RecruitingProcedureTargeted Ablation to Isolate Scar Channels Causing Ventricular TachycardiaThe goal of this study is to map conducting channels within scar that cause ventricular tachycardia (VT) in patients with scar in their hearts in order to block these channels from causing VT with targeted radiofrequency ablation (cautery). Participants undergoing VT ablation mapping of these channels by pacing many sites within the scar area and determining where these channels exit the scar into normal tissue. These exits will be ablated. Immediate success and success at 1 year will be evaluated.