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.
A 60 year old woman with hypertension. Atrial fibrillation with pre-existing left bundle branch block Sometimes this can be confused with ventricular tachycardia but closer inspection can identify the irregularity. Irregularly irregular rhythm - suggesting AF. Features of typical left bundle branch block wide QRS >120 ms (3 small squares) no secondary R wave in lead V1 no lateral Q waves with permision from the site of Dr. Dean Jenkins
