Acquired and Inflammatory Heart Disease
Kawasaki disease
Kawasaki disease is a medium-vessel vasculitis and the leading cause of acquired coronary artery disease in children in high-income countries. Diagnosis is clinical: fever for at least five days plus four of five features-bilateral nonexudative conjunctivitis, oral mucosal changes, polymorphous rash, cervical lymphadenopathy, and extremity changes. Incomplete Kawasaki disease is common in infants and requires echocardiography and laboratory support. Treat with IVIG 2 g/kg and aspirin; do not delay IVIG for echocardiography. Coronary artery dimensions determine risk and follow-up.
Myocarditis, rheumatic disease, pericardium
Myocarditis presents with troponin release, ventricular dysfunction, and arrhythmia; treatment is supportive, with avoidance of vigorous activity. Acute rheumatic fever follows group A streptococcal infection and uses Jones criteria; carditis may cause mitral regurgitation. Pericarditis causes positional chest pain and diffuse ST elevation; tamponade produces hypotension, distended neck veins, and pulsus paradoxus.
Traps
Kawasaki is not diagnosed by a positive echo alone. Thrombocytosis is a late finding; a normal early platelet count does not exclude disease. Aspirin is used for Kawasaki and rheumatic fever but should be avoided in children with viral illness because of Reye syndrome. In pericarditis, do not miss tamponade; electrical alternans is supportive but not required.
Worked example
A 3-year-old has six days of fever, red cracked lips, conjunctivitis, rash, and a swollen right neck node. This is Kawasaki disease. Obtain baseline echocardiography, but give IVIG and aspirin promptly; coronary findings guide later surveillance. Rule of thumb: treat clinically diagnosed Kawasaki disease within ten days of fever onset.