PMC5286492_01
Twelve-lead ECG of IVT.
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fig1
The frequent unifocal initiating IVT had a unique morphology characterized by a left bundle branch block (LBBB) pattern with very late precordial transition and a left superior axis (Figure 1).
(a) Pacing mapping showed that the morphology of pacing QRS complex is identical to the QRS complex of clinical IVT (inside the red box). (b) A complex fractionated, high frequency potential with long duration of 57 milliseconds, preceding the QRS onset of the IVT by 23 milliseconds. (c) A conduction block of Purkinje potential (red arrow) was observed during the sinus rhythm after successful ablation during the first procedure.
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fig2
A complex fractionated, high frequency potential with long duration of 57 milliseconds, preceding the QRS onset of the arrhythmogenic VT by 23 milliseconds, was mapped at the site of the earliest myocardial activation (Figure 2(b)). Pacing mapping showed that the morphology of pacing QRS complex is identical to the QRS complex of clinical VT (Figure 2(a)). RFCA was delivered at the free-wall insertion along the MB which can successfully terminate the VT, with a conduction block of Purkinje potential observed during the sinus rhythm (Figure 2(c)).
(a) Ablation catheter at the earliest activation site on the MB using fluoroscopy. (b) Electroanatomic mapping showed that the ablation zone (red points) was placed at the site of earliest activation at the middle RV of lower septum. (c) Ablation at the earliest activation site on the MB (red arrow) guiding by TTE; the ablation catheter (yellow arrow) was placed at the septum insertion of MB. RAO: right anterior oblique; LAO: left anterior oblique.
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fig3
This potential was systematically mapped from the middle RV at the lower septum, along the papillary muscle to the insertion at the RV apex and the extension to the interventricular septum (Figures 3(a) and 3(b)) via the MB. The anatomical site of the earliest activation and the location of distal catheter were at the MB as visualized by TTE (Figure 3(c)).