Wolff-Parkinson-White syndrome: T wave abnormalities during normal pathway conduction.

Forty-five patients with Wolff-Parkinson-White syndrome (WPW) were reviewed. The preexcitation using Boineau's classification was: right anterior (six patients), left lateral (nine patients), right posterior (15 patients) and left posterior (15 patients). Normal pathway conduction was observed to occur either spontaneously or after administration of ajmaline, procainamide, or by eye-ball pressure. Disappearance of preexcitation was associated with T wave abnormalities in 39 patients (86.6%). The orientation of the T spatial vector (SAT), after suppression of the WPW aspect, varied according to the site of ventricular preexcitation. In eight patients with left lateral ventricular preexcitation (LLVP), the frontal T wave axis was between +70 degrees and +120 degrees (mean +92 degrees) and the horizontal T wave axis was located in the left anterior quadrant. In the five patients with right anterior ventricular preexcitation (RAVP), the frontal axis was between + 40 degrees and - 10 degrees (mean + 26 degrees) and the horizontal axis was in the left posterior quadrant. The 26 cases with right posterior ventricular preexcitation (RPVP) and left posterior ventricular preexcitation (LPVP) had a frontal axis between - 10 degrees and - 70 degrees (mean -39 degrees) and the horizontal T wave axis in the left anterior quadrant. This study suggests that the T wave anomalies observed after suppression of the WPW aspect are in direct relation to the localization of the preexcitation according to Boineau's classification. The analogy between the abnormalities of the T wave and those which are observed after right ventricular pacing (VP) or after disappearance of left bundle branch block (LBBB) is discussed.