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)?.