PMC5420045_01
Twelve-lead ECGs with paced QRS complexes and during a spontaneous sustained ventricular tachycardia (VT) episode with a cycle length of 560 ms. Note that the ventricular pacing morphology, albeit not fully identical, is closely related to the morphology of the VT. The slight difference in QRS morphologies is explained by the anatomic location of the scar (see Figure 3 for details).
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It also was clinically relevant according to a previous ECG of a spontaneous VT episode with a cycle length of 560 ms (Figure 1).
Fluoroscopic images in the left anterior oblique (LAO) and right anterior oblique (RAO) projections depicting the mapping/ablation catheter (M) placed in the right ventricle via transjugular access. The site of origin of the ventricular tachycardia is in close proximity to the tip of the shock lead (L). RV = diagnostic catheter in the right ventricle.
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A magnetic navigation enabled catheter was used in the left ventricle, but the ablation attempts were not successful (Figure 2).
Top: Oblique cross-sectional macroscopic pathology specimen of the explanted heart at the apical level of the right ventricle (white dotted circle) demonstrating scar tissue (black dotted circle) around the tip of the explanted implantable cardioverter-defibrillator lead and the 3-week-old necrotic, hemorrhagic lesions of 2 radiofrequency applications (arrows). One lesion was created from the left ventricle and the other from the right ventricle. The location of the scar explains why a fully identical pace-map could not be achieved, because this region was unreachable by any of the catheters. Note that the extensive scar of the old myocardial infarction is separated from this scar. Bottom: Another aspect of the explanted heart showing the distinct scar caused by the tip and the extensive infarction scar tissue. Orientation: A = anterior; L = lateral; P = posterior; S = septal.
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This provided us the unique opportunity to investigate the explanted heart with the electrode tip in situ and to directly visualize the tip-related scar (Figure 3), which corresponded to the site of origin previously identified by pace-mapping. Moreover, this scar was well separated from the infarct-related scar, which was unrelated to the ultimate tachycardia (Figure 3).