Evaluation of the Chest Radiograph in Children with Known or Suspected Heart Disease, by
Dr. George Taylor.
My name is George Taylor from the Department of Radiology at Boston Children's Hospital.
And in this session we're going to be talking about how to evaluate the chest radiograph
in children with known or suspected heart disease.
We will be following a systematic approach to the evaluation of the chest x-ray focusing
on the heart, the pulmonary vasculature, airway, the situs of the abdomen and chest, and bony
abnormalities.
Heart,
In terms of the heart, we need to look at the size of the heart and, whenever possible,
the presence of specific chamber enlargement.
The factors that generally increase heart size are increased volume within the heart,
obstruction to that specific chamber, pump failure, pericardial diseases, and associated
heart or mediastinal masses.
Here, our first child we have an eight-month-old who presents with cyanosis and a murmur.
And we see that there is diffuse cardiomegaly, but specific enlargement of the right atrium.
The atrium is bulging laterally, and on the lateral view, we can see that the right atrium
also extends behind the trachea.
This is a congenital abnormality of the tricuspid valve with enlargement of the right atrium,
atrialization of the right ventricle, and often associated with decreased pulmonary
vascularity.
Here is another child with a large heart.
A 14-year-old who presents with fever, arthralgias, and shortness of breath who has rheumatic
fever.
In this child with mitral valve disease, we can see enlargement of the right atrium, with
enlargement of the right atrial appendage as well, and displacement of the posterior
heart border behind the trachea, which is a good sign of left atrial enlargement.
This six-month-old with respiratory distress has diffuse cardiomegaly and under inflated
chest as a result of a dilated cardiomyopathy.
In this situation, looking at specific chamber enlargement in an infant can be very, very
difficult.
This eight-year-old presenting with shortness of breath has a "globular" looking heart.
It's enlarged, but the contours are slightly different in that they more resemble a bag
full of water, rather than specific chamber enlargement.
So when we see a child with a large heart, we need to consider the possibility that either
the heart is enlarged, or there is fluid surrounding the heart, so that the shadow of the hard
looks much bigger than it normally is.
Here the same child is shown after a drainage catheter has been put in the pericardium,
and you can see a marked difference in the size of the heart.
Lung Vasculature.
When we look at pulmonary vasculature in children with suspected or known heart disease, we
need to look at the extent of pulmonary vascularity, whether it's normal, increased, or decreased.
There are a number of diseases that decrease pulmonary vascularity, and they're almost
always associated with cyanosis.
The most common cause is that of significant pulmonary artery narrowing.
And that is often seen with Tetralogy of Fallot, or pulmonary atresia, or stenosis, but can
be a part of any complex congenital heart disease with pulmonary narrowing.
It can also be seen with right atrial obstruction in infants with tricuspid atresia, or Ebstein's
anomaly, and it can be an acquired condition in children with pulmonary artery hypertension,
especially those who developed the Eisenmenger complex.
Here is a newborn who presents with deep cyanosis, respiratory distress, and a murmur.
And on initial inspection, we can see that the heart is large.
It is-- has a very prominent ventricular border, and if we focus on the lungs, the lungs are
very black.
We can't see any pulmonary markings at all.
This is not because the child has a pneumothorax, it's because the pulmonary vascularity is
markedly diminished.
An enlargement of the left hemithorax shows you that there are hardly any blood vessels
that can be seen in the left lung.
This is the result of a child that has Tetralogy of Fallot with severe infundibular narrowing
and decreased pulmonary vascularity.
Diseases that increase pulmonary vascularity are almost always related to left to right
shunts, and the most common ones are atrial septal defects, ventricular septal defects,
patent ductus arteriosus, and atrio-ventricular canal.
Here we have a three-month-old who presents with respiratory distress and a heart murmur.
And we see on the frontal and lateral x-ray that there is marked cardiomegaly that is
involving multiple chambers of the heart.
