Changes in the pacemaker function of the sinus node after closure of atrial septal defect. Temporary and stable iatrogenic sick sinus syndrome.

The alterations in the clinical symptoms and the pacemaker function of the sinus node following open heart operation were studied in 26 patients suffering from atrial septal defect. The most characteristic electrophysiological change was the prolongation of the sinus node recovery time as consequence of surgical repair of the atrial septal defect. The clinical symptoms of the sick sinus syndrome could be detected in all 26 cases after the open heart surgery. In 16 patients the symptoms of iatrogenic sick sinus syndrome (SSS) were only transitory, while in 10 patients a stable iatrogenic SSS developed after the operation. In the basis of these data the pathological mechanism of the iatrogenic SSS is discussed.