Fetal Heart Screening Guidelines - Basic and High Risk - HD

Introduction to Fetal Heart Screening Guidelines

I am Dolores Pretorius
and I'm from the University of California San Diego.
And I'm gonna talk to you today about fetal heart screening
guidelines from the AIUM for the basic heart
and for the advanced high risk heart,
which we use 76811 code for.

I'm gonna talk about fetal heart screening guidelines from
the AIUM, both the 76805 basic guidelines, as well
as the high risk guidelines that we've been given
by the 76811 billing code.

These two little twins, I just love them.
They look like they're talking to each other
and one is saying, shh, don't tell anyone.
But now they have to look at our outflow tracks too.

Adoption and Classification of AIUM Guidelines

So the obstetrical guidelines from the AIUM have been
adopted by the AIUM, the American College of Radiology,
the American College of OB GYN
and the Society of Radiologists in Ultrasound.
And these were all adopted in 2013.
They are clinical standards and practice guidelines,
and they allow for a minimal criteria for complete
a complete exam identified
for doctors performing obstetrical ultrasound.
They're often used for malpractice cases as standards.

Now, exams for the guidelines are classified
as first trimester standards, second
and third trimester limited exams that you can do in the ER
as follow up to a prior exam
or specialized exams, including cardiac echo
and detailed exam based on history of biochemistry
or biophysical profile in Doppler.
And the three in blue here all have cardiac in them.

First Trimester Guidelines

So in the first trimester, we need
to document cardiac activity.
Now either using the M mode, like in this case,
or where we got 172 beats per minute
or by a video showing
that there is indeed cardiac activity here.

Changes in Criteria for Diagnosing Failed Pregnancy

Now the criteria
for diagnosing a failed pregnancy has also
changed in the new guidelines.
We used to use five millimeters for a crown rump length
and 16 millimeters for no sac or no embryo within it.
And now with the new guidelines, it's been changed
to seven millimeters and 25 millimeters for the sac.
And if we have an embryo
that's less than seven millimeters, we're supposed
to bring them back in approximately a
week to see what it is.
And the reason this happened was
because a woman in the UK went viral when she had a crown
rump length that was around five millimeters,
and she was told it was a demise
and she carried the pregnancy to term.
So they did a large study in the UK
and they found that in this group of patients that were five
to 5.9 millimeters, that there were actually six patients
who had no heartbeat at that time,
and they came back with normal pregnancies.
So we moved the number from 5 to 7
because of just measurement accuracy
and how good we are.
And that was done with another study.

Heart Axis in the First Trimester

Now, in the first trimester,
we look at the heart at our institution to look at the axis
of the heart within the chest.
And this was done
because of this study
where they looked at a hundred consecutive fetuses
and found that the normal axis in the first trimester from
11 to 14 almost 15 weeks was between 34 and 56.
And the patients who had abnormal axis, six fetuses
with congenital heart disease had four abnormal axis.
So we look at that on all
of our first trimester patients.
And sometimes the color
actually makes it a little bit easier
to see here's the spine here and that axis is there.
So I think we're gonna get better
and better at looking at the heart in the first trimester.

Second Trimester Guidelines

Now in the second trimester, we need to look,
the AIUM guidelines tell us that we need
to look at the fetal cardiac activity to look
for an abnormal heart rate and or rhythm.
And that should be reported.
We should also identify the fetal number
and we should call the presentation, which is important
for thinking about the heart because of situs.

Determining Fetal Situs

Now how do you decide situs?
Well, we always let our sonographers do it for a long time
and just label it as left.
But we did have some errors with very senior sonographers
who miss the abnormal situs.
So we decided that we would take image documentation
that allowed the reader
to actually figure out whether it was a correct situs.
So you have to have the presentation.
So we have them take a picture of the fetus right
before they take this double image.
And then they tend to write on it breech
or cephalic or whatever it is.
And then we have to, I have a picture, a cross section
through the fetal abdomen showing us where the stomach is
and where the heart is,
and then we can figure out with this information,
which side is left.

