Ventriculo-atrial conduction in patients with normal and impaired atrio-ventricular conduction.

Ventriculo-atrial (VA) conduction was studied in 133 patients with various kinds of arrhythmias using intracardiac electrograms and programmed stimulation. One-to-one VA conduction was observed during RV pacing at the rate just above the sinus rate in 6 of 31 patients (19.4%) with advanced AV block, in 7 of 26 patients (26.9%) with impaired AV nodal conduction, in 25 of 71 patients (35.2%) with normal AV nodal conduction and 3 of 5 patients (60%) with enhanced AV nodal conduction. However, the differences between these groups were not significant. There was no significant difference in either the AH block rate during RA pacing or the antegrade functional refractory period (FRP) of the AV node in patients with or without VA conduction, and the VA block rate during RV pacing was not significantly correlated with the AH block rate or the FRP of the AV node. VA conduction time (S-HRA) also showed no significant differences between these groups. The mean VA conduction time during RV pacing at rates of 60 to 80 bpm was 208 +/- 87 msec, ranging from 100 to 395 msec. In conclusion, AV conduction disturbances may influence VA conduction, but VA conduction cannot be predicted from antegrade conductivity.