Atrioventricular Block

(Second of Two Parts*)Rules and Exceptions about Locus of A-V BlockFrom what is generally known about human pathophysiology, it might be anticipated that strict separation of nodal from infra-nodal block would not be as perfect as the previous discussion implies. In fact it is not. Some patients may have electrocardiographic findings of both A-V nodal and infra-nodal block. Typically, block of second or third degree is seen with fixed P-R intervals in the conducted beats (characteristic of Mobitz Type II infra-nodal block), but with a normal QRS (as found usually in Mobitz Type I A-V nodal block). . . .