[Ultrastructure of the sinoatrial area of the heart during the long Q-T syndrome].

The conducting myocardia of the sinus node and prenodal working ones of the right atrium, which had been dissected from 6 patients aged 10-40 years with the prolonged Q-T interval syndrome during an operation on implantation of an artificial pacemaker were examined. Acute and chronic destructive changes were found in the conducting and working myocytes of the sinoauricular region in the heart. Some cases displayed abnormal contact interrelationships of myocytes. Destructive changes were observed in non-myelinated and myelinated nerve fibers, microcirculatory bed, and the connective tissue component of the conducting and working myocardium. The abnormalities found in the cardiac sinoauricular region are discussed to be a possible substrate for the development of life-threatening arrhythmias in patients with the prolonged Q-T interval syndrome.