Unipolar and bipolar electrogram characteristics of recurrent cases of idiopathic ventricular arrhythmias undergoing repeat catheter ablation

Figures

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  Fig. 1. Electrogram (EGM) characteristics at unsuccessful and successful sites. In site 1, the earliest activation (EA) of bipolar electrograms (ABLd and ABLp) was 23 msec before QRS onset and there was polarity reversal. Unipolar EGM contained a small r wave before QS and rapid negative deflection was noted after onset of QRS. Ablation was unsuccessful. Site 2, EA = 32 msec and a discrete potential was noted at bipolar EGM, but unipolar EGM contained a small r and rapid negative deflection was almost the same time of QRS onset. Ablation was unsuccessful. Site 3, successful ablation site, EA = 32 msec and a discrete potential and polarity reversal were noted at bipolar EGMs, and unipolar EGM showing initial slow QS complex and rapid negative deflection was slightly earlier than onset of QRS. (Dotted line indicates beginning of QRS complex, asterisk indicates beginning of unipolar EGM, red arrow indicates rapid negative deflection).

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  Fig. 2. Site (left panel) of unsuccessful ablation at right ventricular outflow tract (RVOT) shows the earliest activation (EA) 26 msec before QRS onset on bipolar electrogram (ABL-d and ABL-p) and in unipolar electrogram (ABL-Uni), tiny r wave (arrow head) and rapid negative deflection (activation slope 0.161 mV/ms) was noted after onset of QRS. Site of successful ablation at RVOT shows the EA 24 ms before QRS onset on bipolar electrogram, however, unipolar QS morphology (ABL-Uni) with initial slow negative deflection (red arrow) followed by rapid negative deflection (slope of initial deflection = 0.036 mV/ms, slope of rapid deflection = 0.158), which was prior to onset of QRS (indicated by a red arrow). A right panel is 1.5 times of zoom in figure of successful RVOT.

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  Fig. 3. Site (left panel) of unsuccessful ablation at right ventricular outflow tract (RVOT) shows the earliest activation (EA) 45 ms of a discrete potential before QRS onset on bipolar electrogram (ABL-d and ABL-p) and in unipolar electrogram (ABL-Uni), QS morphology (an asterisk) and rapid negative deflection was noted much later than onset of QRS (indicated by a red arrow). Site of successful ablation at RCC (right coronary cusp) shows the EA 30 ms before QRS onset on bipolar electrogram and initial slow negative deflection (an asterisk) followed by rapid negative deflection prior to onset of QRS (indicated by a red arrow) on unipolar electrogram. A middle is 1.5 times of zoom in figure of electrogram at successful RCC (right panel).