Now when we look at the stomach, it's also important
to look at the aorta
and notice that the aorta is on the left
and that the IVC is a little bit anterior and on the right.
So it's just an extra little pearl of something else.
You can pay attention to focus on these pictures.

So how do you figure it out from those pictures?
Well, I've found
that personally if I'm training radiologists, that they tend
to do better figuring out situs by thinking about the fetus
as if it is on the CT scanner.
So you say this fetus is breech,
so the head is going into the table
and this little fetus is lying there on its left
side and it's going in.
And so it's lying with the spine off to the left
and it's lying with its right side down
and it's left side up.

Now most sonographers
and obstetricians do better thinking as if they're fetus
and they're scanning the fetus
and trying to figure out the lie by kind
of positioning their body.
If we do this daily like I do, looking at fetal situs,
then I use a rule that I've memorized,
which is if it's cephalic, it's spine to the right,
right side down and spine to the left, left side down.
If it's breech, it's the opposite.
And if it's transverse head to the right,
it's a cephalic baby, because it's the right way.
And if it's transverse, head
to the left, it's a breech baby.
And just think of it like that. So that is important.

Importance of Situs

Why do we care about situs?
Because we talk about situs inversus if the entire,
heart and stomach are on the wrong side.
And then if we have situs ambiguous,
we start thinking about things like isomerism or asplenia
and bilateral right sidedness, Ivemark syndrome.
Or if we think about polysplenia,
we think about bilateral left sidedness and left isomerism.
And these of course are associated with cardiac disease
and congenital cardiac disease
and they can be an incredible clue
that something's going on.

The guidelines tell us that we should assess anatomy
after 18 weeks and document any technical limitations
or follow up that may be necessary.
So I think for the cardiac views, this is very important
and we now document the BMI.
If the BMI is elevated
and we'll say BMI equals, you know, 25
or 30, and imaging is suboptimal.

Cardiac Views in AIUM Guidelines

So what do the guidelines say about the heart?
Let's get to the money. They say that we need
to look at the four chamber view.
We need to look at the left ventricular outflow tract,
which is new in the 2013 guidelines
and we have to look at the right outflow tract.
Now these were in previous guidelines of if feasible,
but now the if feasible was taken out, we're supposed to try
to get it, but the guidelines don't tell us
what a normal four chamber is.
So how do we decide what a normal four chamber is?
And we at UCSD have 10 things that we try to remember
to call a normal four chamber.

Four Chamber View

So this is a clip.
We look to see that the heart is a third the size
of the chest, that it at a 45 degree axis,
that there are equal ventricles
and equal atria, that the septum is intact,
that the crux is intact in the middle here,
that the tricuspid valve is a little bit offset.
This is the tricuspid valve is a little bit offset from the
mitral valve and usually about a millimeter more apical than
the mitral valve.
And then we go to the next four,
which are trying
to get better at picking up heart disease.
And that's that the moderator band is in the right ventricle
instead of in the left.
That there's no pericardial effusion
that the aorta is on the left
and that pulmonary veins enter into the left atrium.
So we remember this as the two basic
or the two global things about the heart.
Then the four basic and then the four more advanced
and the pulmonary veins is something we've added
and we often get it on a clip.
Very important to notice that the
red is going up towards the atrium.
'Cause we found that often at the beginning
of getting our sonographers to do this, that they had the wrong color going up towards the atrium
and they were really arteries and not veins.

The other tip I'd like to just give you is
that if you use a PRF of someplace around 25 to 35,
that is optimal
and you'd put your color box just over the left atrium,
not over the entire heart.
That's much harder to show it.
Your PRF will be identified at the bottom
of your color bar on most pieces of equipment.

