Efficient and Effective Interpretation of the Four Chamber Heart View and Views of the Great Arteries - SD

Introduction

Hello, I'm Roy Philly.
I'm an emeritus professor at the University of California San Francisco,
and this evening I'm gonna be talking to you about effective and efficient evaluation
of the four chamber heart view and of the great arteries.

Importance of Fetal Heart Evaluation

The fetal heart is the most common organ affected by anomalous development in California where I live.
The incidence of myeloma Menil is one in 1600,
and yet there are statewide programs initiated to detect this abnormality.
Serious heart defects,
I'm not talking about all heart defects,
I'm talking about the kind of heart defects that we would like to detect as early as possible
are present in something greater than one in 500 pregnancies.
So from a perspective of prevalence, there really is no comparison.
Cardiac anomalies are the most common.
Furthermore, if a child is going to die from an anomaly in the neonatal period,
the most likely reason for that will be a cardiac anomaly.
So despite its obvious importance, fetal heart evaluation is consistently an area of weakness in the interpretation of obstetrical ultrasound examinations.
Why is that? Are we stupid or are we lazy?
The answer is definitely no.
There are two reasons why this is problematic.
Number one, the job isn't as easy as it appears at first blush.
Secondly, it requires that we make very specific observations and understand why we are making them,
and those concepts have not been proselytized very well throughout the ultrasound community.

Risk Factors for Congenital Cardiac Anomalies

Now, it is possible to identify a group of women who are at greater risk for congenital cardiac anomalies than other women.
On this list, we find a family history of congenital heart disease if in fact the mother is the one with the congenital heart disease.
The recurrence risk is the greatest at about one chance in 10 maternal ingestion of drugs or teratogens.
This is an area where there's a lot more smoke than fire.
The most famous one, however, is lithium causing Epstein's anomaly.
The fetus may have a non-cardiac fetal abnormality known to be associated with cardiac abnormalities, so for example, a two vessel cord or a missing kidney, either of those would instigate a fetal echocardiogram.
Then we have non-immune hydrops fetalis.
This is sort of a grab bag of many etiologies, but since overwhelmingly non-immune fetal hydrops is heart failure, abnormalities of the heart, top the list,
and indeed this abnormality has the highest payback on our list.
Approximately 15% of fetuses with non-immune hydros will be shown to have a cardiac anomalous etiology.
We may see a fetal arrhythmia.
Now with tachy arrhythmias, there's virtually never a cardiac abnormality, but with Brady arrhythmias sometimes yes.
Then we have monozygotic twins and maternal diabetes.
Both of these show an increased incidence of congenital heart lesions, but overall a lot more smoke than fire.
Now, I am not an echo cardiologist.
In fact, if I encounter a patient whose indication for the sonogram is on that list, then just like you, I am required to recommend a fetal echocardiogram in those instances.

Detection Rates and the Role of Basic Obstetrical Sonogram

Now, let's assume that we go out into our community and very assiduously identify every patient on the at risk list,
and let's further assume that we happen to be fortunate that in our compu in our community is the greatest living echocardiographer whom detects a hundred percent of the cardiac anomalies among the patients we send,
we would still have only detected approximately 20% of the cardiac anomalies in the fetal population at that moment.
Why? Because 80% of cardiac anomalies occur in fetuses whose mother has no risk factor actor.
Our only chance to find the cardiac defects in fetuses without risk factors is during a basic obstetrical sonogram.
So for four out of five fetuses with serious congenital cardiac anomalies, we are their last best hope for detection.
There is a doctor named Lindsey Allen who's an echo cardiologist.
She started her career in England and she went out and taught sonographers and ologists in her community how to evaluate the four chamber heart view,
and she asked them to refer all cases that failed to meet the normal criteria that she had just discussed.
It led to an exponential increase in the number of referrals, but far more importantly, it led to a concomitant increase in the number of serious fetal cardiac abnormalities that were being detected.
Remember our list going through our list, the largest payback from a known risk factor was non-immune hydros at 15%.
However, if we refer a patient for an echocardiogram because of an abnormal four chamber view, the payoff is substantially greater than 50%.
So both in terms of the number of fetuses potentially detectable and the payoff for sending them for echocardiograms, there is absolutely no comparison.
Now the American Institute of Ultrasound in Medicine and the American College of Radiology define guidelines about which aspects of fetal anatomy must be included in the examination of a patient who has no risk factors for a congenital anomaly,
and you can appreciate that there is a very heavy emphasis on the fetal central nervous system, but only two views are required for cardiac evaluation.

Challenges in Cardiac Anatomy

Why is it that this job is not as easy as it seems at first blush?
Well, first of all, cardiac anatomy is more difficult than it seems.
Now when the heart is dividing from a two to a four chamber structure, it would've been really nice if it divided exactly down the midsagittal line such that the right atrium, the right ventricle, and the pulmonary ar artery were immediately right para sagittal and the left atrium, left ventricle and aorta were immediately left para sagittal.
Unfortunately, that is not even close to the truth.
The truth is that the heart divides with a twisting motion and as it undergoes that twisting division, the great arteries end up being twisted together exactly like a pretzel.
So we end up with the situation that the right ventricle ejects blood toward the left shoulder of the fetus and the pulmonary artery.
The right-sided great artery lies to the left of the ascending aorta, the left-sided great artery and similarly, the left ventricle ejects blood toward the right shoulder and the ascending aorta lies to the right of the pulmonary artery.
Furthermore, the right ventricle isn't exactly right.
It is more anterior than it is right, and the left ventricle isn't exactly left.
It is more posterior than left.

