Kawasaki disease is an illness that makes the blood vessels in the body swell and become inflamed. The exact cause of Kawasaki disease is unknown. Because it causes a high fever and swelling of the lymph nodes, Kawasaki disease is thought to be related to an infection. It may occur in children who have a genetic predisposition to the disease. The disease is not contagious.

The symptoms of Kawasaki disease often go away on their own, and the child recovers. Without medical evaluation and treatment, however, serious complications may develop and not be initially recognized.

Kawasaki disease more commonly affects children younger than 5 years old, with the majority of children being less than 2 years old. But Kawasaki disease can affect older children as well. The disease occurs more often among boys. It is more commonly seen in the winter and spring months.

Diagnosis

There is no one specific test to diagnose Kawasaki disease. The doctor makes the diagnosis based on your child’s signs and symptoms. Lab tests may help with diagnosis. A prolonged fever (i.e., more than five days and generally higher than 101.3 F) is often the first symptom that alerts a doctor to consider Kawasaki disease. Other signs and symptoms that help make the diagnosis include:

• A nonspecific red rash that often involves the groin area and may peel
• Red eyes, or conjunctivitis without drainage
• Very red lips and tongue
• Enlarged lymph nodes on one side of the neck
• Swollen and red hands and feet occasionally followed by peeling of skin
• Painful joints
• Irritability in younger patients
• In some children, enlargement of the gall bladder can cause belly pain and vomiting

Other diseases and common viruses may have these same symptoms. To determine if a child has Kawasaki disease, the doctor may order blood tests to look for:

• Recent strep or viral infection
• Body’s immune response

Sometimes a urine sample is also collected.

These laboratory tests are helpful; however, the only way to make the diagnosis of Kawasaki disease is by meeting the clinical criteria for most of the signs and symptoms listed above.

If your child meets the criteria for the diagnosis of Kawasaki disease, the cardiology team is consulted. The cardiologist and / or nurse practitioner will perform a history and physical exam. Your child will have an electrocardiogram (to assess the electrical system of the heart) and an echocardiogram (ultrasound of the heart). Even if these studies are normal, your child will receive treatment based on clinical symptoms and lab work.

Effect of Kawasaki Disease on the Heart

Kawasaki disease can affect the heart by causing the following complications:

• Coronary artery aneurysms (or ballooning of the arteries)
• Leakage of valves (often mitral valve regurgitation)
• Build-up of fluid around the heart (pericardial effusion)

Kawasaki disease is the leading cause of acquired heart disease in children. In as many as 25% of children with Kawasaki disease, the heart becomes affected without proper treatment. Aneurysms of the coronary arteries, the blood vessels that supply oxygen to the heart itself, are the most important complication of Kawasaki disease. With appropriate and timely treatment, the risk of coronary artery involvement decreases to around 5%.

In general, if coronary artery changes have not occurred by six to eight weeks after the onset of the illness, the risk of developing these changes is very low.

If a coronary aneurysm develops, the presence of long-term coronary artery changes depends on the size of the aneurysm – the coronary artery changes can resolve, remain unchanged, or progress. Patients with large aneurysms are at risk for developing coronary artery clots or stenosis (narrowing) as the aneurysms heal.

It has been reported that in half of the patients with small coronary aneurysms, the changes resolve during the first year following the illness. Unfortunately, doctors cannot predict which course a patient will take.

Regardless of coronary artery involvement, your child will need to see a pediatric cardiologist through childhood and often into adulthood. Cincinnati Children’s Heart Institute has a Coronary Artery Clinic that specializes in this patient population.

What if coronary artery changes occur?

Due to the vessel wall irregularity, a coronary artery aneurysm can become a site of blood clot. If a large enough blood clot forms, it can block the blood flow, and the heart tissue becomes deprived of needed oxygen, and in rare cases, could lead to a heart attack.

Depending upon the size and number of the coronary aneurysms, your child may need to be on medicine to prevent blood clotting. If the aneurysms are small and few, the medicine will usually be only 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 check the size of the vessels. Periodic stress / exercise tests are used to check the heart’s ability to get enough oxygen during exertion.

Children with larger coronary artery aneurysms or abnormal stress / exercise tests may have restrictions from certain physical activities.

Treatment for Kawasaki Disease

Children are usually admitted to the hospital for two to five days.

Treatment includes intravenous gamma globulin (IVIG), which is an infusion through your child’s IV and high-dose aspirin every six hours.

• These medicines help reduce the swelling and inflammation in the blood vessels. 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, decreasing the risk of developing coronary changes from 25% to less than 5%.

After discharge, your child will continue to take high-dose aspirin until the signs of inflammation and fever have resolved.

• Children continue taking a low-dose aspirin every day for usually six to eight weeks or more.
• Your child will continue to be followed by a cardiologist after Kawasaki disease resolves.

Parents are often concerned about using aspirin in children due to the link of aspirin use and Reye syndrome. Reye syndrome is an inflammatory process that occurs in the brain and has been connected with patients who have long-term aspirin use and have chicken pox or influenza. Some doctors suggest that if your child is taking aspirin for a long period for any reason, they should have a flu shot to avoid influenza infection.

If your child is on aspirin and they have been exposed to or have chicken pox, you should contact your doctor immediately for advice.

Cardiology Follow-Up

Your child will follow-up with cardiology after discharge. Your child will initially be seen at two weeks and six to eight weeks. The echocardiogram and electrocardiogram will be repeated during these visits to check your child’s coronary arteries. If by six to eight weeks there is no evidence of cardiac involvement, your child's cardiac risks are extremely low.

If there is no coronary artery involvement by six to eight weeks, your child will then see the cardiology team every year to every few years. Your cardiology team may also ask for more blood work such as cholesterol and triglyceride levels.

Long-Term Outlook

If after one year from the diagnosis of Kawasaki disease there is no heart involvement, your child’s cardiology visits are spaced out to annual visits or even every few years.

Patients that have coronary aneurysms 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 12 months. With the right medical care, these patients also generally have a good prognosis. Since Kawasaki disease affects the coronary arteries, it is prudent for families and patients to practice heart healthy habits that help to prevent adult coronary artery disease and heart attacks.