aparna Baheti]
You got your catheter, your C2 made, your modified C2, and now how can you get into that right adrenal vein?
[Dr. Fritz Angle]
I've got a good idea from the CAT scan where it is, but the thing Dr. Matsumota taught me is that it's almost always exactly one vertebral body above the right renal vein. First thing I do is drop that catheter in the right renal vein, which is easy to find, and save a levity loop of that. So I've got a mental image of where that is. I'm focusing my attention just about exactly a vertebral body above, straight posterior.
[Dr. Aparna Baheti]
Okay, so you're straight AP with your II, or do you do an obliquity?
[Dr. Fritz Angle]
No, I almost never, that's a good point. I think most of the time, an AP view keeps you oriented. Once you're in it, lateral views or comb beams we can talk about that but just in terms of that catheter work. In fact, I always liken it to sort of mowing the lawn because what I do is I put the thing just about a vertebral body above, or pull it down slowly, puffing contrast, didn't see anything then I'll go back up, turning it a little bit, just going next to the previous path, and do again, and just keep going up and down, up and down, turning it just a few degrees.
So I get the whole back wall of that IVC searched looking for it. It's not something where you see it plop in, and you're like, "Oh, I'm clearly in something let's puff now." It's kind of a deal where you've got to keep puffing contrast. So doing this procedure as someone who has severe renal deficiency can be problematic.
[Dr. Aparna Baheti]
Sure sure. Okay, yeah, that's the part that takes forever is just trying to figure out exactly where that right is.
[Dr. Fritz Angle]
Yes. I'm doing half of vertebral body above and below where I think it is. It keeps the zone I'm mowing very small. Small yard. I got a small yard and if I don't find it, I start looking a little bit left of center and a little bit right of center. Usually, from the CAT scan, I've got an idea if the adrenal vein looks like it's a little bit off to the right or straight in the posterior.
[Dr. Aparna Baheti]
What do you do if you just keep selecting other veins, like hepatic veins, accessory hepatic veins, and you feel like you were talking about where the confluence of that vein is very close to one of the other veins?
[Dr. Fritz Angle]
Yeah, your biggest problem is you keep finding things that you're really confident are hepatic veins, and you can't find the thing that you're looking for and that's a usual frustration. My first piece of advice there is to switch to a different catheter pretty quickly what's that mean? Two minutes of fluoro, probably time to think about a different catheter. A lot of different operators use different catheters, but I find a Mickelson or maybe a Left Gastric or even a Simmons 1 is a good choice and they have varying degrees of pointing down this that you need to change. You try one of those and see and, of course, when you first start, you see how big a cava it is.
Sometimes you can just tell that the C2 is just rattling in that cava it's not even touching the back wall. Then I'll go straight to one of those reverse curved catheters. Sometimes the vein has got a real caudal tilt on it the C2 just slips over it every time and you never see it.
[Dr. Aparna Baheti]
I see. Yeah that's some very good technical points of how long you should flex around with one before switching.
[Dr. Fritz Angle]
Most of the time it's not like, "Oh, I've looked everywhere. It's got to be in a common trunk with this hepatic vein," that's not usually the case. Usually, it's just that you get into some trunk that you can't quite tell if it's just a hepatic vein or it's a hepatic vein and adrenal vein and that's where you got to, I think, break out the cone beam CT. That's so helpful. See, you get into something it's like, "Well, I think it's right where the adrenal should be but, boy, it sure looks like I'm filling in a hepatic vein." Maybe you don't see the collateral's running off into the right or middle hepatic vein. That's a good place to do a cone beam, then you really know you're in the right place or not.
(5) Cone-Beam Settings For an Adrenal Vein Run
[Dr. Aparna Baheti]
That kind of brings me to an interesting question. One of the things you worry about when injecting the adrenal gland is injecting too forcefully or too much. What are your settings for your cone beam that you use to prevent that? Because when you're hand injecting, you can kind of control it but once you have your cone beam in place, what do you do?
