Kawasaki Disease Diagnosis

Kawasaki%20disease Diagnosis

Diagnosis

In the absence of a specific diagnostic test or pathognomonic feature, clinical criteria have been established to assist physicians in diagnosing Kawasaki Disease
Taking a careful history is necessary in children who lack a clear explanation for fever
Clinical features may not be present simultaneously, watchful waiting is sometimes necessary before a diagnosis can be made
Three clinical phases occur in the natural history of Kawasaki disease
- Acute phase: 1st 2 weeks of illness; characterized by fever & other acute signs of illness
- Subacute phase: 3rd & 4th week of illness; characterized by desquamation, thrombocytosis, development of coronary aneurysms & is associated w/ highest risk of sudden death in patients in whom aneurysms have developed
- Convalescence phase: from 5th to 8th week since the onset of illness; all clinical signs of illness have disappeared & continues until erythrocyte sedimentation rate (ESR) & C-reactive protein (CRP) returns to normal level

Incomplete Kawasaki Disease

Patients w/ an inflammatory disorder who did not meet the clinical case definition but w/ persistent fever, at least 2 of the principal clinical features, & echocardiography revealing coronary artery abnormalities
More common in young infants <1 year of age
Accurate diagnosis & timely treatment is important due to substantial risk of developing coronary abnormalities
Lab findings similar to those of classic cases
These patients may also clinically display noncoronary cardiac lesions (eg pancarditis, conduction system abnormalities, subclinical ventricular dysfunction or subtle ventricular dilations) which are possibly independent of coronary artery abnormalities
Atypical Kawasaki disease refers to patients who have a problem (ie renal impairment) that generally is not seen in patients w/ Kawasaki disease

Refractory Kawasaki Disease

Approximately 10-20% of patients fail to respond to initial intravenous immunoglobulin (IVIG) treatment
- Failure may be described as patients in whom inflammatory parameters do not subside & fever persists or recurs 24-48 hours after intravenous immunoglobulin (IVIG) infusion

Patients who failed to respond to treatment have a higher risk of developing coronary artery abnormalities

Even though nonspecific, can provide diagnostic support in patients w/ clinical features that are suggestive of Kawasaki disease
Certain lab findings are characteristic of Kawasaki disease
Complete blood count (CBC)
- Neutrophil leukocytosis (predominance of immature & mature granulocytes)
- Mild to moderate normochromic anemia [hemoglobin levels <2 standard deviation (SD) for age]
- Platelet count rapidly increases w/in the next 2 weeks (ranges from 500,000 to >1 million/mm³)
  - A low platelet count at illness presentation is a risk factor for coronary aneurysm
  - Thrombocytopenia is seen rarely in the acute stage & may be a sign of disseminated intravascular coagulation

Inflammatory markers
- Elevated erythrocyte sedimentation rate (ESR) & C-reactive protein (CRP), usually returns to normal by 6-10 weeks after the onset of illness
  - Erythrocyte sedimentation rate (ESR) often above 40 mm/hour; C-reactive protein (CRP) typically reaches levels of 3 mg/dL
  - C-reactive protein (CRP) is more accurate after intravenous immunoglobulin (IVIG) therapy since intravenous immunoglobulin (IVIG) elevates the erythrocyte sedimentation rate (ESR)
- Elevated serum amyloid-A (SAA)

Mild to moderate elevations of serum transaminase may occur in ≤40% of patients
Mild hyperbilirubinemia in approximately 10%
- Hypoalbuminemia is common & associated w/ more severe & prolonged acute disease

Urinalysis: proteinuria, leukocytosis, Intermittent mild to moderate sterile pyuria
Cerebrospinal fluid analysis
- Approximately 50% demonstrate evidence of aseptic meningitis w/ predominance of mononuclear cells, as well as normal glucose & protein levels
Synovial fluid analysis
- Purulent fluid w/ white blood cell count of 125,000-300,000/mm³

Plasma lipids are markedly altered; depressed plasma cholesterol, high density lipoprotein & apolipoprotein
Cardiac enzymes
- Serum cardiac troponin I - marker specific for myocardial damage reported in acute Kawasaki Disease

Electrocardiogram (ECG) at rest

During acute phase, reveals findings suggestive of myocardial injury & abnormal repolarization: prolonged PR interval, deep Q waves, prolonged QT interval, low voltage, ST-T changes & arrhythmias

Holter Electrocardiogram (ECG)

Patients w/ stenosis or giant aneurysm should undergo holter electrocardiogram (ECG) recording at least once to determine whether ischemic findings are present or development of high-risk arrhythmias is possible
Used in patients complaining of frequent chest pain, chest discomfort &/or palpitations

W/ the exception of echocardiography, imaging studies are not performed routinely in suspected Kawasaki disease patients
Evaluation of cardiovascular sequelae requires serial cardiac ultrasound studies

Chest X-ray (X-ray)

Abnormalities are observed in about 15% of patients
Peribronchial cuffing or increased interstitial markings w/ occasional pulmonary nodules
Abnormal or enlarged heart shadow in patients w/ poor cardiac function due to chronic myocardial infarction (MI) & in patients w/ volume overload caused by mitral or aortic insufficiency
Presence of calcification of coronary aneurysm suggests the presence or progression of giant aneurysm or stenotic lesions

Echocardiography at rest

For uncomplicated cases, should be performed at the time of diagnosis, at 2 weeks & at 6-8 weeks after the onset of illness
More frequent echocardiographic evaluation is needed to guide management in children w/ higher risk
Ideal imaging modality for cardiac assessment
- Has a high sensitivity & specificity for the detection of abnormalities of the proximal left main coronary artery (LMCA) & right coronary artery (RCA)
- Frequent sites of coronary aneurysms are the proximal left anterior descending coronary artery, proximal right coronary artery & left main coronary artery (LMCA)

Can be used to evaluate coronary morphology over time to detect coronary dilatation specific to coronary artery lesions associated w/ Kawasaki disease
Can also determine the presence/absence of thrombi w/in aneurysms
Most useful method in evaluating cardiac function deterioration due to myocardial injury & the severity of valvular disease

Stress Echocardiography

Indicated to assess the existence & functional consequences of coronary artery abnormalities in children w/ Kawasaki disease & coronary aneurysm
Enables real time evaluation of left ventricular wall motion in patients during exercise (treadmill or ergometer) or w/ administration of Dobutamine or Dipyridamole

Other tests

Coronary artery aneurysms or ectasia develop in approximately 15 to 25% of untreated children & may lead to myocardial infarction (MI), ischemic heart disease or sudden death
Although damage of coronary vessels is the main complication of Kawasaki disease, systemic inflammation in other organs (eg myocardium, liver, lungs or kidneys) has been documented
Leading cause of acquired heart disease in children <5 years of age living in developed countries

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