0:00

So let's take this same example.

0:02

As you remember, it's a 47-year-old male with chest pain.

0:05

He's had some negative ECG and troponin value workup,

0:08

but we know he has coronary disease

0:09

'cause we saw some calcium on his calcium score.

0:12

So let's take this and use that

0:13

to delve into myocardial and segmental anatomy.

0:16

So this is that c view, uh, kind of a match view

0:19

that you might see in the invasive angiogram,

0:21

but we're worried about a stenosis here.

0:23

And before we go and look at whether we, uh,

0:25

got an invasive angiogram and proved ourselves correct

0:28

or not, uh, let's look at the myocardial function.

0:31

So this is a short axis view

0:34

of the left ventricle of this same patient.

0:36

Uh, a couple of things to point out.

0:38

Um, we are at the mid segment level

0:40

because we see two papillary muscles.

0:41

So if you're more at the basal,

0:43

you won't see papillary muscles.

0:44

And if it's a smaller further apical displacement,

0:47

we won't see the papillary muscles

0:48

and the the ventricle will be smaller.

0:50

Uh, you're also noticing that there's probably some noise,

0:53

uh, apparent to your eye in some phases.

0:56

That's because we used, uh,

0:57

radiation dose protection methods.

0:59

'cause we don't need to have the entire

1:01

scan be super high quality.

1:02

We're really just getting this

1:03

because of the retrospective gating.

1:05

So, uh, the nice thing about the the scan is even though it

1:08

has some noise, we can see all of the myocardial segments

1:10

and at first glance you might

1:12

say, Hey, everything's squeezing.

1:13

This is a nice, um, contracting ventricle.

1:16

Uh, unfortunately it's not.

1:17

And a better way to look at that would be

1:19

to cover up either the bottom or the top half of the heart

1:21

or the from side to side.

1:23

And then look and say, okay, I'm looking at the wall motion.

1:26

And the wall motion, um, can be graded

1:28

as normal Kinesis hypokinesis a kinesis

1:31

or dyskinesis dyskinesis being,

1:34

it's moving the opposite direction

1:35

of the rest of the myocardium.

1:37

So we don't have any kinesis on this slice.

1:39

Uh, and by the way, it's a short axis slice.

1:41

And let's go over some segmental anatomy.

1:44

So, um, this is the anterior, the lateral, the inferior

1:48

and the septal wall spells Alis a LIS.

1:51

So, uh, we're gonna ignore the right ventricle for now.

1:54

Um, and, uh, we're gonna also, I'm just point out

1:56

that you do see a little coronary anatomy on this short axis

1:59

slice at the mid ventricular level.

2:01

That's the left anterior diss descending,

2:03

which lives in the anterior interventricular groove.

2:05

So there's your LAD. And when we look at the segmental

2:09

anatomy, um, we are always gonna use those descriptors,

2:12

so basal mid to apical as our level

2:14

and then anterior lateral inferior septal

2:16

as the segments we're describing.

2:18

And then there's some things in between.

2:19

So if I put my, uh, mouse cursor here, that's the, uh,

2:23

anterolateral segment.

2:24

This is the anter septal.

2:26

Um, this is the infer septal, this is the inferolateral.

2:29

So that, and then the true inferior wall,

2:32

those things matter because they tend to match

2:34

to coronary territories, especially if you know the anatomy.

2:36

And what better to know the anatomy than a cardiac ct.

2:39

So as we look at this, uh, this short axis slice,

2:43

you can see that the anterior wall has normal kinesis.

2:46

Every segment thickens by 50% and translates inward.

2:50

Conversely, if you look at the inferior wall,

2:52

and if it's not apparent, again,

2:53

just cover up the bottom half of the heart

2:54

and then cover up the top and compare.

2:56

There is relative

2:58

Hypokinesis of this inferior wall.

3:00

So if you look here, it doesn't thicken quite by 50%

3:03

and it certainly thickens less than the other segments.

3:06

Uh, as you may know, the inferior wall is supplied

3:10

by the right coronary artery in most patients,

3:12

and certainly in this patient

3:13

who we just saw has a dominant, a right coronary artery.

3:16

It wrapped around the inferior AV groove

3:18

and it then gave rise to posterior descending

3:21

and posterior left ventricular arteries.

3:23

This is the patient's anatomy, a dominant right coronary

3:27

with multiple segments

3:28

and giving rise to the PDA and the PLV.

3:31

So posterior descending artery

3:32

and posterior left ventricular branch.

3:34

You can have left dominance

3:36

where the circumflex stays in the AV groove

3:38

and it supplies these vessels.

3:40

You can have code dominance where one of,

3:42

of each comes from, from both the right and the left.

3:44

So it's really what supplies the inferior

3:46

wall determines dominance.

3:47

So again, we have a right coronary stenosis on a dominant

3:50

right patient, and we have an inferior wall, uh,

3:53

wall motion abnormality.

3:54

By the way, this, uh, I would read this, uh, set of anatomy

3:57

as a 47-year-old male

3:59

with an acute subtotal right coronary artery occlusion.

4:01

We know he is in the emergency department

4:03

and he has inferior wall hypokinesis.

