With prompt treatment, most children make a full recovery from Kawasaki disease. However, complications can develop. These are mainly related to the heart. Complications occur because of the inflammatory (swelling) effect that Kawasaki disease has on blood vessels.
Aneurysm
Inflammation in the coronary arteries (the blood vessels that supply blood to the heart) can cause a section of the artery wall to weaken. As the blood passes through the weakened part of the artery wall, the blood pressure causes it to bulge outwards like a balloon. This is known as an aneurysm.
Some aneurysms heal by themselves over time. However, sometimes a blood clot (thrombosis) can form in a weakened section of the artery. This can cause a heart attack (when part of the heart muscle dies because it is starved of oxygen) or heart disease (when the heart's blood supply is blocked or interrupted).
In rare cases, the aneurysm may rupture (burst), which could cause severe internal bleeding.
It is also possible for other major arteries to be involved, such as the brachial artery (the main blood vessel in the upper arm) or the femoral artery (the main blood vessel in the upper thigh).
The risks
Approximately 15-25% of children with Kawasaki disease who do not receive treatment (because their condition is not diagnosed correctly, for example) may experience complications associated with their heart.
For children who receive intravenous immunoglobulin (IVIG) to treat their Kawasaki disease (see Treatment of Kawasaki disease), the risk of complications is reduced to 5%. These complications are serious and, in 1% of cases, may be fatal.
Treating complications
If your child develops a serious heart abnormality, they may require medication or, in some cases, surgery. Possible treatments include:
- Anticoagulant medicines and antiplatelet medicines: medicines that stop the blood from clotting, which may prevent your child from having a heart attack if their arteries are particularly inflamed.
- Coronary artery bypass graft: a surgical procedure that diverts blood around narrow or clogged arteries, improving the blood flow and oxygen supply to the heart.
- Coronary angioplasty: a surgical procedure to widen blocked or narrowed coronary arteries to improve the blood flow to the heart. In some cases, a stent (a short, hollow metal tube) is placed in the blocked artery to keep it open.
Some children with severe complications may experience permanent damage to their heart muscles or valves (the flaps that control the flow of blood). Their condition will be closely monitored and they will usually have regular follow-up appointments with a heart specialist (cardiologist).
Complications in later life
If your child has experienced any heart complications as a result of Kawasaki disease, they may be at higher risk of developing cardiovascular complications in later life. Cardiovascular means related to the heart and blood circulation and includes conditions such as heart attacks and heart disease.
As Kawasaki disease was only discovered in 1967, its long-term effects are still unclear. The long-term risk for children who do not experience any complications is also unknown.
Glossary
Disease
A disease is an illness or condition that interferes with normal body functions.
Heart
The heart is a muscular organ that pumps blood around the body.
Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Blood vessel
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.
Arteries
Arteries are blood vessels that carry blood from the heart to the rest of the body.
Aneurysms
An aneurysm is a blood-filled sac that forms in a weakened part of a blood vessel.