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Kawasaki Disease Replaces Rheumatic Fever as Leading Cause of Acquired Heart Disease in Children

Isaacs, Lawrence MD

doi: 10.1097/01.EEM.0000340950.69012.8d
Id Rounds

Kawasaki disease, which was first described in 1967 by Tomisaku Kawasaki, MD, has become the leading cause of acquired heart disease in children, replacing rheumatic fever. Diagnosis of the classic syndrome requires the patient to manifest a fever and at least four of five clinical criteria. There are also criteria for incomplete or atypical Kawasaki disease, where the patient does not have four of the five criteria, but still has the same (or greater) chance of complications. Due to its potentially serious complications, this disease should be on your differential for a child with a long-lasting fever.

Although it has been more than 30 years since Kawasaki disease was first recognized, the etiology of the syndrome is still elusive. Researchers have pointed to some 30 different infectious agents as the cause, although none has been proven. (J Infect Dis 2006;193[2]:283.) A recent study, however, suggests that superantigens (genes that code for toxins, in this case Streptococcus and Staphylococcus) seem to have a direct relationship in developing the disease.(J Pediatr 2009;155[2]:266.) The most current theories suggest an infectious host and possibly environmental factors in determining who contracts the disease. Some evidence suggests that the levels of tumor necrosis factor and interleukin (IL)-1 are elevated in the acute phase of the illness. (J Pediatr 2006;148[6]:800.)

Because there is no diagnostic assay for Kawasaki disease, the diagnosis is based on fever lasting at least five days and having at least four of these five major diagnostic criteria: conjunctival injection, cervical lymphadenopathy, oral mucosal changes, polymorphous rash, and swelling or redness of extremities. (Am Fam Physician 2006; 74[7]:1141.) These criteria may not manifest simultaneously, and because many clinical features of Kawasaki disease may be present in other diseases, these alternates often must be exclused.

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The fever in Kawasaki disease is usually above 102.2°F, and lasts an average of 11 days if untreated. The conjunctival injection is typically bilateral, with clear discharge and no photophobia or eye pain, and the swelling or erythema of the extremities is notable for a sharp demarcation at the ankles and wrists. The classic peeling of the digits does not usually occur until two to three weeks after symptom onset. Oral changes can manifest as red and cracked lips, strawberry tongue, or diffuse injection without exudates. The rash is usually on the trunk, and is usually erythematous and maculopapular, although it may be urticarial or erythema multiforme-like. The cervical adenopathy is the least common clinical feature, but may be the most prominent sign, often leading to the diagnosis of lymphadenitis. The lymph nodes should be at least 1.5 cm in diameter to be Kawasaki disease. Other symptoms (especially early ones) include cough, vomiting, diarrhea, and irritability. (J Pediatr 2009;154[4]:592.)

Incomplete (atypical) Kawasaki disease refers to patients who fulfill the classic criteria, and it is more common in children under 1 year of age. Here, a fever for more than five days with at least two of the criteria should prompt a search (using laboratory and radiology studies) for evidence of the disease.

No diagnostic laboratory tests confirm the diagnosis, but the erythrocyte sedimentation rate and C-reactive protein are useful because they are usually elevated to a degree not found in nonspecific infections (ESR>40 mm/hr and CRP >3 mg/dl). (Am Fam Physician 2006;74[7]: 1141.) No other laboratory studies are useful. Approximately 15 percent of patients will have chest x-ray abnormalities, usually increased interstitial markings or peribronchial cuffing. (Pediatr Radiol 1989;20[1-2]:48.) Echocardiography is the key ancillary study.

The most feared complication of Kawasaki disease is coronary artery aneurysm, which develops in 15 percent to 25 percent of untreated cases (5% or less if treated). Any patient in whom Kawasaki disease is strongly suspected should have an echocardiogram. Aneurysms are generally not found in the first 10 days of the illness, but there are some early nonaneurysmal findings that can suggest Kawasaki disease in the first 10 days of fever. Other pathological effects of Kawasaki disease include aseptic meningitis, arthritis, uveitis, myositis, gallbladder hydrops, cranial nerve palsy, ischemic colitis, and pancreatitis. Arthritis is a common component of Kawasaki disease, with as many as 31 percent of patients in the pre-IVIG era manifesting joint inflammation. This arthritis usually responds to the treatment of the disease, and is felt to be a benign component of the syndrome. (J Pediatr 2006;148[6]:800.)

In the United States, the treatment of Kawasaki disease consists of a single dose of IVIG (2 g/kg) and high-dose aspirin (80 to 100 mg/kg/d divided QID). The aspirin therapy is continued until the child has been afebrile for two to three days. Low-dose aspirin therapy (3-5 mg/kg/d) should be continued for six to eight weeks if the echocardiogram is normal or indefinitely if aneurysms are found. Corticosteroids have been studied and no benefit (reduced incidence of aneurysms) has been shown. (N Engl J Med 2007;356[7]:663.) Another potential treatment option includes TNF-alpha blockers, which in one study showed no inferiority to a second dose of IVIG in patients resistant to the first dose of IVIG. (J Pediatr 2008;153[6]833.)

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Diagnostic Criteria for Classic Kawasaki Disease

  • ▪ Fever for more than five days and
  • ▪ At least four of these:
    • ▪ Conjunctival injection
    • ▪ Cervical lymphadenopathy
    • ▪ Oral mucosal changes
    • ▪ Polymorphic rash
    • ▪ Erythema and/or swelling of extremities
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In Brief

Many EPs Burned Out

A third of EPs suffer from burnout, but most are still satisfied with their careers, according to a study published online February 6 in Annals of Emergency Medicine.

Researchers led by Gloria Kuhn, DO, PhD, of Wayne State University, surveyed a random sample of American College of Emergency Physicians members. Nearly 75 percent of respondents were male with an average age of 41 and an average of 12 years practicing emergency medicine.

They found 32.1 percent showed at least one component of burnout, most commonly emotional exhaustion. High anxiety, chiefly attributed to a strong emotional involvement with patients and a deep sorrow when the patient fares poorly, was the single greatest predictor of career burnout. The scores for low personal accomplishment and depersonalization were far lower.

© 2009 Lippincott Williams & Wilkins, Inc.