A histopathologic study of the conduction system in an elderly patient with partial atrial standstill

Electrophysiologic and histopathologic studies were performed on an 83-year-old man with partial atrial standstill. In the electrophysiologic study, no atrial electrical activity was recorded in the right atrium, but f waves were seen in the coronary sinus electrogram. Although the high right atrium and the atrial septum could not be activated by electrical stimuli of up to 10 V, the low atrium could be stimulated. The pathologic examination showed that there was extensive fatty infiltration into the sinus node and fibrosis in the atrial muscle. In the low right atrium, the musculature was partially preserved.