THE USE OF BODY-SURFACE POTENTIAL MAP FOR IDENTIFYING SITES OF ACCESSORY PATHWAY IN PATIENTS WITH WOLFF-PARKINSON-WHITE-SYNDROME

The body surface potential map (BSPM) may reflect regional myocardial electrical activity. This technique can thus provide information regar ding the excitation of ventricles. This study is an attempt to evaluat e the usefulness of BSPM in determining the sites of the atrioventricu lar (AV) accessory pathway (AP) in patients with Wolff-Parkinson-White (W-P-W) syndrome. The BSPMs were obtained from 40 consecutive patient s with W-P-W syndrome in a fasting state, using the heart potential ma p system designed by Toyama et al. Unipolar electrocardiograms were re corded simultaneously from 87 lead points on the chest surface, includ ing 59 lead points on the anterior chest and 28 on the back. Wilson's central terminal was used as a voltage reference and BSPMs in an isopo tential distribution pattern were made every millisecond throughout ve ntricular activation from these unipolar ECGs with the use of a microc omputer system. All patients underwent an electrophysiologic study (EP S) at cardiac catheterization. We analyzed the potential distribution during ventricular depolarization and compared the results between EPS and BSPM findings. The following results were obtained: (1) seven typ es of BSPM pattern were identified in accordance with the sites of the AV AP confirmed by EPS; (2) the location of the potential minimum of ventricular depolarization and the direction of the excitation wavefro nt during early ventricular depolarization, the reversal pattern of ve ntricular potential distribution, the epicardial right ventricular bre akthrough and the dynamic change of ventricular potential distribution were useful for the detection of the ventricular pre-excitation site; (3) epicardial right ventricular breakthrough occurred in nearly all patients with left ventricular free wall accessory AV connections; (4) the abnormal early reversal pattern of ventricular potential distribu tion did not occur in patients with left ventricular AV connections bu t did appear in most patients with right ventricular free wall AV conn ections. Accordingly, BSPM is a reliable noninvasive procedure to dete rmine the ventricular pre-excitation sites of patients with W-P-W synd rome.