Heart Disease in the First Week of Life: Cyanosis, by Dr. Michael Freed.
My name is Michael Freed, and I'm a Pediatric Cardiologist at Boston Children's Hospital
and at Harvard Medical School.
I want to spend a little time today talking about congenital heart disease in the newborn
period.
Introduction.
Children come in in the first week of life, they present in one of four ways: with a heart
murmur, with an arrhythmia, congestive heart failure, or with cyanosis.
Let's deal with cyanosis.
Cyanosis is actually more complicated than the others.
I would maintain that, on the basis of physical exam, EKG and x-ray, we can sort out the main
types of cyanotic congenital heart disease before we get an echocardiogram, before we
raise the flags.
Approach to Diagnosis of Cyanotic Congenital Heart Disease.
Let's start with different types of cyanotic congenital heart disease that present in the
first week of life.
And these are the kids that are really blue.
Kids with common mixing, like single ventricle or truncus, as I said, usually come in in
heart failure a little bit later.
So these are the kids who have saturations in the 40s, 50s, 60s, 70s, the really blue,
blue ones.
The first type is transposition of the great arteries with an intact ventricular septum.
And these kids have relatively normal hearts.
But instead of the pulmonary artery coming off the right ventricle, the aorta comes off
the right ventricle, and the pulmonary artery comes off the left ventricle.
So blood from the body goes right atrium, right ventricle, out the aorta, back to the
body.
Blood from the lungs-- left atrium, left ventricle, out to the pulmonary artery.
And these kids, to survive, need some kind of mixing, usually at the ductile level and
the atrial level.
But these kids come in very sick in the first few days of life.
The second is total anomalous pulmonary venous connection.
These are kids who the pulmonary veins never get back to the left atrium.
So they do okay in utero, because there is usually some connection from the common pulmonary
vein behind the heart to the right superior vena cava or left superior vena cava or umblical
vitelline system.
When they're born, all of a sudden, they can't get blood out of the lungs.
The blood backs up into the lungs.
They get very high pulmonary venous pressure and go into pulmonary edema.
Ebstein's, which is an abnormality of the tricuspid valve.
So they get severe tricuspid regurgitation, elevating their right atrial pressure.
And they shunt right to left at the atrial level.
Tricuspid atresia-- so in tricuspid atresia, the tricuspid valve never forms.
The right ventricle is either very small or nonexistent.
Blood comes back to the body into the right atrium, can't get through here, goes across
the foramen ovale into the left atrium, left ventricle, out the aorta to the body.
Some of it goes through the ductus arteriosis, out to the lungs, where it gets oxygenated,
and comes back again.
So in utero, this is not a problem.
And after birth, this isn't a problem.
But when the ductus arteriosis starts closing, then the amount of blood going through here
diminishes.
The blood going to the lungs to get oxygen is reduced.
And gradually, the arterial saturation will decrease.
There will be more hypoxemia.
Pulmonary atresia, intact ventricular septum.
So these kids have no outlet to the right ventricle.
Usually, right ventricle doesn't grow very much.
So these kids, blood comes back from the body, right atrium, can't get out this way, goes
out this way, out this way.
And again, these kids are dependent on their ductus arteriosus for their blood flow.
And when the ductus arteriosus closes, they get into difficulty.
Pulmonary stenosis-- we talked about before.
If you look at pulmonary stenosis, these kids have severe right ventricle outflow tract
obstruction.
The right ventricle has to generate a higher pressure to pump blood out.
And if it starts having difficulty generating that higher pressure, by Starling's law, it
increases preload.
If you increase the preload in the ventricle, the atrial pressure goes up.
And in the newborn period, if the right atrial pressure exceeds the left atrial pressure,
you start shunting right-to-left and you end up with cyanosis.
Tetralogy of Fallot with pulmonary stenosis, or Tetralogy of Fallot with pulmonary atresia.
So with these kids with a ventricular septal defect and pulmonary stenosis, blood coming
back from the body, right atrium, right ventricle, difficulty going out here.
So some goes out to the body.
Some goes through here to the lungs and back again.
With pulmonary atresia, nothing goes out this way.
And they're dependent on the ductus arteriosus.
So as mentioned before, they get into difficulty when the ductus closes.
Now, all of these children are blue for one reason, with the exception of one group that's
blue for a different reason.
All of these kids from here down are blue because blood that should have gone out to
the lungs somehow gets diverted into the systemic circulation.
So in Tetralogy, at the ventricular level, tricuspid atresia, pulmonary atresia, pulmonary
stenosis at the atrial level, total anomalous pulmonary venous connection, either right-to-left
shunting at the ductus.
Or if the ductus closes, they right-to-left at the atrial level, Ebstein's at the atrial
level.
So if you were to look at a chest x-ray and look at the pulmonary blood flow, all of these
guys have diminished pulmonary blood flow.
If you look at the hilar vessels, you see very little hilar vessels and almost nothing
out in the periphery.
As opposed to transposition, who remember have these two separate circulations, but
have a normal amount of blood flow, or it sometimes is actually increased-- nobody knows
what sets the cycle of how much it flows-- but if you were to get a chest x-ray and look
at the pulmonary blood flow, if they have normal pulmonary blood flow, they've got transposition
of the great arteries.
There's nothing else in the newborn that gives you cyanosis without respiratory distress
and normal pulmonary blood flow.
In fact, this is not new.
This was information that Dr. Taussig published in a paper in 1938.
Using fluoroscopy, she could tell the kids with transposition from everyone else because
of their normal pulmonary blood flow.
There are a couple of other patterns on the chest x-ray that are pathognomonic.
One of them is Ebstein's disease.
And they have a huge heart.
And this is all right atrium.
The in utero tricuspid regurgitation dilates the right atrium.
