0:00

In this case, I will take you through cardiac anatomy.

0:03

We won't focus on the coronary

0:04

arteries, but the chambers.

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So one of the things, if you have a 3D

0:08

monitoring session, is that you can play

0:11

around with the planes quite easily.

0:14

But it's always a good idea to try and get to

0:16

these cardiac planes through first principles.

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So the first principle is that you find an axial

0:23

image where you see the apex and the mitral valve.

0:29

And then draw a line that bisects the mitral

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valve and the LV apex, like I'm doing here.

0:35

And what you get as a result of

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that is the two-chamber view.

0:39

You can always tweak it, but it's a two-chamber view.

0:43

Now, with off-axis cardiac anatomy, or rather

0:47

cardiac anatomy as the cardiologists look

0:49

at it, is along the planes of the heart.

0:53

And the heart is in an off-axis plane.

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It's not in your usual axial, coronal, sagittal plane.

1:00

It's slightly off-axis.

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So this is the vertical long-axis view, also known

1:05

as the two-chamber view, and the two chambers

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are the left atrium and the left ventricle.

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The heart consists of the anterior wall and the

1:16

inferior wall, so notice the difference here is

1:18

not anterior posterior but anterior inferior.

1:22

And when you think about the heart,

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you think about base, apex, so you say that

1:27

this part is more apical than this spot,

1:32

so that's a better way to describe relationships

1:34

of things rather than anterior and posterior.

1:37

This is the anterior third, this is the

1:40

middle third, and this is the apical third.

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This is the apex, the true apex.

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This is the inferior third,

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middle, and apical inferior.

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So basal inferior, middle inferior, apical inferior.

1:54

So basal anterior, mid-cavity, and apical.

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Left atrium, left ventricle, the structure

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here coming out is the left atrial appendage,

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and this is the anterior part of the mitral valve.

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And this is the posterior part of the mitral valve.

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You can always play around and try and guess

2:14

what anatomical structure you're dealing with.

2:17

So here's the left main coming off.

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Notice that the left main, and here it

2:23

gives off the LAD and the circumflex.

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Notice that the left main is related

2:30

to the left atrial appendage.

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Okay, so this is the vertical long-axis view.

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Now, if we then drew a line that bisected

2:40

the mitral valve and the apex again, we would

2:44

have what's known as the four-chamber view.

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It's never turned out to be quite like they show in

2:50

the books, but we've got it roughly: right atrium,

2:54

left atrium, left ventricle, right ventricle,

2:58

anterior left ventricle to the mitral valve,

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posterior left ventricle to the mitral valve.

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The right ventricle isn't terribly

3:03

opacified, which makes seeing the tricuspid

3:07

valve difficult, but it's somewhere here.

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So the relationship I want to emphasize here

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is that this leaflet here, which is the septal

3:16

leaflet of the tricuspid valve, is more apical

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than the septal leaflet of the mitral valve.

3:24

So this relationship is a normal relationship.

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But when the septal leaflet of the tricuspid

3:31

valve is way too apical, you have an

3:34

abnormality known as Epstein's anomaly.

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Epstein's anomaly is when the septal leaflet of the

3:42

tricuspid valve is far too apical, leading to parts

3:45

of the right ventricle being in the right atrium.

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So it leads to a big right atrium.

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And, um, box-shaped hearts and stuff like that.

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So that's the important thing to appreciate:

4:00

this is a normal relationship.

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But this has consequences.

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Now the consequence is that this is the septum.

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And the septum separates the left

4:09

ventricle from the right ventricle.

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Until you come to this point.

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At this point, the septum is separating

4:16

the left ventricle from the right atrium.

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Why is that?

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Because the septal leaflet of the tricuspid valve

4:25

is more apical, therefore now you have the right

4:28

atrium bordering the left ventricle, so you can

4:32

have a VSD, ventricular septal defect, you can

4:36

have an ASD, atrial septal defect, but you can

4:41

also have what's known as an AVSD, which is a

4:44

canal defect, which tends to be one of the most

4:47

consequential left-to-right shunts because you

4:50

have the left ventricle and the right atrium, so

4:54

a high-pressure system and a low-pressure system.63 00:03:10,255 --> 00:03:12,495 So the relationship I want to emphasize here

3:12

is that this leaflet here, which is the septal

3:16

leaflet of the tricuspid valve, is more apical

3:21

than the septal leaflet of the mitral valve.

3:24

So this relationship is a normal relationship.

3:28

But when the septal leaflet of the tricuspid

3:31

valve is way too apical, you have an

3:34

abnormality known as Epstein's anomaly.

