Reentrant tachycardia: participation of the distal A-V conduction system.

Paroxysmal supraventricular tachycardia (SVT) is commonly produced by two mechanisms: atrial reentry via an A-V nodal pathway or a rapid firing ectopic focus. Studies in the experimental animal and in human beings with sustained SVT have sbown that the site for reentry appears to be the upper A-V junction. This report documents an unusual site d reentry in a patient with recurrent SVT. Progressive intraventricular conduction delay with prolongation of the H-V interval resulted in initial conduction delay and then sustained reentry. This strongly suggests that, in man, the distal A-V conducting system may participate in a reentry circuit producing and perpetuating SVT.