In the previous session, we talked about the basic beginning steps in making a diagnosis,
the history, the physical exam, the electrocardiogram.
Now we're going to talk about more sophisticated tests, imaging test in particular
that will help us diagnose heart disease and in particular, the commonest heart disease,
atherosclerotic heart disease which can lead to heart attacks and sudden death.
Here's a list of the non-invasive tests.
What we mean by a non-invasive test is that we do not have to introduce anything inside the body.
We also have invasive tests and I'll talk about that in just a moment.
And you can see here that the basic tests are still included for example the electrocardiogram, the chest x-ray,
and then we move on to more sophisticated imaging test such as ultrasound test, the echo test.
We move from there to x-ray sophisticated test such as the CAT scan also called the CT scan
which gives us very exquisite images of the heart.
And finally the magnetic resonance imaging test, the MRI,
which gives us very detailed pictures inside the heart.
And of course we also can record the electrocardiogram over a long period of time,
24 hours, 48 hours, 72 hours, in order to see if there are abnormalities in cardiac rhythm.
Let's start with the very basic test that is the chest x-ray.
And I will show you some examples a little later in this talk,
but basically what the chest x-ray shows us, it shows us the heart, ribs and the lungs
and gives us a rough picture of what's going on in the chest,
nowhere near as detailed as the CT scan or the MRI.
There are also nuclear tests. In these we inject a small amount of radioactive substance
that can end up showing us damaged myocardium or abnormalities in blood flow in the heart
depending upon how the radio nuclei distribute themselves.
These are very common tests even though they involve a small intravenous injection
we still call them non-invasive because we don't put major catheters inside the body.
Just for an example, here we see an MRI of the chest.
You can see the black areas on both sides of the lung, the heart is in the middle
and the little lighter colored material just below the heart
is actually some fluid inside the pericardial space,
so this MRI would be read as a small pericardial effusion.
Now, again, we're gonna talk about invasive tests.
Now, invasive tests involve introducing catheters inside the body.
We talked a little bit about this before when I showed you the balloon catheter
that is threaded into the right side of the heart and it enables us to give pressures
and blood flow measurements, but we also do more sophisticated things with the catheterizations.
We are able to inject dye, take x-ray movies, look at the insides of blood vessels,
the insides of cardiac chambers and then of course
we can also do recordings of the electrical activity inside the heart
and this can actually lead to therapy where we actually can burnout or eradicate areas,
small areas of the heart of course, that lead to this arrhythmias.
Since ischemic heart disease is the most common cause of death throughout the world,
both in Western Europe and the United States and of course rapidly now,
it's become the commonest cause of death in Asia.
We have a whole series of graded tests you can see in this pyramid shape.
The most basic and commonly used tests are at the bottom.
We start with the ECG both with an exercise or an at rest.
We move up to imaging tests with the exercise test, for example nuclear or echo test
that use imaging alongside of exercise or drugs to stress the heart.
And from there, we rarely have to do a CT or an MRI or a plain echo,
because we usually get the information we need from the previous test
such as the imaging tests with stress, either exercise stress or drug stress.