Now, going back to the
stress test, we can
do the stress test with a transthoracic echo,
as I told you, and the electrocardiogram.
But one can also inject some radioactive material
that’s taken up by the heart cells in direct
proportion to the blood flow. So, you do a
baseline study, you exercise the patient,
you give them the radionuclide again and you
see if there are areas of the heart muscle
that don’t get blood flow. That would be
a positive test.
Now, if the patient’s had a previous heart
attack, there won’t be any radionuclide
in that area where the heart attack was, but
guess what? During exercise, it won’t get
any bigger. It will just stay the same, showing
you that there is a permanent scar there,
but not lack of blood flow during exercise.
Now, we can do very much more detailed imaging
as I said before, using the CT scan or the
The MRI gives us the most detailed picture
of the heart. It’s also the most expensive
test. Patients have to go into a little chamber
to have this done. And some people are claustrophobic
and cannot tolerate this test. But, it’s
a very, very detailed test.
I wanted to show you some examples here. First,
the nuclear stress test and then the MRI test.
This shows you three nuclear studies. The
top one is normal and you can see nice, uniform
distribution of the different views of the
radionuclide. The middle one shows you, in
comparison by the way, to the normal above,
some small deficits. So, this is a moderately positive
test. And the lowest one shows you a lot of
deficit. There’s very severe atherosclerotic
heart disease here. The heart is really hurting
during exercise. It’s not getting enough
Now, it turns out that how much of the heart
doesn’t get blood flow during the nuclear
stress test is a very important piece of information
because the more severe the deficit; and you
saw the severe deficit versus a mild deficit,
the worst is the long term prognosis. And
you can see from this study, as you get from
left to right, more increasing deficits on
a nuclear scan, the long term outlook for
death and for heart attack is much greater,
the worst the scan is. So, the scan also tells
us a little bit about the possible future
for this patient.
The CT scan is particularly good in a very
sort of low-grade CT scan for looking for
calcium in the coronary arteries. If we see
calcium in the coronary arteries, that tells
us that atherosclerosis is present. It doesn’t
tell us how bad it is, but it tells us that
there is atherosclerosis.
We can do something by injecting dye. We can
do a CT angiogram where we actually see the
inside of the blood vessels. Not quite as
good as the invasive images of the blood vessels,
but pretty good. The CT angio is particularly
good if the patient has a normal study. Then
we can say, “Your chest pain or your shortness
of breath is not due to narrowing in the blood
vessels of the heart.”
And here we see a CT angiogram. You saw this
slide before in the Anatomy Lecture as an
example of how nicely we can see the coronary
arteries. Above is a colorized version done
by the computer. Below are the actual images.
But you can see that we get really good pictures
of the insides of the blood vessels, and we
could see if there were narrowings there.
This is a very popular test.
Of course, it requires that the patient receive
some radiation. And we always worry a little
bit about that. We don't like to give too
much radiation to the patient long term. We
worry of course, about an increased risk
The MRI uses magnetic resonance imaging. There
is no radiation involved, but it’s, as I
said before, more expensive and the patient
has to be willing to sit in this little chamber,
which some claustrophobic individuals are
not capable of doing.
Here we see an MRI in a child that actually
demonstrates a ventricular septal defect.
You can see the chest X-ray on the left and
the MRI on the right. And you can see exquisite
detail of the anatomy, all the chambers are
labeled and you can actually see the VSD,
that there is a connection between the two
ventricles, the septum is incomplete. And
MRI is used quite often in diagnosing congenital
heart disease. It shows us complex anatomy
very, very well.
Now, the simple chest X-ray is a very good
initial screening test. It’s not very good
for just diagnosing whether a patient has
coronary disease or not, but it tells us - is
the heart enlarged? Is the lungs normal? Is
there pneumonia? Is there severe lung disease?
We get a whole lot more information baseline,
just like in the baseline electrocardiogram.
Often these two tests are done as baseline,
particularly if we are considering taking
the patient to catheterization or of course,
So, let me just show you something about the
chest X-ray with a few examples to show you
the kinds of things we get from the chest
Here’s a normal chest X-ray. And we have
labeled all of the various components. You
can see the heart in the center, you can see
the lungs, the ribs. Down below, the diaphragm
with the stomach on the left and the… and
the liver on the right. By the way, when I
say the stomach’s on the left, remember,
this person is looking towards me. So, it’s
our right, but it’s the patient’s left.
And the convention is you use the patient’s
left and right, not your left and right. So,
the stomach is on the left side of the body
and the liver is on the right side of the
body. And this is a totally normal chest X-ray
- nice clear lungs, nice normal heart size.
Now here, what’s wrong with this patient?
Clearly, the heart is enlarged, right? What
could be doing that? Well, it could be a patient
who'd had multiple heart attacks or it could
be an individual who has a heart muscle disease
that results in dilatation of the heart and
heart failure. And we are going to talk about
the various diseases that can cause this enlargement
of the heart and the symptoms and the treatment
as we go along in this series.
Here we see a very enlarged heart, but in
this case, the enlarged heart is because of
fluid in the pericardium. The pericardial
space is swollen with fluid and that fluid
can put pressure on the heart and actually
decrease the pumping efficiency of the heart.
So, this is consistent with a large pericardial
effusion. It could be a very large heart,
but the uniform roundness makes it more likely
that it’s a large pericardial effusion.
Here is an example of a patient with pneumonia.
The heart is not enlarged, but look on the
right side of the diagram. You can see that
part of the lung is filled in with white material.
That’s a pneumonia. So, this is a patient,
perhaps with a normal heart, but who has pneumonia.
So, their symptoms of shortness of breath
might not be from heart disease, but from
lung disease. So, you can see the kinds of
things that the chest X-ray can help us with.