About this video
Kawasaki disease is a medium-vessel vasculitis, meaning inflammation of blood vessels, that mainly affects young children. Its cause is still unknown, but it shows a characteristic pattern of fever, rash, red eyes, red mouth and changes to the palms and soles, and it can damage the heart if not diagnosed early. The video explains the name history, the diagnostic clues and the serious heart complications to watch for.
You'll be able to
- describe Kawasaki disease as a medium-vessel vasculitis and explain what that means.
- list the clinical features and the age and fever criteria that should prompt suspicion of Kawasaki disease.
- explain how damage to blood vessels can lead to heart complications, and why early diagnosis matters.
Key words
- Vasculitis
- Inflammation of blood vessels, which can damage the vessel walls and the tissue they supply.
- Mucocutaneous lymph node syndrome
- An alternative name for Kawasaki disease that describes its mucous membrane, skin and lymph node features.
- Conjunctivitis
- Red eyes caused by inflammation of the conjunctiva, one of the clinical signs of Kawasaki disease.
- Myocardial infarction
- Death of heart muscle cells caused by lack of blood supply, also known as a heart attack.
- Pericardial effusion
- A collection of fluid, here blood, around the heart, usually caused by a ruptured blood vessel.
Transcript
- [Voiceover] Kawasaki disease is a type of vasculitis that affects medium blood vessels. It was first discovered in Asia by a doctor named Tomisaku Kawasaki. And since then, it's been noted to affect mostly children of an Asian descent. As I mentioned, it was first discovered by a doctor by the name of Tomisaku Kawasaki in January of 1961.
With the first diagnosis, he actually had no clue what was going on. But he did note that patients typically had a fever along with a body rash and rash elsewhere. The rash seemed to affect the mouth, the eyes, and on the palms and the soles. He also discovered that some rash was a body rash.
When Dr. Kawasaki first saw this disease, he didn't know what it was. So, he diagnosed fever of unknown origin. This is a blanket term given when a patient has a fever that is not found to have a diagnosis. However, after encountering a lot of patients with rash in their mouth, red eyes, maybe on their body and on their palms and soles, Dr. Kawasaki decided to publish about this disease.
And thus we have the name Kawasaki disease today. Now, Dr. Kawasaki stated that since the symptoms were so clear cut, he felt that they were pretty close to a discovery of the cause. But unfortunately today, we actually still don't understand what causes Kawasaki disease.
And the geographic and genetic influences are still really unknown. Now as the years have gone on, Kawasaki disease has also been given the name mucocutaneous lymph node syndrome. That's quite a very long description. But it actually really makes sense based off of the findings and symptoms.
The word mucocutaneous refers to mucous membranes. Mucous membranes are wet surfaces such as the mouth. And cutaneous refers to skin. So for example, skin on your hands or on your feet or on your body. Another mucous membrane affected is the eyes. Now, where does the word lymph node come from?
Well, commonly in this disease, you can see swelling of nodes in the neck. These are lymph nodes. Specifically, they're known as cervical lymph nodes. Cervical means neck. Now, as I mentioned earlier, this is a medium vessel vasculitis. A vasculitis is an inflammation of blood vessels.
And it's believed to be caused by the immune system. Though why the immune system decides to damage the blood vessels in this disease is really not known. The diagnosis is essentially based off of the clinical symptoms that you see. You can see red eyes, which is known as conjunctivitis.
A more prominent redness of the mouth, this is oral erythema. You may see redness of the palms and redness of the soles and you may also see a red body rash. So the common theme in this is rash, red rash. So now if we see some sort of rash or redness and we also see a fever more than 5 days and a child is less than 5 years old, you should be thinking about Kawasaki disease.
Now, this is actually a disease that's very important to diagnose early. The reason for that is you can see symptoms affecting the heart if this disease continues for a longer period of time. Remember, Kawasaki disease is a vessel disease. Inflammation of blood vessels.
So if you see damage to some of these blood vessels, you can get clots in the blood vessels of the heart, which causes the heart to not be able to contract. So maybe it can contract well up here. But down here, it's not contracting as effectively. Remember, heart cells need blood.
And if they are not getting their blood, they are going to die and they can't contract anymore. This cell death of heart cells is called myocardial infarction, myocardial infarction. This is also known as a heart attack. Along with myocardial infarction, you might have cell death of the valvular muscles.
These are known as the papillary muscles of the heart. If you cause damage to these, you're not able to pump blood effectively out of the heart because the valves are damaged and not functioning properly. Something more severe that might be seen is known as pericardial effusion.
Pericardial effusion is a collection of blood outside of the heart. This is caused by blood vessel rupture. Blood pours out of the heart because of a ruptured blood vessel and accumulates around the heart. This is a very serious issue and so it makes sense, if you see a kid with fever who is less than 5 years old and has all these red rashes, you should be very serious about considering Kawasaki disease.
Now, since we don't understand the cause behind Kawasaki disease, using a mnemonic may help you remember the symptoms. I like to remember a kid on a motor cycle, a Kawasaki motorcycle driving really fast. When he drives really fast, he gets his heart rate going really quickly.
And he drives a motorcycle using his feet and his hands. And so this may help you remember the rash on the hands and the feet as well as the heart symptoms. Remember, it's linked to Kawasaki disease.
Video © Khan Academy, used under CC BY-NC-SA. Watch on Khan Academy. Puzzicle is not affiliated with Khan Academy.