Ultrastructure and biosynthetic activity of polyploid atrial myocytes in patients with mitral valve disease

Biopsies of right auricle of human heart have been obtained during open heart surgery from 6 patients aged 23 to 49. The DNA and total protein content have been determined in isolated myocytes by two-wavelength scanning cytophotometry after double staining: Feulgen and naphthol yellow S. In all the biopsies predominant are polyploid hypertrophied myocytes. Both hypertrophied non-degenerating cells and cells with different extent of degenerative changes, primarily of myofibrils and membranes, are present. The highest extent of cell ploidy is in patients belonging to functional class IV according to the classification of New York Heart Association (NYHA); in these cases 72 to 98% of cells have nuclei with 8 c and more DNA content. With an increase in ploidy level, cells grow in size and in protein content, however the rate of this growth is much lower than that of DNA content in cells. There is no direct relation between ploidy and cell degeneration extent and no inverse relation between degeneration extent and ejection fraction.