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 with a first degree heart block (pr > 120ms), there is a wide QRS (>120ms.) with a RBBB morphology and a left axis deviation consistent with a left fasicular block. The combination has been called a "trifasicular block" suggesting that the prolonged pr interval is due to slowing in the left posterior fascicle, but in fact this can be due to slowed conduction in the A/V node.
