The ECG shows a regular sinus tachycardia at 105 beats/min with an undetermined axis, normal conduction and repolarisation intervals, and normal R-wave progression in the precordial leads (Fig. 1). The notch in the rising portion of the S-wave and the subsequent subtle ST-segment elevation in lead V1 may be noted. The fundamental feature is a very short-coupled (coupling interval: 270 ms) ventricular premature beat (VPB) with a left bundle branch block (LBBB) morphology and superior axis, most probably arising from the right ventricular apex or lower free wall.
Fig. 1
Twelve-lead electrocardiogram upon presentation (25 mm/s, 10 mm/mV)