So we do have a mnemonic for the four chamber view.
It is that 33 to 45%
of energetic sonographers create many TV episodes
about pregnant patients.
But I think the mnemonic is harder
to remember than just remembering the groups of the global,
the first four basic and the next four advanced.

Okay, so this is an AV canal
and I just wanna show you that the crux is not there
and the septum is not intact.
So that's the type of thing we're looking for now.

Left Ventricular Outflow Tract (LVOT)

Now we're gonna move on
to the left ventricular outflow tract.
So this is a diagram from Kathy Reed's book
that she's given me permission to use.
And when we look at an LVOT, what do you look for?
Well, first you look to see that the septum is intact.
Look at the high membranous part for VSDs up here,
because that's where a lot of pathology occurs.
Second, we look to see that it merges the top
of the aorta merges down with the septum.
And that is not overriding, like you see in Tetralogy
of Fallot, for example.
Third, we look to see that the valve is
parallel and comes and goes in the cardiac cycle.
And that you'll see on the video in a moment
and that there are no parallel vessels.

Now this is the normal, so you can see the valve coming
and going from the left ventricular outflow tract.
And this is looking for parallel vessels in someone
who does have parallel vessels.
Those parallel vessels are gonna be at the valve level,
but your sonographer has to look for the
parallel vessels because they're not necessarily there on
every left ventricular outflow tract view.

The things that we're gonna see on this view are we're gonna
look for those VSDs, particularly the high membranous,
but you'll see other muscular VSDs as well.
We will think about tetralogy of Fallot
with the overriding aorta that you can see here,
that there's the aorta and there's the right ventricle
and there's the left ventricle
and the override is right here in the middle.
You can also see this with transposition of the great vessels,
that the left outflow tract will be
abnormal with that parallel.
And then truncus arteriosus.
This was a tetralogy of Fallot.
This is a transposition
with the clip again showing the two parallel vessels.
But once again, you have to look for the vessels
and they are parallel at the level of the valves,
not higher up.

Right Ventricular Outflow Tract (RVOT)

Okay, how about the right ventricular outflow tract?
Well, this is a picture
of the right ventricular outflow tract showing the right pulmonary artery going into the ductus
and then coming into the right pulmonary artery,
it hugs the aorta.
We call that the sausage and the egg view
with this being the sausage and this being the egg.
And you'll see in the clips that the tricuspid valve will be right over here.
So we look for that branching right here.
To tell us that we're in the pulmonary artery, we look
to see that the pulmonary artery is slightly larger than the aorta,
or the aorta is slightly smaller than the pulmonary artery at the level of the valve.
So you can't measure it down here.
You need to measure it right
where you are if you're worried about whether it's
the correct size.
And then the valve has to come
and go, just like the aortic valve had to come and go.

So here are two pictures of the valve being there
and being gone, totally gone.
And then here is a clip showing the valve coming and going.

So what are the things that you might see abnormal on the
right outflow tract view?
The transposition, these two vessels will not be positioned
like this because the aorta comes out anteriorly.
In truncus arteriosus you only have one vessel
and pulmonic stenosis.
We will look for a small narrowed pulmonary artery here.
And that is something that you see in this case
with there's the aorta
and here's a really small pulmonary artery
coming in and out right there.
And that is patient with tetralogy of Fallot.

Crossing of the Great Vessels

Okay? We take a crossing
of the great vessels at the level of the valves.
And the reason we did this is this is not in the
guidelines that you need crossing.
They just tell us that we need to look at the right
and the left, but we have found that this is helpful to us
to rule out transposition of the great vessels.
There's the pulmonary artery,
and let me just play that one more time for you.
And here's the LVOT, the left,
and then you'll see the PA come in.
And when we added this to our views,
our sonographers actually really liked it
because they felt like we could see the pulmonary valves,
the valves better on these crossing vessel views often than
we did even on our outflow tract views.

Three Vessel View

Now, some people are using the three vessel view
to help look at the outflow tracks for their basic exam,
and taking those as their levels.

