Figure 1 (A). Simultaneously recording electrograms using the standard bipolar electrodes and microelectrodes (MEs). The standard bipolar electrode detects near-field signals (arrows heads), whereas the MEs did not detect any near-field signals corresponding to these signals. Vertical solid and dotted arrows indicate the scale of ABL and ME, respectively. ABL, ablation catheter; ME, microelectrode; d, distal; p, proximal. (B). The orientation of the catheter to the tissue on the three-dimensional mapping system.