Abstract
Using 3-dimensional speckle-tracking echocardiography-derived activation imaging system, we visualized interventricular dyssynchrony in a repaired tetralogy of Fallot case with pacing-induced left ventricular dysfunction. The activation imaging system visualized interventricular dyssynchrony and resynchronization after cardiac resynchronization therapy and may be useful to assess electromechanical disturbance in complicated congenital heart diseases. (Level of Difficulty: Intermediate.).