So this is the pulmonary artery first,
and then we have the aorta and then we have the SVC.
The trachea will be right underneath here
with a bright echo around it.
And you can see that in these pictures as well.
We call this PA, A, S, T to remember the order.

Now, here's a patient with coarctation
and you can see that the pulmonary artery is larger
than the aorta.
And so often if you're sitting there with a particular case,
you're trying to decide is the PA big enough
to be worried about or is it normal?
You go from this view, you go down
and you look at your right outflow tract view again
and see if the PA's bigger.
And you also look at your four chamber
and see if you have a little bit of disproportion
of the right heart being bigger than the left.
So when you get one view, then you go look at your others
to try to confirm it one way or the other.

And this is a, let me see if this video works here.
This is the pulmonary artery
and then the aorta is right next to it.
And you can see that they're both coming over here onto the
right side of the trachea for a right aortic arch.

Advanced Exam: 76811 Requirements

Okay, now I'm gonna jump to the 76811 requirements for the advanced exam
that we do in the United States.
And these interestingly, they didn't come to us
through the AIUM.
They came to us through a billing committee
who was setting up what you should have to have to
be able to bill for that.
The article was published in the AIUM from this group.
And the purpose of the task force who put this together was
to develop appropriate indications
for performing the detailed fetal anatomic exam,
which we code as a 76811,
and to define the components of that exam
and to identifying the training required
to interpret the exam.

So the 76811 is an indication driven exam
and it's not intended to be used
for routine obstetrical exams.
Only one 76818 exam can be billed per pregnancy in the
United States per practice
unless there are extenuating circumstances.
And patients can be brought back to reevaluate structures
that are not seen clearly on a focused exam
by using the 76816 follow up code.

So this is a list of the indications,
and you can get this by looking at this paper if you would like to.
But there are many reasons for the 76811, one
of them being the body mass index
of greater than 35 kilograms per meter squared.

So we have quite a few reasons as
to why we should be doing this exam
for an advanced exam.

Interpretation Requirements for 76811

So what are the interpretation requirements
that obstetricians,
maternal fetal medicine specialist radiologist
with specialized expertise in fetal imaging,
physicians in other areas of the specialty
who have satisfactorily demonstrated specialized expertise
in fetal imaging, that they've performed more than a hundred detailed exams
and that they've completed 30 AMA PRA category one credits
per every three years in fetal ultrasound imaging.

Basic vs. Advanced Anatomy Requirements

So the basic code, the basic anatomy that's required
for the basic code, the 76805,
are the lateral ventricles, the choroid plexus,
the midline falx, the cavum septi pellucidi, the cerebellum,
the cisterna magna the upper lip, the cardiac views
that we just went over the four chamber
and the outflow tracts, the stomach, the kidneys,
the bladder, the cord insertion into the abdomen,
the umbilical vessel number, the spine,
the extremities, and the genitalia, particularly in multiple gestations.

Now the 76811 has added on some of these requirements
and these views that we found particularly important
for our group or the aortic arch,
the superior inferior vena cava, the three vessel view,
the three vessel trachea view and integrity of the diaphragm.

Now there are other anatomical things that were added in
as well,
but I'm just talking about the heart today,
so I won't go over like the mandible and placental masses
and some other things that they said.
We had to talk about the three vessel view
and the three vessel trachea view were added.

Three Vessel and Three Vessel Trachea Views

And these are planes
that we take in the axial plane in the upper
mediastinum above the heart.
And these show the course
and the connection of the ductal
and the aortic arches, the relationship of the arches
to the trachea, the location of the vena cava, the size
of the vessels relative to each other,
and with addition of color Doppler and direction of flow.

So I showed you a little bit of the three vessel view
before, but I'm gonna go over it in a little
bit more depth here.
Here's the, again, the pulmonary, the aorta
and the SVC, just like in this nice diagram from JTI,
the pulmonary aorta is straight
and in this diagram it's blue
and it's always to the left side of the fetus.
The ascending here is this red one, the aorta,
and that's always right next to it
and in between where the SVC is.

