Fig. (2).

Perimitral macroreentry after direct left atriotomy. Activation proceeds in the clockwise direction around the mitral annulus and also through a reconnection in the atriotomy line. The circuit uses a narrow isthmus between the scar and the mitral annulus, where radiofrequency pulse (dark red dot) terminated the tachycardia. Orange dots represent pacing sites, light blue dots mark double potentials, grey dots electrically silent areas, and pink dots represent fragmented signals. Light red dots mark the mitral annulus. PPI post-pacing interval after entrainment, TCL tachycardia cycle length.