RÉSUMÉ
To localize bypass pathways, left and right ventricular regions were analyzed at rest by phase image analysis in 6 patients with Wolff-Parkinoson-White syndrome and 5 patients with concealed bypass pathway. These were compared with image findings in 12 normal subjects. In normal subjects, the earliest emptying occured in ventricular septal, apical and left basal segments. Mean difference between the earlist left and right ventricular phase angle was 2.3+/-5.6degrees in patients with normal conduction, -14.0+/-15.1degrees in patients with left bypass pathways, 15.0+/-0degrees in patients with right bypass pathways and -6.6+/-12.3degrees in patients with concealed bypass pathways. In patients with bypass pathways, there was complete agreement between phase and electrophysiologic maps, but incomplete agreement(4 of 6) between surface ECGs and electrophysiologic map in a patient with left posterior and left bypass pathways. The phase image represents a new, noninvasive method of evaluating ventricular pre-excitation. The method may provide useful information complementary to that of electrocardiographic and electriphysiologic analysis.