Transcript

All right.

Welcome everybody. You are now attending the, uh, webinar

for the Institute for Advanced Medical Education.

Uh, we have these webinars every month on the last Wednesday

of the month for different topics relating to ultrasound.

Um, tonight I have a very special guest with us here, one

of our, uh, lead authors.

And, uh, we will be introducing her shortly.

But first, we have some things to go over.

I, So, um,

what do you wanna know about our webinars?

So, basically, the webinars are intended for members

of I-A-M-E-I-A-M-E Institute for Advanced Medical Education,

has been around since 1991,

and is one of the leading, uh, educators of sonographers

and physicians that, uh, use sonography in the world.

In fact, we educate more, uh, physicians

and stenographers than any other

organization in the United States.

Um, the webinars, which are the last, uh, Wednesday

of the month, are free to the members.

They offer one CME credit, that credit, uh,

once you're enrolled with that and you just go online

and attest that you were there,

will then be automatically transferred to the A-C-C-M-E

or A-R-D-M-S or CCI, depending on the, the topic

and which organization you're a member of.

Um, if you are a non-member and you happen to be on this

and you, uh, attend the whole webinar, reach out to us

and we can sign you up for the membership,

and you can get credit for this, this webinar.

Um, remember, you have to stay till the end

to get the credit, Uh, like I talked about in the beginning.

Um, Institute for Advanced Medical Education offers

unlimited CME on our website, on on demand, either

through on-demand webinars

or over 160 courses that we have published already.

Uh, we add 30 to 50 courses a year onto the website

to keep that content fresh and new.

Um, we offer category one A-M-A-P-R-A credits

and are accredited

by the A-C-C-M-E-A-C-C-M-E Credits are accepted

by A-R-D-M-S as well as CCI,

and when you get credits through us,

we transfer those immediately over to your respective,

um, regulatory bodies.

Um, when we're looking at credits and,

and what we're doing here, uh, we also want to, uh, say

that in Canada, any Canadians on our channel right now, uh,

the Sonography Canada does also accept these credits.

The, um, the 10 webinar bundle, if,

if you're on here from that, you know, we, we offer that

for people, um, at a reduced rate,

and then also you can join the membership at a reduced rate.

Um, what's our philosophy for education?

Uh, we know that teamwork actually helps learning

and helps improve patient outcomes.

Um, sonography is one of the few, um, specialties

and, um, areas of medicine where you work so closely

with a sonographer and a physician,

and you have this close bond

and close working environment together.

And so it's my philosophy personally as the program director

that, uh, people

who do ultrasound together should learn together.

And, um, I am medical director of a,

uh, clinic in St.

Louis where we do over 7,000 ultrasounds a year

throughout all modalities.

I scan myself, um, especially the musculoskeletal cases,

and, um, also some vascular cases

and things like that, that are specialty cases.

But, um, I really rely

and work closely with my sonographers,

and we have a great relationship and I, I hope that, um,

that can come through on this, this, uh, webinar here.

Um, so our content is intentionally designed

for both the physicians and the sonographers.

And no matter if you're a physician

or a sonographer, you're gonna get a lot out

of this webinar, and you're

also gonna get a lot out of our courses.

Um, before we begin, the A CC ME always requires us

to show this, uh, accreditation and designation statement.

Um, this activity has been planned

and implemented in the accordance

with the accreditation requirements

and policies of the Accreditation Council

for the continuing medical education.

A-C-C-M-E-I-A-M-E is UCCE is accredited by the A-C-C-M-E

to provide continuing medical education for physicians.

IAE designates this live online webinar for a maximum

of one A-M-A-P-R-A category one credit physicians

and other attendees should only claim the credit

commensurate with the extent

of their participation in the activity.

So if you only stay half of the time,

you can only claim half a credit.

Uh, our disclosures in compliance with the essentials

and standards of the A-C-C-M-E, the authors of this activity

are required to disclose any significant financial

or other relationships that they may have

with commercial interests.

Myself, Ann Lauren Pellegrini, our other speaker tonight,

disclose no such relationships exist.

IAME has assessed conflict of interest with its faculty,

authors, editors, moderators,

and any individuals in a position to control the content

of the CME activity.

And any identified relevant conflicts

of interests have been medicated.

So tonight

what we're gonna talk about is enhancing duplex ultrasound

assessment of the mesenteric circulation.

Um, In talking about this,

I'm gonna start out the conversation,

talk a little bit about this, uh, from the

clinical perspective and give a little insight on this.

Uh, then Lauren is gonna finish up the talk,

talking about the technical aspects

and performance of the exam,

and I really encourage both sonographers

and physicians to listen to this.

It's great insight so that you know what's going on at the

point of care and at the view box.

So, without further ado, I'd like

to introduce Lauren Pellegrini Salzman.

Um, she is the program director of Sonography at St.

Louis Community College.

Um, she's also, uh, a lead author of courses

at the Institute for Advanced Medical Education,

where she's also on the education committee.

And she, um, is I,

I'll actually let you her tell you about this,

but she's on this, uh, massive journey right now to, uh,

see all the national parks,

and so we're really lucky

to have her back from one of the parks.

So, uh, Lauren? Yeah.

Uh, can you just, uh, give your, give a shout

or, you know, talk about yourself a little bit?

Sure, absolutely. So, I'm really excited to be here.

So I am definitely passionate about education.

So just like Dr. Cox said, I am the program director

of a local ultrasound program here in St.

Louis. I've been the program director

for the last two years.

I was an adjunct instructor for a year before that.

Um, and before I got into the official sphere

of working at the college, I,

my favorite part was always working with the students,

and then, of course, working with the radiologist

to make myself better so

that I could teach the students more.

So, education's been a really big part

of my ultrasound journey,

and I love teaching people about all the cool things

that you can do with ultrasound.

So I'm excited to teach you some new things tonight.

Awesome. So, Joanna,

we'll go ahead and move forward with these.

