Health and medicine
Created by Amy Fan.
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- What is considered the start of the circulation between the lungs and heart? When oxygenated blood goes from the lung (left lung?) to the left atrium or when deoxygenated blood comes from the right ventricle to the lung (right lung)?(1 vote)
- [Voiceover] So, threading a catheter directly into the heart might be the most direct way, the gold standard, of measuring pulmonary hypertension, but there are certainly other ways we can do it. So, if we think about the relationship of the heart and lungs in the cardiovascular system, we have the heart here, and the lungs, the next step in where the blood is going, so here we have our lungs. In blood, or deoxygenated blood, well, first let's draw some chambers. We have four chambers, two on top, and two on the bottom. It's from this right ventricle that we get deoxygenated blue blood into the lungs. Remember that everything's flipped, like the person is standing in front of you, so this is the right, and this is the left. So, blood goes from the right ventricle into the lungs, and then back over into the left atrium. It's gonna be oxygenated red blood. So given this relationship, if we have hypertension in the lungs, that backs up into the right ventricle, and then, not putting as much forward into the left atrium, then, another way of evaluating the heart can tell us about pulmonary hypertension. And this is a task we call echocardiogram, usually just echo for short. So, echocardiogram. This test is basically putting an ultrasound probe over the heart in different directions, and just looking at how the chambers in a different compartment of the heart are working. So, for our purposes of pulmonary hypertension test, the echocardiogram can show us the right ventricle. The flow going on in there, how hard it's working, will give us a clue of pulmonary hypertension. We can also see the left atrium, see how much blood it's receiving. So this is a very powerful diagnostic tool in pulmonary hypertension, is to look at how the heart is functioning. But an added bonus, is that, since we can see ALL parts of the heart, we can also see the left ventricle, and remember that, if the left ventricle has a problem pushing blood forward, then the backup can be a cause of pulmonary hypertension. So, the echo can tell us more than whether or not we HAVE pulmonary hypertension. It can also give us a clue as to the reason. So it can tell us yes or no, pulmonary hypertension, but it can also tell us about cardiac function as a whole, which can give us another additional layer of clue as to why this patient has pulmonary hypertension. So, that's the echo. And another test that we might do for patients, obviously it's done a lot with any pulmonary complaint, is the x-ray. The x-ray involves radiation, although for a chest x-ray it's not too bad. X-ray. And from the total picture, we can see if the lungs are over-inflated, if there are other clues of pulmonary disease, but specifically for hypertension, the vessels in the lungs, if they have chronic hypertension for a while, they become thickened. So, for an x-ray, we can see the markings in the lungs along the pathway of the vessels, and the kind of scarring, and the enlargement that happens over a period of time. Usually, we should only be able to faintly see the pattern of the airways and the vessels, but when there's pulmonary hypertension, it can be really prominent, depending on the degree. So an x-ray is very reasonable to start out with. Next, we have some tests that can tell us how the lungs are performing their job, so we can do an arterial blood gas. This analyzes the amount of oxygen and the carbon dioxide in the blood, and the lungs are responsible for keeping that in balance, so this is not specific, so if we have a bad arterial blood gas, it can tell us that the gas exchange here is not efficient, not necessarily that they have pulmonary hypertension, but given the history, combined with the blood gas, it can tell us how well the lungs are functioning, also how bad the hypertension is, if they do have it. So, along with the arterial blood gas, we can also do pulmonary function tests, which is a direct way to measure exactly what the lungs are doing, and what it's capable of doing. So, we're still gonna put history here as the most important component in diagnosing pulmonary hypertension, or to make you suspicious of pulmonary hypertension. These tests can push you one way or the other towards the diagnosis, and of course you can always thread the Swan-Ganz catheter to get a definite measurement.