The characteristic features of second degree AV block Type II are a constant PR interval with occasional or repetitive non-conducted P waves. The QRS is usually wide reflecting the location of the block in the His-Purkinje system. Second degree AV block Type II is related to more extensive conduction system disease, usually degenerative but occasionally accompanying anterior myocardial infarction. The following animation illustrates what we have just described. Note in the animation the fixed block in the right bundle and left anterior fascicle with periodic block causing complete heart block in the left posterior fascicle.