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Introduction – Invasive and Non-invasive Tests (Diagnostics)

by Joseph Alpert, MD
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    00:09 Welcome back! This is Part 4 of “Cardiology: An Introduction”.

    00:13 This is going to be a continuation of our examination of the various cardiovascular diagnostic approaches for patients with suspected heart disease.

    00:23 In the previous session, we talked about the basic beginning steps in making a diagnosis - the history, the physical exam, the electrocardiogram. Now, we are going to talk about more sophisticated tests, imaging tests 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 is a list of the non-invasive tests.

    00:56 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 will talk about that in just a moment. And you can see here that the basic tests are still included.

    01:11 For example, the electrocardiogram, the chest X-ray, and then we move on to more sophisticated imaging tests such as ultrasound test, the echo test. We move from there to X-ray, sophisticated tests 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, the 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 radionuclides redistribute 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.

    02:50 Just for an example, here we see a MRI of the chest. You can see the black areas on both sides of the lungs. 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 are going to 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.

    03:37 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 burn out or eradicate areas, small areas of the heart, of course, that lead to these arrhythmias.

    04:08 Since ischemic heart disease is the most common cause of death in… throughout the world, both in Western Europe and in 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.

    04:26 You can see in this pyramid shaped, the most basic and commonly used tests are at the bottom.

    04:31 We start with the ECG, both with an exercise or/and at rest. We move up to imaging tests with the exercise test. For example, nuclear or echo tests 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 tests, such as the imaging tests with stress, either exercise stress or a drug stress.


    About the Lecture

    The lecture Introduction – Invasive and Non-invasive Tests (Diagnostics) by Joseph Alpert, MD is from the course Introduction to the Cardiac System.


    Author of lecture Introduction – Invasive and Non-invasive Tests (Diagnostics)

     Joseph Alpert, MD

    Joseph Alpert, MD


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