PMC5771928_01
(A) A 12-lead electrocardiogram during PVC1, PVC2, and pacing in the right ventricular outflow tract, RCC-LCC commissure, and RCC. (B) Three-dimensional electroanatomical mapping and the radiofrequency application points. PVC, premature ventricular contraction; RCC, right coronary cusp; LCC, left coronary cusp; Com, RCC-LCC commissure; RF, radiofrequency; RVOT, right ventricular outflow tract.
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The PVCs all had the same coupling interval of 440 msec and showed two different morphologies (PVC1, PVC2), with PVC1 having a deeper S wave in lead V2 (Fig. 1A). An ultrasound imaging system (CARTO SOUND ; Biosense Webster) was utilized for reconstruction of the geometry of the RVOT and aortic cusp, providing extra information about the structural relationship between them (Fig. 1B). First, we performed pace mapping at the mid-septum in the RVOT, which produced a QRS morphology similar to PVC1 with a stimulus-QRS latency of 81 msec (Fig. 1A); there was no other site where pace mapping produced a QRS complex identical to that of the clinical PVC. Pacing with an output of 10 V at 0.5 msec at the RCC-LCC commissure produced a QRS morphology quite similar to that of PVC2, with a stimulus-QRS latency of 63 msec (Fig. 1A). In contrast, pacing at the RCC with the same settings produced a QRS morphology identical to that of PVC2, with a stimulus-QRS latency of 41 msec (Fig. 1A).
(A) Intracardiac electrogram showing a local potential preceding QRS onset (blue asterisk) and a late potential during sinus rhythm (red asterisk) at the RCC. The interval between the second component of the local potential and the QRS onset was 41 msec during PVC2. (B) Diagram showing the origin and route of the preferential pathways that we postulated (red line). Abld, distal electrode of ablation catheter; Ablp, proximal electrode of ablation catheter; CS, coronary sinus electrode; HIS, His bundle electrode; LCC, left coronary cusp; LV, left ventricle; PVC, premature ventricular contraction; RCC, right coronary cusp; RVOT, right ventricular outflow tract; SR, sinus rhythm.
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Furthermore, we were able to record a local potential preceding the QRS onset during PVC2, as well as late potentials during sinus rhythm that consisted of two components in the RCC (Fig. 2A).