[Dr. Fritz Angle]
Yes, super important point. You got to be really gentle, and going all the way back to the beginning of this talk, I always tell patients, complication I worry most about is if you over-inject the healthy adrenal gland, you box them out of getting the operation they need because if you blast, the good gland, give it a venous infarct. How would they know that? Well, unfortunately, you may not find it until post-op when they get adrenal insufficiency. It's just something you want to be really careful about. I don't ever want to inject hard enough that I'm seeing blush. I want to see that sort of ferny pattern, but I don't want to see a blush. So gentle injections.
Now, when it comes to the cone beam, fortunately, almost never have to stand in there and use contrast because I figured out and I'm sorry I can't give credit, but I heard this talk I saw years ago. You put an 0.014 wire through that catheter and push it into the branch you're interested in to be forced on the back then you do just a dry scan. It's really like the 0.014 wire. Is it pointing at the gland or is it pointing at the liver and you got your answer?
[Dr. Aparna Baheti]
Wow, that's amazing.
[Dr. Fritz Angle]
Yeah, because we've got one of these little electronics, safe badges now. We stand in there, you just can't believe how fast you eat the dose up standing in there. No matter how you do it, standing in there for cone beams is a bad idea so don't do it.
[Dr. Aparna Baheti]
Life tips.
[Dr. Fritz Angle]
We used to do this a little years ago, but not anymore. So if I got any questions, I just put a 0.014 wire in there. Actually, that trick often helps with the sampling because the second hardest thing about this procedure, besides selecting the right adrenal vein, is getting the blood out of the adrenal vein.
(6) Confirming Right Adrenal Vein Cannulation on Angiogram
[Dr. Aparna Baheti]
Yes. Okay, I want to back up a little bit. How do you know on an angiogram that you're in the right adrenal vein?
[Dr. Fritz Angle]
You love to see that sort of upside down Y shape, that sort of triangular shape. It's usually very fine branching pattern. If you're in a hepatic branch, it can sometimes be a little bit rounder, looks more like a guitar pick, if that's what you're seeing, you're probably not in the right place. Obviously, if you see some branches that go beyond that blush to the hepatic vein you're in the wrong place, and if you see some go in the retroperitoneum, it might be okay but you can get into an intercostal vein. It's usually not it but sometimes there's a commonality with hepatic veins or with the intercostal or even capsular branches of the kidney.
Those are secondary signs I look for to help me decide if I'm in or not in the right place. So it's an art. I'll tell you. I've searched for years to find the right terms to describe what the blush looks like. I say this is the hardest part of this procedure is knowing from an interventional standpoint is am I in the right place or not. Years ago, in our lab, you could send off a stat cortisol, which was great because you get this blush of like, "I don't know," and you do a cone beam, like, "I think it's okay."
We can send a state cortisol level, because if you're in the right place, cortisol levels are going to be high, and if you're not in the right place, they're not going to be high. Now our lab has gone to some automated machine that takes 45 minutes to get a cortisol level run, which means it takes an hour to get it back, and it's just not practical anymore. If you still have a place that can do stat cortisol, that's a great trick.
(7) Sampling From the Adrenal Vein
[Dr. Aparna Baheti]
That's a good thing to know. Well, I think you were telling me before I interrupted you about how you actually get the sample from the right adrenal vein. Literally, tell me what syringe you put on there and what your technique is for how to get that sample.
[Dr. Fritz Angle]
Yes. In my mind, I envisioned that this vein is really, really small, you've completely filled it with a catheter, and it's dripping at an insanely small rate, and so the trick is to draw the sample really slowly. Most of the time, what I do is I just take that 5F catheter, and I very slowly put the hub down about the tabletops and bring it over to the side and let it dangle down, and the blood will drip out of there really slowly. That works most of the time. I just put a syringe underneath it with a stopcock, pull the plunger out, stopcock, I just put it under there, just collect the blood dripping out of the 5F catheter, and that works most of the time.
If that doesn't work, you gotta put really low suction on. I find the issue of a small syringe, people always use too big a syringe, a 5 cc syringe, and put a couple of 3 cc of air in there, and that'll keep you from making too much suction, so low suction is the key.
