[Ultrastructural study of the myocardial cells of the human sinus node in sudden coronary death].

Light- and electron-microscopic studies were performed on hearts from 23 males (aged 34 to 69 years) who had died suddenly with coronary heart disease. The hearts from 6 males of the same age group who had succumbed to extracardiac causes (including injuries) served as controls. Chronic abnormalities and acute destructive changes in the sinus node were observed in 82.6% and 87% of the cases, respectively. Various types of destructive changes seen in specialized conducting myocytes of the sinus node are described. Lesions in the microcirculatory bed, neural elements, and the connective-tissue component of the nodal myocardium were detected. Contributions of the detected changes to cardiac arrhythmia and sudden coronary death are discussed.