How To: Mesenteric Duplex Examination - SD

Introduction to Mesenteric Duplex Examination

Welcome.
My name is Billy Zang.
Today I'd like to teach you how to do a mesenteric duplex examination.
I have a good friend as my model today.
His name is Demetrius Make.
We have a system here, and we're gonna start by talking about the transducers that we have available when we do this examination.

Transducers for Abdominal Imaging

The transducer that you will find yourself going to most of the time when you're in the abdomen is a curvilinear transducer, such as this one.
We also have another curvilinear transducer that has a slightly higher frequency.
And because Demetrius has such a thin body habitus, I'm going to be prompted to use this transducer over the lower frequency curvilinear transducer for this specific examination.
In fact, I might even find myself going to a linear transducer with a higher frequency on patients that are this thin.

And for mesenteric duplex examinations, you are gonna find that the patient population coming in will have lost a lot of weight because they have a fear of food.
And most of them, after not eating for long periods of time, have a tendency to lose many pounds, and they come in very, very thin.
So you do have the opportunity in those situations to take advantage of higher frequencies that most of the time we don't have when we're doing abdominal work.
And we have to work within the constraints of a sector transducer or a low frequency curvilinear transducer.

So, as I said, I'm going to choose the curvilinear transducer with a higher frequency.
That's the M seven C in this regard.
I have Demetrius laying in a supine position.
Obviously, when Demetrius came in for this type of examination, he came in with a certain indication.
Like I stated before, that indication is usually abdominal pain coupled by weight loss because of the fear of food factor that happens when patients have mesenteric ischemia.
Demetrius probably didn't have this as an acute onset.
Most acute cases you may not see in a vascular lab setting because they would go directly to an angiographic suite, probably because that is truly a life threatening symptom when they present to the hospital if it's in an acute setting.
So Demetrius has probably had this problem for a long time.
Obviously, he's our model, so I don't foresee seeing any problems while we're doing this, but you never know.
We'll see what things show up once he's down here.

Patient History, Setup, and Positioning

I've taken the history and physical making sure that everything matches up with the indications that were presented to me prior to Demetrius coming to the room.
I've set up my machine, I'm ready to do the scan.
I have him in a supine position.
I want his head to be slightly elevated.
In the situation that we are here now, we have kind of a table that does not allow me to put the patient in a slight reverse trendelenburg, which I prefer because I want the organs to drop down a little bit, giving me better access, allowing me to use that left lobe of the liver as a nice window to evaluate the mesenteric arteries that we're gonna be able to see during this examination.

So what I've done is in this situation since I don't have reverse trendelenburg bed, is that I've raised Demetrius up a little bit by kind of doubling over his pillow, bringing his shoulder blades off a little bit off of the bed, having him in a situation where those organs are dropped down a little bit.
And that should afford me a much better window when I'm doing this exam.

Patient Communication and Breath-Holding Techniques

So I've also want to talk to my patient, right?
I want to talk to Demetrius and say, this is the exam we're gonna do.
We're gonna do a mesenteric duplex.
It's going to consist of an ultrasound transducer.
It's much like a microphone.
I'm gonna place some gel on your stomach area in the areas where I believe that these arteries will lie.
I may have to roll you over from one side to the other to gain access because you may not.
We look for certain windows and because of all your organs and your mesenteric and your bowel gas will be in my way and I'll have to move from one side to the other, even roll you up into a lateral decubitus position.
So I may ask you to do that, and certainly during this examination, I'm gonna ask you to hold your breath.
So most of the time you'll see me kind of playing over here with the machine, and then I'll ask you to take a deep breath in and hold it.
Or I'll ask you to exhale and hold your breath, and we'll work together as a team.

