Figure 94-14

Premature atrial beats showing increasing degrees of (incomplete and complete) LPFB aberration. The first beats in all panels are escape beats with the same morphology as that of the sinus beats. The second , aberrantly induced ventricular complexes show different degrees of right axis shift with an increase in size of the R waves in leads 11 and 111. Note that the fundamental characteristic of LPFB was not right deviation( beyond + 90 degrees), but an inferior axis shift.

(Reference:A.CASTELLANOS AND OTHERS: The Hemiblocks in MI.NY,Appleton-Century-Crofts.1976.