So, let's talk about what we're gonna do today, um,

with our objectives.

So today you're gonna identify

mesenteric anatomy and variations.

You're gonna learn to recognize mesenteric ischemia causes,

and learn duplex ultrasound techniques, as well

as apply criteria for diagnosing chronic

mes enteric ischemia.

Along this process, you're also gonna learn about some

of the surrounding anatomy that you might run into.

That could be, um, some incidental findings

that are very common, especially in this

demographic of patient.

So, while we're moving through this, um, evaluation

of the patient, uh, for mesenteric uh, issues,

we're gonna be looking at the abdominal aorta,

the celiac axis, the splenic artery, hepatic artery,

superior mesenteric artery, and inferior mesenteric artery.

These are the typical vessels

that you're gonna include in your protocol.

Uh, we're gonna evaluate these with, uh,

gray scale and color doppler.

Um, you may use power doppler, um,

and then we'll do some spectral analysis.

Um, so why is this a knowledge gap?

Or why is this something that, uh, sonographers

and radiologists, vascular surgeons,

emergency room physicians, um, family practitioners,

internal medicine, all the,

everybody needs to know about this?

Well, so it, it is rare,

however, the natural history of this disease process, uh,

when talking about the superior mesenteric artery, um,

occurs in a, uh, somewhat linear pattern over time.

So at, at age, 46% of people have this condition.

At age, 60 14% of people have it, and between 18

and 67% above the age of 75.

Now, that's a huge range, right?

So basically, you know, all of these people have it,

but they're not symptomatic, so they don't present with it.

And now we're talking about chronic mesenteric ischemia.

Um, and,

and really, you know, we're also talking about levels

of stenosis and whether

or not it's becoming clinically relevant.

You know, because you don't do a whole lot when you're,

or some people don't do a whole lot at that age,

it may not manifest itself.

So it's twice, it's twice as common in women than in as men.

And when we look at CT angiography,

it's seen 40% of patients

that have an abdominal aortic aneurysm,

and 29% of patients that have aortic sten stenosis,

and 25% of patients with peripheral arterial disease.

And what do all these people have in common?

They're all smokers.

You know, they all have high cholesterol.

They all have smoking in their history.

Um, so the first thing

that we're gonna do is we're gonna make this, um, branch

or dichotomy between how these patients are presenting

and when they show up to the sonography department, um,

the patients you see are most likely gonna be chronic

mesenteric ischemia patients.

These patients present as postprandial pain

or discomfort, anorexia and substantial weight loss.

And by definition, it should be for at least three months.

Um, they get these symptoms about 20 to 30 minutes

after a meal, and it can last for about one to two hours.

Um, typically the patient will become afraid to eat

or scared of eating.

And, you know, they come

to their doctor and they tell 'em about this.

And then they also have, you know, significant weight loss

as opposed to the acute mesenteric ischemic patient.

These patients are absolutely acute patients.

They have abdominal pain, peritoneal symptoms, uh, bloating,

malaise, nausea, vomiting, diarrhea.

They have laboratory, uh,

disturbances like elevated lactate.

Um, they may have perforation, you know,

they have some serious stuff going on, and it's very acute.

Um, typically, whereas chronic mesenteric ischemia is caused

by atherosclerotic stenosis,

an acute mesenteric ischemic episode occurs when there's a

rupture of an atherosclerotic plaque upstream,

and it goes downstream into the artery,

or if they're in a hypercoagulable state,

sometimes you'll see this with, um, uh, bacteremia

or, um, shock

or other, uh, causes where the, uh,

even if there's a venous occlusion

and you get back up the blood flow and in congestion.

So these patients present very differently.

And most of the time,

sonographers should not be seeing an acute

mesenteric ischemia patient.

Um, and I'm just gonna talk about the workup here.

So it's just like a blue toe or a, a cold foot.

Um, patients with these problems

shouldn't really be going to ultrasound.

They should be getting a CT angiogram

and having a vascular surgeon put

their hands on 'em immediately.

Um, the chronic mesenteric patient, um,

mesenteric ischemic patient is the one

that you will be seeing in your ultrasound lab.

Um, and they should be getting an ultrasound

and a CT angiogram.

Uh, remember they're not emerging.

Yes, they're losing weight and they're uncomfortable eating,

but we have time to work them up and,

and really figure this out.

Um, and in fact, the ACR appropriateness criteria, um, says

that, you know, you shouldn't do the ultrasound,

you should have the CTA and vascular surgery consult

and imaging should not delay treatment.

So, you know, if you've got a call in a sonographer, not

that anybody has call anymore, they have

to work overnight now, but if somebody has to drive in

to do this, it's, it's not okay.

You know, they've gotta, they've gotta get to surgery.

So, um,

when we're looking at this chronic mesenteric ischemia

workup, um, again, CTA

and ultrasound, they're complimentary.

You know, the CTA, you know, you'll see

that there's a stenosis there.

Um, you measure it similar to NASA criteria for, uh,

measurements of the area of stenosis

and the post stenotic lesion downstream.

Um, and then you, you get a ratio.

So, um, you know, just

because it's there, it may be asymptomatic.

You know, if you have a 70% stenosis on CTA,

it doesn't mean they're symptomatic.

So I see that a lot of time on call.

Um, I just, incidentally I'll see that just reading cases,

um, that have nothing to

do with that, and they don't have symptoms.

Now if, um, you know, on the CTA, you know,

it could be under read or, you know,

it doesn't really show well

because it's so ha atherosclerotic

and you can't really get a good look at it,

or it was a bad study

because of motion or something like that.

The ultrasound is gonna be additive to the workup.

So, you know, using B mode, um, Doppler waveform analysis,

um, you can look at the patient in the fasting state.

That's very important and Lauren's gonna

tell you about that shortly.

