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What is vasculitis?

Vasculitis is a group of medical conditions which cause damage to the blood vessels through inflammation. Depending on which blood vessels are affected, vasculitis can be classified as large vessel, medium vessel, or small vessel vasculitis. Learn about the signs and symptoms of vasculitis such as purpura, bloody stool and urine, and bruits. Created by Ian Mannarino.

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Video transcript

- [Voiceover] So here we have our vascular man and he's got blood vessels that supply every part of the body. He's got blood vessels supplying the heart, blood vessels supplying the lungs, some supplying the kidney, the liver, the intestines, the skin, the nerves, really all over the place. So here's a blood vessel I'm drawing, of course your blood vessels will be carrying blood, but they also carry nutrients and oxygen and all sorts of proteins. Now what happens if these blood vessels get damaged, or inflamed? What if the inside of the wall of the blood vessel gets very inflamed? Well intuitively it makes sense, blood will not be able to pass as well through here and be delivered to the different organs. You know the intestines, the livers, the lung. All of the organs of the body need blood and need nutrients. This damage is precisely what happens in the disease known as Vasculitis. Vasculitis is damage of blood vessels and inflammation of blood vessels. Itis means inflammation and vascul means vasculature or blood vessels. Essentially this damage is caused by the immune system. White blood cells mistakenly release small molecules that can damage the blood vessels. Essentially the immune system makes a mistake and thinks that blood vessels are foreign. So Vasculitis is an autoimmune disease. Now I know what you're probably thinking, you might be thinking if I destroy all my blood vessels, how is that compatible with life? Well there are different types of vasculitides, the plural for vasculitis and these different types might affect different parts of the body. For example one type of vasculitis might affect the lungs and the kidneys only. Another type might affect the intestines, the kidney, the heart and the lungs and still another type might only affect the big blood vessels that come out of the heart. The different organs affected in patients lead to the different symptoms that you might see. For example loss of blood flow and nutrients to the heart tissue means heart cell death, this is known as a heart attack and this might cause symptoms such as chest pain. The severity of symptoms might also be different, so for example with abdominal pain a patient might have a range from a small amount of blood in their stool to full on bowel perforation. This all depends on how severely the blood vessels are damaged. Now along with these local symptoms patients might also experience general symptoms such as night sweats or fever, so there's a little thermometer right here, as the patient might have a fever or the patient might have chills or generalized muscle aches, or they may also experience lethargy or a feeling of being very tired. This all comes from what's causing this problem, remember white blood cells are releasing little immune molecules, these immune molecules can travel down to the rest of the body. These immune molecules are normally used to fight off pathogens and so a patient might feel like they have a general illness or a virus. Now let's take a step back. Why are only certain types of vessels affected in vasculitis? The different types of vessels that are affected usually depends on the size of those blood vessels and so vasculitis has been classified into three different categories. Large vessel vasculitis, Medium vessel vasculitis and Small vessel vasculitis. Here I'll draw a blood vessel to show a little bit about what's going on. Here let me draw this large blood vessel and I've got the blood vessel wall and the outside and the inside of the blood vessel, out and in, and of course on the inside you have the things I have mentioned before. Blood, oxygen, nutrients, that all travel through your blood vessels like water through pipes. Now the purpose of large blood vessels is to get blood distributed quickly through the body to where it needs to go. So if we have inflammation and damage of the blood vessel wall so it's bulging out from inflammation, swelling, scaring and then repeating that process, the blood trying to pass through can't do so effectively and so there's decreased blood flow and also after this constriction you'll see decreased blood pressure as well. And now a physician listening over the skin using a stethoscope may actually hear this blockage, it's the same thing that happens when you put pressure on a hose. If you put a kink in the hose, not only will water stop flowing through as quickly but also if you listen at the kink you can hear that blood trying to rush through and that's the same thing the physician hears. This is known as a bruit and if the physician feels the area they may also feel what's called thrill, this feeling of blood rushing through. Now for medium sized blood vessels . When scaring occurs for these vessels it can potentially block flow all together. This leads to blood cells kind of getting stuck behind the blockage and little proteins in the blood known as clotting proteins can form a clot and completely stop blood flow. Along with clot formation, you can also see the blood vessel wall bulge out. This is due to increased pressure, the blood has nowhere to go so it pushes up against the walls. And since medium sized blood vessel walls are thinner they are prone to this bulging. It's kind of like when you take a water balloon and squeeze it on one area, all the water bulges to one side of the wall. The bulging and weakening of the blood vessel walls are known as aneurysms. The most fear complication from aneurysms is rupture, leading to blood spilling out of the blood vessels. Last of all the final classification of blood vessels are small blood vessels. And by small I mean microscopic so we've got blood cells marching through nearly single file and a very thin blood vessel wall. You can imagine that damage to this wall can lead to breakage of the blood vessel really easily and depending on where the blood vessel is that's where you might see symptoms. For example if the small blood vessels are in the intestines you might see bloody stool. If the blood vessels are in the kidneys you might see bloody urine. If the blood vessels are just under the skin you might actually see a rash that kind of gives a dotted pattern where all these different small little blood vessels have ruptured. So in general the symptoms you see in vaculitis depends on where the blood vessels are that are affected, what size they are and how sever the damage is.