The lungs are hyperinflated with very flat diaphragms on the lateral view, and the pulmonary
vessels are very easy to see.
In fact, they're fuzzy and indistinct, suggesting that there is pulmonary venous or pulmonary
vascular congestion.
This child also has increased pulmonary vascularity.
One of the ways of identifying increased pulmonary vascularity is to identify a bronchus on end,
here shown as a circle.
And the blood vessel that's immediately adjacent to that bronchus is the pulmonary artery.
And we look at the size of the pulmonary artery relevant-- in relation to the bronchus.
If the pulmonary artery is bigger than the bronchus, then we have at least a two to one
left to right shunt.
If the pulmonary artery is the same size as the bronchus, then the pulmonary vascularity
is normal, or the shunt is less than two to one.
If the vessel, on the other hand, is smaller than the bronchus, we have diminished pulmonary
vascularity.
This child has a left to right shunt as the result of an atrio-ventricular canal.
It is also important to pay attention to how the pulmonary vascularity changes with time.
Here is a child with an untreated atrio-ventricular canal, who at four years of age has cardiomegaly
and increased pulmonary vascularity.
If you look at the right pulmonary artery, it is enlarged, and you can see increased
pulmonary vessels are rising from that pulmonary artery.
Over time, he developed pulmonary hypertension, and at six years of age, the central pulmonary
artery is still enlarged but the peripheral pulmonary vasculature is diminished.
It's a term called pruning of the pulmonary vasculature that is associated with pulmonary
hypertension.
This child developed the Eisenmenger syndrome related to secondary pulmonary hypertension.
Pulmonary venous congestion and edema is another feature of the pulmonary vascularity that
is important to pay attention to.
The three main things that cause pulmonary venous congestion are obstructive pulmonary
venous return, and that is often seen with total anomalous pulmonary venous return that
is obstructed, or pulmonary vein stenosis, or atresia, and other causes of left sided
obstructions, such as cor tritriatum, or mitral atresia, or stenosis.
It can also be seen with left ventricular obstruction or dysfunction, such as hypoplastic
left heart, or critical aortic stenosis, patients with cardiomyopathy, or severe coarctation
of the aorta.
And finally, it can be seen with children who have large left to right shunts with congestive
failure.
Here are two patients with pulmonary venous congestion and edema.
The patient on the left side is a three-month-old that we have seen before.
This child has increased pulmonary vascularity, cardiomegaly, and pulmonary venous congestion.
This child has an atrio-ventricular canal.
The vessels look as if they were drawn with a crayon rather than with a sharp pencil.
That is the feature of pulmonary vascular congestion.
The second patient has a similar pattern, except that the markings in the lungs are
much finer and more interstitial.
These increased linear markings extend all the way to the pulmonary edge, and are associated
with pulmonary venous obstruction.
This child has a total anomalous pulmonary venous return that is obstructed below the
diaphragm.
Here, I've included a CT venogram showing how the pulmonary veins, rather than joining
the left atrium, join a vertical vein that courses under the diaphragm and joins the
ductus venosus.
And you'll notice that there's a mild obstruction below the diaphragm.
There is also asymmetry of pulmonary vasculature that one needs to consider.
And the causes of asymmetric pulmonary vascularity that we can see are pulmonary stenosis or
hypoplasia, pulmonary venous obstruction, or post-operative changes.
Here, we have a six-month-old with single ventricle who had a Glenn shunt, which is
a superior vena cava to right pulmonary artery stent.
We can see that there is marked asymmetry in the pulmonary vascularity, with more vascularity
in the right lung then the left lung.
And this is related to the fact that Glenn shunts shunt almost 70% of the blood to the
right side compared to the left.
Here, we can see a venous catheter that has actually crossed from the superior vena cava
into the right lower lobe pulmonary artery.
I would like to have you focus on the course of the right-sided venous catheter.
It goes down the superior vena cava and exits to the right, here shown by the arrow.
