Patient 7. ( A ) Intracardiac electrograms demonstrating the local potentials, LVP and LVP vpb . Shown are: standard electrocardiogram lead I, V 1 , and V 6 . A high amplified bipolar electrogram is recorded close to the site of origin of the VPB (ABL d), together with a unipolar electrogram (ABL uni) and a bipolar electrogram from the proximal pairs of the ablation catheter (ABL p). The LVP potentials (red arrows) are recorded 75 ms after the earliest start of the QRS complexes of S −1 (black line in V 1 ). The LVP ampl is 2.00 and 0.93 mV, and the LVP dur is 56 and 48 ms in S −1 and S −2 , respectively. ( B ) Magnification of the LVP vpb (red circle). The amplitude of the LVP vpb is 2.33 mV, the duration 65 ms, and it is preceded by a slow and low-amplitude potential not present in the LVP of S −1 and S −2 . The LVP vpb starts 42 ms prior to the earliest start of the QRS complex of the VPB (black lines in V6), and the ABL uni shows no LVP vpb , due to far-field sensing of the V potential and a QS pattern indicating optimal ablation site. For further discussion, see text.
