Runs of Ventricular Tachycardia

Report:

Sinus rhythm 85/min

VEBs, couplets

Runs of ventricular tachycardia 164/min

Left atrial abnormality (LAA)

Left bundle branch block

V2-V3 lead reversal

Comment:

The patient had many brief runs of VT, always introduced by the qR VEB couplets. The VT complexes are rather narrow, approximately 0.12”, with qR morphology and ST segment elevation in V1. They are faster than the initiating couplets. It remains unclear whether the couplets and the VT are from the same “focus” or circuit, with varying conduction, or from separate loci in the ventricles. The second complex in the two runs present looks like a fusion beat; if so, it represents fusion between two ventricular complexes.

The runs may pass for “fascicular” on the strength of their narrow QRS and marked left axis deviation in the limb leads. They are certainly dissociated from the large P waves marching through them. The last sinus beat has a longer PR interval, attesting to concealed retrograde conduction of the last beat of the VT. None of this (including start by obvious VEBs) completely rules out, say, junctional origin of the runs. What makes it most improbable, however, is their unlikely aberrancy – unlikely-looking RBBB and unlikely choice of the bundle branch aberration in the light of basic LBBB in sinus rhythm. The latter has somewhat atypical symmetrical complexes in V1 and V6.

The first qR couplet also produces concealed retrograde conduction, foreshortening the following sinus R-R cycle. This is better appreciated in the trace below (Fig 18a).

Fig 18a. The first sinus cycle after the couplet is foreshortened. 19. 69 year old man with chronic ischæmic heart disease, in pulmonary oedema.