Connective tissue components of conducting and working myocardium of the sinoatrial region of the heart in patients of various ages with idiopathic long QT syndrome (quantitative evaluation)

: Ultrastructural analysis of cells, collagen and elastic fibres and connective tissue matrix was performed separately in sinoatrial node (SN) and the right atrium (RA) perinodal working myocardium in 12 patients of different age with idiopathic long Q-T syndrome. Despite the variability in SN and RA connective tissue component content in different patients these parameters were often significantly different for working and conducting myocardium. In senior group SN and RA elastic fibres content showed 1.9 and 1.8 (P < 0.05) fold increase, respectively, although RA collagen fibres content was 2.2 fold (P < 0.02) lower as compared to younger patients. In general, difference of SN from RA was noted in 3 parameters of the 4 assessed, with the content of cells, collagen fibres and connective tissue matrix in conducting myocardium exceeding those in working myocardium.