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.
The rhythm is sinus but the pr interval is prolonged (greater than 200ms) and the QRS is wide (> 120ms). The loss of the septal Q waves and the tall broad R waves in leads I, aVL and V6 are diagnostic of a left bundle branch block.
