BODY-SURFACE ISOPOTENTIAL MAPPING OF THE ENTIRE QRST COMPLEX IN THE WOLFF-PARKINSON-WHITE SYNDROME - CORRELATION WITH THE LOCATION OF THE ACCESSORY PATHWAY

Body surface potential maps were recorded during sinus rhythm and during atrial pacing at the time of electrophysiologic studies in 42 patients with Wolff-Parkinson-White syndrome. The locations of the accessory pathways were determined by epicardial mapping during surgery in 34 patients and by multicatheter endocavitary electrophysiologic studies in eight additional patients. During delta wave inscription, the shape and extension of areas of the negative and positive potentials on the thorax correlated better with the preexcitation site (69% of patients) than with the localization of the minimum potential alone (45.2% of patients). Typical potential distributions were present from the beginning of the delta wave and remained stationary during the first half of the QRS complex. During marked preexcitation, the superposition of atrial activity on the delta wave produced a mixed pattern in the earliest maps. However, these alterations of early delta thoracic potential distribution did not persist longer than 30 msec. The spread of the negative potentials during the last half of the QRS complex also characterized each localization: right-sided preexcitation reproduced the depolarization sequence of left bundle branch block, left-sided preexcitation reproduced that of right bundle branch block, and posterior pathways resembled left anterior fascicular block. Anterior left ventricular and more anterior left lateral ventricular preexcitations mimicked a right bundle branch block-left posterior fascicular block pattern. There was good correlation between the body surface potential map obtained during the ST segment and the site of the right-sided preexcitation. However, in left-sided preexcitations, ST patterns concordant with delta wave patterns were found less frequently than in right-sided preexcitations. With multiple pathways there was a lack of agreement between the body surface potential maps obtained during the delta wave and those obtained during the second half of the QRS complex. In conclusion, analysis of body surface potential maps obtained during the entire QRST sequence can furnish additional clues that may be useful in predicting the location of the accessory pathways and the presence of multiple pathways.