[Age-related structural changes in the stimuli-conducting system of the human heart]

The cardionectors of 32 patients who had died at different ages without clinical or morphological indications of heart disease were examined. The autopsy was performed 8 to 24 h after death. Histochemical and histomorphometric tests were used to detect age-related changes in the conduction system (sino-auricular and AV nodes). The proportion of connective tissue increases in the cardionector and diminishes in the muscle tissue with increasing age, the changes being more pronounced in the sino-auricular than in the AV node. In the age group over 60, for instance, the proportion of connective tissue by volume is over 120% higher, in the sino -auricular node and 90% higher in the AV node than in the age group under 10. The correlation coefficient between age and proportion of connective tissue is also higher in the sino-auricular node (0.65) than in the AV node (0.53).