ECG Library
All ECG 36
There are no P waves evident. The irregularly irregular QRS duration is approximately 0.20 sec with a left bundle branch configuration. The third beat on the tracing is aberrantly conducted (long/short “Ashman” phenomenon). The next-to-last beat is a premature ventricular contraction (PVC).
At times, it can be difficult to distinguish “supraventricular tachycardia (SVT) with aberrancy” from ventricular tachycardia (VT). This QRS morphology does not meet the Brugada criteria for VT (see Ventricular Tachycardia ECG Review; link below).
One of the Brugada criteria to diagnose VT when the QRS pattern is similar to a left bundle branch block (LBBB) is a wide R wave in lead V1 or V2 measuring > 40 msec. This is not the case in the QRS complex on this ECG, except for the next-to-last beat in the lead V1 rhythm strip at the bottom of the tracing. This beat is a PVC and does have a wide R wave measuring about 80 msec and a left bundle pattern. This beat alone is ventricular in origin (not the rest of the QRS complexes which are simply a LBBB of supraventricular origin).
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