Um, the peak systolic velocity overall has accuracy

of greater than or equal to 50% for stenosis,

or greater than, or equal to 70% stenosis with, uh,

peak systolic velocity of 295 centimeters per second,

or 400 centimeters per second for the SMA.

So that's 295 for 50% or greater,

and 400 for, uh, 70% or greater.

And typically the, the treatment threshold is the 70%, um,

for the celiac artery,

which can sometimes cause these issues too.

It's 240 centimeters per second.

Um, and then we have some varying different, uh,

organizations that say, you know, 200 or two 40.

So it kind of goes back and forth between that

and usually your vascular surgeon's gonna have a preference.

So, um, this is where Lauren's gonna take over.

So Lauren, I'll let you go ahead and get started.

Awesome. Sounds good. Alrighty.

See, let me go forward here.

Oops, Sorry about that. Okay. Alrighty.

So mesenteric studies, why do we do them?

Um, so I'm used to teaching to students that, you know,

don't always know every little detail.

So I like to break things down into

all of these different buckets.

So the first place that I always start

with ultrasound studies is, why are we doing them?

That's really important to understand, right?

Um, so some of the things that we look

for when we are doing these mesenteric dopplers is

that we are checking for stenosis.

And that can of course be in any

of these arteries that we're evaluating.

Occlusion, of course, that's very important.

Aneurysms, uh, median arcuate ligament syndrome,

which we're gonna talk about some more later,

dissections and more.

So there's a lot that we can evaluate with these studies

that show a lot of really important

information for our patients.

So patient prep. So that's a big deal.

So the patients need to be NPO.

So a lot of literature says at least six hours,

but I think we all know by now,

if you are actively scanning, people are really gassy.

So the longer that somebody's NPO, the better you are going

to get image-wise.

So we would prefer 12 hours.

Um, another thing that I still have not convinced scheduling

of at the hospital is these would really probably be done in

the morning if able,

because that is gonna give you your best imaging window

with the least amount of gas.

Now these patients tend to schedule at like 3:00 PM Why

that is, I don't know.

Um, but in our ideal world,

we'd probably wanna do this in the morning,

but if for whatever reason you're doing this in an emergent

situation, the patient of course didn't prep for it

and they're not NPO for whatever reason,

make sure you notate that

and we'll talk about why that's really important here soon.

But making sure that you either notate that they're not NPO

or if you have control of the situation

that they are truly NPO is a big deal.

Um, and also of course, we want a patient that's going

to be able to do the things that we need them

to do to make the best study.

That includes having them be able

to lace the pine even potentially up

on their side a little bit.

If we need to move someone of the gas outta the way,

we ideally would like them to be able to take big breaths in

and hold it as well as let that breath out

and hold it that way as well.

And then just follow the sonographers

instructions as a whole.

Um, we know as sonographers, you know,

every patient's a little different.

We have to use our critical thinking skills

to get the best images, but if a patient is able to kind

of do what we need them to do, that

of course is gonna make the study a lot better.

So we're gonna time kind of talk about the physiology

of intestinal blood flow.

So first thing you need to know is

that it's very dynamic, right?

So it's always kind of changing,

it's not always the same thing.

So that blood flow is regulated by several factors,

including circulating hormones, your nervous system,

local metabolic factors,

and the presence of systemic low flow states.

The greatest change in flow occurs when a meal is consumed.

And again, I promise we're gonna touch on this later,

but if you've eaten or if you have not eaten, really,

really affects that intestinal blood flow.

So with the increase in the metabolic work of digestion,

there are increased requirements for oxygen and

therefore blood flow.

So our blood flow is always changing.

Uh, the dynamic pattern

of it is always changing based on if we've eaten recently

or if we have not eaten recently.

So some more about the physiology.

So increases in overall blood flow velocity falling a meal

are seen in both the SMA and the celiac.

So the SMA and the celiac are both affected by,

if we've eaten recently,

and how much, uh, velocity change there is.

So although the apparent response in the celiac artery in

the branches is quite small compared to the SMA,

so really this is just saying those SMA changes in flow

velocity are gonna be a lot more dynamic

and change, uh,

more significantly in comparison to the celiac.

These changes seem to occur at re response

to a decreased vascular resistance

as the sphincters in our digestive system relax,

as the resistance falls flow will

increase in healthy patients.

Key there, healthy patients,

we're gonna talk about some pathology

where this normal change in blood flow

doesn't occur like it should.

And then with the small bowel, the SMA feeds that

and the blood flow changes most

with conversion from a high vascular resistance

to a low vascular resistance waveform.

So we go from seeing

that high resistance waveform all the way to

that low resistance waveform

and it all changes having to do

with if somebody has eaten or not.

All right, so now we're talking about some

of my favorite things, which are the scanning

techniques and the anatomy.

So as you can probably imagine just about anytime you're

looking at anything in the abdomen, you're gonna be using

that Kline probe.

Now, we've already kind of briefly talked about this,

but a lot of patients

that are gonna be getting this study done are going

to be patients that are ha going

to have something called fear of food.

Now, fear of food occurs

because these patients are having pretty severe abdominal

pain from these various pathologies we're gonna talk about.

So if you have a fear of food, you're probably not eating

as much as you normally would.

So a lot of these patients are on the thinner side as well

as, as Dr. Cox said, a lot of these patients

that are affected by stenosis in these vessels, um,

they also have are smokers more than likely.

And a lot of smokers tend to be a little bit thinner.

So moral of why I just talked about

that is you're definitely gonna wanna

use your curve linear probe.

But if you do have a thinner patient,

which is the typical patient population for this exam,

you wanna try and find the highest frequency curve linear

transducer that you can.

So once you've found the transducer you're gonna use

that works best on the machine that you have,

which you're gonna do to get started with the exam,

is you're gonna place the transducer right below

that xiphoid process.

So you're pretty much gonna be at the highest point of

that abdominal cavity

and you are gonna kind of start to scan through the aorta.

