A His bundle electrocardiographic analysis of cardiac conduction in the pediatric and adolescent patient.

Bipolar electrode catheter recordings of His bundle electrograms with three simultaneously recorded surface electrocardiographic leads were obtained from 30 pediatric and adolescent patients (aged 3 to 18 years). In 14 patients, cardiac murmurs were proved to be innocent by cardiac catheterization. The control conduction intervals were compared to those of 13 patients with congenital heart disease, and three with acquired heart disease (myocardiopathy, rheumatic valvular disease, and Friedreich's ataxia). P-R, intra-atrial (P-A), A-V nodal (A-H), and intraventricular (H-V) conduction intervals were measured to the nearest 5 msec. Conduction delays were analyzed in each of the three components of the P-R interval. These delays occurred both in single components of the system as well as in combined conduction delays and were not always demonstrable by surface electrocardiograms. The Wenckebach phenomenon induced by atrial pacing was localized to the A-V node as well as the His-Purkinje system. This technique of intracardiac electrogram recordings is safe, does not significantly prolong cardiac atheterization time, and often yields unique and useful data concerning A-V conduction.