Evaluating the Four Chamber Heart View

Identifying Specific Chambers

What then do we need to look for when we are evaluating a four chamber heart view?
Well, most people start by saying we need to count chambers.
I have been an expert witness in a number of cases where the defendant doctor stated, I only need to count to four.
Well, to be perfectly frank, I have a three and a half year old granddaughter that can count the four, but I don't think there are any pregnant women out there that would like to have her interpreting their obstetrical sonogram for cardiac anomalies.
If that doctor is correct that all we need to do is count to four than this is a normal four chamber heart despite the obvious fact that the heart isn't even within the fetus's body.
Indeed, we do not want to count chambers.
We are all medical professionals and we don't identify chamber one.
Chamber one has a name like left atrium or right ventricle.
Our job is to identify specific chambers.
Now because the fetus can lie in multiple orientations, in order to do that we need a system that works in all orientations and this is the system that I recommend to you.
First you identify the spine.
In front of the spine is the descending aorta.
The chamber that lies closest to the descending aorta is the left atrium across the atrial ventricular valve.
You find the left ventricle across the interventricular septum is the right ventricle and back across the atrial ventricular valve is the right atrium.
Here is a fetus. In a different orientation, we identify the spine descending aorta, left atrium, left ventricle, right ventricle, right atrium.
Here are three fetuses all in different orientations.
Spine descending aorta, left atrium, left ventricle, right ventricle, right atrium, spine descending aorta, left atrium, left ventricle, right ventricle, right atrium.
Spine descending aorta, left atrium, left ventricle, right ventricle, right atrium.
The system works in all orientations.
Here we're looking at a fetus where again we start at the spine descending aorta, left atrium, left ventricle.
We try to cross an interventricular septum.
Obviously we have a problem.

Evaluating Chamber Sizes and Overall Heart Size

In addition, we are going to evaluate the size of individual chambers and the overall size of the heart.
Now, when I am evaluating the size of the chambers, I look at diameters more so than the black area.
It isn't that I don't pay attention to the black area, but I know that because of a structure known as the moderator band, the blood is typically cut off from the apex of the right ventricle making for a smaller black area of the right ventricle than there is a black area of the left ventricle.
Now I am more critical of ventricles than I am of the atria.
It isn't that I don't pay attention to the atria.
It is that I am more critical of the ventricles.
I am more interested in being certain that I believe the ventricles are normal size than I am in being certain that I believe the atria are normal in size.
Part of the reason for that is that because of the fetal circulation, oxygenated blood comes in through the ductus venosus billiard shots off of the eustachian valve through the foramen oval from the right atrium into the left atrium.
That course of the blood causes the interatrial septum to bow from right to left, thereby often making the right atrium appear larger than the left atrium.
So in evaluating these hearts, I see that in this instance the diameter of the right ventricle is slightly less than the diameter of the left ventricle, but I'm willing to call that within normal limits.
Here the diameter of the left ventricle is the same size as the diameter of the right ventricle.
Excuse me. I am willing and obviously delighted because that is normal here.
The diameter of the right ventricle is slightly greater than the diameter of the left ventricle.
But again, that is within my normal range.
I am not a measurer.
I do not measure the size of the various chambers.
If you want to please do so. I do not.
Now the next criterion is that the blood in the left ventricle goes all the way to the apex.
The blood in the left ventricle goes all the way to the apex.
The blood in the left ventricle goes all the way to the apex.
The blood in the left ventricle goes all the way to the apex.
If this is not the case, I consider this a hard line.
Do not cross it.
If you are thinking, hmm, does that blood get all the way to the apex, then by all means pick up the dictaphone and recommend a fetal echocardiogram.
So we see spine descending aorta, left atrium, left ventricle, right ventricle, right atrium, diameters of the ventricles about the same diameters of the atria, about the same, the blood goes to the apex.
We have evaluated points one and two.
We also want to look at the overall size of the heart.
Now in in the usual normal sized heart, I expect the heart to be about a third, possibly up to about a half of the transthoracic diameter.
Clearly in this instance, the heart is far too large.
So in looking at these two cases, we have spine descending aorta, left atrium, left ventricle, right ventricle, right atrium.
The right ventricle is clearly too small both in diameter and black area.
Spine descending aorta, left atrium, left ventricle, right ventricle, right atrium.
Clearly the right sided chambers are larger than the left sided chambers.
That is because the right sided chambers are too large.
How do I know that? Because the heart is also too large, it's more than half the transverse thoracic diameter.
Therefore, the more likely scenario is that the right sided chambers have enlarged.
Not that the left sided chambers are too small.
Here we have spine descending aorta, left atrium, left ventricle, right ventricle, right atrium.
The diameters of the ventricles are good, the blood goes to the apex, but clearly the right atrium is very much larger than the left atrium.
So if you go to the intensive care ward in your hospital and identify everybody who has an enlarged right atrium and open their charts, you can rest assured that one of the diagnoses that will be listed in their problem list is congestive heart failure.
And lo and behold, we look here and we see that the fetus has already developed a pleural effusion.
As soon as you see that that right atrium is too large, you are done.
It isn't up to you to diagnose heart failure, but it is up to you to realize that right atrium is too large.
Here we have spine descending aorta, left atrium, left ventricle, right ventricle, right atrium.
The diameters of the ventricles are about the same, but the blood does not go to the apex in the left ventricle, hard line, never cross.
Typical case of hypoplastic left heart syndrome.
Here we have spine descending aorta, left atrium, left ventricle, right ventricle, right atrium.
Obviously the diameter of the left ventricle is too great compared to the right now of interest is that both of these fetuses have hypoplastic left heart syndrome.
Remember that hypoplastic left heart syndrome does not always mean that the chamber size is small.

