Altered Z-disks of myofibrils in the cardiomyocytes from patients with Ebstein's anomaly

Abstract

The aim of the study was to examine the peculiarities of the changes in Z-bands of myofibrils in the cardiomyocytes from patients with Ebstein's anomaly. Electron microscopy assay of intraoperative biopsies of the right heart chambers in 41 patients aged from 9 months to 57 years was performed. Some patients exhibited Z-disk alterations of two types in individual cardiomyocytes, namely: local symmetrical bead-like expansions of Z-disks or longitudinal deposits of Z-material of different lengths along the myofibrils. Z-disk alterations were more common in atrial cardiomyocytes than in the ventricle. The presence of Z-disk alterations in the cardiomyocytes correlated with a number of clinical parameters. In particular, the occurrence of longitudinal deposits of Z-material in atrial cardiomyocytes directly correlated with the manifestation of the Wolff-Parkinson-White syndrome in the patients. Above characteristic ultrastructural changes in Z-bands of myofibrils in the cardiomyocytes from patients with Ebstein's anomaly have a certain similarity to Z-band diseases in skeletal muscle at sarcomeric protein gene mutations described in the literature, which suggests the mutations in the genes of proteins included in Z-bands of myofibrils in the cardiomyocytes from patients with Ebstein's anomaly.