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Studying for a test? Prepare with these 15 lessons on Circulatory system diseases.
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- [Voiceover] Take a look at this heart I've drawn here. The heart has this main blood vessel coming off right here, the aorta. Off of the aorta branches three huge main vessels. First, you've got your brachiocephalic, which actually branches a little further down to become the right common carotid and the right subclavian. The next vessel that comes off is the left common carotid. Lastly, this other vessel, right here, is called the left subclavian. These are huge blood vessels, and this is how the rest of your body gets blood. The aorta travels down here, but this is how your upper body gets blood. The brachiocephalic supplies mostly the right upper body, and the left common and the left subclavian supplies the left part of the body. These directions seem kind of messed up because you're thinking this is the left of my screen, and over here's the right. But remember, we're looking at a patient so this is the patient's left and this is the patient's right. The reason I bring all this up is because there's a vasculitis, inflammation of blood vessels, called Takayasu arteritis, that affects these main blood vessels coming from the heart. Obviously, this is a large vessel vasculitis. You really can't get much larger than these main vessels. Let's take a look a little bit further up, and you can see this brachiocephalic artery branches into your right subclavian and your right common carotid. What's happening in Takayasu arteritis? You've got narrowing due to fibrosis, scarring of your blood vessels because of repeated inflammation, so these main blood vessels are really scarred up. The narrowing is also known as stenosis. You may hear that word thrown around a few times. Blood that passes through here will actually run into resistance and bounce around and you get this turbulent blood flow. Think of it as stepping on a hose. You're going to have decreased force, right? So it's got this decreased force, so that leads to decreased blood pressure. You also notice the rate at which blood can get through here is decreased. That means decreased flow of blood through. Less blood is able to get in and it's not as strongly pushed forward. This is going to be very important when you consider the symptoms of this patient. Let's actually start with the arms. I think that's a great place to first focus in on. If you're checking for the pulse in this patient, you might actually notice that there is no pulse. That's not because the patient's heart's not beating, it's just blood isn't getting through to the arms. Remember, the pulse is created by the blood pressure. You're getting decreased blood pressure, so you'll have decreased pulse. In fact, Takayasu's is sometimes referred to as the pulseless disease. Realize not all these blood vessels are going to be narrowed in the same way. Maybe you have more narrowing of your left subclavian than any of the others. You think about it, you're going to have decreased blood pressure, a lot of it, right here on the patient's left side of the body, whereas blood's still decreased on the patient's right, but it's not as much so. You might be able to feel the patient's pulse here, but not on this side, not on the patient's left side. It makes sense that if you take a patient's blood pressure with a blood pressure cuff on one side of the body versus the other side of the body, you might notice a discrepancy. Here, for example, remember we said there's decreased blood flow here, but it's not as severe, so you might get decreased blood pressure on this side; but on this side you take the blood pressure and it's very much so decreased. Let's think about the common carotid arteries, the right and the left common carotids. If there's narrowing of these arteries, you see decreased blood flow to the brain, right? This may result in vision and neuro problems. Blood isn't flowing to the head, and so you might see decreased cognition, the patient will feel dizzy because their brain isn't able to process. It doesn't have enough oxygen, so the patients might feel drowsy. Also, if there's not enough blood to the eyes, the patient may experience blurry vision, double vision, and difficulty with vision in general. With plugged up carotid arteries, if you put your stethoscope up to here, you might actually hear what's called a bruit. This is just the sound of rushing blood through this area. You might hear this. If you feel it with your hand, you might experience what's called a thrill. This isn't a thrill you get at an amusement park. This is a thrill of feeling blood rushing through underneath your fingers. These are some signs you can see in Takayasu arteritis. Lastly, to diagnose Takayasu arteritis, you may first notice that the patient has an increased ESR. This is a lab you get for acute inflammation. Basically, you're finding that the patient has an inflammatory issue. That's what it is in vasculitis, inflammation of blood vessels. After you see the clinical symptoms, you'll want to diagnose this. You can do that by taking a biopsy. If you go on the inside of the blood vessel to get this biopsy, it's a lot safer than trying to take an entire chunk of the wall from the outside. This is actually a more common practice now, taking from the inside of the blood vessel. This biopsy you can look at under the microscope and you can see what are known as granulomas. Granulomas are white blood cells attempting to wall off something they think is foreign. There's something in the blood vessels that the immune system is reacting to. It's actually not quite understood what that is. These granulomas are formed in order to wall this off and protect the body. Lastly, the treatment of Takayasu arteritis is going to be steroids. Steroids are used to prevent the immune system, white blood cells, for example, from migrating over to blood vessels. With no migration to blood vessels, these white blood cells carry on downstream and don't cause any issues. Steroids also inhibit the release of immune proteins, immune peptides, and immune molecules that actually hurt the blood vessels. Again, we're stopping this process as well, so thatwe can decrease the damage caused by the immune system.