Kawasaki Disease (KD), also known as “mucocutaneous lymph node syndrome”, is an autoimmune disease that manifests as a systemic necrotizing medium-sized vessel vasculitis. It affects many organ systems, mainly those including the blood vessels, skin, mucous membranes and lymph nodes; however, its most serious effect is on the heart where it can cause severe coronary artery aneurysms in untreated children.
Kawasaki Disease most often affects children less than 5 years old with the majority being less than 2 years. The disease occurs more often among boys.
The cause of Kawasaki Disease has not been identified. Due to the findings of high fever and enlarged lymph glands, Kawasaki Disease is thought to be an inflammatory process. The cause of this inflammatory response is not known.
In as many as 15-25% of children with Kawasaki Disease, the heart is affected, causing the following complications:
- Coronary artery aneurysms
- Leakage of valves (often mitral valve regurgitation)
- Accumulation of fluid around the heart (pericardial effusion)
Kawasaki Disease is considered a self-limited disease — after a period of time even without medical consultation, the symptoms often resolve and the patient recovers. Without medical consultation, however, potential serious complications may develop and may not be recognized.
There is not a specific test to diagnose Kawasaki Disease. A prolonged fever is often the first symptom that alerts the physician to consider Kawasaki Disease. Features that make the diagnosis include:
- Prolonged high fever (lasting longer than 5 days)
- A non-specific rash that often involves the groin area
- Painful joints
- Red eyes, or conjunctivitis without discharge
- Very red lips and tongue
- Enlarged neck lymph gland(s)
- “Puffy” hands and feet occasionally followed by peeling of their superficial skin
- Irritability in younger patients
- In some children, enlargement of the gall bladder can cause abdominal pain and vomiting
These symptoms are nonspecific and mimic other diseases such as Scarlet Fever.
If your child meets the criteria for the diagnosis of Kawasaki Disease, a cardiologist will be consulted. The cardiologist will obtain an electrocardiogram and an echocardiogram.
Outpatient echocardiograms are performed 6-8 weeks, 6 months, and 1 year after the onset of illness. In general, if coronary artery changes have not occurred by 6 months after the onset of the illness, the risk of developing the changes is very low.
If your child does have cardiac involvement, they will need regular cardiology visits. Depending on the size of the aneurysm, the coronary changes can resolve, remain unchanged, or progress. It has been reported that in 50 percent of the patients with small coronary aneurysms, the changes resolve during the first year after the illness. Patients with large aneurysms are at risk for developing coronary artery stenoses or narrowing as the aneurysms heal. Unfortunately, physicians cannot predict which course a patient will take.
Currently, high dose aspirin and an intravenous infusion of gamma globulin (body’s natural product formed to counter an infectious agent) are used as a treatment. The medical literature indicates that an infusion of gamma globulin (IVIG) can decrease, but not eliminate, the risk of developing coronary aneurysms. The infusion is most effective if given within the first 10 days of the illness. The risk of developing coronary changes decreases to less than five percent when treated in the first 10 days.
Your child should receive these medications even if the cardiologist’s test results are normal to prevent the complications of Kawasaki Disease by minimizing the degree of inflammation. Usually your child will be admitted to the hospital for at least 1-2 days. After discharge, they will continue to take aspirin until the signs of inflammation have resolved (usually 2 weeks or more).
Parents are often concerned about using aspirin in children due to the concern over the association of aspirin use and Reye syndrome. Reye syndrome is an inflammatory process that occurs in the brain and has been associated with patients using aspirin chronically and who also have chicken pox or influenza. Some physicians will recommend that if your child is taking aspirin chronically for any reason, he or she should have a flu shot to avoid influenza infection. If your child has been exposed to or has chicken pox, you should contact your physician immediately for further advice.
Due to the vessel wall irregularity, a coronary artery aneurysm can become a site of blood clot formation. If a large enough blood clot forms, it can cause obstruction to blood flow, and the heart tissue becomes deprived of needed oxygen. Depending upon the size and number of the coronary aneurysms, your child may need to be on medication to prevent blood clotting. If the aneurysms are small and few, the medication is aspirin taken once a day. If the aneurysms are large (termed “giant aneurysms”), a blood thinner such as Coumadin (warfarin) is used.
Children with giant coronary aneurysms will need periodic cardiac catheterization to assess the size of the vessels. Periodic stress/exercise tests are used to assess the heart’s ability to obtain adequate oxygen during exertion. Children with larger coronary artery aneurysms or abnormal stress/exercise tests may require restriction from certain physical activities.
If after one year from the diagnosis of Kawasaki Disease there is no heart involvement, the patient is often discharged from further cardiology evaluations. The majority of patients fall in this category, and have excellent prognosis.
Patients that have coronary aneurysms will require periodic cardiology evaluations. The frequency of these visits varies depending on the extent of coronary changes. Often these visits are scheduled once every six to twelve months. With appropriate medical care, these patients also have an excellent prognosis.