Electrophysiological significance of rapid atrial pacing as a test of atrioventricular conduction.

Although rapid atrial pacing is frequently used as a test of atrioventricular conduction, no studies have compared this method with other conduction parameters. The purpose of this study was to compare the results of rapid atrial pacing with refractory period measurements utilizing the extrastimulus technique. Determination of the refractory periods of the atrium, A-V node, and His-Purkinje system were accomplished in 41 patients undergoing diagnostic cardiac catheterization, and the results compared with rapid atrial pacing to the point at which A-V Wenckebach occurred (WP). The results showed significant correlation (P less than 0.01) between the WP and functional refractory period (FRP) of the A-V node (r=0.89, FRP=865-2.6 WP), and significant correlation between the WP and the effective refractory period (ERP) of the total A-V conducting system(r=0.81, ERP=729-2.6 WP). The relationship between WP and the refractory periods also allowed prediction of the occurrence of physiological His-Purkinje block during introduction of premature atrial contractions and the site of the effective refractory period of the total A-V conducting system. This study establishes a close relationship between these methods and confirms the usefulness of rapid atrial pacing as a reliable test of A-V conduction in man.