Figure 1. Schematic rationale of rotor detection using a hypothetical 12-pole mapping catheter. (A) A stable rotor would theoretically show fractionated quasi-continuous electrograms on the bipoles placed on the rotor core (6-7), as the mapping area of that bipoles would detect electrical activity during almost all the cycle length. Other bipoles may (or may not) show some degree of fractionation. Red arrow represents rotor spiral wavefront. (B) If the rotor core meanders around the neighboring tissue, the fractionation would move between different bipoles through time, resulting in non-continuous fractionation. Red arrow represents meandering of the rotor core.