Double nuclei in endomyocardial biopsy: a comparative study of the incidence in myocarditis and chronic right ventricular overloading.

The incidence of double nuclei in myocarditis and in cases with right ventricular overloading (CRVO) was histopathologically assessed in a minimum of 100 longitudinally cut myocytes in specimens obtained at right ventricular endomyocardial biopsy. In myocarditis, the incidence of double nuclei was shown to be 5.8 +/- 1.8 and in CRVO and in normal heart tissue it was seen in 3.0 +/- 0.8 and 3.2 +/- 0.9% (m +/- S.D.), respectively, of the population of myocytes. It is concluded that double nuclei result from either the activity or the reparative process of myocarditis and that it is not the expression of chronic right ventricular overloading. It is suggested that quantitative assessment of the frequency of double nuclei is an useful method in the interpretation of myocardial biopsy.