[A clinical study of induction rate of atrioventricular reciprocating tachycardia in WPW syndrome].

The differences in induction rate of atrioventricular reciprocating tachycardia (AVRT) were analyzed in 76 consecutive patients of WPW syndrome with tachycardia attack, confirmed by either ECG or history, and who underwent electrophysiological study. AVRT was induced by programed electrical stimulation in 72% of patients with manifest WPW syndrome, in 77% of patients with intermittent WPW syndrome, and in 96% of patients with concealed WPW syndrome, respectively. There was a significant difference in induction rate between manifest WPW syndrome and concealed WPW syndrome (p less than 0.05). Induction rate of AVRT in patients with accessory pathway (AP) located in the ventricular septum was significantly lower (50%) than in patients with AP located in the left ventricle (88%) and in the right ventricle (72%) (p less than 0.05). Ventricular atrial conduction was found in only 56% of patients with AP located in the ventricular septum, while it was found in 94% of patients with AP located in the left ventricle, and in 100% of patients with AP located in the right ventricle (p less than 0.05). There were no significant differences in antegrade effective refractory periods of atrioventricular node and AP between patients with and without inducible AVRT. There was also no significant difference in the retrograde effective refractory periods of AP between patients with or without inducible AVRT. We concluded that the induction rate of AVRT would be affected by the location of AP and the mode of delta wave appearance in the surface electrocardiogram.