Morphological remarks regarding the structure of conduction system in the right ventricle.

BACKGROUND The knowledge of conduction system morphology has a vital significance in cardiology and cardiac surgery - it enables to interpret pathologies and choose treatment. This has been confirmed by numerous accounts, both in the context of e.g. atrial fibrillation ablations as well as treating septum defects. Due to diversity and changeability of conduction system structure and their clinical implications, its thorough analyses seem to bear special importance. AIM To examine the structure of selected elements of conduction system present in the right ventricle (RV). METHODS Elements of conduction system present in RV of 6 foetuses (from 12 to 32 weeks of foetus age), 6 children (from 1 day to 7-year-old) and 10 adults (from 37 to 79-year-old) were histologically examined. Cross sections of 10 moderator bands and 10 anterior papillary muscles of adult human hearts were made. Specimens including membranous and muscular parts of the septum along with diverging moderator band were taken from a group of foetus, child and adult hearts. Cuttings of 10 micron width were stained with Masson's method in Goldner's modification. On the basis of the sections of membranous and muscular parts of the septum, the continuities of the elements of the conduction system were analysed. RESULTS It was observed that in most cases the right branch of His' bundle locates itself deep in the muscular tissue of the septum irrespective of age; it is clearly separate along its whole run and gradually penetrates the muscular tissue with its fibers. Hardly ever does the right branch of His' bundle locate itself on the surface, subendocardially, with a minimum penetration into the muscular tissue. Moreover, in most cases, elements of conduction system are present in moderator band. The main tissue constituting its stroma is above all muscular tissue and to a lesser extent, connective tissue. In addition to this, fat tissue in variable proportion was also observed. In cross sections of the moderator band a distinctively circumscribed stripe of fibers of the conduction system was found. However, one could also observe samples in which its identification was not possible. CONCLUSIONS The right branch of His bundle within the muscular part of the septum in most cases is located intramuscularly irrespective of age. The results of analyses prove a relatively constant character of the presence of the conduction system within the moderator band.