Role of the notched unipolar electrogram in guiding catheter ablation of frequent premature ventricular contractions originating from the ventricular outflow tract

Figures

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  Figure 1.. The workflow used in the current study for premature ventricular contractions originating from the ventricular outflow tract (VOT-PVC). PM, pace mapping; N-uniEGM, notched unipolar electrogram.

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  Figure 2.. An example of a notched unipolar electrogram (UEGM) and a deduction of its mechanism. The notches in the unipolar electrogram represent local myocardial activation at the breakthrough of the premature ventricular contraction, depolarization of the ventricular outflow tract (VOT) and far field ventricular potential, respectively. BEGM1, distal bipolar electrogram; BEGM2, proximal bipolar electrogram.

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  Figure 3.. Representative recordings showing the use of a notched unipolar electrogram (N-uniEGM) in the ablation of premature ventricular contractions originating from the right ventricular outflow tract (RVOT-PVC). (A) 12-lead surface electrocardiograms of sinus rhythm (SR), PVC and pacing. In this patient, the surface electrocardiogram indicated that the PVC originated from the RVOT. (B) Activation mapping of the origin of the PVC in the RVOT using the CARTO® 3 System with simultaneous recordings of surface electrocardiogram, unipolar and bipolar electrograms. The earliest ventricular activation (EVA) site was proved to be located near the anterior septum of the RVOT by 3-dimensional electroanatomic mapping. Pacing mapping morphology at this site coincided perfectly with the spontaneous PVC. An N-uniEGM was also recorded at the EVA. Radiofrequency energy delivery for 2 s at this site terminated the clinical PVC. The colour version of this figure is available at: http://imr.sagepub.com.

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  Figure 4.. Representative recordings showing the use of a notched unipolar electrogram (N-uniEGM) in the ablation of premature ventricular contractions originating from the left ventricular outflow tract (LVOT-PVC). (a) 12-lead surface electrocardiogram of sinus rhythm (SR), PVC and pacing at the right ventricular outflow tract (RVOT) and LVOT. (b) Activation mapping of the PVC target from the RVOT and LVOT using the CARTO® 3 System with simultaneous surface electrocardiogram recordings, bipolar and unipolar electrograms at the same sites and uniEGM. In this patient, the initial activation mapping at the RVOT revealed that the earliest ventricular activation site (EVA) was in the septum of the RVOT, which preceded the onset of surface QRS complex for 107 ms. Pacing mapping at this site produced a QRS morphology with a low similarity with the morphology of spontaneous PVC. The uniEGM at this site presented a QS morphology with a blunt initial part and no characteristics of N-uniEGM. Ablation at this site did not show any impact on the PVC. Activation mapping at the LVOT revealed an earlier EVA site (–116 ms) in the right coronary sinus and pacing mapping at this site produced a QRS…