3:37

Epstein's anomaly is when the septal leaflet of the

3:42

tricuspid valve is far too apical, leading to parts

3:45

of the right ventricle being in the right atrium.

3:51

So it leads to a big right atrium.

3:55

And, um, box-shaped hearts and stuff like that.

3:58

So that's the important thing to appreciate:

4:00

this is a normal relationship.

4:02

But this has consequences.

4:04

Now the consequence is that this is the septum.

4:06

And the septum separates the left

4:09

ventricle from the right ventricle.

4:13

Until you come to this point.

4:14

At this point, the septum is separating

4:16

the left ventricle from the right atrium.

4:21

Why is that?

4:22

Because the septal leaflet of the tricuspid valve

4:25

is more apical, therefore now you have the right

4:28

atrium bordering the left ventricle, so you can

4:32

have a VSD, ventricular septal defect, you can

4:36

have an ASD, atrial septal defect, but you can

4:41

also have what's known as an AVSD, which is a

4:44

canal defect, which tends to be one of the most

4:47

consequential left-to-right shunts because you

4:50

have the left ventricle and the right atrium, so

4:54

a high-pressure system and a low-pressure system.

4:56

You don't have that counterbalance that

4:58

you have with the atria or the ventricles.

5:01

So this is the anterolateral view of the mitral valve.

5:04

It's pretty important.

5:05

But before we get to that, let's do another plane.

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So remember I said that there are two long-axis planes?

5:13

I may not have said it, but

5:14

that's what I wanted to say.

5:15

One is a vertical long-axis, and if you do an

5:18

orthogonal view to that, you get a four-chamber view.

5:22

But what if you do something that

5:24

is at right angles to both of them?

5:27

Then you have what's known as the short-axis view.

5:31

We're going to try and get it perfectly

5:33

orthogonal; it doesn't always come that way.

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But this is the main view of looking at

5:39

the heart, so always get into the habit of

5:41

looking at the heart in this particular view.

5:43

It reveals a lot of pathology that you would miss if

5:49

you're only looking in the axial coronal central plane.

5:52

So remember I said that you have the anterior

5:56

wall and the inferior wall in the two-chamber view.

5:59

In the four-chamber view, you have the lateral wall

6:04

and septal.

6:06

So it's not anterior-posterior; it's anterior-

6:08

inferior; it's lateral-septal, not lateral-medial.

6:14

So this is kind of like a sum of all four, so

6:17

you have anterior-inferior, septal-lateral,

6:24

and we're now at the base of the heart,

6:28

and now we're at the apex of the heart.

6:31

So if you're at the base, the basal anterior,

6:35

basal septal, basal inferior, basal lateral.

6:42

Now you're at the apex, you're at the apical,

6:45

anterior apical, septal apical, inferior apical,

6:52

and then you've got this, which is also

6:54

known as Segment 17, which is the true apex.

6:57

So it's not really lateral, whatever.

6:59

It's actually the apex itself.

7:02

So as you can appreciate.

7:05

So you have the right ventricle, left ventricle.

7:07

This is a very important view for understanding the

7:10

pathology, the structure, the motion of the heart.

7:12

Here are the papillary muscles, and

7:16

they're at the 2 and 5 o'clock positions.

7:20

Anterolateral, posterior, and medial.

7:23

You can confirm why they're called that when

7:26

you cross-link to axial, cranial, and sagittal planes.

7:32

Alright.

7:33

One thing I want to show you, so I, so far I

7:36

mentioned the importance of these three planes.

7:39

There's another plane, which is

7:40

a very nifty plane to look at.

7:43

So here’s your short-axis plane, here I’m going

7:46

towards the apex, and here I’m going towards the base.

7:51

Alright, as I go to the base, right when

7:54

I’m in the left atrium, so here I’m in the

7:57

left ventricle, here’s the mitral valve that I’m

7:59

seeing on this view, and here I’m in the left atrium.

8:04

You’ve got this almost snowman appearance.

8:06

If you draw a line that bisects that snowman,

8:11

you have what’s known as the three-chamber view.

8:13

It’s a very important view anatomically

8:17

and also for understanding function.

8:21

So you have the left atrium, left

8:22

ventricle, and right ventricle.

8:25

This is the basal septum and this is

8:28

the anterior for the mitral valve.

8:30

Notice how There is a continuity between the

8:34

anteroliferal mitral valve and the aortic valve.

8:36

So if you were at the aortic valve, you would

8:39

end up in the anteroliferal mitral valve.

8:41

This is a property of the left ventricle.

8:44

The left ventricle isn't simply

8:46

defined by its laterality.

8:47

It's defined by its morphological characteristics.

