Ultrastructural features of the myocardium of children with dilated cardiomyopathy

We analyzed the electron-microscopic features of endomyocardial biopsy from pediatric patients with dilated cardiomyopathy (DCM). The specimens examin ed were taken from the right ventricle of ten patients aged from 2 to 15 ye ars (mean 9.7 years). Biopsy specimens from eight patients with congenital heart disease (tetralogy of Fallot), aged from 3 to 12 (mean 7.3 years), an d ten adult patients with DCM, aged from 32 to 60 (mean 45 years), were als o examined. Patients considered to have endocardial fibroelastosis, arrhyth mogenic right ventricular cardiomyopathy, specific cardiomyopathy, or coron ary heart disease were excluded from this study. Specimens from pediatric p atients with DCM showed various degrees of ultrastructural abnormalities of myocytes, including myofibrillar fragmentation, mitochondrial abnormalitie s, and intracellular edema. The ultrastructurally determined contractility failure index based on the severity of myocardial degeneration at the elect ronmicroscopic level was 4.9 +/- 1.1. This value was significantly higher t han that in patients with tetralogy of Fallot (0.9 +/- 0.6, P < 0.001) but was not significantly different from that in adult patients with DCM (6.1 /- 2.6). The index of pediatric patients with DCM who died within 3 years w as high (6.0 +/- 0.8). Basal lamina layering of a capillary (BLL) in the my ocardium was revealed in 1 of the 10 (10%) pediatric patients with DCM and in 6 of the 10 (60%) adult patients with DCM (P < 0.05), No BLL was noted i n the patients with tetralogy of Fallot. These findings may be related to t he pathogenesis of DCM in children and adults.