So the heart is just almost sometimes wall to wall.
I usually pick this up when I'm looking for the pulmonary blood flow.
And I'm looking for the lungs, and I can't find the lungs, because there's this big white
blob in the middle.
A big white blob, oh big heart, Ebstein's disease.
So blue with a huge heart, these are the-- you get a huge heart because of congestive
heart failure or because of significant volume overload.
None of these other kids have significant volume overload.
So the hearts are normal.
So cyanosis, huge heart, Ebstein's disease.
The other pattern that's typical is total veins.
And these kids have pulmonary edema.
Pulmonary edema in a newborn is just a white-out of the lung.
They get fluid in all their alveoli.
So they just don't-- it just shows up white on an x-ray film.
There's another disease in the newborn that gives you a white-out of the lung.
And that's RDS.
So how do we separate these kids from RDS?
Well, I usually do it from across the room.
If they're this big, they have RDS.
And if they're this big, they have total veins.
I think if you have a 25-week-old, 26-week-old premature, the overwhelming odds are that
he's got RDS.
If he's 38 weeks, be careful about atypical RDS in 38-weekers, because some of them will
have total veins.
In fact, it's sometimes quite hard to tell these apart.
I mean, pathophysiologically, there are a lot of similarities.
Both of them have fluid in all the alveoli, so they don't oxygenate very well.
And both of them have high pulmonary resistance, so they shunt right-to-left at the atrial
or great vessel level.
So these are actually hard to tell apart.
And we have a standing rule here that any baby, any newborn, who's going on HIFI respirator
or ECMO has to get an echo to make sure they don't have total veins.
And every couple of years, we find a baby who the neonatologist thought probably had
RDS who actually had total veins.
The x-ray is telling you what's going on in that 1/30 of a second that you snap the picture.
The EKG is telling you something different-- what the blood flow was in utero.
Which was the ventricle that was doing most of the work in utero?
Which ventricle was the predominant ventricle?
With tricuspid atresia, remember these are the kids where the blood is shunting at the
atrial level.
Not very much blood goes into the right ventricle.
The right ventricle is usually quite hypoplastic.
In these kids, the left ventricle is doing most of the work.
In pulmonary atresia, intact ventricular septum-- again, these are the kids with a very small
right ventricle-- left ventricle is doing the work in utero.
In Tetralogy, both ventricles are working in utero.
And when you have both ventricles of equal size on the electrocardiogram, you get right
ventricular hypertrophy.
Pulmonary stenosis.
I could make a good case for either of these.
And it turns out that, if you present in the newborn period, you have LVH.
So now, if you have a newborn who is blue with diminished pulmonary blood flow, and
he doesn't have pulmonary edema or a big heart, if he's got left ventricular predominance,
he's got one of these things, he's got a small right ventricle.
He's got right ventricular predominance, he's got Tetralogy of Fallot.
There's something characteristic about the QRS axis in tricuspid atresia.
And that is, it's superior, minus 30 to minus 90 degrees.
So if we look at the heart sitting in the chest, this is the left ventricle, this is
superior, inferior, left, right.
Normally, the heart depolarizes down in this direction, so we get a QRS axis in the 70
or 80 range.
Newborns, a little bit further, but it's still depolarizes down in this direction.
These kids, the heart depolarizes up in this direction.
And we see this in one other disease in complete AV canals.
And remember the His-Purkinje system runs along the tricuspid annulus and then escapes
out into the myocardium.
Well, in both these diseases, the tricuspid valve is displaced.
So somehow, the His-Purkinje system comes more inferiorly, and they depolarize in a
superior direction.
These kids are plus 30 to plus 90, plus 30 to plus 90.
So if you have this hypothetical child with diminished pulmonary blood flow, left ventricular
predominance, if he's got a superior QRS axis, he's mostly likely got tricuspid atresia.
If he's got an inferior QRS axis, then he's got either pulmonary stenosis or pulmonary
atresia.
And kids with pulmonary stenosis will usually have a systolic ejection murmur.
[MURMUR SOUNDS] Kids with pulmonary atresia usually have no murmur.
If this hypothetical baby has diminished pulmonary blood flow, doesn't have pulmonary edema or
a big heart, and has RVH, then he's likely to have Tetralogy of Fallot.
And you can tell these apart-- children with Tetralogy of Fallot and pulmonary stenosis
will have that systolic ejection murmur.
[MURMUR SOUNDS] While kids with pulmonary atresia have no murmur.
Or sometimes you can hear continuous murmurs from the collateral vessels.
A pearl is, watch out for continuous murmurs in the newborn period.
It's not a ductus arteriosus.
Usually, the pulmonary pressure isn't low enough to give continuous murmurs in the first
few days of life.
If you have continuous murmur, worry about pulmonary atresia.
And that separates out all of these.
Now, this type of pattern is not perfect.
If it were perfect, you wouldn't need pediatric cardiologists or echocardiographers.
But when it's been studied in a large group of people, it's about 60% to 70% accurate.
It falls down where you would expect it to fall down.
You can't separate out single ventricles with pulmonary stenosis from Tetralogy.
You're just not going to be able to tell the size of the VSD from this kind of pattern.
And you can miss malaligned AV canal with pulmonary stenosis.
So they look blue, they look like tricuspid atresia, but it's really just a malaligned
canal.
But this is a pretty good way of looking at newborns before you get the echocardiographers
involved.
So this is a relatively straightforward way of looking at newborns with heart disease.
It's a good overview on how congenital heart disease presents in the first week of life.
Thanks very much for listening.
This concludes our video on Clinical Presentation of Congenital Heart Disease in the First Week
of Life: Cyanosis.
Please continue with the next video in this series, Clinical Presentation of Congenital
Heart Disease in the First Week of Life: Congestive Heart Failure.
Thank you.
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