Mediastinal Shift

Next, we are going to look for mediastinal shift.
Mediastinal shift is really something that we look for more to detect other types of thoracic abnormalities more so than cardiac abnormalities.
However, typically people doing obstetrical sonography are more focused on lateral mediastinal shifts, but it is important to realize that the heart can also be shifted anteriorly or posteriorly.
So when we are looking at our four chamber view, as we said, we're using the proximity of the left atrium and the aorta to identify the left atrium, but also that proximity is important.
Unless the left atrium is in close proximity to the aorta, the heart has been shifted anteriorly.
Similarly, the anterior wall of the right ventricle must touch the anterior chest wall.
If it does not, the heart has been displaced posteriorly.
So here we see spine descending aorta, left atrium, left ventricle, the aorta and the left atrium are separated y there is a mass which has interposed and displaced the heart anteriorly.
Similarly here we have spine and the, we don't have the left atrium in this picture, but you can see the anterior wall of the right ventricle clearly a long way away from the anterior chest margin why there is a mass in the pericardium, which is pushing the heart posteriorly.
Now these cases are pretty obvious and reasonably straightforward, but here is a case where we see spine descending aorta, left atrium, left ventricle, right ventricle, right atrium, but the left atrium and the aorta are far apart.
Once you make that observation, this small lenticular shaped mass that is separating the two structures is much more readily detected.
As I said, our focus is typically on detecting lateral mediastinal shifts.
Why? Because the most common anomaly besides the heart in the thorax is congenital diaphragmatic hernia, which causes a lateral mediastinal shift.
We again have a problem because the heart is canted into the left hemothorax.
If we draw a line from the mid sternal position to the mid portion of the spine defining the mid sagittal plane of the thorax, we see that only the right atrium is predominantly in the right chest.
The left atrium and left ventricle are almost exclusively in the left chest and most of the right ventricle is in the left chest.
Now here we draw our midsagittal line.
The heart does not even touch the line, so we have a very large left to right mediastinal shift from a congenital diaphragmatic hernia.
Here we have a moderate mediastinal shift where only the tip of the left ventricle is in the left chest.
Most of the left ventricle, the left atrium, right atrium and right ventricle are entirely in the right hemothorax.
Here we have a more minimal mediastinal shift because the right ventricle is in the right hemothorax.

Cardiac Axis

Next we are going to check the axis of the heart.
Now I have been complaining bitterly that the canting of the heart into the left hemothorax causes us a variety of problems.
But the good news is the degree of camping is almost the same in every fetus and it's about 45 degrees, not exactly 45 degrees, about 45 degrees.
So here we identify a normal cardiac axis.
Here we draw our line. Clearly the heart is too horizontal.
Here we draw our midsagittal line and clearly the heart is too vertical.
Both of these fetuses have significant cardiac abnormalities.
Now Two vertical heart doesn't always mean that the fetus has a cardiac anomaly.
In both of these instances, the fetus has a diaphragmatic hernia.
Now, I venture to say that I'm one of the most experienced people in the world at looking at congenital diaphragmatic hernias.
Someone who has a lot of experience might have seen a hundred congenital diaphragmatic hernias.
I've seen over 600 congenital diaphragmatic hernias and I make that point only for one reason.
This case right here is the most difficult congenital diaphragmatic hernia I ever diagnosed.
Why? Because that is not a right lung and that is not a left lung.
This is the right lobe of the liver and this is the left lobe of the liver in a fetus with bilateral congenital diaphragmatic hernia.
Now the important thing is that the case was sent to me because the doctor who did her sonogram said, Dr. Philly, the heart just isn't in the right position.
And that was also true of this referral.
Now this is another congenital diaphragmatic hernia.
This is not the left lung.
This is the right lung, and if you are a careful enough observer to see the difference between them, you probably don't need this lecture to begin with.

Situs

The last thing we are going to do is check citus.
What I am interested in is that the heart and the stomach are both on the same side.
I don't really care very much whether the fetus is cito sous or has citus inverses totalis.
What I am interested in is detecting the fetus where the apex of the heart and the stomach are on opposite sides or they have ambiguous sinus.
Why? Because of a fetus's cyto sous or has citus in versus totalis.
They have an incidence of congenital heart disease about where most of the population has it.
But if they have ambiguous us, more than 90% have congenital heart lesions.
So if you don't see it, you almost certainly missed it.
So what am I interested in?
Apex and stomach, apex and stomach are on the same side.
In this case, the stomach is up, the apex is down, stomach up, apex down,
and you don't have to be much of a fetal echo cardiologist to realize that that is not going to be a normal four chamber view.
So here is my list.
It might seem like a lot, but I absolutely assure you that with practice it will only take you about 10 or 15 seconds of effort to evaluate each of the items on the list.