Okay, here I've just put this in my,
put the letters out here for you to see.
Now several millimeters cephalic to that we
see the three vessel trachea view
and you can see that here with the pulmonary artery,
the aorta at the SVC.
And then you see this trachea
and you see both the pulmonary aorta
and the aorta traversing over to the right, I mean,
to the left of the trachea here.
And that gives us this V sign that is
so important to look for.
The position
of the trachea in the esophagus will be over here.

So when we think about this view, what is our checklist
that I gave you for the outflow tracts?
What's our checklist for the three vessel view?
Well, first we wanna think, are there three vessels?
If there's an extra vessel,
then you might have a persistent left
or something else left.
SVC. So we wanna find three vessels.
We wanna see that the PA's larger than the aorta,
which is larger than the SVC.
When we look at their size, we wanna look for that V sign
to make sure that they're both coming down on the left.
And we wanna look at the correct direction
of flow on the color Doppler
to make sure we don't have reversed flow.

The V sign is the key to the trachea view.
You need to make sure that both the ductus
and the aorta meet to the left of the trachea.
So start at the four chamber and go up
and move straight into the outflow tract
and then up into the three vessel view.
So you can see that's what we're doing over
and over here, that we're just going straight
up into that V.

Now just to slow it down, here's the trachea view
as a static image showing it off here over to the left.
And notice that the color is both coming
in the same direction.
We don't have any change of color at the bottom to show
that it's going backwards.
They should be going the same direction.

So what does an abnormal look like?
So now you know what a normal looks like,
but an abnormal will be something that doesn't go
on the correct side
or you're gonna have direction of flow differences.
So you can see here there's a U shape to this confluence,
with the artery, the pulmonary artery and the aorta.
And you can see that the trachea
and the esophagus are in between them.
So this would be a right-sided aortic arch.

So here's a case, there you see the U-shaped sign
to this, just like this diagram from Ante
with the trachea in between the two.
And here we have the U-shaped sign on.
There's the two vessels coming straight
with the trachea in between
and the same over here with it going straight up.
And then there's your trachea
and your two vessels coming on either side.
And then here we have it with color
as well showing the two vessels on either
side of the trachea.
So that's a right aortic arch.

So the first time we added these views into our lab,
I can tell you that within the first week we had two
abnormal right aortic arches.
So it is gonna work, it's going to actually find disease
that then we are going to recommend fetal echocardiography.

Aortic Arch View

Okay, so the next view that is in the new 76811 guidelines is the aortic arch.
Now the aortic arch, we always say
that it looks like a candy cane
because it has that curved kinked appearance to it.
The aorta arises from the center of the chest
and gives rise to the head
and neck vessels, the innominate,
the left common carotid artery
and the left subclavian arteries
that the normal arch will have slight progressive tapering
with the ascending aorta being the largest segment
and the smallest segment at the isthmus, which is located
between the ductus arteriosus and the left subclavian.
And then color flow should be propagated across the arch
and should be smooth and laminar.

So if you look at this anatomic diagram, you see
that the aorta, this candy cane comes out of the middle
of the heart and that it goes up
with your arch vessels coming off
and then comes down into the descending aorta.
And in this is the exact same correlative on ultrasound
of a sagittal picture, there's the diaphragm.
Here's the IVC going up into the right atrium
and here's the aorta coming down in that candy cane.
And you can see the vessels coming off to the head.

So how do you get this image?
Well, if you will align your beam along from the sternum going through the ascending
and the descending aorta in that plane,
and rotate 90 degrees,
then you should get your candy cane arch.
So that's one clue as to how you get it.
Another clue is often your spine is right back in here
and you can rock back
and forth on that spine, find your descending aorta,
and then make it into your candy cane.
Here's another picture.
If the fetus is spine up,
then you do the same thing along the descending aorta
to the ascending aorta.
Turn 90 degrees and you'll be in this area.
So here it is with the three
vessels coming off the arch.

