Heterodromia in accessory A-V connections.

In 15 patients with WPW-syndrome the atrio-ventricular and ventriculoatrial conduction was studied by recording of intracardiac potentials during atrial and ventricular pacing. Typical differences in the patterns of normal and accessory A-V conduction identified accessory V-A conduction in 13 patients. According to the evaluation of accessory A-V and V-A conductivity by high rate pacing the patients studied can be divided into three groups: Group I (5 pat): equally good accessory A-V and V-A conductivity. Group II (5 pat): good accessory A-V and impaired accessory V-A conductivity. Group III (5 pat): impaired accessory A-V and good V-A conductivity. In group I the course of investigation was repeated after the application of Ajmaline. The distinct heterodromia in group II and III and the different behaviour of the accessory A-V and V-A conduction after Ajmaline can be explained by the in vitro experiments of Fuente (3). According to our results and to the finding that an excellent accessory V-A conduction is a presupposition for the initiation of supraventricular re-entry tachycardia, it seems mandatory to analyze accessory A-V and V-A conduction properties as well.