kawasaki%20disease
KAWASAKI DISEASE
Kawasaki disease is an acute, febrile illness that is self-limited. It is a systemic vasculitic syndrome that primarily involves the medium- and small-sized muscular arteries of the body.
It is also known as mucocutaneous lymph node syndrome.
It affects primarily children <5 years old with peak incidence in 1-2 year of age.
The cause remains unknown but current research supports an infectious origin.
Epidemiological findings suggest that genetic predisposition and environmental factors play a role in the pathogenesis of the disease.

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
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
  • 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)
  • 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
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

  • 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
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