Obtaining the Four Chamber View

Now let's move on to talk about how we get the four chamber view.
The problem with phrases like the four chamber view is it doesn't tell you what plaintiff section you need to get in order to obtain that view.
And when you don't know what p of section you need, the usual result is that people keep twisting their hand around until the image looks like it does in a textbook.
If this is your plan of attack, you will not be successful.
If you wanna get a four chamber view of the heart, think axial, a four chamber view of the heart is an axial plane of section through the lower fetal thorax.
If I tell you to go and get me a four chamber view, you're not entirely sure how you're gonna go about doing it, but if I tell you to go in and get me an axial plane through the lower thorax of the fetus, you may not be able to get the picture, but you know exactly what you are going to do in order to obtain the picture.
So how do we know we're looking at an axial plane?
Well, you don't look at the heart and you don't look at the lungs.
You look at the ribs.
If the ribs are long, the plane is axial.
If the ribs are long, the plane is axial.
So at that point that you have decided you're looking at an axial plane through the lower fetal thax, you are either happy that that is a normal four chamber view or you are not happy.
Let's return to the case we looked at a little while ago.
When we look rib is long, we look, rib is long.
This is an axial plane.
The biggest mistake you can make now is to go in and start twisting your hand around trying to make it look normal because you may convince yourself that it is normal, which would be flagrantly erroneous.
The next thing to understand is that the four chamber view plane is exactly the same as the abdominal circumference plane.
The abdominal circumference is an axial section through the upper abdomen.
Now in an adult like myself, it might be 10 centimeters from my abdominal circumference plane to my four chamber heart plane, but in a fetus it's only a couple of centimeters.
So in this example, I actually started with the four chamber view and worked down to the abdominal circumference view.
My point is when you are happy with the abdominal circumference, the next picture you take isn't the cord insertion.
The next picture you take is to slide toward the fetal chin and get your four chamber view.
Interestingly, the four chamber view is often the same view as the view of the lips.
Why is that? Because the fetus is different than us.
The fetus, 25% of the fetal body weight is in the head.
Now when you take a coronal plane through the lips to show that the lip is intact, in fact you also usually get an axial plane of section through the fetal thorax.
So in this sonogram, the sonographer was actually trying to show me this very nice picture of the fetal lip, but in the meantime she also got me a very nice picture of the fetal heart.

Opportunities to Assess Fetal Cardiac Anatomy

Now I want to, and I cannot stress this too emphatically, take every opportunity to assess fetal cardiac anatomy.
Don't just look at the view that's labeled four cv.
Every time you have a chance to look at the heart of the great vessels, make a judgment as to whether what you're looking at makes sense or not.

Evaluating the Great Vessels

Left Ventricular Outflow Tract (LVOT)

We are now going to turn our attention to the great vessels, and as you are well aware, there are two views that are commonly stated to be the ones that should be obtained, the left and right ventricular outflow tract views.
Now the left ventricular outflow tract is sometimes called the long axis view.
What plaintiff's section is the LVOT view?
Is it an axial plane? Is it a sagittal plane? Is it a coronal plane?
Do those names help you one bit to know what plane of section you are required to obtain to get the left ventricular outflow tract?
The answer is no.
And whenever the answer is no, that begets twisting your hand around until it looks like it does in the book.
In fact, when the left ventricle ejects blood, the blood is driven between the anterior leaflet of the mitral valve and the interventricular septum to the base of the aortic valve.
Therefore, this is the left ventricular outflow tract.
It's not an easy plane of section to describe because it is sort of an inclined angled up view.
Now these views were originally described in adults and children.
So when you have a supine child, it's much easier to figure out how to get this plane of section than it is in fetuses that can that can assume multiple variations in position.
The right ventricular outflow tract is sometimes called the short axis view.
Do these names impart any knowledge whatsoever as to the plaintiff section in which you need to orient the transducer?
The answer is an emphatic no.
And as I previously stated, when the answer is no, that begets the twist your hand around method For a moment.
Let's forget about getting the left ventricular and right ventricular outflow tract views and analyzing the left ventricular and right ventricular outflow tract views, and instead ask ourselves the question, why do I want these views in the first place?
What observations do I need to make?
Now what I'm gonna give you is the important anatomy of the great arteries, at least according to me.
Not everybody's gonna agree with me, but I absolutely assure you if you look for the things that I'm about to say in the great arteries, you will do an outstanding job of detecting abnormal fetal cardiovascular systems.
First, the aorta is the stem of the apple of the heart.
If the heart is an apple, the aorta is its stem.
Now this is more of an identifier of the aorta.
I see a structure beating. I'm going with heart.
I see a blood vessel coming out of the dead center of it.
I'm going with aorta.
The anterior wall of the aorta is continuous with the interventricular septum.
Anterior wall of the aorta is continuous with the interventricular septum.
Here we have our left ventricular outflow tract view in diagrammatic form, and you can appreciate that the anterior wall of the aorta is continuous with the interventricular septum.
It is also true that the posterior wall is con continuous with the anterior leaflet of the mitral valve defining the left ventricular outflow tract.
But I don't care about that.
I care that the anterior wall of the aorta is continuous with the interventricular septum.
The aorta and the pulmonary artery are about the same size.
Just as the ventricles are about the same size.
The aorta and the pulmonary artery are about the same size.
Now I will modify this slightly at a later time in the lecture, the pulmonary artery is anterior to the aorta at the root of the great vessels.
The pulmonary artery is the branching vessel.
So if you look at the root of the great vessels, it is the pulmonary artery that branches, again, I use this more as an identifier like I use the aorta is the stem of the apple next.
And if possible but not a mandatory observation, I would like to see the right pulmonary artery pass behind and touch the aorta.
This is more easily seen.
When we look at the back of the heart, we can see that the right pulmonary artery literally hugs the ascending aorta.
So when we are obtaining a left ventricular outflow tract, what we are actually doing is lining up the long axis of the ascending aorta in our plaintiff section.
That's the long axis view, and here we see that in our left ventricular outflow tracted dia diagrammatic view, we are looking at a long view of the ascending aorta.
Now, if in fact you line up on the long view of the ascending aorta, you will cut through the short axis of a different vessel, the right pulmonary artery.
So we will see the right pulmonary artery and short axis behind the long view of the ascending aorta.
Here we have a left ventricular outflow tract view.
I see this structure, it's beating.
I'm going with heart on that one.
Here's a blood vessel that's coming out of the dead center of the heart.
I'm going with aorta on that one.
We see that the anterior wall of the aorta is continuous with the interventricular septum.
We also see that the posterior wall is continuous with the anterior leaflet of the mitral valve.
True, but it's not an observation that I make.
I am interested in the fact that the right pulmonary artery goes behind and touches the aorta.
So what do I wanna know about the left ventricular outflow tract when I get my left ventricular outflow tract view?
I wanna know that the aorta is the stem of the apple of the heart.
I wanna know that the anterior wall of the aorta is continuous with the interventricular septum and I would like to see the right pulmonary artery travel behind and touch the aorta.
But I have other ways of getting exactly the same information, so I consider that to be gravy.
Furthermore, I can absolutely assure you that if the anterior wall of the aorta is continuous with the interventricular septum, then the aorta is unambiguously the stem of the apple of the heart.
Thus, my bottom line observation on the left ventricular outflow tract is that the anterior wall of the aorta is continuous with the interventricular septum.

