McGill Case 196

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 195 | Next Case: McGill Case 197

This cardiogram shows sinus rhythm with a normal pr interval and a prolonged QRS interval (>120ms). There is a conduction abnormality best described as a right bundle branch block due to the rsR' wave in V1. Note the S wave in V6 which is due to the RBBB is smaller than the R wave in V6. The axis of the QRS is difficult to determine, but one usually looks at the first 60 ms. (1 1/2 small squares) to determine the axis with a RBBB. If the axis of the first 60 ms. of the QRS is more than 90 degrees and there is an rS in lead I and a Q in lead III then on would consider a left posterior fasicular block. This is not the case here.