0:00

And what I really just showed you was something we

0:03

call the ischemic cascade.

0:04

And this was a chapter that I wrote when I was a fellow,

0:07

but the figures adapted from, um, publication, uh, by Dr.

0:11

Nesto ET all back in the 1970s, I believe.

0:14

And they actually figured this out by

0:17

tying off dog coronary arteries in, in a lab.

0:20

And they were able to discern that there's a,

0:23

a stepwise process that can be recursive.

0:25

It goes from earlier to later

0:27

findings when you have ischemia.

0:28

So one of the earlier findings you might see in the setting

0:31

of ischemia is a profusion defect,

0:33

which CT is usually a secondary analysis.

0:36

Um, you can see metabolic disorders.

0:38

That's not something imagers look at.

0:40

Diastolic dysfunction,

0:41

maybe an echocardiographer can see it,

0:43

but things quickly progress towards systolic dysfunction if

0:46

there's interruption of the coronary blood flow.

0:48

And that's what I showed you in this case,

0:50

you had hypokinesis of the inferior wall.

0:52

Uh, if it persists, you can have ECG abnormalities.

0:54

If you could have a transmural infarct,

0:56

you'll have a ST elevation

0:57

and you can even have a in myocardial infarction.

0:59

So now here's an example of a transmural

1:02

infarction on an MRI.

1:03

So as you can see, I've talked about all the ventricular

1:07

and the myocardial manifestations of, of coronary, uh,

1:10

disease, and a lot of those can be looked at with a CT scan.

1:13

So, um, I'm gonna show some

1:16

of our allied fields in cardiac imaging like

1:18

echocardiography, MRI, specked and even PET scanning.

1:22

Um, but if we looked at it,

1:23

we looked at the tissue characterization, so the thickness

1:25

of the wall, we looked at the perfusion

1:27

or we, we will, in future cases, we looked at wall motion.

1:30

We can look at wall motion. I haven't shown you that.

1:32

And you can sum those up and make a diagnosis of viability,

1:35

which is a topic we'll get into further.

1:37

But echocardiography can see the, the wall motion

1:39

or the thickness of the wall.

1:41

Same thing with MRI.

1:42

MRI's, great for looking at profusion defects, SPECT

1:45

and PET are nuclear tests,

1:46

which are only gonna look at profusion.

1:48

And if you're lucky, wall motion, all

1:50

of them can look at all those findings together

1:51

and make an assessment of whether there's an ischemic injury

1:55

and whether there's viability.

1:56

I still haven't talked about coronary arteries though,

1:58

and that's kind of the basis of ct.

2:01

And so if you look at it, the ischemic cascade starts,

2:04

remember where they tied off the dog, LED

2:05

or we had plaque occluding in the right coronary artery.

2:07

So plaque rupture, uh, which leads to obstruction

2:11

or gradual narrowing of the coronary arteries is what we're,

2:14

um, gonna focus on.

2:15

And so when you put all this together, the,

2:17

the look at the myocardium

2:18

and the coronary anatomy, that's kind of the sweet spot

2:21

for CT and how we can make really, uh, interesting

2:24

and comprehensive diagnoses

2:26

and plan therapies in a setting

2:27

of ischemic coronary disease.