Patterns of atrioventricular conduction in children.

In this study, intracardiac electrograms were performed in 20 children--ranging in age from eight months to 18 years and without evidence of conduction disturbances on the scalar electrocardiogram--to determine the normal conduction patterns, response to atrial pacing, and values of refractory periods. Atrial pacing--18 cases--induced a prolongation al AH on increasing heart rates in all; 11 developed Wenckebach block proximal to the bundle of His at the mean pacing rate of 224 per minute +/- 45 (1 S.D.). Refractory periods were shorter than in adults. Study of the pattern of A-V conduction revealed three types of response: (1) the atrium was the limiting structure in 11 cases; (2) the delay occurred in the A-V node only in four cases; and (3) the delay occurred both in the A-V node and His-Purkinje system. This response was observed in one case only.