Acute isolated myocarditis in newborn infants.

Under such names as isolated myocarditis (Sellentin, 1904), Fiedler's myocarditis (Fiedler, 1899), and myocarditis pemiciosa (Boikan, 1931), a rare myocardial disorder of unknown origin has been described which is characterized by progressive heart failure ending fatally after a course lasting weeks or months. In still rarer cases the duration of the illness is measured in days or hours. No age period is exempt from either form of the disease but the fulminating variety is perhaps commoner in young patients. Three cases occurring as early as the neonatal period have already been described. One was an infant aged 6 months (Singer, 1932), the others were newborn babies 9 and 5 days old respectively (Lind and Hultquist, 1949). To this small group the present report adds two other cases. Case 1, a boy, aged 4 weeks, was seen in October, 1950, and case 2, also a boy and aged 1 week, was seen a year later in October, 1951. Because these young patients succumbed so quickly to the disease an unusually early type of myocardial lesion was preserved for examination. Particular interest therefore attaches to the histological findings in the cases described below.