Now, before you even really get started with this exam,

one thing that I would recommend is checking

that entire abdominal aorta from proximal all the way

through distal, just to see

before you even get started, does there appear to be a lot

of calcifications throughout the aorta?

Is there an aneurysm?

Um, you know, is there any kind of pathology

that you should know about before you even get started?

Because that's probably gonna give you a really good roadmap

to what kind of pathology you might see

after you start the exam.

So again, like I just talked about,

and you can kind of see here in this drawing,

you can see you have the aorta here.

Of course, you're gonna start up proximal as you can

and move your way coddly down through into the bifurcation.

Some of those important landmarks you're gonna evaluate are,

of course the abdominal aorta, the celiac access,

the proximal common hepatic artery, the splenic artery,

the SMA and the IMA.

But again, make sure you evaluate all the way down through

that aorta to see if there is any pathology

even before you get started.

I always tell my students it's okay to cheat a little bit

by looking ahead.

So here is just a nice image of an aorta.

Don't we wish that every patient looked like

that when we put the probe down?

That would be our ideal world, right?

Um, but here we have a beautiful image of an aorta as well

as an anatomical drawing nearby.

So as we can see up near that proximal aorta, we have

that celiac artery

or that celiac trunk coming off as well as just inferior to

that we have the SMA.

Okay? So per IAC guidelines,

a mesenteric arterial study must include gray scale

and color images of the proximal to mid aorta,

the celiac artery, the SMA and the IMA.

Now we can't see the IMA in this particular ultrasound

image, but that is an important part

of a mesenteric doppler study.

So these are all the requirements of images

that must be taken to meet the IAC guidelines.

So again, per IAC spectral Doppler waveform,

so you're gonna do your gray scale,

you're gonna do your color, and then you're going

to pulse wave doppler throughout these vessels here, right?

So per IAC, you're gonna do the spectral doppler waveforms

and velocity measurements.

And they must again include the proximal to mid aorta,

the celiac artery origin or the trunk or the axis,

however you wanna refer to it, the hepatic artery.

But per IACA velocity in

that hepatic artery is not technically

required by their standards.

Um, you also are going to need to doppler the SMA origin,

the proximal SMA and the IMA.

Now we will talk about, you know, doppler in that prox SMA,

but a lot of places that I've worked also want you

to doppler the mid and distal SMA as well.

Now follow your facility protocols.

But I always say they're never gonna get upset if you

take a couple extra pictures.

You'd rather have a little bit more than not enough

when you turn your study in.

So with the technique, so this is a, you know,

this can be a hard study especially

'cause a lot of these patients, you know,

they may have a lot of plaque, um,

they maybe they can't hold their breath, you know,

whatever the situation is, these can be hard.

But there are some things that you can do to try

to optimize those images.

So with the technique wise, you're gonna

of course do the pulse wave doppler

and you're going to want to use a really small gait, right?

So when you're using that pulse wave doppler, make

that gate a little bit smaller

because these vessels are so small.

So decrease that gait size to make sure

that it is equivalent to the size of the vessel there.

So decrease the gait there.

Uh, typically about 1.5 to three millimeters in size.

So you're also gonna wanna make sure,

just like you should be making sure always when you're doing

ultrasound studies that the doppler angle is

60 degrees or less.

If it is above 60 degrees, it is a non-diagnostic study.

So make sure you're always paying attention to that.

A lot of ultrasound images,

the degree will turn red on the screen.

If you're going above 60, it tries to highlight it

and say, Hey, this isn't right.

Um, but just make sure that you're at 60 degrees or less

whenever you are doing that doppler evaluation.

All righty. So now we are starting

with our first anatomic piece here, the celiac artery.

So the celiac artery supplies the organs of the four gut.

So that includes the stomach, the liver, the spleen

and portions of the duodenum and the pancreas.

So for evaluation of the celiac artery,

make sure you begin at the proximal abdominal aorta

and move about one to two centimeters below the diaphragm.

So again, start up by that xiphoid process

and just start to kind of move your way down until you see

that celiac artery.

So for evaluation, begin at the proximal abdominal aorta.

Move about two to four centimeters

or I'm sorry, move just a little bit down

about two centimeters still.

Um, but the celiac artery itself is about two

to four centimeters in length.

The celiac artery or trunk,

however you wanna call it, then has

that traditional ultrasound Segal sign there

and it splits into the left gastric, the hepatic

and the splenic arteries.

Now we're gonna talk about the hepatic

and the splenic artery some more here.

Um, but that little celiac trunk splits

and then has some really important jobs and organs to feed.

Uh, so again, you'll see that segel sign

and this is typically best seen in the transverse view,

which we have some images of that coming up.

So one thing that I like to say,

again, patients are not always easy.

So you know, ideally you'd love this awesome scan,

but let's be real, that doesn't always happen.

So just a little trick.

I wanted to make sure I popped in when we were talking

about scanning the celiac.

One thing that you can do if you're having a hard time

finding the celiac, 'cause it is such a short vessel, is

that you can go and you can look at that aorta, right?

You can find it in transverse at about mid

and then you can start to move up superiorly towards the

patient's head or PHA I guess I should say.

And you can move up towards the patient's head

and look for that little SMA.

We can almost always see the SMA, right?

So we're gonna look for that abdominal aorta, we will look

for that SMA and keep following up,

scanning towards the patient's head until you get to

that celiac access.

So follow that SMA up

and then you should see a dive towards the aorta

and then hopefully just a little more maneuvering up,

your celiac access should pop out nicely.

Now in an ideal world, you're gonna put the probe down

and see the celiac access no problem.

But if you're having some issues, that's just a little tip

to try find that SMA

and move up towards the patient's head until you see

that celiac access come off there.

Um, so again here you have that aorta,

you have the SMA, right?

We moved up a little bit more

and we were able to see that uh,

celiac access coming off nicely in gray scale

and then down here in color as well.

So here is that beautiful sgu sign.

