PACE MAPPING USING BODY-SURFACE POTENTIAL MAPS TO GUIDE CATHETER ABLATION OF ACCESSORY PATHWAYS IN PATIENTS WITH WOLFF-PARKINSON-WHITE SYNDROME

Background. A pace mapping technique using body surface potential maps (BSPMs) was developed to guide the positioning of an ablation catheter at the ventricular insertion point of accessory pathways (AP) in patients with the Wolff-Parkinson-White syndrome (WPW). Methods and Results. The study was performed on 30 WPW patients. BSPMs were recorded with 63 leads distributed over the entire torso surface. The catheter used for radiofrequency ablation was first placed in the vicinity of the ventricular preexcitation site predicted by BSPMs recorded during the DELTA wave. BSPMs were then recorded during pacing with this catheter, the comparison between the preexcited and paced BSPMs indicated whether the pacing site was too anterior or posterior with respect to the preexcitation site, and the catheter was moved accordingly. This process was repeated until the preexcited and paced BSPMs were highly correlated (r greater-than-or-equal-to 0.8), and ablation then was attempted. It was possible to successfully ablate the AP in 28 patients after an investigation that lasted 54+/-44 minutes between the recording of the first paced BSPM and that of the BSPM paced at the successful ablation site. Patients with left free wall pathways needed less investigation time compared with patients with pathways of other locations (46+/-9 versus 100+/-25 minutes, p=0.031). The sensitivity of BSPM pace mapping was assessed using pacing with a multipolar catheter, and significant changes were observed on the BSPMs for beats with pacing sites that were only 5 mm apart. Conclusions. BSPM pace mapping allowed us to achieve a 93% success rate with short investigation durations, provides significant information that cannot be obtained with the standard 12-lead ECG, is a self-correcting procedure that reduces the importance of BSPM alterations due to individual differences in the shape of the torso or heart, and is applicable only to patients with AP showing antegrade conduction.