And the one thing you want to remember is you'll get caught up in what you're doing here.
So you'll can forget to tell them to breathe again.
And to keep a friend here, you want to make sure that you kind of remember that Demetrius has to breathe.
He wants to leave this examination.
So what I usually tell them is breathe when you have to.
And one of the tricks that I also use is that I hold my breath also when I'm doing the exam.
So when I ask Demetrius to hold his breath, I hold my breath, and if I have to breathe, I know that it's probably well past the time that Demetrius had to breathe.
So that kind of triggers me to know that I better ask them to do just that.
And that is to breathe.
So I have this all set up.
I have my gel in the center of the body right below the xiphoid process because the celiac, which is gonna be the first artery I'm gonna interrogate, is gonna be the first major branch off of the descending aorta as it comes into the abdomen, as it breaks through the diaphragm.
So I'm gonna look for that pretty superior here.
So my transducer's gonna lie right below this area of the sternum.
And then I'm gonna move down the belly.
So I have kind of nice glob that I can kind of push my way over and as if I move over here, I may add more gel to look at the lateral, the decubitus positions if needed during the examination.

Initial Scanning: Visualizing the Aorta

So why don't we start by taking the transducer?
I place the transducer.
So I see a transverse image on the screen, and you can see that that left lobe of the liver is right there for me.
What I'm looking for is kind of a big circle, right?
That's gonna indicate that the aorta, it's going to be the aorta, right?
That big circle that's pulsating, it's gonna be the aorta.
And I'm going to move up and down the belly specifically to the bifurcation, which is called dead.
To kind of look at my whole aorta in total, to make sure there's no aneurysmal disease, to make sure that there's no buildup of calcifications.
That may be an indication that, you know, frankly, I might be finding something because I see in this large vessel plaque already, so I can see that aorta, and here it is, I'm pointing to it, and you can notice that it's bouncing up and down.
I see the bifurcation of the iliac vessels.
If Demetrius had gas in this area, I would kind of move in an oblique position.
And if I do that, let's see what kind of image I get.
And you can see that I get a very nice image on Demetrius of his bifurcation.
Here's the aorta and moving into the left and right iliac vessels, right and left respectively here.

Now I look at this image and you know, the machines still need our help, right?
I mean, a lot of the major manufacturers try to do the work for you, but you still have to look at the image and based on the patient's body habitus adjusted.
So I see the Demetrius, like we mentioned before, is very thin.
I can decrease my depth and Demetrius to look at these vessels.
I can bring my gain down to make them look as clean as they are within this image.
If there is plaque there, I want to make sure I don't over or under gain it.
So we see that pathology.
And then once I get very comfortable with where my focal zones are and my focal zones for you, for those that aren't familiar with that terminology or these areas right here, and that's where the beam is the thinnest, and that's where I'll get the best image.
So I want those to be targeted at the area that I'm looking at.
So I want my focal zones to be in the location of where that disease is gonna be.
And that's a pretty good location right there for me.

Vessels of Interest: Celiac, SMA, and IMA

And now I'm gonna go back up and I'm going to look for the vessels of interest.
And once again, those vessels are gonna be the celiac artery, the SMA and the IMA.
Now, the SMA and the IMA have branches, but we're not gonna specifically look at those individual branches.
But on the celiac, we certainly are gonna look at the proper hepatic, common hepatic and the splenic branches.
We will not look at the left gastric.
So once again, on the celiac, there are three major branches.
The left gastric, the hepatic, and the splenic.
We're gonna look at the hepatic and the splenic, but the left gastric going up into the abdomen, we might be able to see it.
But in most of your protocols, you're gonna notice that that is not one of the vessels that we're gonna interrogate.

Locating and Identifying the Celiac Artery

So let's start looking for that celiac as it comes off the aorta, and you can see that it's sitting at the bottom of my screen here.
So that's telling me as I was down in his iliacs, looking at the bifurcation that was a little bit more superficial.
The celiac is a little bit deeper.
I'm gonna have to use my depth to bring that vessel into view where I want it.
And I'm bringing it down here and I can see it coming off right here.
And most people look at this vessel and say that it reminds them sometimes of a seagull, right?
Because it has the two wings of those vessels that I just mentioned, the splenic and the hepatic artery, with a celiac being the body of the bird there.
So some people think it's a seagull that you would kind of draw when you were a kid in kindergarten, right, with the little check mark.
And here we see that right here.
So I know that I'm in the right position to start interrogating these vessels.

