Click on image to view larger version.

Figure 1 The technique of sequential withdrawal mapping. Sequential withdrawal mapping in the cavotricuspid isthmus was performed at high gain (0.1 mV/cm) from the margin of the tricuspid valve to the inferior vena cava in the line of electrograms coinciding with the center of the surface electrocardiographic plateau in inferior leads during counterclockwise (CCW) atrial flutter (AF) (left panel) and coinciding with the initial downslope of the positive flutter wave during clockwise (CW) AF (right panel). ABL = bipolar electrogram from ablation catheter.