8:50

One of them being the fact that its left

8:55

ventricular outflow tract is a fibrous outflow

8:57

tract, and there is aorto mitral continuity.

9:01

So what are the consequences of this continuity?

9:02

The first consequence is that if you have

9:05

You can have a regurgitation jet hitting

9:11

the anterolifer of the mitral valves.

9:12

Remember, regurgitation happens in diastole.

9:17

And that's when the aortic valve is supposed to

9:18

be closed, but it's not, so it's regurgitating.

9:23

And then it hits the antilever of the mitral

9:30

So that’s one consequence of the aortomitral

9:32

continuity, is this regurgitant jet

9:35

hitting the anterior leaflet of the mitral valve.

9:37

In fact, there’s actually a murmur named after it.

9:39

That’s the Austin Flint murmur.

9:41

That’s what you get when you

9:43

have that jet impinging on it.

9:47

Second consequence.

9:48

Is that you see this is the basal septum in

9:53

conditions such as hypertrophic cardiomyopathy,

9:56

the basal septum can thicken, and by thickening,

10:00

it can narrow the left ventricular outflow tract.

10:03

And when it narrows the left ventricular outflow

10:05

tract, it leads to flow acceleration through

10:08

the LVOT, which causes a pressure drop, and it

10:12

sucks that anterior leaflet from the mitral valve in.

10:15

It’s known as the Venturi effect.

10:18

And it’s a consequence of obviously the pathology,

10:22

hypertrophic cardiomyopathy, but this predisposing

10:24

anatomical relationship of aortomitral continuity.

10:30

And you can imagine that if you have anything

10:34

going on with the mitral valve, like repair,

10:37

that sort of patients that have a valve

10:40

repair that has failed and they put another valve and

10:42

you can push that anterior leaflet towards the left

10:45

ventricular outflow tract and narrow it further.

10:48

So this relationship is very

10:49

important for those reasons.

10:52

We should also take a look at the aortic

10:54

valve because that’s also interesting.

10:56

So again, I’m going right in the plane of

10:59

it and then going at right angles to it.

11:03

You can always get your plane’s prescription

11:05

very good by getting orthogonal planes in

11:08

two long axes, so here’s the LVOT, here’s

11:10

coronal, here’s a three-chamber, I can really

11:14

kind of get the right angles nicely in this

11:18

by getting it at right angles in two places.

11:21

And you can see that what the aortic valve is,

11:23

it’s comprised of three sinuses, they tend to be

11:27

of the same size, that is they’re symmetrical,

11:29

and where in aortic stenosis they confuse.

11:34

and that can lead to size discrepancies.

11:38

You can also follow the arteries and see what they are.

11:44

You get very confusing at times, but

11:46

there is a logical way of following it.

11:49

So the logical way is to look for

11:54

structures that you know are related.

11:58

So let’s look at this artery here.

12:01

What is this?

12:01

Is it the left or is it the right?

12:05

So remember the left coronary artery is

12:07

related to the left atrial appendage.

12:10

So even though this appears anterior, it isn’t.

12:12

I’ve just turned this all the way around.

12:15

So this is the left coronary artery,

12:17

and this is the right coronary artery.

12:22

So this is the anterior cusp, this is the left

12:24

posterior, and this is the non-coronary cusp.

12:27

So the non-coronary cusp has a property that it

12:30

points in the direction of the interatrial septum.

12:34

So it’s good spatial exercise for spatial

12:38

reasoning to try and figure out the anatomy

12:41

by playing around with the planes.

12:45

So I spoke to you about the, um, defining

12:49

characteristics of the left ventricle.

12:51

What about the right ventricle?

12:53

The right ventricle too has defining characteristics

12:56

and one defining characteristic is that

13:01

it’s not the left ventricle, which of course

13:07

isn’t much of a definition, just to say

13:10

what they’re not, but it’s important to

13:11

understand the distinction between the two.

13:14

The right ventricular outflow tract is muscular.

13:17

The left ventricular outflow tract is fibrous.

13:20

In the right ventricular outflow tract,

13:22

there is no continuity between the

13:25

pulmonic valve and the tricuspid valve.

13:28

Now the two are linked, so stuff that goes

13:31

on the pulmonic valve can of course affect

13:32

the tricuspid valve, but it does so directly.

13:35

So this is a muscular infundibulum without

13:40

continuity between the two valves.

13:42

The opacification of the RV could have been better,

13:45

although it’s fine because it’s a coronary

13:48

study and we’re not interested in the RV.

13:50

So that is your basic and your, um,

13:54

slightly more complex cardiac anatomy.