From a B mode perspective, I'm looking at this to make sure that I don't see any plaque within them.
I'm also looking at it to see how it's positioned in the body.
And you can see I went into a longitudinal position now with my aorta longitudinal view of the aorta here.
And I can see my celiac coming off of here and my SMA, which is my next target vessel coming off very, very close to the celiac.
See how close those origins are.
And that's one of the most difficult parts of this exam, especially in this beginning part.
The celiac and the SMA have various anomalies that may be associated that you may see.
It looks like he has separate origins, but sometimes those origins are combined.
Sometimes the hepatic right hepatic artery comes off the SMA.
These are things that you need to be aware of when you're scanning, there is, you know, the anatomy books show us what we would expect to see.
But when you start scanning, and for those people out there that have been scanning for a long time, you know that reality is that expect the unexpected when you're doing abdominal or any type of vascular work, anomalies are always present, so be wary of those.

Okay? So we can see that we are in the right location.
You can see here we have a lot of gas here in the midline.
So I have to find different windows.
And you can see that I just move laterally a little bit to Demetrius left side, and I could pick up another little area.
One of the tricks when I can't find the origin, the celiac, is to go to the SMA.
And you can see the SMA is juxtaposed to the aorta in this cross-sectional image.
There's the SMA right there, and I know that that SMA is going to be right below the celiac artery.
So I can kind of feed that up cephalad and turn again and know, oh, there's my SMA origin coming in here, and right above that is gonna be my celiac.
And there's my celiac right there.

Median Arcuate Ligament Compression in the Celiac Artery

Now, Demetrius's celiac artery looks like it's got a little hook in it.
When I see that, I get suspicious that the patient may have median arcuate ligament compression.
Median arcuate ligament compression is a ligament that kind of goes around the aorta.
And it will slide up and the aorta will slide up and down underneath of this ligament as your diaphragm drops and rises as you inhale and exhale.
So as you inhale your diaphragm drops and all the viscera drop.
So your aorta kind of goes away from that ligament.
But as you exhale, that aorta will start to rise up in that ligament.
In 20 to 30% of the patients may be in a position where it can extrinsically compress that celiac artery.
A couple things I look for, I look for the patient's age when they come in, when this may be a factor.
I look at the symptoms that they came in with most of the time, patients with celiac artery or median arcuate ligament compression come in because the doctor heard a bruit.
I looked at Demetrius, and I see that there is very little evidence of plaque within a B mode image, right?
I haven't turned my color on yet.
But that would be another indication to me that probably his aorta is crystal clean.
His SMA looks like it's crystal clean also.
But this celiac with this little hook in it kind of piques my interest to say maybe he has this median arcuate ligament compression, and that could be causing the bruit that the Dr. may hear when he's breathing in and out.

Alright, so let's see if that's the case here.
I have a beautiful view in gray scale.
I'm very comfortable in my location.
I see my celiac, I actually see those wings of the celiac.
And you can see this one is going towards the spleen.
So that's the splenic artery.
This one is going towards the liver.
So that's the hepatic artery.
I don't see his left gastric.
And like I said, that is not part of a standard protocol in most vascular labs when you're doing a mesenteric examination.
So I'm very comfortable now that I can move on to turning on the color and then starting to take spectral doppler waveform.

So I'm gonna turn on the color and my suspicion of that celiac artery kind of is a little stronger now, right?
Because I can really see some color aliasing taking place right here where I see that hook, right?
See that hook right there?
I can see some color thing.
And you can definitely see the separation and the size difference, frankly, between the SMA and the Celiac on Demetrius.
Alright?
And you can see the aorta here, and it's very important.
Also, I think especially, you know, we're talking about mesenteric.
But when I teach renal exams also, I use these mesenteric and the celiac arteries as a landmark to where I want to take my aortic velocity for my renal aortic ratio.
So it's also very important, I believe, in a renal examination to also be comfortable with the location of the celiac and the SMA.

