0:00

Okay, so next up is mesenteric Doppler.

0:03

These studies are some of the more physiology-driven exams that we perform in

0:06

ultrasound. There are a couple pathologies that we see involving the mesenteric

0:12

arteries. One of the more common ones that we evaluate for is called median arcuate

0:16

ligament syndrome or MALS, M-A-L-S.

0:19

SMA syndrome, which is not a primary problem of the artery itself, but it is

0:24

more a problem of the artery sort of squeezing the bowel and

0:30

specifically the duodenum that's going under it.

0:33

And then finally, kind of garden variety atherosclerotic narrowing that we would

0:37

see in many patient populations. So first is median arcuate ligament syndrome, and

0:43

so this is a process where you have compression of the celiac artery by the median

0:47

arcuate ligament. That is a normal structure that is attached to the diaphragm, and

0:53

on inspiration and expiration, it changes what that compression looks like.

0:57

When this process presents itself, it tends to be compression during expiration,

1:03

where that ligament tightens, and so patients can have periodic abdominal pain,

1:08

specifically kind of postprandial abdominal pain.

1:10

They may have weight loss and other typical non-specific symptoms.

1:14

Sometimes these patients actually have better symptomatology when they lie down, so

1:18

that can also show you what happens when they decrease that pressure upon the

1:22

celiac artery itself. And then one of the common things that we see is the celiac

1:27

develops kind of a hook-shaped configuration as the vessel gets compressed

1:31

cranially from that ligament, it starts to kind of push the proximal portion down,

1:36

and the slightly more distal area hooks up around that.

1:39

So again, this is a dynamic process.

1:41

This is something that happens at expiration, and if it doesn't change during

1:45

respiration, you want to think about potentially a different process.

1:48

So we have a couple of criteria that are used.

1:51

The baseline elevation of the celiac over 200 centimeters per second is one that

1:56

can be suggestive of median arcuate ligament syndrome, but this is obviously going

2:01

to be non-specific because there are other things that can do that.

2:04

However, if you see an expiration peak systolic velocity of over 350 centimeters

2:08

per second, it's usually pretty indicative of this process.

2:12

And again, you need to see these respiratory-related changes to make this

2:15

diagnosis. On the flip side, there are other criteria for diagnosing mesenteric

2:21

stenosis, and so this is stenosis for any etiology, but primarily, this is for

2:26

typically atherosclerotic or potentially thrombotic-related stenosis.

2:31

So we have some specific PSV thresholds that we use for both the celiac artery and

2:35

the superior mesenteric artery. The classic criteria for these have been 200 and

2:40

275 centimeters per second, respectively.

2:44

That is consistent with 70% stenosis, which again, is the typical threshold that we

2:49

use for hemodynamic significance.

2:51

Like carotid ultrasound, these have been updated within the last number of years by

2:56

some labs where because they have a little bit too high of a sensitivity at some of

3:02

those lower thresholds. So for the celiac artery, they've updated that to 240

3:07

centimeters per second for 50% and then 320 centimeters per second for 70%, and you

3:12

can see the corresponding numbers for the superior mesenteric artery are 295 and

3:17

400 for those 50% and 70% thresholds.

3:21

Using the end-diastolic velocity is less widely adopted, but you can potentially

3:25

use these as an adjunct to go along with it.

3:28

So with the celiac artery, it would be greater than 100 centimeters per second to

3:32

suggest a significant celiac stenosis.

3:35

And then for the superior mesenteric artery, you can potentially have isolated

3:39

elevations over 70 centimeters per second or kind of more modest elevations in

3:44

accordance with elevations of the peak systolic velocity to suggest at least 50%

3:50

stenosis. Again, these are less commonly used, but you may see them in your

3:53

institutions.