Right Ventricular Outflow Tract (RVOT)

If we were to draw our arrow like we did for the left ventricular outflow tract, we would assume that this would be the plane that we would want to line up in to get the right ventricular outflow tract.
But that turns out not to be true.
In fact, the right ventricular outflow tract view is designed to follow the right pulmonary artery.
If in fact you do that, you line it up so that the right ventricular outflow tract flows into the right pulmonary artery.
Two things happen. First, you are going to cut the ascending aorta in short axis.
Second, you are going to show the ductus arteriosis.
So you will see the ductus arteriosis going from the pulmonary artery to the descending aorta.
Also cut in short axis like the ascending aorta.
So here we have our right ventricular outflow tract, right atrium tricuspid valve, right ventricular inflow tract, right ventricular outflow tract, pulmonic valve, pulmonary artery, right pulmonary artery, all going around the short axis view of the ascending aorta.
We see that the pulmonary artery is anterior to the aorta.
The pulmonary artery is about the same size of the aorta, and the right pulmonary artery goes behind and touches the aorta.
We also see the ductus go back to the descending thoracic aorta.
So again, what do I wanna know about the right ventricular outflow tract?
I wanna know that the aorta and the pulmonary artery are about the same size.
I will have some further comments on that aspect later.
Second, I want to see that the pulmonary artery is anterior to the aorta.
Third, I wanna see the right pulmonary artery travel behind and touch the ascending aorta, but again, gravy.
Now, although it is difficult to describe the exact planes of section that these views represent, they do have a very specific anatomic relationship.
In the left ventricular outflow tract view, we get a long axis view of the ascending aorta and a short axis view of the right pulmonary artery.
In the right ventricular outflow tract, we get a short axis view of the ascending aorta and a long axis view of the right pulmonary artery.
Therefore, these are orthogonal views.

Key Observations and Exclusions

Why is it that I observe the features that I told you?
Well, if for example, the aorta and the pulmonary artery are about the same size, the fetus does not have tetrology of fellow, the fetus does not have hypoplastic left heart syndrome.
The fetus does not have hypoplastic right heart syndrome.
The fetus does not have a truncus arteriosis or the pulmonary arter pulmonary atresia VSD complex.
It also does not have an interrupted aortic arch.
Now, are those easy diagnoses to make? Absolutely not.
Can I make all of those diagnoses? Absolutely not.
But I can exclude them by seeing the aorta and pulmonary artery to be about the same size.
I see the anterior wall of the aorta continuous with the interventricular septum.
I know now that the fetus does not have tetrology of fellow double outlet, right ventricle, the taussig bing anomaly truncus arteriosis, posterior malalignment VSD.
Now, are these easy diagnoses to make? Definitely not, but it's not my job to make the diagnosis.
I'm very good. However, at excluding them when I see the anterior wall of the aorta continuous with the interventricular septum, we observed the pulmonary artery to lie anterior to the aorta.
We now know that the fetus does not have transposition of the great arteries.
And by the way, if I see the right pulmonary artery travel behind the ascending aorta and touch it, I also know that the fetus does not have transposition of the great arteries.
The fetus does not have tetrology of fellow, and it also excludes some uh, types of double outlet, right ventricles.