So I'm very intrigued that Demetrius may have some increase in velocity.
He is asymptomatic, you know, he came in here with he's volunteering basically.
So there's no need for concern with Demetrius in this standpoint, but I definitely want to document if there is an increase.
And I want to show you some tips and tricks of the trade here when we come across this.

Okay?
So there's my aortic signal.
I'm going to decrease my scan area a little bit, my color box.
You can see me doing that kind of hone in on exactly the area that I want to be in.
There we go.
Just adjusting things and we can see that.
So now I'm going to watch Demetrius's breathing patterns with my hand.
I'm watching it.
I'm feeling my hand rise up and down as Demetrius breathe.
I'm looking at the screen and I'm seeing where the my most favorable Doppler position would be for my sample volume.
And then I put take my Doppler signal and I place it in an area using color as a guide to see what I can do.

Now, I'm suspicious that there's disease there, right?
So I can see that I need to raise my PRF right to possibly get into, and you can see that I'm both in, I'm gonna freeze this image 'cause I think it's a great one.
You can see that I'm in both the aorta here and the celiac artery.
So you see both of those arteries in my within my sample volume.
So both of them, both of those arteries are bringing information back to the system.
And I'm seeing that in fact, Demetrius does have an increase in velocity in the position that he's in.
And with his breathing pattern as such, when he's breathing in and out, that raises my interest even more that this may be median ligament compression.

Okay?
So I see that here.
I'm gonna kind of adjust my scale because I can see that the scale itself is too low to compensate for the flow.
So I'm gonna have to increase my PRF.
So I'm gonna do that before I ask Demetrius to hold his breath.
All right?
So I'm gonna get all these things done.
While Demetrius is sitting there, I'm going to go back in.
I'm not gonna ask him to do anything.
I'm just gonna increase my PRF myself, right?
To compensate.
I can hear it.
He's breathing, right?
So the sample volume is moving in and out of that vessel.
That does not concern me.
I'm gonna hit the pause button and I'm gonna ask Demetrius to take a small breath in, and I'm gonna ask him to hold it right there, And I'm gonna freeze that image.

Now, I ask him to take a small breath in.
If you remember what I said before, when Demetrius breathes in, he is dropping his diaphragm, that arcuate ligament is now pushing down, is now staying put.
The viscera the artery is now moving cephalad.
So it's moving away from that extrinsic compression and is opening back up.
So I see a very normal signal in this situation right here, right?
What I'm gonna do now is try to get this signal when he is exhaling, or when the diaphragm now is moved up and the aorta is now positioned itself for that celiac is now being compressed, I think, by this median arcuate ligament, right?
So we're gonna try that.
Now, I'll just take that image.
And of course, during a normal examination, I would label that proximal celiac artery or celiac artery.
However you would like to label that.
You know, we use the terms proximal mid distal, but the celiac artery is a pretty short trunk.
You'll hear it referred to as a celiac trunk.
So say proximal distal in the celiac is kind of a stretch.
Maybe using the terms proximal distal would be better, or just using the term celiac, I think is fine.
Also, it's something that you would have to define within your protocols.

So I'm looking back at this image here, and I can see this color brewing, right?
So I know that's where I want to be.
So I'm just gonna ask Demetrius to hold his breath right there.
I, And you can see the increase now, I'm getting it up to 202 maybe.
Let's see, let's measure that.
I'm gonna put my calipers up here up in the range of 223, you know, which in the celiac Gregory Mineta's criteria for a stenosis, and this is atherosclerotic, is 200 centimeters per second.
So I'm seeing some velocities that if it was an atherosclerotic, the fixed lesion would be concerning.
But because it's median arcuate and most patients don't have symptoms, it's probably something that the Dr. may just want to watch.
In fact, if he decides when he interprets this, that this is in fact median arcuate ligament compression, remember when we're talking about non ath, non atherosclerotic disease and possibly an extrinsic compression type of phenomenon in the abdomen, positioning really is something that in fact, we can manipulate to see if it's relieved or not.

