Normal Sinus Rhythm With Aberrantly-Conducted PACs
This is a normal 12-Lead ECG with two PACs that are aberrantly conducted in a right bundle branch block pattern. (Sixth and ninth beats). In the PACs, the QRS is slightly wider than the normal beats. The aberrantly-conducted beats have an rsR' pattern in V1, and a wide little S wave in aVL. No PACs are seen in Lead I to demonstrate the wide S wave. This represents a right bundle branch block pattern, which is a common form of aberrancy, and is rate-related. That is, the PAC occurs early in the cycle, catching the right bundle branch is a refractory state and unable to depolarize. Slower beats are easily acommodated by the right bundle branch.
