0:00

Okay, this next case is an example of myocardial

0:03

bridging we encounter myocardial bridging all

0:06

the time in Point area CT. So I think

0:09

it's important to discuss this particular patient as

0:12

we follow down from the

0:15

top on the maximum it is you can see the left Main.

0:18

LED

0:19

circumflex, you've got a very

0:22

small branch, which is coming off in the region of

0:25

a ramus sort of debatable. Whether you call it a high first obtuse

0:28

marginal Arrangements branch.

0:30

You can see that this led has some non-calify

0:33

plaque and calcified plaque.

0:36

Proximately, but there's really no significance stenosis. So

0:39

just mild disease and they 10 to 20%

0:42

stenosis.

0:43

And then there's a small diagonal Branch there.

0:46

And then when we follow the LED out after giving out

0:49

another diagonal Branch, you're going to see the LED heads away

0:52

from the epicardial fat here.

0:56

in dives into the muscle

1:00

of The myocardium in the septum just like that so you

1:03

can see there's vessel completely surrounded by muscle.

1:07

And then travels a little bit and then you can see it coming out again.

1:11

So just to show that one more time.

1:13

You've got vessel surrounded by fat.

1:16

Vessel heading towards the surface of the heart.

1:19

Vessel diving through the surface of

1:22

the heart surrounded by muscle.

1:25

Traveling a little bit of distance and then coming back out

1:28

again.

1:29

So that's a really nice example of myocardial Bridging the rest

1:32

of the vessels in this patient showed only minimal disease.

1:36

So let's take a look at the myocardial bridging on another

1:39

view when we take a look at our CPR images.

1:43

You can see this is the mild proximal disease.

1:47

The rest of the LED comes down and then this is the bridge segment.

1:51

You can see because there's this muscle it's basically been

1:54

Incorporated by the curve cleaner reformats when

1:57

we look on sort of a more kind of sagittal view

2:00

you can see this.

2:01

little Loop basically of

2:04

Distal LED that dives into the muscle.

2:07

you can see that the

2:08

Lumen is preserved. You don't really see any significant narrowing.

2:12

The depth is probably in the order of like three to four millimeters

2:15

in depth and the length probably, you know one or

2:18

two centimeters or so.

2:20

So what do we do with these things? So myocardi bridging

2:23

is incredibly common?

2:25

Now they're not often as dramatic as this a

2:28

lot of times. They're just very shallow ridges or very short

2:31

but you'll find them in a lot of patients. And

2:34

so what do you do? So I'm going to switch over to a PowerPoint now

2:37

to talk a little bit about myocardial Britain.

2:40

Okay, myocardial bridging. So how do you define it? It's

2:43

an epicardial coronary artery that takes an intramural

2:46

course when you see them you want to describe the

2:49

length and the depth if you're gonna actually

2:52

describe them at all honestly for a

2:55

lot of these if it's just a very short Bridge or very

2:58

minimal Bridge or if I see a fair bit of disease elsewhere

3:01

that explains the patient's symptoms. I'm usually

3:04

just going to ignore the bridges. I may not even mention them.

3:07

However, if you see a deep Bridge, which is over two

3:10

to five millimeters in depth, depending on what paper you read

3:13

you may want to describe it. And so what does

3:16

that look like? Well, we already saw one of them. This is an example

3:19

on the left of a patient with a very shallow bridge and or even just

3:22

what we call a touchdown meaning the The Vessel

3:25

leaves the fat.

3:27

Touches down on the surface of the heart and then goes back to the fat again.

3:30

So this one has very low risk for the

3:33

patient.

3:34

This one you can see that is actually some tunneling of

3:37

the vessel Through The myocardium you can

3:40

see The myocardium sitting on top of the vessel. However, there's no real

3:43

luminal narrowing.

3:45

A little bit of non-calify black right at the

3:48

origin of this bridge.

3:50

Generally, the bridge segments themselves are protected

3:53

from getting atherosclerox disease, but it's not uncommon

3:56

to see atherosclerosis. That's kind of

3:59

Developed just proximals the bridge.

4:02

So it turns out that these bridges are very very common.

4:05

And if you're reading coronary CT you're going to see them all the

4:08

time. They have been widely studying the literature. There

4:11

were 36 different articles included in a met

4:14

analysis from 2020. And if you're

4:17

looking on autopsy on average that seems

4:20

to be where they've been found the most often and on CT

4:23

on average people have seen

4:26

them about 20% of the time but

4:29

the rates vary widely depend on what paper you look at some

4:32

papers site 80 90 percent of cases

4:35

others 5% of cases. So it's it's really dependent

4:38

and it depends a lot on how people categorize them

4:41

and how they decide what is and is not a bridge.