A magnified view shows that this catheter is actually in the inferior right pulmonary
artery, as the result of the Glenn shunt connecting the superior vena cava to the pulmonary artery
circulation.
Here's another child who presents with focal abnormal pulmonary vascularity.
She is 21 years old and presents with mild hypoxemia.
And on the chest x-ray, in general, the pulmonary vascularity is symmetrical, but if we look
in the right lower lobe, we see that there is an abnormal vessel coursing from lateral
to medial and seems to dive down below the diaphragm.
This is a child who has partial anomalous pulmonary venous return, here shown in the
MR venogram, where the abnormal right lower lobe pulmonary vein joins directly with the
inferior vena cava and joins the right atrium.
Airway and Mediastinum.
The airway and mediastinum are also very important in evaluating patients with potential heart
disease.
We need to evaluate the trachea for possible displacement or narrowing, and the position
of the aortic arch is very important.
Because patients with congenital heart disease may present with a right aortic arch, a double
arch, dilitation of the arch, or constriction of the descending aorta depending on the patient's
pathology.
This 20-month-old presented with acute onset of stridor.
And we can see that the trachea on the frontal film, rather than being slightly to the right
of midline is to the left of midline, and is mildly displaced by a structure to the
right side.
On the lateral view, the trachea is anteriorly displaced by a structure running posterior
to it.
This is a child with a right aortic arch and aberrant left subclavian, causing a vascular
ring.
Here we have an asymptomatic five-year-old who presents to his pediatrician for a checkup,
and his blood pressure in the upper extremities is high.
Now in a 50-year-old, the mild uncoiling of the ascending aorta would be a normal finding.
However, in a five-year-old this is a highly abnormal finding that is seen with bicuspid
aortic valve or aortic stenosis.
This child had both, had a congenitally aortic stenosis related to a bicuspid aortic valve.
Bony Abnormalities.
Bony anomalies are also very important to pay attention to, because they can be signs
of underlying heart disease.
And here we need to focus on the vertebrae, the ribs, and on occasion the sternum, because
sternal abnormalities are often associated with cyanotic heart disease.
Here we have a 13-year-old who also presents with hypertension.
And very much like the prior chest x-ray that we were just seeing, there is some mild uncoiling
of the thoracic aorta.
When we focus on the ribs, we notice that there is inferior rib notching in a number
of ribs on the left side.
When we look at the ribs on the right side, there is a milder version of this rib notching.
This is due to coarctation of the aorta and multiple collaterals that course along the
inferior surface of the ribs, and the pulsatility causes notching and pressure erosion of the
ribs.
We can also see, if we focus on the descending aorta, that there is a focal constriction
of the aortic arch, here represented by a 3.
At the same level, there is a focal constriction related to the aortic coarct and the poststenotic
dilatation.
Here we see it without the three overlying it, again focusing on the poststenotic dilatation.
Situs of Chest and Abdomen.
Finally, situs is a very important part of evaluating the chest x-ray, and we have three
different possibilities.
Situs solitus, which is the normal situation, situs inversus, where everything is completely
reversed, and this has about a 2% risk of having associated congenital heart disease.
And patients with heterotaxy, where the cardiac apex and the abdominal viscera may be variable
and different.
Here we have on the left side of the screen situs solitus, where we have the stomach bubble
shown by the arrow being in the normal left-sided position.
And it is in the same side of the patient as the cardiac apex.
On the other hand, we have a child with heterotaxy, where we have the stomach on the normal left
side, but the cardiac apex on the right side.
So this is highly associated with complex, congenital heart disease.
So we've covered a systematic approach to the patient with known or suspected heart
disease.
Looking at heart size and location, evaluating the pulmonary vascularity for an increase,
a decrease, asymmetry, and abnormal vessels.
We've looked at the airway, size, and displacement or a compression by abnormal vessels.
We've looked at situs solitus, or heterotaxy, and we've looked at some of the bony abnormalities
that can be seen.
Thank you.
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