1. Normal sinus rhythm
2. Rate-dependent right bundle branch block (SVT with aberrancy)
This ECG is challenging to determine the etiology of the wide complex. There is a right bundle branch block pattern. Examining the Brugada criteria for ventricular tachycardia we see that there is no concordance (QRS up in V1 but has a downward component in V5). The RS interval is short and there is no AV dissociation. Moving to the morphology criteria when a right bundle pattern is present, there is no reversal of the RR' pattern in V1 (there is no RR' pattern at all), but there is a monophasic R wave in lead V1 which would favor ventricular tachycardia as the etiology for this set of criteria. The American College of Cardiology has different criteria when a right bundle branch block pattern is present and this morphology would NOT meet those criteria. So who do we believe? Remember, assume ventricular tachycardia until proven otherwise when treating a patient. Also, it is important to interpret the ECG in the context of the patient. If this was a healthy 20 year old, we would think SVT with aberrancy would be likely, however if systolic heart failure is present, then ventricular tachycardia is much more likely. This was from a healthy person and was a rate-dependent right bundle branch block.
