PMC5412630_01
A: Electrocardiogram-gated cardiac computed tomography image with a volumetric, color-coded, first-pass contrast enhancement map of the left ventricle (LV). Note an area of hypoenhancement in the inferolateral wall of the LV (arrows) suggesting abnormal myocardial substrate. B: Epicardial voltage map demonstrates an extensive area of low-amplitude (<1 mV) and fractionated electrograms consistent with "scar" in the inferolateral LV. Sites with diastolic potentials recorded during initially induced ventricular tachycardia are shown as blue spheres. Teal and red spheres represent ablation lesions color-coded according to their duration. Phrenic nerve capture sites are marked with white spheres. C: An example of high-frequency multicomponent potentials (Maps 1-5) recorded in the area of epicardial "scar" in sinus rhythm.
gr1.jpg
PMC5412630_01_gr1.jpg
f0005
First-pass contrast-enhanced images suggested loss of myocardium predominantly within the inferolateral wall of the LV (Figure 1A). There was a large area of low-amplitude (<1 mV) fractionated electrograms (EGMs) in the inferolateral wall of the LV consistent with "scar" (Figure 1B). The "scar" area corresponded to the area of abnormal substrate on the CT images (Figures 1A and 1B). High-frequency (mostly multicomponent) potentials were noted predominantly at the border of the "scar" (Figure 1C). SR. Sites showing sharp high-frequency mid- or continuous diastolic potentials were tagged on the map (Figures 1B and 2B). High-output pacing was performed to mark the course of the phrenic nerve (PN) (Figure 1B).
A: Twelve-lead electrocardiogram of the initially induced ventricular tachycardia. B: Examples of high-frequency diastolic potentials (Maps 4 and 5) recorded in the area of the epicardial "scar."
gr2.jpg
PMC5412630_01_gr2.jpg
f0010
A monomorphic VT with RBBB/superior-axis QRS morphology and a cycle length (CL) of 305 milliseconds was easily (double extrastimuli) and reproducibly induced with programmed ventricular stimulation (Figure 2A). SR. Sites showing sharp high-frequency mid- or continuous diastolic potentials were tagged on the map (Figures 1B and 2B).
Twelve-lead electrocardiograms of ventricular tachycardias induced following initial ablation.
gr3.jpg
PMC5412630_01_gr3.jpg
f0015
Two other VT morphologies, which were suspected to be epicardial in origin, were then induced with a more aggressive pacing protocol (Figure 3).