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.