RBBB as Monophasic R wave in V1

Report:

Sinus rhythm 94/min

Left anterior hemiblock

QRS axis –40o

Right bundle branch block

Comment:

RBBB can be manifest as pure R wave in V1, especially in the presence of a hemiblock. One could not, without a baseline trace in sinus rhythm, diagnose SVT in this patient. It would look like VT.

Oddly enough, to disprove the above, the patient did develop SVT while still in ICU (below) but its QRS pattern was typical rsR’ of RBBB and there was clear-cut evidence of associated regular atrial activity. The hemiblock remained unchanged.

The tracings are a good illustration of lead V1 superiority over lead 2.

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