Um, so it doesn't really get too much better than this.

So we can see that abdominal aorta, we see that short uh,

celiac axis are trunk again only

about two to four centimeters.

So pretty short there. And then we can see the split

with the hepatic artery and the splenic artery.

So as you can imagine, and I'm sure you all already know,

but I like to talk to you all like I talked to my students.

The hepatic artery goes towards the liver

and the splenic artery goes towards the spleen.

So that hepatic artery is coursing over towards the right

side of the patient's body

and that splenic artery is coursing over towards the left

side of the patient's body there.

So of course you can also get the celiac access in the

longitudinal view as well.

This is a beautiful image here

and this is a longitudinal image of that celiac artery

and they are getting a nice pulse wave Doppler image.

Um, I did put a little star on the image

because if you see the angle there, it is 50.

So it is good. So anything above 60 not going to work 50,

that'll be perfect there.

So the celiac artery, so we've talked about it,

but what is normal?

What does that mean? What does that look like?

Like I tell all my students every single day, you have

to know normal before you can know abnormal.

So you have to know and be able to interpret

what normal looks like to figure out what's wrong,

if there is anything wrong.

So what is the normal celiac artery, waveform and velocity?

So Dr. Cox already kind of briefly touched on this,

but in a really important note is

that the celiac artery waveform,

or I'm sorry, peak systolic velocity,

it should be about 1 25, right?

So we're gonna talk about when it starts to get elevated,

what that means, what that looks like,

what velocity that is.

But you wanna make sure that it's that normal low

resistance waveform and it's less than 125.

Once you get over that, you start to get concerned

for some stenosis.

So what is abnormal? So we just talked about

normal, what's abnormal?

So it's considered abnormal if the peak systolic velocity is

200 centimeters per second or greater

and this equates to a 70% or greater stenosis.

And as we know by now,

if somebody has a severe enough stenosis

that it's in the 70%

or greater category, some things that you are going

to see on ultrasound include, uh, turbulence, right?

So when you turn on that color box, you are gonna see a lot

of mosaic flow there.

Um, and then of course when you put your doppler signal

right into that stenosis, you're going

to get a really high velocity.

Now, one thing I always tell my students,

even if you put the uh, signal in

and you think you found the highest velocity right off the

bat, you know, I always recommend doppler

through that stenosis.

'cause you never know, you may move up just a couple

millimeters and get an even higher velocity

than you thought you were going to.

So always doppler before, within and

after that stenosis there

because you never know where you're gonna get

that true peak stenosis until you truly doppler through it.

That's a really important vascular tip there.

Um, so a CR, so the American College of Radiology,

they actually recommend two 40

or greater means 70% stenosis or more.

So if you're at 200 or more, very concerning.

But then once you hit that two 40

or greater, a CR says this is even more accurate

of a peak systolic velocity to prove

that there is a great stenosis there.

And then of course you have the end diastolic velocity.

So 55 centimeters per second

or greater there is equivalent to a 50% stenosis or greater.

So evaluating the peak systolic velocity

and the end diastolic velocity is very important.

So these values have been found to be well correlated

with angiographic evaluation.

So they did these ultrasound studies

and they found the stenosis, they sent them off

for more testing and they found these

to be very accurate numbers.

So we're gonna switch gears a little bit

to the splenic artery.

So we talked about the celiac axis,

but we talked about how the celiac axis branches into

the splenic artery.

So what do we know about the splenic artery?

So the splenic artery normally has a low

resistance, uh, waveform.

It can be tortuous.

So make sure you're always watching those doppler angles.

So when you are doppler through a vessel that is tortuous a,

make sure that that angle's in

above 60 like we already talked about.

But make sure your doppler angle is in line

with those vessel walls.

You can't keep it at the same angle throughout.

If you do have a tortuous vessel, you are going to have

to continuously change that angle

to make sure you are in line with the vessel walls

'cause that's what makes it the most accurate.

So among visceral artery aneurysms,

the splenic artery has the greatest incidence.

So the splenic artery aneurysm, that is decently common

and it's actually four times more common in women

than it is men.

So with that splenic artery aneurysm, it's typically caused

by arterial fibrodysplasia portal hypertension

or multiple pregnancies.

So when I was doing a lot of research into this,

whenever I saw the multiple pregnancies, I did not know

that I thought that that was a really good thing to add in

because that just proves a lot

of people are at risk for this.

And so that splenic artery aneurysm is also a big deal

because if it does rupture, it can be fatal.

So that is a really important thing

to document if somebody does have one.

And if a patient is pregnant with a splenic artery aneurysm,

they are at a pretty high risk of it rupturing.

So a 95% rupture rate,

a 70% me maternal mortality rate if

splenic artery does rupture.

And then a 95% fetal mortality rate if

that splenic artery aneurysm does rupture during pregnancy.

So if you see one on ultrasound,

absolutely make sure you document it,

especially if it has not been documented before,

and make sure that you take good images of this

'cause that can be a really, really big deal in

a patient's plan of care.

So now we're gonna talk about the other side of

that SL sign, right?

So we have that common hepatic artery.

So again, this is gonna be a low resistance waveform.

Now the incidence of aneurysm in this is lower.

It's at about a 20% rate there.

Um, so again, normally you're gonna have

that low resistance waveform.

A lot of times whenever a sonographer is doppler the hepatic

artery, it's more so if they're worried about the liver

specifically and they are getting a liver doppler ultrasound

done, that is when the hepatic artery is more

commonly evaluated with, uh, spectral doppler.

So now we're gonna talk about the SMA.

So that's something we're gonna talk about a lot

throughout the rest of this lecture.

It's a, a big player today.

So the superior mesenteric artery

or the SMA is the second branch of the abdominal aorta.

So you have your celiac axis and then just below that

or just distal to that, you have the SMA.

So this is one to two centimeters distal to the origin

of the celiac artery.

So what does the SMA do? It supplies organs of the midgut.

