[Idiopathic asymmetric heart hypertrophy in a newborn infant].

A sporadic case of idiopathic asymmetric heart hypertrophy in a newborn infant is reported. Despite drug therapy the baby died in progressive heart failure at 23 days of age. At necropsy there was cardiac hypertrophy with features similar to those of the usual asymmetric from observed in adults. On gross examination the myocardium of the ventricular septum and the free wall of the left ventricle showed a disorganized structure. Microscopically, the changes consisted of an abnormal arrangement of muscle cells and muscle bundles with areas of hypertrophied myofibers. In agreement with other authors myocardial disorganization ("disarray") is interpreted as a form of dysplasia, hypertrophy being a secondary phenomenon. The hypothesis that these abnormalities represent the persistence of the embryonic myocardial structure is discussed. The pathogenetic significance of focal myocardial dysplasias is apparently related to the amount of myocardium involved.