HUMAN VENTRICULAR-TACHYCARDIA - PRECISE INTRAOPERATIVE LOCALIZATION WITH POTENTIAL DISTRIBUTION MAPPING

Electrophysiologically guided operations for ventricular tachycardia ( VT) have been directed exclusively by activation time maps. Even with computer-assisted mapping, extensive editing is required, which prolon gs the duration of the operation and which may introduce significant e rror. In contrast, potential distribution maps can be constructed in l ess than 3 minutes and can be viewed as a movie of developing and rece ding potentials. In 4 patients undergoing operation for VT, endocardia l mapping was performed using form-fitting electrodes containing 160 p oints. A computerized mapping system, capable of simultaneously record ing 256 channels of data, was used to analyze data and to display pote ntial distribution maps sequentially at 1-millisecond intervals as a c olor movie. A total of eight morphologies of sustained VT were mapped. The mean VT cycle length was 340 +/- 40 milliseconds (range, 274 to 3 94 milliseconds). In 3 patients with ischemic heart disease, four VT m orphologies originated from the subendocardium. All were successfully ablated with cryoablation alone or in conjunction with aneurysmectomy and endocardial resection. A fourth patient with VT secondary to cardi omyopathy had multiple morphologies and received an implantable cardio verter defibrillator. Potential distribution maps correlated well with the concomitant activation time maps. Thus, potential distribution ma pping provides a rapid and accurate means of identifying the site of o rigin of VT facilitating intraoperative mapping in patients undergoing surgical ablation.