Obtaining LVOT and RVOT Views

Okay, I know what the views look like.
Now I know what I'm gonna look for when I get the view.
I even have a pretty decent understanding of how they help me.
But all right here we've said that the four chamber view is an axial sonogram through the lower thorax.
But what happened here or what happened there is that the beam was angled up slightly such that it pointed toward the root of the aorta.
So in fact, this is the aorta and the aortic valve, and this is the left ventricular outflow tract.
So I can observe that the anterior wall of the aorta is continuous with the interventricular septum.
So this gives me both my four chamber information and my bottom line observation for the left ventricular outflow tract.
Some people call this the five chamber view. I hate that.
Just like I hate calling chambers by numbers.
All of these things have names.
Spine descending aorta, left atrium, left ventricle, right ventricle, right atrium, left ventricular outflow tract and aorta.
If you are desirous to get the actual standard left ventricular outflow tract view, start with a four chamber view, then angle up toward the root of the aorta.
Mentally say to yourself, I am going to fix this portion of the transducer on the maternal abdomen, and I am then going to rotate this portion of the transducer and try to point toward The aortic root.
If you go the wrong way, you'll know instantaneously go the other way.
Now you will notice these little ears off the left atrium.
Those little ears are the pulmonary veins.
If you see the pulmonary veins coming off the left atrium, the fetus does not have total anomalous pulmonary venous return.
Is that an easy diagnosis to make? No way, but it's easy to exclude.
This fetus doesn't have the little ears coming off the left atrium.
It does indeed have total anomalous pulmonary venous return.
So here's something we see all the time, and when I see it, I love it.
Why? Because it's my four chamber view, which is normal, and I also get my left ventricular outflow tract.
So I can see the interventricular septum continuous with the anterior wall of the aorta, two jobs done.
How about the right ventricular outflow tract?
It is actually better to think of this view as a midsagittal view of the fetal thorax.
Now, if I tell you to go get me a right ventricular outflow tract view, you don't know exactly what you're gonna do to get it.
But if I said, look, please go in and get me a midsagittal view of the thoracic spine, you may not be able to get it, but you know exactly what you're going to do to try to get it.
Now, when the picture of a fetal heart is drawn, it is usually drawn like this so that the uh right ventricular outflow tract is pointing toward the left fetal shoulder.
But fetuses are not children. Their lungs are atelectatic.
Their left hemi diaphragm is therefore elevated, which elevates the apex of the heart, such that the right ventricular outflow tract is now closer to a midsagittal view than it is to something pointing toward the fetus's left shoulder.
Now in this view, the sonographer is trying to get me a picture of the thoracic spine and doing a heck of a job at it.
But what else did she get?
She got me a beautiful view of the right ventricular off flow tract.
So again, I cannot stress this too much.
Take every opportunity to assess cardiac anatomy.
Don't just look at the image that is labeled RVOT.
Every time you see any heart or great artery in the picture, make an effort to decide whether it actually makes sense and looks normal or not.
Now, what I would like you to do in these three examples is to identify the time in the syne clip when the thoracic spine looks the best to you.
And when it does, please look up and see what you see in the heart.
And what you will see is the right ventricular outflow tract might not be perfect, but it gets you close.
Then you can make slight angular adjustments.
And once you're at this point, you'll know instantaneously whether you slightly angularly corrected in the wrong direction or in the right direction.
Also, the right ventricular outflow tract is often the same plaintiff section as the profile view.
Now, sonographers spend inordinate amounts of time trying to get this picture for the mother, but look down here right ventricular outflow tract.
Let's look at some examples. I'll take the one on the left.
You take the one on the right. Here's this thing beating.
I'm going with heart on that one.
There's a blood vessel coming out of the dead center.
I'll go with aorta on that one.
And the anterior wall of the aorta is continuous with the interventricular septum.
Yes, the posterior wall is continuous with the anterior leaflet of the mitral valve.
Not interested. I am interested in this.
I'm calling this a normal left ventricular outflow tract.
Your turn. Well, here's the structure.
It's beating be a good idea to go with heart.
There is this great artery which is coming out of the center of the heart.
So go with aorta.
Here is its anterior wall, interventricular septum, anterior wall, interventricular septum.
They don't meet. This is an example of Tetrology of fallot.
It is not your responsibility to diagnose Tetrology of fallot, although it is far and away the most common reason.
You are going to see the aorta override the interventricular septum.
I'll take the case on the left.
You take the case on the right. Uh, let's see.
This is the right ventricular outflow tract.
I see the pulmonary valve.
I see the pulmonary artery, the pulmonary artery's anterior to the aorta, pulmonary artery about the same size as the aorta.
The right pulmonary artery is going behind the aorta duct is back to descending aorta.
I'm going with normal right ventricular outflow tract.
How about you? Well, here's the right ventricle, the pulmonic valve, the pulmonary artery.
I see the right pulmonary artery.
I see the ductus going back to the descending aorta and all of that is going around the, Hey, wait a second.
Where is the ascending aorta?
Very, very difficult to see.
You can see these little calcified valve leaflets right there.
Very bad hypoplastic left heart syndrome.

