CARDIAC DEPOLARIZATION AND REPOLARIZATION IN WOLFF-PARKINSON-WHITE SYNDROME

Delta wave and QRS complex polarities have been extensively studied in preexcitation syndromes. However, only limited data exist about ventr icular depolarization and repolarization in the setting of maximal pre excitation in relation to the site of insertion of the accessory pathw ay. Therefore this study was designed to systematically analyze cardia c depolarization and repolarization in patients with maximal preexcita tion. We analyzed the polarity of the QRS complex and T wave on the fr ontal plane on the conventional 12-lead electrocardiogram in 118 patie nts with maximal preexcitation. Fast atrial pacing was used to provoke maximal ventricular preexcitation. The 32 patients with a left latera l accessory pathway showed right-axis deviation of the QRS complex (11 0 +/- 20 degrees) with a left-axis deviation of the T-wave axis (-40 /- 25 degrees). The 54 patients with a posteroseptal accessory pathway had a left axis of the QRS complex (-50 +/- 20 degrees) with a right- axis deviation of the T-wave axis (95 +/- 15 degrees). The 11 patients with a right lateral accessory pathway had a left axis of the QRS com plex (-40 +/- 20 degrees) and a right axis of the T wave (110 +/- 10 d egrees). In 7 patients with a left anterolateral accessory pathway and 14 patients with a right anteroseptal accessory pathway, the axis of the QRS complex was 50 +/- 25 degrees and 45 +/- 20 degrees, respectiv ely. T-wave polarity, however, showed two distinct patterns with a ver tically directed T-wave axis (60 +/- 25) in left anterolateral pathway s and a T-wave axis directed in the upper right quadrant (-145 +/- 20) in right anteroseptal pathways. In conclusion, electrocardiographic a nalysis of ventricular depolarization and repolarization in Wolff-Park inson-White syndrome revealed characteristic polarities for the QRS co mplex and T wave depending on accessory pathway localization. These da ta are helpful in noninvasively localizing the site of insertion of th e accessory pathway.