0:00

So CTA findings were kind of tallied up over the, uh,

0:03

course of years and then turned into a grading algorithm.

0:07

And so, uh, it's very simple.

0:08

There's a couple of different acronyms, uh, describe them.

0:10

But what you wanna focus on is whether there's multiple

0:13

occlusions you wanna talk about whether there's a blunt

0:15

stump, as in the case I just showed you at the proximal

0:18

end, or is there are more of a beak.

0:19

Um, look at severe calcification or dense calcification

0:22

and how much of the radius of the artery it covers

0:26

and then bends over 45 degrees.

0:28

As you can imagine, when you're trying

0:29

to wire an occluded stenosis

0:31

and you have an acute angle

0:32

that's a bend sharper than 45 degrees, the likelihood

0:35

that the wire pierces the coronary artery rather than

0:38

following the vessel becomes higher.

0:40

Um, now, CTA can't predict success of the, uh, procedure,

0:45

but rather can you get a wire across.

0:47

And everything in interventional cardiology works off

0:49

of Did you cross with a wire?

0:50

And what that, that scoring system, so there's JCTO,

0:53

it's out of Japan CT Rector score.

0:56

Um, but what they did was they, they tallied up the number

0:59

of features and high scores mean lower likelihood

1:02

of crossing a wire, uh, in 30 minutes.

1:05

Most other interventional procedures are done

1:07

by the 30 minute mark,

1:09

but in chronic total

1:10

occlusion, you can be in there for hours.

1:11

I once saw somebody literally spend all day in the cath lab

1:14

and did a achieve success.

1:16

Um, so you're gonna look for multiple occlusions,

1:19

a blunt stump, calcifications bending, um, no so's,

1:22

certain things that the imagers can't see.

1:24

So second attempt, you're only gonna know that by history.

1:26

And then the duration of the chronic total occlusion,

1:29

if you're lucky, you have a CT scan within 12

1:30

months, but probably you don't.

1:32

So you're gonna have to look in the chart

1:33

or as we do it, we just give the CT findings

1:36

and let our clinical colleagues fill in the rest.

1:39

Um, and then you could provide a score,

1:41

or what we do is just report in bullet form all

1:44

of the features of high risk that we might see.

1:46

Um, and it's very important, uh, to note

1:49

that the prior exams for, uh, CTA

1:52

for chronic total occlusion

1:54

or for any routine stent, um, maybe, uh,

1:58

an invasive angiogram.

1:59

So it's really important that you as the CT imager learn

2:02

that basic anatomy on cath

2:05

and you're gonna pull those, um, cath images

2:07

or make any effort to get the

2:09

reports if you can at all help it.

2:10

But I strongly encourage you to review the CTA next

2:14

to the calf, and I always pull them up side by side.

2:16

Some of these cases involve me sitting

2:18

with the interventional cardiologist

2:19

and us each contributing and,

2:21

and saying, what do you see here?

2:22

What do you see here? Let's

2:23

ask questions and have a dialogue.

2:26

Um, you may also consider looking at ischemia

2:29

because if the right coronary art is occluded

2:31

and then the inferior wall has a transmural infarct,

2:33

there's no point in revascularizing

2:35

that's a dead myocardium.

2:37

Maybe a way to use other cases, like I've shown you

2:40

that catalyst case and, um, the infarct detection paper.

2:43

We're also, um, gonna look at that.

2:45

In our case reviews is how we often are asked

2:48

to look at myocardial function on these CTO cases

2:51

and sometimes, uh, get a delayed image,

2:54

although often we're getting a nuclear test.

2:56

Um, these are tough cases. They involve really

2:58

Exquisite detail.

3:00

Here's a case where we have, um, a chronic total occlusion

3:03

of the circumflex artery.

3:04

You can see there's retrograde profusion,

3:06

but helping the interventionalists know that

3:08

that's a densely calcified native artery will help them

3:12

decide whether or not they can use certain techniques.

3:14

Some of the techniques involve intentionally dissecting

3:16

coronary arteries, or in a case like this, they may avoid it

3:19

and go retrograde through collaterals to get to that distal

3:21

because it's a higher risk phenomenon

3:23

to pierce calcified plaque.

3:25

Um, there are some softwares that let you plot the course.

3:29

Um, it's hard to see that there's a vessel

3:30

that's not there on this calf

3:32

because no contrast arrives at the distal circ.

3:34

But this same, um, vessel outline shows you

3:37

that there's an occlusion here

3:39

and then retrograde profusion.

3:41

So the only way an interventional cardiologist would see the

3:43

distal circumflex would be to inject

3:45

to the right coronary artery

3:46

and watch the collaterals, uh,

3:47

come from the right to pacify the C.

3:49

So this is definitely, um, an achievable case

3:52

and it was, uh, solved and, and opened.

3:54

Um, but it was very helpful information

3:56

to know there's an occlusion, it's calcified, uh,

3:59

then it's noncalcified and calcified.

4:01

Again, all detail that the interventionalist needs to know.

4:04

Uh, and again, we may look at the viability

4:06

of this segment in the first place if we're gonna do things.

4:09

Um, so, uh, there's, you know, other things to remember,

4:13

which is, can you match your CT views to the calf?

4:16

Um, there's some prototypes.

4:17

We've published one that allow you to fuse images, um,

4:21

but it doesn't absolve us from the need

4:23

to look and look carefully.

4:24

And if you don't have a known chronic total occlusion,

4:26

it might be you the first to know it.

4:28

So you do have to make careful reforms.

4:30

Uh, and these, these can be, um, helpful.

4:33

Here's an example where the CTA volume rendered image shows

4:36

you the extent of the calcified and interrupted RCA.

4:41

The cath doesn't see it until you inject the left

4:43

and see these collaterals fill from the

4:45

left, uh, main injection.

4:46

And this is the distal RCA.

4:48

So the dynamic info from a cath can be helpful,

4:51

but it's only achieved with cathing from

4:53

both the left and the right.

4:55

Um, and here's now, uh, just some measurements.

4:57

So some, this was only done

4:59

because we knew it was going for a, a procedure.

5:01

So we would want to, uh, give some measurements.

5:03

Show how long the noncalcified segments, uh,

5:06

really they're flying blind in the cath lab

5:07

until you give them this information.

5:09

You can also make a short axis set of reformats.

5:12

Let them kinda, uh,

5:13

look in short axis throughout the course of the vessel.

5:15

And that helps me interpret to know where the calcium is.

5:18

If you do one thing and just say whether it's calcified,

5:20

I think that's tremendously helpful.

5:22

You can live lesion lengths,

5:23

and this is a straightened CPR where we've

5:25

pulled out the vessel and stretched into a linear format

5:28

just to make some measurements.

5:29

You could do a scoring sheet,

5:31

or what we do is have a macro that just, um, we say whether

5:33

or not there's occlusions, multiple occlusions, stumps,

5:36

calcium, et cetera.

5:38

Uh, and then lots of an angiography review.

5:40

So in summary, uh, CTA for CTO

5:43

and for stents underutilized,

5:45

it requires careful acquisitions.

5:47

It requires collaboration correlation

5:49

with invasive coronary angiography, careful,

5:52

but straightforward interpretations.

5:53

And it's, it's rewarding when you can help a patient

5:55

that might not be a surgical candidate

5:57

or might not want a surgery but can get revascularized.

6:00

And the CTA can be the, the keys to those, uh, vessels.