Diagnosis and treatment of this rare disease is described by Dr Taqi Hashmi.
Kawasaki disease is a rare acute vasculitic syndrome first described in 1967 by the Japanese paediatrician Dr Kawasaki. It is the commonest cause of acquired heart disease in children in the developed world.
No known causative factor has been found, but it is thought to have an infective aetiology in a genetically-predisposed population because of its periodic and geographical spread.
A toxin superantigen mediated mechanism has been postulated, but is as yet unproven. Mortality from Kawasaki disease in the UK is 3.7 per cent.
There are no specific diagnostic tests for Kawasaki disease and diagnosis is primarily clinical. The natural history of the disease can be divided into three early stages and a subsequent chronic stage.
In the first acute stage (days one to 11) the presence of five out the six major CRESTS signs (see box below) will be noted. These symptoms may occur sequentially rather than simultaneously.
Other symptoms include aseptic meningitis (50 per cent), diarrhoea and vomiting (25 per cent), arthritis (25 per cent), urethritis (with sterile pyuria) and rarely hepatitis.
Investigations at this first stage show raised inflammatory markers (ESR, CRP) and a mild normochromic normocytic anaemia with a polymorph leucoytosis.
In the following subacute phase (days 11 to 21), cardiac pathology develops with coronary aneurysms, thrombosis, myocarditis and arrhythmias. Aneurysms can occur in up to 40-70 per cent of cases and remain permanent in 10 per cent of cases.
MI and sudden death can occur during this sub-acute stage. The probability is increased by acute symptoms lasting more than 16 days, non-resolving or recurrent fever, age less than one year and male gender.
A demonstration of coronary aneurysms plus four major signs is also diagnostic.
In the extremes of age the diagnostic threshold may be lowered to three major criteria.
Irritability, anorexia, conjunctivitis and desquamation of the skin from the digital tips also marks this stage.
In the recovery stage (day 21 to 60) all the clinical symptoms and signs resolve and ESR and CRP return to normal. Coronary aneurysms may also be discovered at this later stage.
Beyond 60 days may be considered as the fourth stage - dealing with the long-term consequences - in which there are increased chances of rupture or stenosis, and regular cardiac follow up will be needed.
Management and outcome
The earlier that treatment is instituted, the lower the mortality and morbidity.
Treatment during the acute phase is with aspirin and IV gamma-globulins (IVGG) 2g/kg as a single infusion over 12 hours. IVGG should be initiated within 10 days of the onset of symptoms.
Aspirin is continued initially for 14 days at a high dose (30-50mg/kg/day) in four daily divided doses and is then continued at a lower dose (3-5 mg/kg/day) as a single dose.
Aneurysms which are less than 4mm spontaneously regress, while larger ones remain. The possibility of rupture is not insignificant in adult life. Apart from aspirin and IVGG, other interventional therapies (cardiac catheterisation, CABG, transplant) may be indicated. The use of corticosteroids (pulsed methylprednisolone 600mg/m2 twice daily for three days or prednisolone 2mg/kg/day, weaning over six weeks) is not standardised and expert opinion should be sought before their usage.
- Dr Hashmi is a GP and part-time problem-based learning tutor at St George's Hospital, south London
CRESTS SIGNS OF KAWASAKI DISEASE
- Cervical lymphadenopathy. Unilateral. Greater than 15mm.
- Widespread polymorphic rash.
- Eye signs. Non-exudative bilateral conjunctivitis.
- Strawberry tongue (red and prominent papules). Other mucocutaneous signs include pharyngitis and fissured red lips.
- Raised temperature which does not respond to antibiotics or antipyretics and which persists for more than five days.
- Sausage-like fingers and toes due to oedema of the extremities.