Echo phase analysis for noninvasive localization of accessory pathways: an adjunct to endocardial mapping in the Wolff-Parkinson-White syndrome

In patients with the pre-excitation syndrome undergoing catheter- or surgical ablation, accurate localization of accessory pathways is critical. In pre-excitation the ventricular activation sequence is altered resulting in focal areas with pre-systolic contraction. This report delineates the application of Fourier phase analysis to echocardiographic cine loops to objectively identify these focal areas and thus to localize accessory pathways. Echocardiographic phase images were prospectively obtained in 17 patients with the WPW-syndrome during normal sinus rhythm and maximal pre-excitation induced by right atrial pacing. A group of 11 normal subjects served as controls. The accuracy of phase imaging, of routine 12-lead electrocardiograms and of visual inspection of cine loop images was determined using electrophysiologic endocardial mapping as reference method.