Aberrancy and a Complete LBBB That Isn’t! Jerry W. Jones, MD FACEP FAEM This post is about aberrancy, retrograde P′ waves and disease of the conducting system. This ECG was recorded in 2011, so the patient is an 80 year old female who presented to the emergency room for an unknown complaint. There’s a lot to learn on this 12-lead ECG… First, the patient is in sinus rhythm and therein lies our first problem. We see obvious P waves in the inferior leads (II, III, aVF), but not much in Leads I, aVL or aVR. This tells us that the P wave axis is very vertical: the impulse is traveling almost straight down toward the recording electrode on the left foot – which happens to be the positive pole for Leads II, III and aVF. Leads I and aVL are left-sided and Lead aVR is right-sided. They are seeing little to none of the P wave vector, so that tells us that the vector is directed very vertically and downward. There is no suggestion of a P wave in Lead I, which tells us that the P wave vect...