Figure 2
A) Holter traces. Top panel shows sinus rhythm (vertical arrows) with interpolated wide-QRS complex extrasystoles (annotated + ). The coupling interval of the extrasystolic beats is consistent. Bottom panel shows the irregular narrow complex tachycardia with sinus p waves annotated by vertical arrows.
B) 12-lead rhythm strip during tachycardia. Sinus P waves are observed with a regular rate approximately 65 bpm (red arrows). The extrasystolic beats have several different morphologies: Right bundle branch block (RBBB) with left anterior fascicular block (LAFB) (✦), normal QRS (#), RBBB (+) and LAFB (✧).