Unpinning of a Vortex in a Chemical Excitable Medium

Rotating vortices are easily pinned to any defects in excitable media. Moderate advective fields cannot remove the pinned vortices. We have found and tested experimentally a mechanism for unpinning a vortex. To unpin a vortex, we created additional waves close to its core. A vortex can be unpinned when a new created wave is pinned to the same obstacle and has a topological defect. This mechanism works perfectly both in experiment and in numerical simulations. A hypothesis is put forward that similar mechanisms may underlay pacing for tachycardia control used in cardiac clinics.