Figure 8. Simulation of a drifting rotor with peripheral wavebreaks (WB) in an atrial model.

A. Snapshots of the model membrane voltage are at times indicated by the green markers. A 20 electrode catheter (D-20) shown on snapshots indicates locations of 10 pseudo-bipoles shown below maps. Red squares: Pivoting sites of rotors (i.e., singularity point; SP) Numbers on bipoles 3–4 and 13–14 indicate cycle length in ms. Horizontal gray arrows indicate episodes with a single mother rotor (MR, 1 SP), additional 2 short living rotors after ~0.9 sec (3 SPs) and their disappearance after ~1.5 sec (1 SP). Red arrows denote return of cycle length to pre-shortening phase. B. Trajectory of the drifting rotor's tip (yellow trace and arrow) superimposed on a snapshot of voltage at time=0. Red square, starting point of the drift; green dots, the location of the tip at the completion of each of 9 initial rotations; blue square, location of bipoles 13–14; double-headed blue arrow, distance between 13–14 bipoles and a sample position of the rotor's tip. C, Systolic Interval (SI) at bipoles 13–14, as a function of distance between the rotor's tip and the bipoles' location. As the drifting rotor gets closer to the bipoles, SI abbreviates due to Doppler shift, particularly after the 3^rd rotation. After the 7th rotation, local conduction impairment at 13–14 increases SI with an eventual WB.