Short Compensatory Pauses?

Report:

Sinus rhythm.

VEBs, some in pairs (couplets).

SVEBs, couplet, following the last VEB couplet.

Comment:

The single VEB in the middle of the strip appears to have the usual, fully compensatory pause, being contained in a space of two sinus cycles. Indeed, a sinus P wave can be traced immediately after the ectopic QRS in the pause.

Other VEBs behave differently. The first two pauses and the last one are longer than expected, implying retrograde conduction to the atria and depressing as well as resetting the SA node. The couplet with a seemingly short pause does not in reality have a “proper” pause at all: it is followed by two ectopic atrial impulses, with different P waves, with a faster rate than sinus. In this setting, a reentry beat from a VEB may look like a short pause; then the P wave morphology would be decisive.

As Schamroth emphasised, the compensatory pause is, diagnostically, a feeble reed to lean on.

149. Digoxin-toxic 84 year old man.

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