Developmental aspects of atrioventricular node reentry tachycardia.

Atrioventricular node reentry tachycardia is an incompletely understood substrate for supraventricular tachycardia. Although there is agreement that the mechanism involves functionally separate fast and slow AV node pathways, which are somewhat anatomically discrete, the anatomical basis for the reentrant circuit is not well defined. Furthermore, the nature of the long fast pathway effective refractory period is not known but most likely involves electrotonic interactions between fast and slow AV nodal pathways. The proposition that the mechanism is related to features of cell coupling has been studied in a finite element computer model. Because the calculations rely on assumptions about nodal size and space constants, clinical studies in smaller and younger patients are naturally of interest.