This includes portions of the duodenum, the pancreas,

the small intestine, the and the ascending

and transverse colon.

So it feeds a lot of our, uh, gut here.

And typically that SMA is gonna be best visualized

in the longitudinal plane.

So even though that clic access can be really,

really seen nice in that transverse view for that SQL sign,

the SMA is evaluated very nicely in the longitudinal plane.

So as we can see here in this ultrasound image, again,

don't we wish all of our patients imaged like this?

Um, but we have this very elongated out SMA

and as you can see here, I put these little uh,

blue areas within that SMA.

The first one here is simulating prox and then mid

and then distal SMA.

If you remember from the lecture a couple slides ago,

per the IAC, you only have to technically, uh,

doppler evaluate that proximal SMA.

But if you can see it this nicely,

I really would recommend doppler all the way through

that SMA, just to prove there aren't any stenosis anywhere

throughout that SM.

So again, you can see the little first blue square that

that's prox mid and distal here.

Okay, so a normal SMA is gonna run parallel to

that abdominal aorta, right?

So it's going to run just adjacent to it and parallel to it.

So with the SMAA normal fasting SMA will have aphasic

or high resistance waveform.

So that's a little different than everything else

we've talked about so far.

A normal fasting SMA is going

to have a high resistance waveform.

So doppler evaluation of the SMA,

so the doppler sample at the proximal mid

and distal portions of the SMA if possible.

And again, it should be below

that 125 centimeters per second

for the peak systolic velocity.

If it gets above that, you start to get worried

that this patient does have a stenosis here.

And as you can see from this waveform here,

it's a nice beautiful phasic waveform.

That means it goes above the baseline, below the baseline

and then back above the baseline again, which is ideally

what you want in a normal fasting SMA.

So what is the difference between a fasting

and postprandial SMA waveform?

So when the patient is fasting, again, you can see

that phasic waveform.

But after somebody eats, if you check here right,

you can start to see it kind of switches over.

That waveform is gonna start to switch into that low

resistance waveform there.

So again, like we talked about, if you end up having

to do a mesenteric doppler study

and this patient has eaten recently

and they're not an outpatient

that you can reschedule, it has to be done.

Make sure you take really good sonographer notes of that

'cause it really does change what you're looking at

and what normal looks like versus abnormal.

So for that SMA stenosis, so with an SMA stenosis, so uh,

greater than a 50% stenosis,

that in diastolic velocity is going

to be five centimeters or greater.

And that peak systolic velocity is gonna be 275 centimeters

per second or greater.

So as we can see here, this velocity is absolutely elevated.

We're at 433 centimeters per second for

that PSF there.

So it's very elevated, it's absolutely stenotic.

Now if we were scanning this live

and we were able to put our color box on there,

we would absolutely see some turbulent flow.

Now it's a little bit hard to see in this image,

but one thing I did wanna point out while we had this color

image up here is

that you wanna make sure you have your scale at

the proper settings as well.

You don't want them too high

and you don't want them too low.

So between about 40 to 60 for

that scale will be a good place to sit

to best optimize those ultrasound images

of those mesenteric vessels.

But as you can see here, they were able

to optimize this image.

Well you can see a little bit of mosaic flow here.

It looks like we have some blues

and some yellows right in the middle

of this very high velocity, which again is at 4 33,

which absolutely correlates to a stenotic SMA.

So now we're gonna switch gears a little bit

to the inferior mesenteric artery.

So the IMA supplies the hind gut

and that includes the transverse colon, descending colon

sigmoid and proximal portions of the rectum.

It's most, I easily identified in the transverse view,

but it's not as easily seen as the celiac

and the SMA the IMA can be harder to visualize for sure,

but if you are going to be able to visualize it,

what you're gonna wanna do is you're gonna wanna go all the

way down through the distal aorta into the bifurcation,

into those iliacs and you're gonna find that bifurcation

and now you're gonna kinda move up towards the

patient's head or pha.

You're gonna typically go up about one

to three centimeters from where that bifurcation is in order

to try and find that IMA.

So the IMA why it can be a little bit harder

to see too is it actually comes off the anterior portion

of uh, that aorta and it's pretty small.

Um, but if you come down to that bifurcation

and move up a little bit pha, you should be able to find

that IMA ideally,

but it's also gonna have a similar doppler waveform

to the fasting SMA ak, it's going to be high resistance.

So how do I find it? So the IMA again can be found

transverse and it's gonna be arising from the left anterior

lateral aspect of the aorta.

So if you wanna kind of focus a little bit on the patient's

left side, that is going to help you find it.

Um, so again, about one to three, four-ish, somewhere in

that realm it's always gonna be a little bit different.

You're gonna come up s PHA towards the patient's head

from the bifurcation.

So with the IMA, the IMA is diving left lateral

and into the pelvis, therefore flow is directed away

from the transducer.

So again, like I always tell my students, um, you know,

flow is all relative to your transducer.

It's not that it's just randomly switching

around depending on where you're looking, it all has to do

with the direction you were looking at that vessel from.

So because of the angle that we're looking at that IMA,

it's going to look like it's reversed but it's really not.

It's just that angle that we're looking at it from.

So it's important to ensure that the IMA is patent

for a mesenteric study.

So you can see here in this IMA it appears blue

'cause it's going away from that transducer, right?

And then it looks like the waveform is reversed.

But really it's just that angle

that we're evaluating that IMA with.

So here is a really beautiful IMA image.

So this is it in transverse

and this is a transverse colorful image

of the abdominal aorta and the origin of the IMA

and it arises again from the left anterior

lateral aortic wall.

And if you see here from this color image,

another thing I like to point out is that you really do want

to optimize your color box.

If you are looking at something as small as the IMA,

you don't want this huge color box.

You wanna make sure you make your color box small

and over the appropriate vessel that you're wanting

to evaluate as well

as make sure you're paying attention to that focal point.

