View source for McGill Case 37

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[[File:E000622.jpg|thumb|600px|left|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)?.]]