Right ventricular apical activation time in children. Reference standards for clinical use.

To differentiate proximal from peripheral right bundle-branch block, several investigators have used the right ventricular apical (RVA) activation time, but there is a lack of reference standards for infants and other children. Using intracardiac electrography, His bundle and RVA electrograms were recorded in 123 children before surgery for various types of congenital cardiac malformations. None had evidence of conduction defects on their surface ECG. The average RVA activation time was 15 +/- 7 msec (+/- SD) linearly increasing with age from infancy to adolescence. The values found in this large population may be useful as reference standards for right bundle-branch conduction times in other infants and children.