VEBs: Long Compensatory Pauses

Report:

Sinus rhythm 97/min

VEBs

Right bundle branch block

Probable old inferior infarction

Comment:

The pauses containing the VEBs are obviously longer than two sinus cycles. This admits only one explanation – the VEBs have been conducted retrogradely to the atria, not only resetting the SA node, but depressing it as well. The retrograde P waves remain invisible but are there by inference. The proof is in the length of the first subsequent sinus cycle: it is longer than its successor. The post-ectopic SA depression (overdrive suppression) has taken place here.

These VEBs are also a good example of the left rabbit ear sign denoting their ventricular ectopic origin.

The computer reported this patient’s axis as +154o and called his conduction “bifascicular block: RBBB & LPFB”. This is not so: the axis of the initial 0.06” in the frontal plane is normal. The late contribution of the RBBB must be discounted in calculating the frontal plane QRS axis.

If you have any suggestions for or feedback on this report, please let us know.