[Dr. Aparna Baheti]
Low suction, okay. Okay, that's important because for our younger listeners, if you do apply suction to this, to a side-hole catheter that's in a small vessel, tell us what happens and how that you know you've caused trouble.
[Dr. Fritz Angle]
Right. So if you're trying to draw blood off, most people go to a bigger syringe, they think I need more suction, so they'll put a 10 cc on there, and that creates more suction, but that's not what you need because it just collapses the vein right down around the catheter tip and the side hole. So small syringe, 5 cc is my preferred, and I'm not pulling that plunger back more than a centimeter, very small, half a centimeter. Sometimes pull a little bit release, pull a bit release, and I'll see as you release it, when it's almost to the point where there's no suction, that's when you actually see the blood come into the syringe. This is good in other territories who might do some kind of sampling out of a small hole, low-flow structure.
(8) Additional Pearls for Right Adrenal Vein Sampling
[Dr. Aparna Baheti]
Any other tips on the right side that you'd like our audience to know about?
[Dr. Fritz Angle]
If you're having trouble getting a sample, put that 0.014 wire in there, put a tuohy on there because sometimes that will keep the tip from sucking up against the wall. You can get a sample out that way, so that's one other trick.
[Dr. Aparna Baheti]
How about if you get into the right, and then you definitely selected it, but it keeps kicking your catheter out?
[Dr. Fritz Angle]
Oh, my goodness, yeah yeah. You’re bringing back a lot of bad memories, right? I think you and I shared some of these with a few patients like this. You're in there, and then you're not. That's so frustrating, it happens. Of course, you'd like to tell the patient to hold their breath away while you do the sample, but not practical, right?
[Dr. Aparna Baheti]
Yeah.
[Dr. Fritz Angle]
There's just nothing you can do about that, and that's where the reverse curve catheter. That's a really good point, Ally, because you got to know when enough is enough. The C2 is in there, you can see it. It took you 15 minutes to find it, you hate to give it up, but if it keeps falling out, it doesn't make any sense to keep trying. You got to do something different. So get a reverse curve catheter. I find most of the time that's more stable than the C2, and that usually is going to sit in there more stable, again, that 0.014 trick if someone's breathing, I find that often makes it more stable too.
[Dr. Aparna Baheti]
So much of this procedure is really just knowing when to move on to the next thing, or knowing when you flogged enough at one thing that you should try something else. I think that's like a lot of IR though, right?
[Dr. Fritz Angle]
It really is. We all have our internal timer, which, of course, runs a lot slower than the real clock. You're like, "I'm going to give this two minutes," and then your techs at 20 minutes later, "You said two minutes?" It's true of a lot of things in IR. We don't do much selective catheterization of the 5F catheters anymore. I grew up in era we did a lot of diagnostic angiography, diagnostic runoffs, and diagnostic mesenterics, and we still do some of it, but manipulating 5F catheters is an art form, no question, but it's still a lot of fun.
(9) Cannulating the Left Adrenal Vein
[Dr. Aparna Baheti]
Moving on to the left side, because I know you do this before the right, but tell me how you catheterized the left adrenal vein.
[Dr. Fritz Angle]
So the textbook answer is to use a large reverse curve catheter, a Simmons 2, or a Simmons 3. You forward on the bifurcation. You drag it down into the left renal vein and then as you pull it back, and it starts to unfold, it plops into the phrenic adrenal chunk, and that works really well. However, that's not what we do because we like to get the catheter a little bit deeper. The problem with that is the tip of it is just barely in there, which is probably fine, but we tip deflect a Berenstein catheter with a side hole on it into the left renal vein and push it out beyond the phrenic adrenal trunk.
Why did we do that? This catheter is going to allow you then when you pull it back, pointing it up, you puff, it should come back, you find that phrenic adrenal trunk, and then you can puff and push it up into there, and you can actually put it right into the adrenal vein.
[Dr. Aparna Baheti]
I see. So that avoids you selecting the phrenic. Yes, okay.