Three Vessel View

Now we've said a lot about the left and right ventricular outflow tracts.
I know what they look like.
I know what I'm going to look for when I interpret them, and I know what value they have to me when I make the observations that I talk to you about.
But I will honestly tell you that if my sonographers never again get me a left or right ventricular outflow track view, but every time get me a very nice three vessel view, I will never complain.
You again, start with your four chamber view and then you simply slide toward the chin until the transducer intersects the base or the root of the great arteries.
When that happens, you will see the great vessels lined up, thusly, superior vena cava, more posterior aorta, somewhat more anterior and most anterior is the pulmonary artery.
You may see the right pulmonary artery, you may see the ductus or the left pulmonary artery.
It doesn't really matter to me, although if given the choice, I would rather either see the ductus or the right pulmonary artery than the left pulmonary artery.
Here's the sonographic representation. Here's the spine.
SVC aorta, pulmonary artery ductus to descending aorta.
What do I wanna know about the three vessel view?
I wanna know that the artery that branches is on the end.
That's the pulmonary artery.
I wanna know that the aorta and the pulmonary artery are about the same size is I wanna see that the branching artery is the anterior vessel.
In other words, the pulmonary artery is anterior to the aorta.
And if possible, I would like to see the right pulmonary artery travel behind and touch the ascending aorta.
Now you will notice that that is everything that I wanted to know about the great arteries, except that the anterior wall of the aorta was continuous with the interventricular septum.
Here is a fetus in the opposite orientation.
So we're looking at the sonogram.
This is the spine, so that's anterior.
We see that the vessel on the end is the one that branches and it is more anterior than the other vessels.
That's good. That's gonna be the pulmonary artery.
That means that I'm calling the middle vessel.
The aorta and the aorta and the pulmonary artery are about the same size.
Again, two fetuses, three vessel view.
Branching artery is on on the end.
Branching artery is more anterior than the other vessels.
That's the pulmonary artery that makes this. The aorta.
The pulmonary artery is about the same size as the aorta.
The branching artery is on the end.
The branching artery is more anterior.
This is the pulmonary artery, this is the aorta, the pulmonary artery and the aorta are about the same size.
Now, just as in the heart, I focused on the ventricles much more so than I focused on the atria in the three vessel view.
I focus much more on the pulmonary artery and aorta than I do on the SVC here.
There's a very diminutive SVC here.
There's a pretty juicy SVC.
I'm not saying that you won't sometimes detect an abnormality of the fetus by observing something odd about the SVC.
What I am saying is that I focus on the pulmonary artery and the aorta.
I do not focus on the SVC.
Furthermore, with regard to the branches, these branches are all within a couple millimeters of each other.
So we have SVC aorta, pulmonary artery.
You can see left pulmonary art, left pa, left pa, left pa, right pa, right pa, right pa, ductus, ductus, ductus.
All three are very close together.
Once you have your four chamber view, just slide the three vessel view or vice versa.
So if you have your four chamber view, you slide up to the root of the great vessels.
You have your four chamber slide up to the root of the great vessels, root of the great vessels.
Alternatively, if you start with the three vessel views, slide down to the four chamber view.
Now, I told you earlier that the view of the lips, the coronal view of the lips usually produces an axial plane of section through the fetal thorax.
And I showed you that it can demonstrate a four chamber view for you, but in fact it actually works better for the three vessel view than for the four chamber view.
So here the sonographer is actually getting me a picture of the lips, but again, I get an excellent view of the three great vessels.
Normal. Okay, so you recall that this is what we wanted to know about the great arteries on the three vessel viewing.
And I've been telling you that the aorta and the pulmonary artery are about the same size, but I was gonna modify that slightly and now is the time to do that.
If the pulmonary artery is a bit bigger than the aorta, that's okay, but if the aorta is a bit bigger than the pulmonary artery, that is definitely not okay.
Most cases are abnormal, and according to my own echo cardiologist, it's never normal.
Most cases are tetrology of fellow, but this is another hard line.
Never cross it.
If the aorta looks bigger than the pulmonary artery, you pick up the Dictaphone and say, I recommend a fetal echocardiogram.
If you're having trouble getting the outflow tracks or the three vessel view, then at the very least try for what is called the crisscross view.
What I do is take the closest thing that I've got to an left ventricular outflow tract and then slide toward the chin of the fetus.
If I go the wrong way, I just turn around and go the other way.
No problem. And what you will see is the aorta and the pulmonary artery.
Chris cross just seeing the two vessels.
CRI cross tells you that a whole lot of things went right in the formation of this heart.
But in fact, the Chris cross view shows you virtually everything that you want to see.
First of all, The pulmonary artery and the aorta are about the same size.
In fact, you can see that the pulmonary artery is a little bit bigger than the aorta.
That's in fact the better observation.
You can see that the pulmonary artery is anterior to the aorta.
You had to slide toward the chin to get the pulmonary artery.
That means it's anterior to the aorta.
The aorta is the stem of the apple of the heart.
You can see that the anterior wall of the aorta is continuous with the interventricular septum.
And indeed you can see the right pulmonary artery go behind and touch the ascending aorta.
Now, assessment of the great arteries is in fact more productive and discovers more important anomalies than does the four chamber view.
Therefore, it is truly a sad state of affairs that the A IUM and the A CR have made.
The statement, if technically feasible and extended basic cardiac examination can also be attempted to evaluate both outflow tracts.
Do not use this as an excuse.
Always, always gather information about the great arteries.
Gather as much as you can.

