Localization of ventricular arrhythmogenic foci

To define the optimal site for ablation, a clinical method used to locate the emergence site or initial endocardial activation site of ventricular tachycardia (VT), called “pace mapping” has been adopted. The waveform subtraction method is applied to electro-cardiographic complexes stored in computer memory during VT and during ventricular pacing with a catheter electrode. A “difference vector” between the paced activation site and the VT emergence or activation site is derived by this analysis which is used to guide the operator to the ablation site