McGill Case 178

This case report is kindly provided by Michael Rosengarten from McGill and is part of the McGill Cases. These cases come from the McGill EKG World Encyclopedia. Previous Case: McGill Case 177 | Next Case: McGill Case 179

This is an EKG rhythm from a patient with a Medtronic model 8081 Premier single chamber pacemaker. The patient is a 65 year old man who had a history of blackouts while sitting. During the episodes his wife described him as becoming limp and white. His electrocardiogram showed a left bundle branch block with a normal pr interval. This conduction abnormality had been present for at least 16 years. An electrophsiology test was performed and a pacemaker inserted. What is the native rhythm? Is the pacer working well ( in particular what do you think of the spike on the second QRS)?