VEBs: Couplets & Concealed Retrograde Conduction

Report:

Sinus rhythm

Left atrial abnormality (LAA)

PR interval 0.20”

Intraventricular conduction delay (QRS 0.12”)

VEBs in couplets

Triplet (or more, end of bottom strip) of ventricular tachycardia 102/min

Concealed retrograde conduction

Comment:

The sinus cycles starting with a prolonged PR interval due to concealed retrograde conduction of the VEBs have the subsequent R-R interval foreshortened as the next P wave arrives on time and with a normal PR interval. That’s why the sinus R-R intervals after the long pauses are longer: their PR intervals are identical.

The sharp terminal positive deflection of the VEBs looks like a retrograde P wave - but the presence of the real P waves nearby denies that possibility.

Another source of confusion may be that the VEBs have those small secondary R waves, just like the sinus beats, and the ascent of the primary R wave is rather slow95. They are true VEBs, all the same: not only is there AV dissociation and concealed retrograde conduction, but their initial vector is different. They are qRr’ complexes, not the RSR’ of the RBBB.