Let’s move then from these very nasty or
potentially very nasty AV malformations to
ones that may be of interest to the radiologist
as a curiosity and, occasionally, cause symptoms
and require surgical repair. And these are
congenital vascular malformations of the aorta.
Let’s take a moment to consider what happens
in embryonic life as the heart forms.
When the heart forms, the aorta is often seen
as a series of arches just like one sees in
the fish. And this has been commented on many
times that, in embryonic life, the human fetus
goes through earlier evolutionary stages that
imitate animals that are more primitive shall
we say compared to mammals. And you actually
go through a period as a fetus where you
have the aortic arches of a fish. And gradually
all of those arches involute. They disappear
except from one, which is the main aorta that
remains. I’ll show you a diagram in a moment
of all these arches that disappear.
Occasionally, they don’t disappear and one
remains. And sometimes these arches will put
pressure on the esophagus or on the trachea
and can cause breathing or swallowing problems.
What you see in the x-ray figure here is a
barium swallow. Barium looks white to the
x-ray. And you’ll notice that there’s
an indentation, a partial interruption of
the esophagus. And that’s because there’s
a persistent congenital aortic arch that should
have involuted but didn’t. And it’s putting
pressure on the esophagus. And this patient
would have trouble swallowing because the
food would get stuck where the aortic arch
is pressing against the esophagus. And so
this person would probably need surgery to
remove that arch, to obliterate it.
And there may be also abnormalities in some
of the vascular branches of the major blood
vessels that can also cause some problems
from compression because they’re in a place
they don’t belong.
So here’s the cartoon. You’ll see the
dotted lines there. All represent the embryonic
arches that are supposed to involute. But
in fact some of them may not involute as I
said before and, if they’re persistent,
they may cause problems by compressing either
the esophagus or the trachea.
Here are some examples of these persistent
aortic arches. And you can see they can encircle
the trachea, they can encircle the esophagus.
And they can put pressure on both of them.
And you can see there’s a whole variety
of different ones where they’ve been [Inaudible
0:17:08]. Atretic means involuted or disappeared
or they can be totally persistent in a complete
circle around the trachea and the esophagus.
And the more encircling they are and the tighter
they are, the more likely they are to cause
trouble with breathing or with swallowing.
Here’s a typical example. It’s a double
arch. You can see how it’s pressing on the
oesophagus. It encircles the trachea and the
oesophagus. It cause compression of both structures.
And the degree of compression of course varies.
Sometimes, it’s only a little bit and so
the patient doesn’t need surgery. They’re
going to be able to breathe and swallow okay.
Usually, the right arch is larger and passes
behind the esophagus. And the right common
carotid and the subclavian arteries arise
separately from the right arch as opposed
to from the normal single arch.
In any case, if there’s obstruction to the
trachea or the esophagus, these patients
have to be operated on. Usually what happens
is you interrupt the middle portion and then
you put a graft in so that there’s a normal
arch created surgically. And of course that
eliminates the obstruction to the oesophagus
and the trachea.
Another form of congenital abnormality we’ve
talked about a number of times before because
it’s a cause of hypertension and that is
coarctation of the aorta.
This is a narrowing, or a constriction, in
the aorta just beyond the left subclavian
artery. It’s in the area where the ductus
arteriosus that carries blood during embryonic
life exists. And the area there right around
the ductus fails to develop normally. And
so you end up getting a constriction in the
aorta at that point, usually just beyond where
the ductus would have been.
And you can see it in the diagram in the green
circle. It’s where the coarctation usually
They can be mild or they can be quite severe.
It’s usually picked up early in life because
teenagers are found to have hypertension.
You can get an infection in it – bacterial
endocarditis. And it can even rupture but
those complications are rare.
When it’s picked up beyond age 50, it’s
often associated with brain bleeding because
there are small aneurysms of the cerebral
blood vessels that occur. And it is also associated
with a bicuspid aortic valve. So you may
developed dissection of the aorta. And, even
when this is repaired either surgically or
with a catheter stent, hypertension often
persists in these individuals.
The clue as you may remember we talked about
from the physical exam is: you feel the radial
pulse and you feel the femoral pulse. And
you notice that the radial pulse is occurring
a lot earlier than the femoral pulse. Sort
of, “thump, thump” as opposed to almost
simultaneously in a normal person. And of
course also the patient has hypertension in
the upper extremities and usually hypotension
in the lower extremities. So, if you did a
brachial-ankle index, you would find marked
decrease in the blood flow in the ankle compared
to the arm.
Finally, there’s a very common cosmetic
lesion called a port wine stain. And this
results from areas of abnormal capillaries
and small veins – venules. They’re dilated
and filled with blood and they lie just beneath
the surface of the skin and they’re present
at birth. And they’re quite common. If they
are disfiguring cosmetically like in the little
cartoon here, one can in fact obliterate them
with a laser. And dermatologists do this all
They are called port wine stains because the
colour is often that of a deep purple like
the colour of port wine.