So you see that I have Demetrius in a position here, a supine position with his head slightly elevated.
I could actually bring Demetrius up and I suggest that you try this on your patients also, that you suspect that this might be a problem and scan with him sitting up completely.
I'm not gonna do it for the purposes of this examination.
But I encourage you to have you come into this situation, sit the patient up, and scan him in that fashion.

Celiac Artery Branches: Splenic and Hepatic

Now, what I really want to do now after I've evaluated the celiac artery, is move into its branches.
And the branches, like we mentioned before, are the splenic branch right here.
And you can see how that branches off right here.
I'm using my sample volume as a guide.
You can see that's my splenic artery as it moves towards the spleen.
And I'm just gonna pop a signal in right here.
What you didn't see me use yet, because we were kind of excited about that median arcuate ligament compression is angle correction.
So let's just take two seconds to talk about angle correction.

Angle Correction in Vascular Imaging

Most people are taught carotid duplex imaging first when they start in a vascular lab or start to learn to do vascular scanning and venous duplex, it's the examination that you'll do the most venous duplex imaging and carotid duplex imaging.
Venous duplex imaging.
Obviously there's no velocity criteria par se maybe somewhere in the literature you may find somebody that was out there.
But we use B mode imaging specifically as a gold standard.
We look for the compressibility of those vessels.
Carotid, we do have a standard diagnostic criteria.
We look for certain velocities and we put things in certain percentages, and it's an examination that we need to be reproducible, right?
Because of the way the QA data is collected versus the angiography.
So we're very specific about an angle of insonation.
And because of the vessel and the way it's located in the neck, an angle at a angle of 60 degrees was kind of the angle that everybody rested on, right?
To cosign a 0.5.
So you got 50% of the Doppler strength, you know, a whole bunch of other things that we can go into at another time.
But most people kind of have drilled in their brain that they have to maintain a 60 degree angle when you, and certainly what holds true in that is that you do not want to go above a 60 degree angle in the abdomen without question, you know?
And if you do, you want to make sure you label that appropriately on the screen that, look, this was taken at an above 60 degree angle, and I know that it is probably overestimating the possible velocities within this artery that I'm insonating.
But in the abdomen, the way that these structures come off, it really allows you to go into the lower angles of insonation.
And we all know that the zero degree angle of insonation is the most favorable doppler shift coming back, the strongest doppler shift cosine of one, right?
So that is the angle that we would like to use.
And frankly, in the Celiac.
Now, we can't use Demetrius here as a marker.
But frankly, for most people, that celiac guard is gonna come right at you at zero degrees.
And if it's coming at you at zero degrees, I'd use it.
But I'd go back to the carotid, and this is where most people get stuck with this 60 degrees, and we have to maintain 60 degrees.
When you reexamine Demetrius, look back at the angle that you used where you got that velocity measurement that you're comparing to, and make sure that that angle is the same.
If you're gonna compare those two velocities, that's what I'll tell you in the abdomen.
Do not go for a 60 degree angle in the abdomen.
You do not have to do that.
But what you have to do is maintain a 60 degree or less angle.
And when you are looking to compare one study to the next, make sure you go back in and you evaluate how you insonated that vessel on the previous examination and make sure that your angle of insonation is close.
And if it's not realized that there will be some discrepancies in those velocities.

Okay?
So we're done with that.
Sorry for that little movement away from scanning our patient here.
But you did not see me use an angle of insonation when we did the celiac, and that's something I frankly would've done.
I would've guesstimated or looked to see where that line should be compared to the vessel wall.
And we have color on most of the time, so we're kind of using color as our guide.
A lot of times in the abdomen, unlike the carotids or in the peripheral, we're not gonna see that nice adventitial wall there that's nice and bright.
So we will kind of use the color as a guideline and my memory of how that vessel moves through the abdomen as where I would want to in fact place my angle of insonation.