4:44

And then on angiography they're much less

4:47

common, because the only way they're diagnosed is

4:50

to look at the external compression of

4:53

the vessel caused by the bridge segment.

4:56

This phenomenon called milking where basically insistently when

4:59

the muscle contracts. It squeezes The

5:02

Vessel and makes it look smaller. That's how

5:05

they're identified by a cardiac Cath.

5:08

So we see it most often in the led by far

5:11

80% of bridges are in the LED and usually

5:14

the mid LED but you can have bridges in

5:17

the RCA with RCA goes through the muscle of

5:20

the basil right ventricle or even where the RCA goes

5:23

through the muscle the wall of the right atrium. Sometimes

5:26

you can see

5:28

and similarly with the circumflex, although actually, I think I've seen that

5:31

the least often.

5:32

The length usually two centimeters so

5:35

in length and three millimeters in depth is the average.

5:38

So what do you do with this? So in general the take

5:41

is that these are safe lesions and

5:44

there's not a whole lot of risk related to Bridges. And and this is one of

5:47

the biggest studies of bridging out there.

5:50

One of the problem we run into is that a lot of the early literature on bridging is

5:53

based on Bridges identified by calf and

5:56

Cath sees Bridges a lot less often than CT

5:59

and it you know makes sense that

6:02

Cath probably is picking up bridges that are more severe than

6:05

those we pick up on CT. So it's important to look

6:08

for papers that are specifically looking at

6:11

Bridges detected on coronary CT and this is one of the largest that's out

6:14

there published back in 2017.

6:18

They looked at a thousand patients and now those thousand they found that

6:21

200 patients had a bridging among those 1,000. They

6:24

excluded the patients that had actual coronary artery disease that

6:27

was significant and then they followed all the rest.

6:29

And they saw that there was no difference in outcomes at

6:32

five years between those patients with and without Bridges among

6:35

those ones that did not have the constructive coronary

6:38

disease.

6:40

Now I'm not talking about destructive bridging I'm talking about actually they had plaque. So

6:43

for instance, they had a CT scan for black and they found that

6:46

there was a severe stenosis and led those didn't get

6:49

included in this study because that would explain them having a worse outcome.

6:53

So an editorial was written and basically the editorial

6:56

said in most cases bridging is a benign finding

6:59

most patients can be reassured that this anomaly will not happen

7:02

to adverse impact on the risk of coronary events are sudden death. And so

7:05

having said that clinician should remain a tune to the rare patient with

7:08

angkectors and provocable skin and maybe the exception of rule. So that's

7:11

the one problem here is that there are exceptions to the

7:14

rule and the exception would be that there are cases and tons and

7:17

tons of case reports out there in the literature of patients who have bridges that

7:20

are symptomatic most studies which show that Bridges

7:23

tend not to have any long-term consequence in

7:26

terms of death or myocardial infarction, but

7:29

that there are certainly studies that have shown that Bridges can

7:32

be associated with ischemia in some rare cases

7:35

on say

7:37

Specter stress perfusion imaging of some

7:40

kind

7:41

so the way you manage this is a bit unclear. But

7:44

generally the

7:47

way we use the handle it if you see a mild Bridge

7:50

it's short or shallow, you know

7:53

less than the few millimeters then generally we're going to not say much.

7:57

Maybe not even mentioned at all. But if the patient has clean

8:00

coronaries, but significant symptoms and all

8:03

they have is a bridge and that bridge is, you

8:06

know, three to five millimeters and and a couple centimeters or

8:09

more in length, then we'll say no plaque.

8:12

But there's this myocardial Bridge, you know

8:15

consider functional testing in that case.

8:18

That would be some sort of stress test to really determine whether there's

8:21

any ischemia related to the bridging that can explain

8:24

the patient's symptoms.

8:26

So just to sum up bridging can be a tough diagnosis

8:29

to deal with but in the vast majority

8:32

patients, it's kind of a nothing lesion only in

8:35

those cases where you have something you have good symptoms and no really

8:38

good explanation. And and what looks like a bridge that could

8:41

have some impact in terms of its depth and it's

8:44

length, you know, you might suggest some additional functional engine