What Is Kawasaki Disease?

This disease, first described by Dr. Tomisaku Kawasaki in 1967, usually affects children between the ages of 6 months and 4 years, with most cases occurring between the ages of 18 and 24 months. Its causes are unknown.

Kawasaki Disease affects boys more commonly than girls (1.5 to 1) and affects Asians (especially Japanese) and children of Asian heritage more frequently than other races. It is the leading cause of acquired (rather than congenital) heart disease in the United States.

What Are the Effects of Kawasaki Disease?

The onset of Kawasaki Disease is marked by a sudden high fever that lasts for at least 5 days. This is accompanied by extreme irritability – more than would be expected from the fever alone.

Other symptoms associated with Kawasaki Disease are rashes and/or swelling that affect the extremities (feet and hands) as well as the groin area, mouth, and eyes. There may also be swelling of the glands and lymph nodes. The lips may become cracked and bleeding and the tongue becomes reddened. Also, the patient may have a stiff neck, swollen gall bladder, and abdominal pain as well as joint pain and peeling skin on the feet and hands.

The cardiac affects of this disease consist of the development of myocarditis (an inflammation of the heart muscle) and coronary aneurysms, or swellings, that develop on the coronary arteries. (The coronary arteries are the large vessels on the surface of the heart that arise from the root of the aorta and supply the heart muscle with oxygen-rich blood.) Coronary aneurysms are the most devastating result of Kawasaki’s disease occurring in 20% of untreated children and <5% of treated children. Most of the aneurysms form in the proximal coronary arteries (near their points of attachment to the aorta). They may cause a heart attack if they disrupt the supply of oxygen to the heart muscle.

If these aneurysms do not disappear after the patient has recovered from Kawasaki Disease, or if they result in weak areas in the arteries, they may cause problems later in life. For example, there may be thickening or obstruction of the coronary artery walls because of calcification or the early development of atherosclerosis (deposition of fatty materials).

How Is Kawasaki Disease Treated?

There is no test for Kawasaki Disease, which is diagnosed from the presence of the various symptoms, including the failure to respond to antibiotics and the persistence of high fever for more than 5 days.

Treatment of this disease proceeds in two stages:

Stage One – the Acute Phase. The patient is given aspirin or intravenous immunoglobulin. These medications can prevent the formation of aneurysms on the coronary arteries, especially if administered during the first 10 days of the illness. If small aneurysms form they may resolve over time.

Most children experience a full recovery after Kawasaki Disease has run its course. However, new research shows that Kawasaki patients may be prone to the development of coronary artery abnormalities in later life. Therefore it is recommended that these patients get an echo once every five years.

Stage Two – the treatment of coronary aneurysms. Those patients who develop coronary aneurysms will require regular monitoring by echocardiography and sometimes by coronary angiography and should continue taking aspirin. If the coronary aneurysm is large, other anticoagulation medications (e.g. clopidogrel, warfarin) are usually added.

If coronary stenosis develops, bypass surgery or catheter intervention, usually a rotation ablation, may become necessary. However, new coronary aneurysms may develop after balloon angioplasty if coronary arterial dissection occurred due to excessive dilatation (usually due to the use of a high-pressure balloon). Thus, if coronary dissection was confirmed by intravascular ultrasound imaging, coronary stent implantation may be indicated for prevention of new aneurysm formation.

In cases of serious coronary lesions, there is a risk of myocardial infarction (heart attack). Therefore, it is important to monitor these patients regularly for the development of adverse symptoms.

Kawasaki Disease and the Adult Patient

Most Kawasaki patients recover fully from the disease, with no complications later in life. However, approximately 20% will experience cardiac problems caused by the persistence and/or progressive change of weak areas or swellings in the coronary arteries. Also, the coronary artery walls tend to be somewhat thicker and less flexible than normal after the disease, either through calcification (hardening of artery walls) or the early development of atherosclerosis (deposition of fatty materials on the artery walls).

Normally, aneurysms resulting from Kawasaki Disease will decrease in size as the patient ages. Smaller lesions are more likely to heal completely than larger ones, and the younger a patient was at the time of outbreak, the more likely it is for the aneurysms to disappear.

Those aneurysms that persist in the older patient have a tendency to become narrow (stenotic) or blocked (occluded) over time. Larger aneurysms may contribute to the sluggish flow of blood through the artery, which may promote the formation of blood clots (thromboses). Any narrowing or blockage of the coronary arteries can lead to the disruption of the oxygen supply to the heart muscle, resulting in a heart attack.

Because of these risks, Kawasaki patients are now advised to have their condition monitored through life, with counseling by a physician and a check-up including an echocardiogram once every three to five years, in most cases. Pharmaceutical therapy may be necessary for patients with persistent aneurysms. The development of coronary abnormalities may be accelerated by smoking, hypertension (high blood pressure), and hyperlipidemia (high cholesterol and other fatty substances in the blood stream).

Exercise Concerns

Activity guidelines for the older Kawasaki patient depend upon the level of risk determined by the patient’s physician. For the majority of patients, no restrictions will apply.

For those patients with persistent coronary aneurysms, annual examination by a pediatric cardiologist, with an echocardiogram and electrocardiogram, is recommended. Stress testing with myocardial infusion will usually be applied every two years. If the stress test reveals deprivation of oxygen to the heart muscle (myocardial ischemia), then coronary angiography should be performed.

Patients with large or multiple coronary aneurysms and/or with obstruction of the coronary arteries should undergo annual stress tests, which will help determine safe levels of activity. Contact sports should be avoided – especially by those patients taking anti-coagulants because of the risk of bleeding. However, regular physical activity within safe levels should be pursued and a sedentary lifestyle should be avoided.

Anyone with congenital heart disease, repaired or non-repaired, should consult with their cardiologist about physical activity to review the risks.