Now what's the checklist for the aortic arch?
The aorta should arise from the posterior left ventricle in
the center of the chest, not next to the sternum.
It should give rise to the head and neck vessels.
And the arch should be open in all segments with no evidence
of hypoplasia or narrowing.
And color flow should go right through it in all the segments.

So here's a patient with coarctation
and you can see we've put a normal
for comparison to the right here.
And right here you can see
that this arch is narrowed right here.
And notice also
that this distance is a little bit greater than this
distance, which is another finding for coarctation.
And here is a color picture going through on
that same patient right here, the vessels up there
and there's the narrowing right at the region of the isthmus.
You may not always see turbulence across it in some patients
because the flow's not that high.

Bilateral View (SVC and IVC)

Okay, so the next thing that we look
for is the bilateral view, which is a connection from the
superior vena cava down into the right atrium
and also the inferior vena cava to the right atrium.
And we see this on a sagittal longitudinal view.
They should be similar in size.

So here we have that same diagram from pathology from this book, Silverman's book.
And you can see the SVC, the IVC coming here into the right atrium.
And there's a very nice picture.
It's almost like a bat wing coming in.
And notice that they are similar in size.
You also need to notice that the IVC needs
to go all the way down into the liver,
can't just go into the proximal part of the liver.
'Cause then it could just be the ductus.
So we want to see it coming all the way down.

And how do we do that? Well, you find your SVC over here
and you rotate a little bit more to the right
through there to go back through that SVC
and the descending aorta.
And then you will come up with these views.
And one tip I would tell you about this is don't try
to get one view.
If you can just take a video through it,
it's a lot easier ergonomically on your sonographers.
And that's what we've found.

Our checklist is that it's entering into the right atrium,
that it flows deeply into the liver
and that it should be approximately the SVC
and the IVC should be approximately equal in size.

Now that, what are we gonna look for
as abnormal on our bilateral view?
We're looking for interruption of the IVC
with azygos continuation, which is whether it's isolated
or associated with a heterotaxy syndrome.
Disproportional flow to increased flow in either the SVC or the IVC.
This can happen because
of AV fistulas from large tumors like sacrococcygeal teratomas
with increased vascular flow or like vena
and aneurysms from the head or anomalous systemic
or pulmonary venous drainage,
putting a lot more flow into one versus the other.
The IVC or the SVC.
We can suspect this with disproportion,
which should be confirmed with color Doppler assessment.

So here we have the normal for comparison.
And here we have an abnormal right here with this only coming down just a little bit into this IVC.
And note
that here it goes all the way down into the abdomen
and here it doesn't,
this is really just an hepatic vein going up into the heart
and it's really not the IVC.

Here's an interrupted IVC with azygos continuation to the SVC.
And this kind of looks a little bit like a candy cane heart, but it's not.
It's really the dilated azygos vein demonstrating that flow into the SVC notice.
See, it's going here into the SVC.
It's not going into the heart like that.
And when you look at it down here, you see the azygos that has the flow immediately adjacent
to the aorta here, instead
of having it out anteriorly like we're supposed to.

Diaphragm Integrity

One more view that was added was the diaphragm
needs to be intact.
And so we usually get this on our cardiac images,
a sagittal that shows a video going through the diaphragm.

Conclusion

So I challenge you
to learn a little bit more about heart disease,
congenital heart disease, to do the four chamber view,
the right outflow and the left outflow as recommended
by the AIUM guidelines
to go up a notch in your knowledge about heart disease,
either by Googling, using the internet,
using sonoworld.com.
Read textbooks
and journal articles, talk to clinical colleagues
and learn from and teach your sonographers about
congenital heart disease.
Thank you very much.