Make sure it's right at

or just below the level of the vessel you're wanting

to interrogate, especially when the vessels are as small

as these mesenteric vessels.

So now we're gonna talk about some pathology.

Alright, so we've kind of hinted at this one a little bit,

but the first one we're gonna talk about is median arcuate

ligament compression syndrome or mals.

So this is rare, but it does occur.

So MALS is a transient compression of the celiac artery.

So that's something important to remember.

It's that celiac artery that's being affected by mals.

And this is because the median argument ligament

of the diaphragm is essentially kind of pressing

and compressing on this celiac artery.

So the pressure is relieved when the patient inhales

and it's going to get worse when the patient exhales there.

So again, this is more common in females four to one

and it's thought to be more common in thin patients as well.

So you can see here in this drawing this is supposed

to be a drawing of the underside of the diaphragm.

So here is that median arcuate ligament, right?

It surrounds that aorta

and you can see here this is the aortic ATU near the

proximal aorta there and then this is the arcuate ligament

and it surrounds that aorta

and then can uh, in some patients compress

that celiac artery, which can cause some issues.

So how's a patient gonna present if they do have mals?

So this can be included with chronic abdominal pain,

especially after they eat right.

So, um, that abdominal pain will kinda be a long-term

thing with these patients.

Uh, nausea, vomiting and weight loss.

So you have some of that food fear going on, right?

And then if patients don't feel good

after they eat it makes them not wanna eat.

And if patients aren't eating,

they're gonna lose some weight, right?

Um, and then they're gonna tend to be kind of thin.

So what are we gonna look for in ultrasound?

So on ultrasound you are going to look at that celiac artery

and you're gonna look at that uh, peak systolic velocity.

So you're gonna check

and see if it increases with patient exhalation

and decreases with inhalation.

So you are going to want to document

that on the ultrasound screen.

Is the patient breathing in? Are they breathing out?

Are they inhaling or are they exhaling?

That's a really important thing to document

because that is going

to change if a patient has MALS or if they don't.

So on a patient with true mals,

you're gonna see an increase again in

that peak systolic velocity

and that exhalation, um, an increased color of velocity

and exhalation and the compressed segment should have a peak

systolic velocity of 200 or greater.

So that is where our job is going to come in.

We're gonna document is the patient breathing in,

breathing out, you're gonna take a velocity while they're

doing both and see if there is that increase in velocity if

that celiac artery is being compressed

and essentially becoming stenotic because of that pressure.

So here is a celiac artery doppler

during normal respiration versus a celiac artery doppler

during deep inspiration.

So if you can check here, if you look at that velocity,

so we have a velocity of 521 here

and then also 287.

So that is still abnormal,

but 500 is very high there.

So this patient absolutely has some kind

of pressure going on on that celiac artery

and in this particular patient they had mals.

So because of that they do have some chronic abdominal

pain going on.

So now we're gonna kind of switch gears into

mesenteric ischemia.

So we talked about mals, very, very interesting.

Some big things to remember with

that is the change in velocity with inhalation

and exhalation that can cause chronic abdominal pain.

But now we're gonna talk about the mesenteric ischemia.

So this can be a really, really big problem for patients.

So mesenteric ischemia, you're gonna have atherosclerosis,

which commonly involves the mesenteric vessels reported in

up to 20% of patients over 65.

So if you read

or scan vascular ultrasound at all, you'll definitely know

that this arterial disease, a lot of patients have it,

especially that generation that's smoked a lot.

So that puts them at a pretty high risk of developing some

of these issues such as mesenteric ischemia.

But meso enteric ischemia occurs when perfusion

to the visceral organs does not meet the metabolic demands.

Interpretation of mesenteric duplexes is aimed at

identifying HI hemodynamically significant lesions,

AK a high stenosis and decreased pressure and

or flow is seen beyond the occlusive lesions

of greater than 70%.

So basically if there's a really high stenosis that artery

that's going to feed that oxygenated blood to that organ,

all that oxygenated blood is not going, is not getting to

where it is supposed to be getting to

and that is causing a lot of issues for that patient's.

AKA ischemia, and this can be an acute

or chronic process and we'll talk about both.

So with mesenteric ischemia,

acute ischemia is a highly morbid condition.

So just like Dr. Cox was talking about,

this is an emergency, this is a big deal

and it has a reported mortality rate ranging from 30 to 90%.

90% is a very high stat.

Um, thrombo thrombotic,

arterial mesenteric ischemia is responsible to for 15 to 30%

of cases and has the worst prognosis of any form

of mesenteric ischemia.

So mesenteric art, arterial occlusion, some causes,

so some common causes of this include emboli

to the mesenteric vasculature, which can be caused

by emboli from the left atrium, left ventricle,

or left-sided cardiac valves.

So essentially any kind of clot on the left side of

that heart is gonna get pumped out of that heart.

It's gonna go down to the aorta

and it's going to get lodged somewhere.

And one of the places it can get lodged is any

of these vessels in the mesenteric system there

and then arterial thrombus.

And then rarely you can have aortic dissection which leads

to an SMA dissection and thrombosis.

So there are some variety of things that can cause this,

but a complete arterial acute occlusion of any

of these mesenteric vessels is going to cause a big issue

for the patient that's considered acute is,

um, ischemia there.

And again, that is a really high mortality rate.

So with acute it can range from mild to fatal when acute,

again, high mortality rate, if it is caused by an emboli,

a lot of times it's associated with AFib, which

that makes a lot of sense.

If people have atrial fibrillation, they're at a higher risk

of developing clots.

If they're having a higher risk

of developing a clot on the left side of that heart,

it is eventually gonna get

pumped outta the left side of that heart.

It's gonna go down through the aorta

and it's gonna get lodged somewhere.

Right? And that can include that mesenteric system.

So if arterial thrombus thrombosis, it's associated

with aous disease.

So what are some of the issues? Why is it such a big deal?