Superior Mesenteric Artery (SMA) Examination

So we're gonna look here at the SMA now, and we're gonna angle in the SMA.
So I can see that the SMA kind of moves around a little bit and its origin is right there.
And it looks like, you know what, frankly, his SMA comes off at almost a zero degree angle there, right?
So I'm gonna have Demetrius take a small breath in, right?
I feel pretty confident.
And that's a great image of both the SMA and the aorta, right?
The origins right there.
I'm gonna hit pause here on our system.
I'm gonna adjust my, and I'm not worried about him breathing in and out here right now.
I'm gonna hit freeze, and I can see now I can go in after he's done.
A lot of these high end systems, especially the one I'm using right now, will allow me to do a lot of adjustments after the fact, right?
For instance, I can adjust my PW gain, I can add my measurements, or I can have it on auto measurements package, which I prefer personally to have it on auto measurements.
So, because it's very sensitive to the Doppler waveform.
So it does measurements very well, and most of the high-end systems that you're gonna use, and frankly, when you're doing the in do work, you want to have a high-end system out there.
So look, go to the major manufacturers, make sure they bring in their high end machines.
If your purpose is to scan abdomen, is another pearl that I would like to pass on.

I can place my sample volume here.
I can set that.
People for diagnostic criteria will both use a peak systolic and an end diastolic value.
Dr. Z Wolak at a Dartmouth had a paper out that specifically spoke to the end diastolic values.
And Dr. Mineta, I referred to him before, had values out for the peak systolic.
So in the peak systolic of the celiac, we're looking for 200 in the SMA, we're looking for 275.
And the criteria for the IMA really hasn't been published much.
But Dr. Pato did publish something at RSNA about a year or two ago.
And that IMA criteria was similar to the celiac, where 200 centimeters per second was looked at as a indicator of disease.
Now, when I say that, I also couple with that with you have to look distal to that percent stenosis and make sure that you have the signs of a high grade stenosis, which are post stenotic turbulence and some type of diminution of the vessel of the Doppler waveform, right?
A tardus parvus waveform is a sure sign that something bad happened approximately.
And when you get that after going through a severe stenosis, you can feel pretty confident that any other testing modality that they go to will show that there is disease.

So I have it on the screen here.
My SMA nicely laid out here.
And I'm going to angle correct into it.
And I'm put my angle, and you can see that I'm almost comfortable using a zero degree angle here, because it really suits myself well.
But if I go off of the let's say I angle corrected improperly, you can see how I can make something that was 124 centimeters per second very easily with poor angulation 257, right?
I can even almost get it with without going above 70 degrees of insonation here to make this very normal vessel look very, very diseased.
So, very important aspect when you're doing this examination to make sure that you angle correct appropriately.

So, I'm gonna go back to a proper angle here.
Now, the SMA, unlike the celiac, is very long, right?
So I am going to have an origin.
I'm going to have a proximal mid and a distal section of the SMA when I'm looking at a mesenteric examination.
So I'm gonna label this the proximal SMA and you can see my values are up there.
Now, I'm I measured this twice, so I'm gonna actually take that off there.
Set that at 125, take that picture and what I did in my excitement to get to his SMA, 'cause that was such a great picture, I skipped the splenic and the hepatic artery, right?
So I'm gonna go back to those, and frankly, I'm gonna do the same type of thing.

You can see that this hepatic artery is moving away.
And you can see that, you know, the midline approach may not be the best approach for every single section of these arteries.
I am gonna have to, in fact, to do a proper examination in the aorta, definitely move my patient from one side to the other, use different approaches to insonate every section of these arteries as I move along.
And I want to do that.
I want to walk from knowns like the aorta into the celiac artery, into the SMA or knowns from like the celiac artery into the splenic artery as I do this.
So even though this exam looks like I'm doing it fairly quickly, this is an exam that will take a little bit of time.

