Role of retrograde conduction from the left bundle to right bundle in determining the morphology of premature ventricular contractions triggering ventricular fibrillation

Figures

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  Figure 1. The left ventricular (LV) septum exhibited a relatively preserved voltage area surrounded by infarcted basal and apical regions. The fluoroscopic image depicts the placement of the HD Grid catheter (Abbott, Abbott Park, IL) on the LV septum. LAO = left anterior oblique, RAO = right anterior oblique.

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  Figure 2. A: The triggering premature ventricular contraction (PVC) exhibited a right bundle block morphology with a distinct qR pattern in lead V1. An abnormal Purkinje potential preceded the PVC by 212 ms. The coupling interval from the preceding sinus beat to the PVC was 520 ms. The local left ventricular (LV) potential exhibited a delayed “local reentrant” ventricular excitation following the PVC (∗). Notably, no right bundle potentials were recorded by the catheter placed in the right ventricle during the PVC (dotted circle). B: A nontriggering PVC displayed an rS pattern in V1 with a preceding abnormal Purkinje potential on the LV septum. The coupling intervals from the Purkinje potential to the PVC and preceding sinus beat to the PVC were shorter (88 ms and 452 ms, respectively) but longer from the preceding local LV excitation to the Purkinje potential (260 ms) than the triggering PVC. No delayed ventricular excitation on the LV septum followed the nontriggering PVC, yet a right bundle branch potential was recorded during the PVC, indicating retrograde conduction from the left bundle. The narrower morphology of the nontriggering PVC is attributed to retrograde conduction from the…

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  Figure 3. A: A single episode of spontaneous nonsustained ventricular tachycardia (NSVT) was observed during the procedure, initiated by the triggering premature ventricular contraction (PVC). The triggering PVC lacked a right ventricular potential and involved Purkinje intervention within the ventricular excitation. B: The induced NSVT by programmed ventricular stimulation (600/340/340 ms) mimicked the characteristics of the earlier observed spontaneous NSVT, with the involvement of Purkinje fibers. Interestingly, the initial beat of the induced NSVT displayed a morphology resembling that of the triggering PVC, corresponding to the refractory period of the retrograde conduction from the left bundle. A = atrium; CS = coronary sinus; HIS = His bundle electrogram; LVS = left ventricular septum; P = Purkinje potential; RB = right bundle; RV = right ventricle.

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  Supplemental Figure 2. VF was observed before ablation, but the exact moment when PVC was induced was not recorded. VF: ventricular fibrillation