0:01

Okay, I'd like to also dive in on invasive coronary

0:04

angiography, um, and just show some views.

0:06

We'll see a lot more during the cases.

0:09

Um, but the invasive coronary angiogram is a Lumina Graham,

0:13

and, uh, it involves selectively catheterizing

0:16

and hand injecting coronary arteries.

0:18

So you can see why you're gonna get better contrast

0:20

opacification, and I'm just gonna show this view.

0:22

This is the left coronary artery.

0:24

Um, so the catheter is pointing left

0:27

and you can see that the arteries opacify

0:30

and this invasive angiogram was done carefully.

0:33

So you can see the LED raping around the apex.

0:35

This is the diagonal and then late opacification

0:37

of the cardiac veins.

0:39

So a nice angiogram here. Um, here's another view.

0:42

So just like in musculoskeletal radiology,

0:45

you really need two views and everything.

0:46

And this kind of better reveals the tubular stenosis

0:49

in this LAD.

0:51

So that's the LED septal, perforators diagonals coming off.

0:54

And then the, this angulation throws the

0:56

circumflex outta the view.

0:58

And again, the LED wraps around the apex like most LEDs do.

1:01

So we have kind of a tubular stenosis here on a coronary ct.

1:05

You see all of the arteries are pacified together

1:08

and in invasive angiogram you'd have to selectively inject.

1:11

And so here's a right coronary angiogram, that's

1:13

that C view we talked about in the

1:15

first bit of this lecture.

1:17

And you can see here it's a right dominant patient.

1:19

It gives rise to the PDA and the PLV

1:21

and you can see that the sinus

1:23

of El Salva has a little contrast

1:25

refluxing, which you want to see.

1:26

So you don't miss the fact that you're beyond a,

1:28

an osteo stenosis.

1:30

Here's a second view, a little harder

1:31

to get in the right coronary artery,

1:33

but now you can see the same C view is now turned on edge,

1:35

uh, important to get those views.

1:37

And you can see again that there's a, oh

1:38

and also the tiny collaterals, which we,

1:40

or tiny nodal arteries that are harder to see

1:43

with a CT scan.

1:44

So the resolution far superior, uh, with regard

1:47

to spatial resolution.

1:49

Now if you look at, um, invasive angiography,

1:52

you're judging stenosis much in the same manner as a ct

1:55

and it really becomes a judgment call.

1:57

And the case I just showed you,

1:59

how a tubular stenosis didn't look terribly bad.

2:01

So how do we reconcile those intermediate

2:03

stenosis in the cath lab?

2:04

Well, a technology emerged a few years ago

2:07

called fractional flow reserve.

2:08

And in FFR guided practice

2:10

and numerous studies has been shown

2:12

to reduce MACE major adverse cardiovascular events.

2:15

The reason being, if you treat clear stenosis,

2:18

you pay a price for the early procedure,

2:20

but you prevent late outcomes 'cause you're fixing ischemia.

2:23

So the thought is you can discover stenosis,

2:25

but if it's not significant, then you ignore,

2:27

uh, and treat medically.

2:29

So, uh, this is just one of many papers.

2:31

This one then JAMA, showing how those patients

2:34

with a FFR number below threshold, meaning it's positive

2:38

for ischemia, um,

2:39

those patients do better than their counterparts

2:42

that weren't treated when the FFR was positive.

2:44

And those patients with a high FFR meaning negative did

2:47

worse if you treated them

2:49

because they are going to have more adverse events due

2:52

to the procedure or due to unnecessary, uh, treatment

2:55

and all the heavy hitting, um,

2:57

blood thinners that come along

2:59

With the stent procedure.

3:01

Now, FFR is invasive fractional flow reserve,

3:05

meaning you put a wire down the coronary,

3:06

you give intra coronary adenosine,

3:08

so you're stress testing that vessel.

3:10

There are other methods now that don't involve adenosine.

3:12

They're called DFR, which is, uh,

3:14

diastolic hyperemic free ratio.

3:17

And it's basically just looking at parts

3:19

of the cardiac cycle and pressures.

3:21

And then IFR is instantaneous free wave ratio.

3:24

The the point isn't to learn all these acronyms

3:26

but to know they exist and know they

3:28

may done be done in your case.

3:29

And to know that that's a more objective measure

3:32

of potential significance, maybe imperfect,

3:34

but more objective.

3:35

And there's different thresholds

3:37

for each than just the gestalt eyeball judgment

3:40

of an invasive angiography.

3:42

There are quantitative coronary, uh, angiography methods.

3:45

You just basically drawing ROIs and diameters,

3:48

but it's not as accurate

3:49

as the physiologic assessment you can get with these.

3:51

So, um, all of them though are more objective

3:53

than just gestalt.

3:55

So, um, we can do the same thing

3:57

or some of the same things in ct.

3:59

And so there's some role now for C-T-F-F-R,

4:01

it's in some guidelines and here's some of the rules

4:03

of the game as I see it.

4:04

Um, there's a, a technology, uh, of C-T-F-F-R,

4:07

which is computational fluid dynamics based.

4:10

Um, and they use a central core lab

4:12

that's got FDA approval in the us.

4:13

Now there's a machine learning based tool,

4:15

which is also FDA approved.

4:16

That one requires an onsite

4:18

technologist to segment the case.

4:20

The other one is a central core lab,

4:21

and then there's some, uh,

4:23

non FDA approved tools which have

4:24

been demonstrated in research.

4:25

But all of them aim to infer

4:28

and duplicate that invasive angiogram by some method.

4:31

Uh, and it's some method that you can't do

4:32

with your own eyeball and gestalt.

4:34

You have to use their, uh, underlying technology

4:37

to give it a predicted FFR value.

4:40

And there's thresholds, same as any other technology,

4:43

and you treat the ones

4:44

that have a low fr they're usually designed

4:46

to match the invasive FFR.

4:48

So here is an example of a case.

4:51

So this is a, an early case that I, I had read

4:54

and we see here there's an intermediate grade stenosis

4:56

kind of that tubular nailing.

4:58

In fact, this is the exact case I

4:59

showed you the angiogram of.

5:01

And so it started actually with a CT

5:02

before that invasive angiogram.

5:04

I had read it as CAD RADS three,

5:06

meaning it's about 50% moderate LAD stenosis.

5:09

It's the only vessel. So that was my final impression.

5:12

Now how we handled at our site is we make a second report if

5:15

the C-T-F-F-R is successful and here is that image

5:17

and you can see there's a very clear

5:19

trans lesional gradient.

5:21

So a very clear step down in the predicted FFR value

5:24

and it's far below the threshold.

5:25

The threshold is 0.7 to 0.8 is the intermediate gray zone.

5:28

This is below that meaning very abnormal.

5:30

Now you'll see a gradual decline as the vessel gets.

5:33

The, the gradual stuff we don't worry about,

5:34

it's the trans lesional focal gradients.

5:36

This is clearly positive.

5:37

So we reported as such F FFR CT impression, the lesion

5:41

of concern in the PLAD at the origin

5:43

of the first diagonal artery.

5:44

So I'm giving the interventionalist a very clear position

5:47

where I'm saying this is clearly significant.

5:49

So it's very instructive to the anatomy.

5:52

And then this patient went on to an invasive angiogram,

5:54

successfully stented, and got better.