Nuclear size of myocardial cells in end-stage cardiomyopathies

OBJECTIVE: To determine the alteration of nuclear size in myocardial cells and the relationship between nuclear size and DNA ploidy classes in normal and cardiomyopathic human hearts. STUDY DESIGN: The study group consisted of 46 hearts obtained at biopsy. Th ese patients had undergone cardiac transplantation for intractable congesti ve heart failure (18 cases with ischemic cardiomyopathy and 28 cases with i diopathic dilated cardiomyopathy). Another 10 hearts were collected at auto psy and used as control hearts according to preautopsy, autopsy and histolo gy criteria. One hundred fibroblasts and 200 myocytes were evaluated in eac h ventricle. The nuclear area and DNA content were estimated using image cy tometry. RESULTS: End-stage ischemic and dilated cardiomyopathies were characterized by an increase in nuclear size of both the myocyte and nonmyocyte populati on. The nuclear area of interstitial cells increased about 30% in cardiomyo pathic hearts. Augmentation of average nuclear area of myocytes was 1.2-fol d in the ischemic group and about 1.5-fold in the dilated group as compared with the control group. Also, a tendency was found for the coefficient of variation of average nuclear area to decrease in the interstitial cell popu lation and increased in the myocyte population in cardiomyopathic situation s. Furthermore, the nuclear area of myocytes enlarged as augmentation of nu clear DNA content. The relative nuclear al eas of myocytes can be presented as: 2c:4c:8c:16c:32c:64c = 1:1.65:2.75:4.60:7.25:9.18. CONCLUSION: The increase in nuclear size follows either one of two differen t processes: the first does not involve an increase in DNA content, whereas the second is concomitant with an incremental increase in DNA content. In the first instance, the enlargement of nuclear size is limited. In the seco nd, augmentation of nuclear size can become very impressive. In end-stage i schemic and dilated cardiomyopathies, the nuclear growth of myocytes and in terstitial cells may be due to different mechanisms. Enlargement of the nuc lear area of myocytes represents a complex process, including simple nuclea r hypertrophy, polyploidization and multinucleation. The main pattern of nu clear growth of interstitial cells is nuclear hypertrophy without an increa se in DNA content.