Case Examples

Okay, A few cases, I'll take the one on the left.
Branching artery is on the end.
The branching artery is more anterior.
The branching artery is the pulmonary artery.
It is about the same size or slightly larger than the aorta.
I'm going with normal. Here's your case.
It's true the branching artery is on the end. That's good.
The branching artery is more anterior than the middle artery.
That's good. But the pulmonary artery is much bigger than the aorta.
Now is this too small or this too big?
When you look at the SVC, clearly this is too small.
So you can, you're done as soon as you see that, that doesn't meet criteria.
But you're gonna sound a lot smarter than saying, you know, the aorta looks too small or the pulmonary artery looks too big to me and saying, hypoplastic left heart, how bad is it?
Here we have, again, a perfectly normal three vessel view.
Here we can see that the branching artery is indeed on the end.
That's good, but it is not more anterior than the middle vessel and it is also smaller than the middle vessel.
Definitely abnormal hard line.
Do not cross tetrology of fellow.
Let's analyze these cases as we finish up.
What's wrong here? Well, apex down, stomach up.
That's citus ambiguous. You're done.
Soon as you see that, you're referring the patient for an echocardiogram because you know that greater than 90% of those fetuses are going to have congenital heart disease, spine descending aorta, left atrium, left ventricle, right ventricle, right atrium.
The diameter of the ventricle isn't so bad, but where in the heck is the black spot?
Don't see it. And clearly the left atrium is much smaller than the right atrium.
So we suspect the hypoplastic left heart.
We look at the three vessel view, we see the branching pulmonary artery.
It's nice and anterior, but where's the middle vessel?
We don't see it at all. Makes a lot of sense.
There's virtually no lumen left in this left ventricle to eject blood into the aorta.
Hypoplastic left heart syndrome.
This is a much more complicated case, but easy for us because spine descending aorta left atrium much smaller than the right atrium.
So we're already picking up the dictaphone to refer to the patient for an echocardiogram.
I don't even see a left ventricle.
There's pretty big right ventricle.
Let's look at the three vessel view for fun.
Okay, well first of all, boom right away.
Hey, that aorta is more anterior than the pulmonary artery.
That's wrong. That can't be.
But the real big question is, where in the heck did that aorta come from in the first place?
If I can't even see a left ventricle, well, the only place it could have come from is the same place that the pulmonary artery came from the right ventricle.
So this is a double outlet, right ventricle look, you don't have to diagnose double outlet right ventricle, but you are more than capable of doing it.
These observations are not that difficult to make and they are perfectly logical in interpretation.
Again, branching artery is on the end.
Branching artery is more anterior.
That's my pulmonary artery. That's good.
It's the same actually.
It's slightly bigger than this vessel in the middle, which I'm calling the aorta normal.
Now, again, this is a lip view by the way.
And we look at our great arteries and we say, okay, uh, I see the branching artery, but uh, wait a second.
It's not on the end.
It's in the middle Transposition of the great arteries.
Instead of the right pulmonary artery going behind and touching the aorta, instead of the pulmonary artery being more anterior than the aorta, the pulmonary artery is more posterior than the aorta.
And the right pulmonary artery goes behind the SVC.
Now, people talk all the time about seeing parallel vessels coming out of the ventricle.
That's a waste of time.
This is the way to identify transposition of the great arteries, spine descending aorta, left atrium, left ventricle, right ventricle, right atrium, right away we know we're gut problems.
Clearly the right ventricle and the right atrium are way too small.
So hypoplastic right heart syndrome, we look at our three vessel view.
Indeed the pulmonary artery is the branching artery.
It's on the end. It is more anterior than the aorta.
And not surprisingly it's tiny. Why?
Because the right ventricle is so tiny.
But here's the question, why is the ductus so big?
And the answer is because the flow in the ductus is reversed to get blood to the pulmonary artery.
That makes this a ductal dependent lesion.
Now, if you use color, and I suggest that that's a good idea, although we're not gonna talk about it.
Arches always have the same color.
So the transverse aortic arch and the ductal arch should both be the same color if they ever have opposite color.
Not only are you done, but you have identified a ductal dependent lesion.
This is pulmonary atresia and you can see the ductal dependency.
Last case, spine descending aorta, left atrium, left ventricle, right ventricle, right atrium.
The diameter of the right ventricle is a little bigger than the left ventricle.
I might be willing to pass that, but the blood in the left ventricle does not go to the apex.
That is a hard line. We never cross it.
This is an artifact reduplicating from the rib.
Interpret the picture.
When that is gone, you see the pulmonary artery in the aorta.
The aorta is clearly too small.
This is early hypoplastic left heart syndrome.
Here is the important feature.
I'm prepared to say that 95% of ologists in the United States would walk right past this and miss it, but there's absolutely no way that you can follow the rules we've just established and not come to the conclusion that that left ventricle and that aorta are too small.
So learn to get these views.
You can get the four chamber view, the classical left and right ventricular outflow tract view and the stomach.
Or you can get the classic four chamber.
View the stomach, the so-called five chamber view and the three vessel view or get them all, but get the views that enable you to evaluate both the heart and the great arteries.
Now this is a very nice clip.
It is 12 seconds long.
Stomach and apex are on the same side.
Normal four chamber view, anterior wall of the aorta continuous with the interventricular septum.
Normal three vessel view done 12 seconds.

Conclusion

Now the hardest part, take the pledge
If you are a sonographer, I will never again simply try to make the four chamber and great vessel views look like they do in the textbook.
If you are a sonologist, I will always independently evaluate the four chamber, view the aorta and pulmonary artery.
If they do not meet criteria, I promise to be brave enough to recommend an echocardiogram.
Thank you.