Open-window mapping for ablation of Wolff-Parkinson-White syndrome related hemodynamically unstable tachycardia.

During catheter ablation (CA) of tachycardia, conventional point-by-point mapping may be hindered due to hemodynamic instability. We performed open-window mapping (CARTO, Biosense Webster, USA) in a patient who developed hemodynamic instability during orthodromic atrioventricular reciprocating tachycardia (AVRT) and unwarranted induction of AVRT during attempts to map accessory pathway (AP) with ventricular pacing. With over 11,000 points acquired rapidly, the system accurately identified AP at the mitral valve (MV) annulus where the application of single radiofrequency (RF) lesion promptly eliminated AP's conduction. Our case illustrates the utility of open-window mapping for the ablation of AVRT.