Activation and Voltage Maps, Entrainment Mapping, and Fluoroscopy
(A,) Anteroposterior view of biventricular activation mapping during ventricular tachycardia (VT) with the 64-pole Orion catheter (Boston Scientific, Marlborough, Massachusetts) (electrode area, 0.4 mm2; interelectrode distance, 2.5 mm) showing eccentric activation from both sides of the interventricular septum. Magenta color indicates the onset of activation (Online Video 1). The whole biventricular activation time did not match the VT cycle length; thus, some concealed intraseptal reentrant activation during VT is missed. (B) Biventricular voltage map during VT using tailored thresholds of 0.1 and 0.4 mV for scar voltage and normal voltage, respectively. (Bottom) Twelve-lead electrocardiogram of the VT and during entrainment at the right ventricle (RV) and left ventricle (LV). (Right Upper) Post-pacing intervals and intracardiac electrograms from the ablation catheter at the earliest RV and LV sites during VT entrainment. (Right Lower) Left anterior oblique (LAO) and right oblique anterior (RAO) views of radiofrequency catheters positioned at both sides of the septum at the successful ablation site.