Catheter-based three-dimensional electrogram acquisition and analysis system

Conventional time-domain electrogram (EGM) characteristics have a poor positive predictive value for successful accessory pathway (AP) ablation location. The authors hypothesized that a computer-generated three-dimensional electrogram (3D-EGM) of myocardial activation along the atrial aspect of the tricuspid or mitral annulus created from sequentially obtained, signal-averaged endocardial bipolar EGMs and time aligned to a known myocardial reference could improve AP localization and ablation. Serial signal-averaged EGMs, digitized at 4 KHz and filtered from 1 to 2,500 Hz, were sampled at known locations along the atrioventricular ring. Up to 15 EGMs were time aligned to a known myocardial activation reference and displayed as a 3D-EGM. Time-domain 3D-EGMs were then analyzed for morphologic characteristics corresponding to effective radiofrequency ablation location in 33 patients with leftsided APs, 5 with posteroseptal APs, and 5 with right free wall APs. A characteristic retrograde atrial 3D-EGM polarity reversal identified AP insertion sites in all free wall locations with a 97% sensitivity, 46% specificity, and 72% positive predictive value. Posteroseptal APs were characterized by left posterior paraseptal atrial 3D-EGM polarity reversal, but proximal coronary sinus activation preceded endocardial activation in all. Three-dimensional electrogram polarity reversal of the retrograde atrial activation vector has a high sensitivity and positive predictive value for effective ablation location patients with left and right free wall APs, but should be used with caution in patients with posteroseptal APs.