Premature Ventricular Contractions From the Left Anterior Fascicle: Electrocardiographic and Electrophysiological Characteristics, Mapping Strategy, and Immediate and Long-Term Catheter Ablation Results

FIGURE 1. A flowchart of the study population. PVC, premature ventricular contractions; LAF, left anterior fascicle.

FIGURE 2. An example of a target ablation site for a PVC originating from the LAF (Patient 18). (A) Left panel, HV intervals during NSR and PVC with mapping electrode positioned at the His bundle were 49 and 11 ms, respectively. Right panel, the catheter was positioned at the target site with a recording interval of 30 ms during PVC between local fascicular potential (PP) and surface ECG, this is equal to the predicted value. (B) Fluoroscopy of LAF-PVC target. PVC, premature ventricular contractions; LAF, left anterior fascicle; NSR, normal sinus rhythm; ABL, ablation electrode; H-V, His bundle to the onset of surface ventricular activation; RAO, right anterior oblique; and LAO, left anterior oblique.

FIGURE 3. An example of a failed case that refused more procedures (Patient 5). Left panel, the axis deviation was 45° before ablation, and radiofrequency energy was delivered at the distal site. Right panel, the patient had recurrence after the index procedure, the QRS duration ratio of NSR/PVC after ablation increased from 0.68 to 0.93, and the axis deviation increased to 58°. The abbreviations are as in Figure 2.

FIGURE 4. An example of a failed patient with LAF-PVC who underwent a repeat ablation procedure (patient 22). (A) HV interval during NSR and PVC with mapping electrode positioned at the His bundle was 54 and 10 ms, respectively. (B) The target site was mapped with recordings of local fascicular potential-the onset of the QRS interval of 32 ms during PVC. Three-dimensional activation mapping of the left anterior area showed the target site, and a schematic diagram showed conduction within the Purkinje system. (C) During the repeat procedure, the HVNSR interval was the same as that during the first procedure, while the HVPVC interval was 20 ms; the QRS duration after ablation decreased from 96 to 80 ms, and the axis deviation increased to 21°. Note that NSR-QRS morphology had a slight change, and the QRS duration of PVC was slightly narrower than that before ablation. (D) The same site was identified, and the earliest retrograde PP with 36 ms was mapped and had successful ablation. Three-dimensional activation mapping of the left anterior area showed the target site and a schematic diagram showing the slow conduction within the LAF fiber. It is noted that the target PP was sharp during PVC,…

FIGURE 5. Another example of failed LAF-PVC case (patient 8). (A) The HV intervals during SNR and PVC with the mapping electrode positioned at the His bundle were 46 and 12, respectively; it is noted that the predicted value was 29 ms. (B) The catheter was positioned at the target site with recordings of local anterior PP-the onset of surface ECG interval of 29 ms during PVC. Three-dimensional activation mapping of the left anterior area shows the target site. (C) The HVNSR interval was the same as that of the first procedure, while the HVPVC interval was 28 ms; the QRS duration ratio of NSR/PVC increased from 0.75 to 0.95; and the QRS morphology of PVC was similar to the NSR-QRS morphology. (D) The earliest retrograde PP with 38 ms was mapped and had successful ablation. Three-dimensional activation mapping of the left anterior area showed the target site and a schematic diagram showing the slow conduction within the LAF fiber, which might explain the reason for the narrower QRS. It is noted that the target PP was fragmented during PVC. CS, coronary sinus; the other abbreviations are as in Figure 2.