Fascicular ventricular tachycardia arising from the left side His and its adjacent region: a subset of upper septal idiopathic left ventricular tachycardia

Figures

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  Figure 1. The scalar ECGs during SR and VT arising from the proximal aspect of HPS. Except the Case 9, each figure including 12-lead scalar ECG during sinus rhythm (left) and VT (right or middle/right). The VT morphology is similar to SR in eight patients (Case 1–8); LBBB type in one patient (Case 9, complete atrioventricular conduction block after ablation, no baseline ECG obtained); complete or incomplete RBBB type in seven patients (Case 10–16); both narrow and wide QRS type in two patients (Case 17–18). Sinus rhythm obtained after effective ablation in Case 10, 11, 12 due to incessant ventricular tachycardia. ECG, electrocardiogram; HPS, His-Purkinje system; LBBB, left bundle branch block; RBBB, right bundle branch block; SR, sinus rhythm;

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  Figure 2. Bidirectional activation sequence within right His and right bundle branch. The entire HPS left- and right-sided HPS seems to be activated antegradely by three-dimensional activation mapping during VT (left panel). But after removing LV mapping, a bi-directional activation sequence of His-Right bundle was revealed (right panel). The proximal right His bundle was retrogradely activated and RBB was antegradely activated from earliest PP site, as indicated by the arrows. HPS, His-Purkinje system; LAF, left anterior fascicles; LPF, left posterior fascicles; L-His, left-sided His bundle; LV, left ventricular; RBB, right bundle branch; R-His, right-sided His bundle; VT, ventricular tachycardia.

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  Figure 3. Recurrent VT after previous ablations at LPF (Case 7). (A) Three-dimensional mapping of left HPS during VT. (B) Mapping during SR revealed LPF block due to previous ablations as indicated by absence of fascicular potentials along the distal LPF (LPF1–2 and 3–4). (C) Mapping during VT exhibited antegrade activation sequence of left-sided HPS and right bundle brunch with the earliest PP site overlapped with the left-sided His. PPs were not recorded along the distal LPF (LPF1–2 and 3–4) due to previous ablations. No P1 was recorded along the remaining LPF. QRS morphology of recurrent VT was similar to that during SR. (D and E) Fluoroscopic image shown that the earliest PP site was overlapped with left-sided His, which was close proximity to the right His catheter. The MEC was placed along the left posterior septum. Abl, ablation catheter; CS, coronary sinus; HPS, His-Purkinje system; LAF, left anterior fascicles; L-His, left-sided His bundle; LPF, left posterior fascicle; MEC, multielectrodes catheter; RBB, right bundle branch; R-His d, right-sided distal His; R-His p, right-sided proximal His; RV, right ventricle; SR: sinus rhythm; VT, ventricular tachycardia.

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  Figure 4. Mapping along the LAF and LPF during narrow VT (Case 2). Three-dimensional map (left) and intracardiac recordings during this narrow VT revealed the antegrade activation sequence of LAF (middle) and LPF (right) with the earliest PP overlapped with left-sided His, and the earliest PP exhibited as multiple, low amplitude potentials. Of note, no P1 was recorded along both fascicles. CS, coronary sinus; LAF, left anterior fascicle; LPF, left posterior fascicle; R-His, right-sided His; PP, presystolic potential; VT, ventricular tachycardia.

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  Figure 5. The activation time of left- and right-sided HPS during narrow and wide ventricular tachycardia in a same patient (Case 17). The entire HPS was reconstructed and mapped during narrow (A) and wide (B) QRS VT (32-year-old male). The earliest PP was documented at the same site during the narrow QRS VT (−56 ms) and the wide QRS VT (−53 ms). Depolarization time of the left-sided HPS was similar between the narrow VT (33, −56 to −23 ms) and the wide VT (31, −53 to −22 ms), while it prolonged from 50 ms (−46 to +4 ms) during narrow VT to 71 ms (−41 minus +30 ms) during wide VT on the right side, and this resulted in significant depolarization discrepancy and the typical RBBB with longer QRS duration. The discrepancy is also indicated by the activation-time difference between LV breakout and RV breakout, which increased from 27 ms during narrow VT (−31 vs. 4 ms) to 60 ms (−30 vs. 30 ms) during wide VT. aVL, scalar lead in ECG; HPS, His-Purkinje system; LAF, left anterior fascicle; LPF, left posterior fascicle; LV, left ventricle; MAP, mapping catheter; PP, presystolic potential; RBB, right bundle branch; RBBB, right bundle branch block; RV, right ventricle; VT, ventricular tachycardia.