Abstract
Nine out of 285 (3%) pediatric patients (pts) were found to have pacing-induced infra-His conduction block (B). In 2 pts it occurred following a preceding long cycle as well as a peceding short-to-long sequence cycle length (CL) change. In one of them the infra-his B initiated a short sequence of 2:1 infra-His B. In 5 pts it occurred with an abrupt shortening of the coupling H-H (in one pt it simulated type II 2nd-degree AV B). In 2 pts the pacing-induced infra-His B simulated type II 2nd-degree AV block but the initiating events were not recorded. Rapid atrial pacing-induced infra-His B in children is a rare phenomenon. In many cases it is associated with pacing-induced infra-His conduction delay. The occurrence of either is determined by: (1) a preceding long cycle as well as a preceding short-to-long sequence CL change that can lengthen the refractoriness of the His-Purkinje system (HPS), (2) an abrupt shortening of the coupling H-H interval that exceeds the refractory period of the HPS, (3) a first impulse that results in an infra-His B initiating a series of 2:1 infra-His B due to a self-perpetuation sequence of events, (4) a 1st impulse that results in infra-His conduction delay initiating a series of 1:1 infra-His delay due to repetitive retrograde concealed conduction.
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Young, ML., Gelband, H., Castellanos, A. et al. 160 RAPID ATRIAL PACING-INDUCED INFRA-HIS CONDDCTION BLOCK. Pediatr Res 19, 137 (1985). https://doi.org/10.1203/00006450-198504000-00190
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DOI: https://doi.org/10.1203/00006450-198504000-00190