So here I am, I see the celiac, you know, I make sure that I go back to its origin within the aorta to feel comfortable that that's in fact where I am.
And I see that there's that celiac coming across.
It's now diving down towards the spleen, splenic artery, and I'm now in the splenic artery.
And what you're seeing here is in the position that Demetrius is in, you're seeing a little bit of disturbed waveform.
Some people call it a ratty waveform.
And we'll freeze that and go back to it, let me just clear my comments.
You can see the rattiness in this waveform as I open up my get Demetrius to hold his breath right there for me, Demetrius.
Oh Wow.
Okay.
In this proximal splenic artery, you can see that the waveform, and I'm using my calipers here, is a little bit ratty.
And remember, I came through a pretty high velocity.
So, you know, I frankly expect to see that kind of pattern coming through there.
And what could I do?
Remember, I think that it may be an extrinsic compression phenomenon that's causing this on Demetrius.
So what I'm going to do then is position him in that way that I know that that compression is being relieved, and then reevaluate the splenic and the common hepatic to see if they normalize also.
But certainly the velocity is well within normal limits.
Once again, there's no really set criteria for the splenic or the hepatic artery.
What we're looking for there is any doubling of velocity.
Same thing that we would look for in the peripheral system, and certainly this waveform morphology, which is very crucial when you're doing abdominal work to take note of all.

So that's that.
SMA, frankly, sometimes you'll see me to get the mid and distal portion of the SMA I'll go and put Demetrius in a lateral decubitus position, kind of roll him over, place the transducer over here, visualize the spleen itself, and then take those images from the distal and the mid splenic artery.
Likewise with the common hepatic.
And I want to show you a little bit of something about the common hepatic here.
The common hepatic in most cases, I think, and maybe not in Demetrius, because he has this unique pattern here with the median arcuate compression, it's very hard to insonate.
It seems like it comes off at almost a 90 degree angle off of that celiac artery.
So you see this another like little hook there.
So it's tough to get to the origin of that.
So what I usually do from a midline approach is I take one signal and I'm gonna have Demetrius just hold his breath again for me, kind of judge where I want to be, work around, get back into it, and I see it right there.
A lot of things are going on here, right?
You have the splenic vein going into the meeting with the superior mesenteric vein, all in this area here.
You have the pancreas there as it moves towards the hepatic.
And once again, I see a very disturbed looking waveform.
Sometimes it's because my angle here.
Now you can see I definitely want to angle correct a little bit better here, right?
And I am really hovering around that 60 degree zone here, one angle.
So I'm in that hairy zone where, you know what I might be, it may be a little bit greater than a 60 degree angle.
And in that situation, I certainly would want to reposition my patient and make sure that I come at a less than 60 degree angle to confirm that the velocities are appropriate there.

Waveform Analysis and Diastolic Flow Differences

So we're gonna move now off of that, we saw the proximal SMA and you also noted that the signals probably looked a little bit different.
Demetrius signal within his celiac had a lot more diastolic flow than his SMA did.
And our patients that come in in the mesenteric situation are almost always fasted because of what I said before, that they have this fear of food.
So it's not hard to ask them not to eat breakfast.
But the celiac that's feeding the liver and the spleen is a artery that is constantly demanding blood, right?
So you have a very high diastolic draw.
The SMA in a fasting patient is really just hanging out.
It's waiting for the next food source to come in.
So in that situation that artery is going to have very low diastolic flow.
So I use that as a marker also when I am looking at these vessels.

So you can see them back in.
And I'm going to go back into the SMA here and there it is, Where remember I had that zero degree angle, and you can see how resistant this waveform is, right?
I can tone down my scale after the fact here.
I can measure it.
I would label it once again, I have appropriate angle and I know that this makes sense.
This is a little bit more resistant than the celiac.
It has a nice upstroke.
I don't see any disease from the aorta into the SMA I felt very comfortable.
So in that regards, I feel very good that I don't think for this patient they have anything going on at the origin of the SMA.
Remember I said this is a chronic situation.
This is not acute situation in most part.
So what I'm looking for is that orifice, that origin of these vessels to be where that disease is really located, right?

So I've done that.
As I moved on, I would move into the as I said before, the SMA and the aorta will follow each other juxtapose or parallel to one another.
So I'll just move down and take a mid to distal portion of the SMA.
And then after I do that, my next and usually my last vessel to look at the three important vessels, once again, celiac, SMA and IMA is that IMA, right?
And that's located surprisingly very far away from the celiac and the SMA, which are very, very close to one another, if you remembered.