So with mesenteric ischemia that is acute, it's gonna start

with necrosis of the bowel.

'cause again, that bowel is not getting

that oxygenated blood like it needs, so it's going to die.

So necrosis will occur.

Then bacterial proliferation of the bowel wall, which leads

to gas from the bowel wall

and it travels through the mesenteric

vessels into the portal vein.

And you can actually see this on ultrasound.

I wanted to make sure I added this in

because if you are evaluating

that main portal vein in somebody

that has acute mesenteric ischemia,

you can actually see those gas bubbles going through

that portal vein, which you're going to appear

as little echogenic foci going through that portal vein.

And this will eventually lead to sepsis

and bowel perversion, which then leads to patient death.

So here we can again see

that greater than 70% stenosis of that SMA.

So you're gonna want to check if you are evaluating for

that chronic, uh, mesenteric ischemia.

Is it from a stenosis such as this?

So chronic, so we talked about acute, that's a big deal.

Now chronic is a big deal too,

but it's not as a big of a life altering issue.

So it can, it's also called intestinal angina or pain.

It's not as common as acute

and it's defined as a significant stenosis of two

or more mesenteric arteries.

So patients are gonna present

with postprandial abdominal pain.

So after they eat, they're gonna have that pain.

Again, weight loss, food fear, nausea and vomiting.

If you haven't caught the theme by now, all

of these things kind of go together with any

of these mesenteric vessel pathologies.

So what is the etiology?

So patients are gonna be 60

or older, typically they're gonna be a current

or previous smoker.

All the times that I have seen significant stenosis in the

SMA, the patient was absolutely a previous smoker.

So there is a high correlation there.

50% of patients also have peripheral vascular disease.

So of course if they're having a lot

of vascular disease down in their DPA and their PTA

and their ABIs are bad

and their carotids have a bunch of plaque in it,

there is a pretty decent chance

that they're having some chronic mesenteric ischemia

going on as well.

And these are our resources.

So I hope you all learned something tonight.

If you have any questions, please let me know.

Um, but thanks for being a great audience.

Yeah. Um, we did get one question

that I thought was a good one.

Um, Ving Phillips, I hope I pronounced that right.

Um, if the patient is so thin, is there any chance

of using our linear probe?

And if not, why? Sure. What do you say to that?

Yeah, I think that's a good question.

I mean, I think if they're thin enough, I don't see why not.

Um, I guess you could definitely try.

I don't, I haven't really ever thought of that,

but I think if you could get the proper Doppler

angle, I would say probably.

What do you think Dr. Cox?

Yeah. Um, you know, I think a a nine,

a linear nine mm-hmm.

Is a good probe that, um, that

that could achieve the same thing

and could get you some higher resolution

for the gray scale images than, than a curve linear.

I think my highest one's a six.

So, um, yeah, I think it, it's, it's worth a shot.

You know, these are the kind of things

that on the fly you're gonna be sitting there

and you're gonna think, oh, I, I need, you know,

maybe I could get a better look at this.

So, sure. You know, I, I've actually seen pap people

with their aortas almost touching their anterior,

uh, abdominal wall.

So it, it, um, it definitely is possible.

So yeah, that's a good question.

And I, and I think if, if, if it could, uh,

work, go ahead and try it.

Absolutely. Um, Lauren, I'm,

I'm just gonna kind of play devil's advocate here.

Yeah. Um, how, how often do you, um, look at,

uh, the, uh,

mesenteric veins while you're doing any arterial studies?

Or do you just leave that to an order

whenever it comes over for, you know,

portal vein type stuff?

Yeah, I would say most times when I'm evaluating

that vascular system as if they have really severe portal

hypertension, you know,

and we are worried about some kind of occlusion.

Um, I know that I, when I was doing some research,

I did see some protocols do have, you include those veins,

but I think it's facility by facility.

But I would say most times when I am evaluating

that venous system, a lot of times it's

because I'm worried about a clot from portal

hypertension that's severe enough.

Yeah. And, and that's, that's kind of

what I was hinting at

because I, I've worked with you at two different facilities

so far and we've never included that in our protocol.

Yes. But, um, certainly, you know, uh, um,

you can have a venous infarct of the, of the bowel

and, um, in an acute setting with some

of these other things, obviously it's not gonna be a

arterial em embolic event,

but people a lot of times with, uh, DIC

or um, sepsis or you know, meningococcal septicemia

or something, you know, those are the

patients that they get those kind of things.

Oh, uh, Julie Kini,

she actually asked can a stenosis in the celiac trunk be

stented or what would be the treatment?

Um, yeah, I'll take that one.

You can actually stent a, um, celiac trunk, um, vessel

with a, uh, with a expandable stent that,

that you expand with a, uh, balloon.

The self-expanding won't work, um,

because it's not strong enough.

But, uh, the celiac trunk, um, you know,

sometimes you actually do need to have surgery for that

because, um, you know, it's really caused by

that thickened arcuate ligament,

and that could be too strong for stent to keep open.

Mm-hmm. Um, I've also seen where they will actually,

um, do a bypass.

Mm-hmm. So from one vessel to the other.

Yeah. And I did wanna add too,

that if you do run into a patient that has had a stent,

it looks very, very similar to an ICA stent,

for example, whenever you're looking at it.

So it'll have the same kind of echo texture.

Um, it'll look like a foreign body and that c like axis

or that SMA, but it looks really, really similar

to a carotid artery, uh, stent, just

of course, in a different spot.

Yeah. And at least in my experience,

you don't stent acute occlusions, you stent chronic ones.

Mm-hmm. So if it's an acute occlusion that's a surgery, it,

it's just, there's, there's nothing, you know,

there's a lot more going on there than just, you know,

opening up the artery.

You're gonna have to do some more surgery than that.

Good question. Mm-hmm.

Alright, um,

do we have any other highlighted questions

Enhancing Duplex Ultrasound Assessment Mesenteric Circulation

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