The role of an accessory atrioventricular pathway in reciprocal tachycardia. Observations in patients with and without the Wolff-Parkinson-White syndrome.

To study the pathway of tachycardia in patients with the Wolff-Parkinson-White (WPW) syndrome and reciprocal tachycardias, results from intracavitary recordings and atrial and ventricular stimulation were reviewed in 71 patients with the WPW syndrome and 54 patients without pre-excitation. In all patients a reproducible tachycardia could be initated and terminated by appropriately timed electrical stimuli. The following findings were accepted as suggesting the participation of an accessory pathway in the tachycardia circuit: 1) no increase in ventriculo-atrial conduction (V-A C) time following ventricular stimuli given with increasing prematurity; 2) activation of right or left atrium (depending upon the location of the atrial end of the accessory pathway) prior to activation of atrium in the His bundle lead; 3) slowing of tachycardia following bundle branch block to the ventricle in which the accessory pathway inserts; 4) V-A C time of early stimuli on the ventricle during the tachycardia equal to or les...