Inferior Mesenteric Artery (IMA) Examination

So in that situation, what I do now is I take off all of my color, my power, 'cause I've played around in here and I've gotten all the information that I needed.
And then what I do is I look for that aorta again.
And frankly, I just go right down to the bifurcation of the iliac, right?
I go to the bifurcation of the iliac.
I adjust my depth, right?
Because now remember how that aorta is rising as it's coming up and to go into the iliac regions, especially in thin patients.
So I've adjusted my parameters pretty well here.
I've seen where I want my focal zone, I see where that bifurcation of the common iliac site is located.
And then I put my color back on, right?
Because this IMA is gonna come off and we can, you know, it's so easy to see and I apologize these tests, anybody's out there to think this is an easy test.
You're mistaken.
This is a very, very difficult test and something of a challenge.
And I think that's why I like it so much.
And I think that's why you'll like it.
So don't be surprised that you will don't find this as easily as I find this on our patient here today.

But that vessel that we see right here is in fact the IMA and it's coming off around two o'clock in most patients, you know, if I use a clock here and here's 12, it's about one between one and two o'clock.
And there it is right there.
Very easy to see.
A lot of people think that it's a very difficult artery to see, but they're mistaken.
This is the easier artery to see.
Actually the SMA and the celiac are much more challenging.
If you have those down, you will have no problem finding this IMA.

So I see that IMA I'm gonna do the same type of things that are important to me.
I'm gonna feel I'm gonna look at the color, make sure it matches with the aorta.
'cause I've already noted that the aorta does not have that much in color flow.
I'm gonna adjust my transducer in such a way that I can maintain a less than 60 degree angle or 60 degree or less angle.
I am then going to watch the breathing patterns of my patient.
I am then going to adjust everything.
I have my color gain up a little bit too much now that I've moved down to this region.
I'm gonna place my powered, my pulse wave doppler within the system.
I see that my vessel needs to be inverted, so I'm going to invert that and I can do it before or after it.
So I don't necessarily have to have the patient hold his breath for this.
But now I'm going, I'm ready to take this image.
And I am going to have Demetrius hold his breath.
Wow.
Wow, wow, wow, wow, wow, wow, wow, wow, wow, wow.
And I'm gonna take that image and I see a very nice doppler spectral waveform here.
I'm going to measure that.
I'll label it the proximal IMA, I will move back and forth.
I'm not just taking one image you know, for this demonstration.
The purpose of this demonstration, I'm quickly just showing you the Doppler waveform.
But you know, for each one of these exam, a extensive amount of doppler signals to really prove the fact that there is a problem or there's not a problem.
So I would be doing that.
I took the proximal IMA here.
I may move into the mid IMA section.
A little bit difficult to get the distal IMA as it moves through and feeds the colon areas.
But I can get a pretty good idea of what's going on in this situation based on this proximal IMA signal.

I remember some of the criteria that is out there now, and I think that was, like I mentioned Dr. Pato has published, says that a velocity above 200 in this IMA should be of concern.
But coupling that with the fact that we're looking for some type of post stenotic turbulence and powder harvest waveform after that.
The last thing I like to talk about is the fact that unlike the renals, the mesenteric system as we're looking at it with these machines, is very well collateralized.
So you can be faked out in a situation that you may find here where the SMA meets the velocity criteria, but does not meet the other criteria that I mentioned, the post stenotic waveform, the tardus parvus waveform distally.
But the celiac already, or the IMA may because it such has such compensatory flow, these three vessels will help each other out.
If one is down, the other one will pick up the slack.
Alright?
And in doing that, you know, as well as I do that those velocities may increase because of the compensatory nature.
So be very careful about that when you're out there scanning the mesenteric system.

Conclusion

And with that, I'd like to thank Demetrius, and I'd like to thank you for taking the time out to watch this mesenteric duplex examination demonstration.
Thank you.
Have a great day.