March of Rosenbaum’s Extrasystoles

Report:

Sinus rhythm

VEBs

Runs of non-sustained monomorphic ventricular tachycardia 138/min

Borderline left atrial abnormality

Nonspecific ST/T changes

Comment:

By definition, non-sustained VT lasts less than ½ minute. It is a different species from sustained VT, although, at times, the two occur in the same patient from the same “focus”. The distinction from sustained VT, although based on arbitrary criteria, has clinical significance in that EPS are less reliable guide to therapy18,30.

The VEBs have fully compensatory pauses; so do the 3- and 4-beat runs of VT. The blocked P waves can in fact be made out at the expected P-P intervals.

Schamroth, somewhere, noted the psychological curiosity how people seldom question the diagnosis of single VEBs but often argue at length against the diagnosis of VT. If broad complex tachycardia has the same morphology as the previously observed (and undisputed) VEBs, it is of ventricular ectopic origin.

In this case, the single VEB of the same morphology as the VT does not need fully compensatory pause to highlight its ventricular ectopic provenance: it has a broad primary R wave and slow descent – opposite of a supraventricular, LBBB-aberrant possibility1. All the ectopic activity has a general LBBB appearance and a rightward frontal plane axis; it may be a right ventricular tachycardia, sometimes seen in “otherwise normal” hearts31. A single such beat, having Rosenbaum’s normal pattern is called, unsurprisingly, Rosenbaum extrasystole.

Below (Fig 26a) is another subject’s (healthy 36 year old man with palpitations) ECG, showing VEBs practically identical to those in the index trace. Rosenbaum must have seen a lot of those in Argentina.

26a. Single Rosenbaum extrasystoles in another patient. 27. 81 year old man with weakness and dizziness for three days, unaware of his heart rate. After failed adenosine and verapamil trial, amiodarone 150 IV restored sinus rhythm.