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Figure 3 Substrate mapping and radiofrequency (RF) ablation in Patient #11. A large anterior infarction is noted in the bipolar voltage maps (right anterior oblique view in A and left anterior oblique-cranial view in B). The exit site of the clinically significant ventricular tachycardia (VT) was identified at the septal border of the scar (shown by arrow in A). This and two other VTs (not depicted) were successfully eliminated by the linear ablation strategy shown. Repeat programmed stimulation from two right ventricular sites (using triple extrastimuli and rapid pacing) failed to induce any arrhythmias, but stimulation from the left ventricle induced another hemodynamically unstable VT from the basal-lateral aspect of the scar (exit site shown by arrow in B). Adequate tissue contact could not be achieved using a retrograde aortic approach (as judged by fluoroscopic movement of the catheter within the cardiac silhouette, and by impedance monitoring). During an attempted transseptal puncture, the pericardial space was invaded and the procedure was terminated prematurely. This case was regarded a partial success.