[Dr. Fritz Angle]
Yes. You really get selective on both sides. Now, having said that, the reason most people just use a Simmons and get it into the phrenic adrenal trunk is that almost always is diagnostic, but this allows me to get more selective samples. You don't get that rare case where it's not diagnostic. So little extra work, but fewer surprises when you get those labs. There's this moment, you've seen the patient and you get that inbox message labs are ready, it's like right up there with opening that letter from the ABR. It's like, "Oh, my God. Is this working out? Did I do okay here?"
[Dr. Aparna Baheti]
You get a little bit grayer. You wait a little bit more hair.
[Dr. Fritz Angle]
Oh, you definitely. Yes, that's no question. No question.
[Dr. Aparna Baheti]
Okay, so you've collected your left-sided sample and your right-sided sample at the same time, and then do you do the peripheral sample at the same time as well through your sheath?
[Dr. Fritz Angle]
That's exactly right. If you're doing the one catheter technique, you want to draw them all as quickly as possible, so you probably start with the right, left, and then peripheral. You go from hard to easy, but in ours, we've drawn all of them at same time. I draw two sets. Over the years, I had those cases where you put the patient through this, and then something wonky happens in the lab, and so I draw two sets. I draw right, left peripheral, right, left, peripheral, and I do it about 30 minutes after that bolus of ACTH.
[Dr. Aparna Baheti]
Now, you've already alluded to this, but you do not keep the patients in the room to await the results, correct?
[Dr. Fritz Angle]
Yeah, that's right. I used to call them the next day once I got the cortisol levels back because that'll tell you if you did your job if the sampling was technically good or not. I look at those cortisol ratios. It should be two to three times greater in the adrenal gland in the periphery on the non-sim, and at least three to four times greater on the stim samples because cortisol levels do go up with ACTH. I call them and say, "Hey, we got a good sample," or, "Gee, do you mind coming back and letting me try again?" I do ask them, and in fact, I tell him, before we even do the case, I say, "About 5% of the time, the sampling doesn't work out, and if you don't mind, I'm going to try again."
Now, if you're in a small community practice, you might want to send that to your academic center that does more of these, but that's okay. There's nothing wrong with that, it's a safe test, and repeating it in some patients is not a big deal.
[Dr. Aparna Baheti]
Yes. We've talked about this, but do you think that this is a procedure that should be done in private practice if we're not seeing more than 10 cases a year?
[Dr. Fritz Angle]
I really do. I think that from an IR standpoint, it's a safe procedure. You've got the catheter skills, you should offer this, there's just no reason not to, and hopefully, I've convinced you the screening and the supplies you need are very basic. Probably the most important thing is just you need a good endocrinologist, and hopefully, a local surgeon that's willing to do adrenalectomies, but obviously, they get set up the road for that too. So if you're just working with a good endocrinologist, and he wants a service, yes, go for it, call me, I'll walk you through it, it's easy.
[Dr. Aparna Baheti]
I would always call you, Dr. Angle, unless I've made a giant mistake, and then I'll call Luke.
[Dr. Fritz Angle]
IR is just a huge family. I tell you, it's just one thing that I don't do enough of and particularly early in my career because I had the good fortune, I had great mentors right here on-site, but if you're working a community practice, my goodness, reach back to your mentors there, meet people in meetings that are experts in things and get their cell phone number. They don't mind, call them up, have a conversation, and it's what makes our world go round is just talking, and boy, take advantage of it because it's a great group of people, that's for sure.
(10) Interpreting the Results and Patient Follow-up
[Dr. Aparna Baheti]
I've shared this on prior episodes, but one piece of advice I have for trainees going out into practice, if you practice in a completely different timezone than where you trained at, find some mentors who live in your timezone. It's not fun to call people from back east when it says 7:00 PM. Well, we've gotten a little bit off track, but walk me through the interpretation of the results that you get.
[Dr. Fritz Angle]
Right. You're going to get back cortisol levels initially, and then for a lot of places [aldosterone] is the send out. We now have it in-house, but even then they run it once a week, so it comes later. First thing is I go through those cortisol levels, and I'm just looking to see, is that right side two times or three times greater than the peripheral sample and that tells me I've done my job. That's called the selective index. You don't even need to know that name but the selective index is basically just that ratio.
