Kawasaki disease

Kawasaki disease isn’t at all related to the motorcycle and engine company, other than the fact that they were both founded or first described in Japan.

Kawasaki disease is a vasculitis or an inflammation of the blood vessels, that mostly affects the coronary arteries but can also affect any large- or medium-sized arteries as well.

With Kawasaki disease, the immune system attacks the arteries. Ultimately, it’s not quite known why this happens though, some theories suggest it has some infectious cause, though autoimmune reactions and genetic predisposition probably play a part as well.Whatever the case, when the endothelial cells in the blood vessels are attacked, they become damaged which exposes the underlying collagen and tissue factor found in the middle layer of the blood vessel, or the tunica media.And this leads to a few serious problems: First, these exposed materials increase the chance of blood coagulation.

When blood coagulates it forms clots that can block blood flow in the coronary arteries, leading to ischemia of the heart muscle.

Secondly, damaged endothelial cells in coronary arteries mean weak artery walls, which can lead to coronary aneurysms. These aneurysms form because fibrin is deposited into the blood vessel wall as part of the healing process.

Fibrin makes the vessel stiffer, less elastic, and unable to gently stretch with high arterial pressures; instead, the arteries develop permanent bulges that we call aneurysms.

Aneurysms 8mm or larger are at the most risk of rupturing, which reduces blood flow to the heart, causing ischemia and potentially myocardial infarction, or heart attack.

And third, in some cases, the fibrosis doesn’t lead to aneurysms, but instead, the fibrosis of the blood vessel walls make the vessel walls thicker, which reduces the lumen diameter and restricts blood flow.

If blood flow’s restricted or reduced, the heart again might become ischemic, leading to a heart attack.Kawasaki disease is most commonly seen in infants and children under five years old and is more likely to affect boys.

This disease is self-limited which means that the inflammation will resolve after 6 to 8 weeks but if we left it untreated, there is a 20-25% risk of the heart complications we went over.

Alright, so let’s look at the symptoms of Kawasaki disease. We rarely see any cardiac symptoms in the first few weeks unless the patient has an underlying heart condition already, and so cardiac symptoms typically evolve later.Now the classic symptoms of Kawasaki disease are as follows: conjunctivitis with limbus sparing (which is red eyes with a margin right around the iris that is still white), a rash that might extend across other parts of the body, and starts polymorphous but later desquamates, or flakes off, adenopathy, or enlarged lymph nodes, especially the cervical lymph nodes.

A strawberry tongue which is when the top layer of cells on their tongue slough off giving the tongue a very red, “strawberry” like appearance, also their mouth and throat may look really red too and their lips might become dry and cracked.

Their hands and feet might get swollen and develop a rash as well. And finally, they might have 5 or more days of high fever that typically doesn’t resolve with antipyretics.

Just remember that the patients C-R-A-S-H and burn. Ok, there isn’t a specific test to diagnose Kawasaki disease, but there are a number of lab tests that can act as clues.

At the beginning of the disease, many patients are anemic and have an increased number of white blood cells with a “shift to the left,” which means that there are more immature white blood cells than normal.

After a few weeks, the patient’s platelet count generally rises as well.They’ll also have an increased C-reactive protein and erythrocyte sedimentation rate, as well as increased liver enzymes, which are all good clues to tell us that some sort of inflammation is happening.

After a few weeks the patient’s platelet count generally rises as well. Microscopic urinalysis will show mononuclear white blood cells in the urine without evidence of bacteria.

Whoa, that was a lot of tests, but one last test that we’d want to do is an echocardiogram to take a look at the coronary artery and the heart muscle to see if any of those complications we talked about earlier having to do with the heart are happening.Kawasaki disease is diagnosed based on a combination of patient symptoms and lab tests.

In order for Kawasaki disease to be diagnosed, they need four of the five CRASH symptoms we talked about earlier, as well as a fever that lasts for five or more days.

Sometimes patients don’t meet these strict criteria, though. Vasculitis in the coronary arteries is a definitive sign that the disease is Kawasaki disease, but you probably wouldn’t want to wait to find that out, right?

People who don’t perfectly meet all the diagnostic criteria for Kawasaki disease are sometimes classified as incomplete Kawasaki disease.

There are guidelines in place to help healthcare providers figure out if they should treat these atypical cases as Kawasaki disease or not, but just know that it’s possible to have cases that don’t meet all the clinical diagnostic requirements.

Now treating Kawasaki disease is also helpful diagnostically, because if the therapy works then it also reassures you that the right diagnosis was made.

The main treatment is to give IVIG which is an antibody taken from other individuals. It’s thought that this actually helps to calm down the immune system and reduce inflammation.

We also give ASA, otherwise known as acetylsalicylic acid or aspirin. Aspirin inhibits platelet cyclooxygenase, which prevents platelets from aggregating together.

Now, wait a second. There should be alarm bells going off right?

We’re not supposed to give aspirin to kids because they could develop Reye syndrome (which is encephalopathy and serious liver injury, bad news).

Kawasaki’s disease is also bad news though, so we actually take the risk and monitor the child very carefully. All right, as a quick recap… Kawasaki disease is a vasculitis mostly affecting children where the immune system attacks arteries, which damages endothelial cells of blood vessels.

The mnemonic “C-R-A-S-H and burn” summarizes its classic symptoms. The disease will resolve on its own, but left untreated it can lead to complications like blood clots, coronary aneurysms, and ischemia.

For this reason, it is treated with IVIG and aspirin.