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
Classification
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
- 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
- Several factors may predict patient’s unresponsiveness to intravenous immunoglobulin (IVIG):
- Low levels of sodium & albumin
- Low platelet count
- Day of illness at initial treatment
- Neutrophil leukocytosis
- High C-reactive protein (CRP) level & transaminases
- Patient’s age
- Patients who failed to respond to treatment have a higher risk of developing coronary artery abnormalities
Laboratory Tests
- 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)
- Elevated erythrocyte sedimentation rate (ESR) & C-reactive protein (CRP), usually returns to normal by 6-10 weeks after the onset of illness
- 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
Imaging
- 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
- 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
- Doppler color echocardiography
- Magnetic resonance imaging (MRI) & magnetic resonance angiography (MRA)
- Dual-source computed tomography (DSCT)
- Coronary angiography
- Intravascular ultrasound
- Cardiac catheterization
Complications
- 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