Then the aldo levels come back and the aldosterone levels are always diluted. Even though you've got a catheter right in the right adrenal, that site hole might be in the IVC. It's partially diluted. The right and left cortisol levels will always be different and that doesn't matter because the left one often you don't put the catheter in the right adrenal vein, so it's actually lower than the right cortisol levels. We correct the aldo levels by using the cortisol levels as a marker of dilution because whether they've got a functioning aldo or not, the cortisol levels are relatively constant in both glands.
So you get an A/C ratio for the right and an A/C ratio for the left, and then you want to compare the A/C ratio for the right and the left. There should be about a five times difference, one side or the other with stimulation to call it a lateralization. As simple as that. First, you figure out the selective index, which is really where the IVC numbers are important, and then you are looking for the lateralization index, which is really just the A/C ratio right compared to the left.
[Dr. Aparna Baheti]
What percentage of your cases would you say lateralize?
[Dr. Fritz Angle]
So in the literature, in my practice too, I'd say it's about two-thirds maybe it's a little bit more than that. A lot of people have bilateral adrenal hyperplasia or they have multiple nodules. Surgery's not going to fix their problem. So that's okay. Don't feel like you've done something wrong or didn't get the result you're looking for. As long as you got a good selective index, then don't expect it to lateralize every time, and not everybody gets an operation and that's okay.
[Dr. Aparna Baheti]
That's a very, very good point. Post-procedure, anything that you've seen that people who are doing this procedure should know in terms of patient follow-up or unexpected side effects?
[Dr. Fritz Angle]
Not really. It's really a very safe procedure. We do pretty much our standard post-venous femoral access observation. I don't routinely do follow-up blood work on them. I just get them back on their usual meds, which again, I leave to their endocrinologist or referring practitioner and that's it. Just get a phone number, give them a call.
[Dr. Aparna Baheti]
Fantastic. I'm sure patients appreciate hearing from you the next day. Just you know I'm sure they're anxious about how the procedure went. One of the things that we really try to stress now, especially to younger trainees, is how important it's to have a clinical practice and not just be the proceduralist. That's another step towards showing that you are invested in their care and that you might need a chance to do the procedure again or that you were successful.
[Dr. Fritz Angle]
Well, I'm glad to hear you say that and just to emphasize that for this little procedure, you think after all these years it's very hands-off and it's not. I get out my little Excel spreadsheet and I plug in all the numbers, and calculate the ratios, and then I call the patient. There's no substitute for that and that's true about everything we do in IR. You do a peripheral vascular case, you get the ABIs the next day, and you go talk to the patient. If they've gone home, you give them a call, say, "I think we've got done what we wanted to get done here. We'll see you back in six weeks."
There's no shortcuts, but it's actually one of the best parts of what we do. We got to take a lot of pride in our work and calling patients with the result is one of the most pleasurable parts of our job.
[Dr. Aparna Baheti]
Well, that wraps up what I wanted to talk about. Is there anything that you think we missed talking about for adrenal vein sampling?
[Dr. Fritz Angle]
No, not at all. I think you've done a great set of questions for us here. It's been a lot of fun.
[Dr. Aparna Baheti]
Dr. Engel, thank you so much for being on the show today.
[Dr. Fritz Angle]
Absolutely. I'm glad you reached out. That was a lot of fun.
[Dr. Aaron Fritts]
Thank you so much for listening. If you haven't already, make sure to subscribe. Rate the podcast five stars and share with a friend. If you have any questions or comments direct message us at, @_backtable on Instagram, Twitter, or LinkedIn. BackTables, produced and hosted by myself, Aaron Fritts, and co-host.
Podcast Contributors
Dr. John Fritz Angle
Dr. John Fritz Angle is the division director of vascular and interventional radiologist and a professor with University of Virginia in Charlottesville.
Dr. Aparna Baheti
Dr. Aparna Baheti is a practicing Interventional Radiologist in Tacoma, Washington.
Cite This Podcast
BackTable, LLC (Producer). (2023, June 2). Ep. 328 – Adrenal Vein Sampling [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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