4:04

So he's manifesting in the ventricle some signs of ischemia.

4:08

And what I just showed you is vascular territories.

4:10

So we already know by that example

4:12

that the right coronary artery supplies the inferior wall

4:15

and the left anterior descending wait

4:17

for it supplies the anterior septal.

4:19

So the interseptal walls by the LAD

4:22

and the left circumflex is, uh, in the left AV groove

4:26

and that supplies the lateral wall.

4:28

Now sometimes patients

4:29

with a dominant left artery would also have, instead of RCA,

4:33

be a left circumflex territory

4:34

that extends all the way to the inferior wall.

4:37

The RCA often supplies the, uh, infra septal wall as well.

4:41

So it's pretty simple. Now this is, again,

4:43

a mid ventricular slice,

4:44

but it holds truth throughout the ventricle.

4:46

Obviously. Um, restrictions apply.

4:48

So if you have an anomalous coronary artery,

4:50

then you have to think through that anatomy.

4:52

So it might be that a vessel heading left supplies right.

4:55

If you have strange situations like anomalies, um,

4:58

or if you have lots of collaterals

4:59

and as the complex disease manifests, you can use this basis

5:03

to then sort out what the anatomy might be.

5:06

The uh, other thing about this figure

5:07

that's important is it's not unintentional

5:10

that we've drawn the inner layer to be white here.

5:14

So I'm drawing the vessel territory

5:15

and I'm starting from inner to outer,

5:17

and that's a concept called the ischemic wavefront.

5:20

So when you have the coronary arteries,

5:22

which again live in the epicardial fat,

5:24

the the distal segments are furthest, uh,

5:27

from the supplying artery at the sub endocardial level.

5:31

So an ischemic injury tends to manifest from inward

5:34

to outward, and that's called the ischemic wavefront.

5:36

But the terms you wanna know are sub endocardial,

5:38

meaning it touches just the inner layer,

5:40

mid myocardial or transmural.

5:42

So the degree of transmural extends with the worsening

5:46

of the ischemic injury.

5:48

Um, so what we have here basically is the inferior wall not,

5:51

uh, contracting well because it's starved of blood supply.

5:54

Here's that patient's calf matched their ct.

5:56

Another teaching point to point out is

5:58

that the spatial resolution of a coronary CT is not nearly

6:03

as good as the spatial resolution

6:04

of an invasive coronary angiogram.

6:06

However, the contrast resolution of the CT is far superior.

6:10

So the Lumina Graham can only see a couple of densities.

6:12

It doesn't see what's causing the stenosis,

6:14

but it has a very good look at this hairline lumen.

6:17

So this is a cataracts four, a severe stenosis, uh,

6:20

almost a subtotal occlusion, whereas the ct, uh,

6:24

of the coronary artery shows you the plaque.

6:27

There may be some thrombus in this.

6:28

There's calcified plaque and there's noncalcified plaque.

6:30

So I put a few more arrows just to depict that the,

6:33

the CT is showing you more detail about the cause

6:36

of the obstruction, whereas the obstruction

6:39

only looks significant

6:40

where it's narrowed on the invasive angiogram.

6:44

Uh, and so just to kind of refresh some topics or,

6:46

or cover how you might read this,

6:48

what would be the Cadrad S classification?

6:50

Well, this is a severe stenosis, so this is cadrad four,

6:53

it's four A because it's only one vessel.

6:55

I didn't show you the other as much,

6:56

but they're not obstructive.

6:58

And the other thing to remember is

6:59

that there's different management recommendations.

7:01

This is a patient who we didn't know before.

7:04

The CT has coronary disease,

7:05

but now in an emergent setting gets different, uh,

7:08

follow up recommendations.

7:09

It means admission and it means invasive

7:11

angiography that I just showed you.

7:13

Whereas if you're in the outpatient setting, um,

7:16

it would be elective angiogram.

7:17

You might benefit from looking at a perfusion test

7:20

different than the ct.

7:22

Uh, and so just to close the case out, here's a, uh,

7:25

47-year-old male.

7:26

He's got an acute subtotal right coronary artery occlusion.

7:29

Shortly after the CT discovered this, we sent 'em

7:32

to the cath lab where an invasive cardiologist was able

7:35

to cross this with a wire, deploy a stent and restore flow.

7:39

So we've interrupted the process.

7:42

Another way to just summarize all the way we just looked at

7:44

the anatomy here is that we looked at noncalcified plaque,

7:48

uh, calcified plaque.

7:49

The calcified plaque is depicted

7:51

by the calcium scoring element of the ct,

7:53

but that's kind of limited.

7:54

Um, we've looked at the, uh, anatomic stenosis,

7:57

we've looked at the sequelae if we have it,

7:59

of the myocardial hypoperfusion and thus hypokinesis.

8:03

And then we looked at the, uh,

8:05

verification via an invasive angiogram.

8:07

So CT can see calcified plaque, noncalcified, plaque

8:11

stenosis or lack thereof,

8:13

and wall motion abnormality if present.

8:15

We can also look at profusion

8:16

and we'll, we'll get into that in some, uh, later anecdotes.